System Management Commands

This chapter describes the commands used to manage the router system and its performance on the network. In general, system or network management falls into the following categories. The commands that perform the tasks in these management categories are described in this chapter unless specified otherwise.

• Configuration Management

The configuration of network devices determines the behavior of the network. To manage device configurations, you need to list and compare configuration files on running devices, store configuration files on network servers for shared access, and perform software installations and upgrades. (Configuration management commands required to perform these tasks are described in the chapter entitled "System Image, Microcode Image, and Configuration File Load Commands.")

Other configuration management tasks include naming the router, setting router time services, configuring for synchronous logging of unsolicited messages and debug output, configuring a router for weighted fair queueing, and configuring SNMP support. Configuration management commands required to perform these tasks are described this chapter.

• Security Management

To manage security on the network, you need to restrict access to the system. You can do so on several different levels:

• Assign and encrypt passwords to restrict access to terminal lines, login connections, or privileged EXEC mode.

• Establish one of three versions of Terminal Access Controller Access Control System (TACACS) protection for network servers that have shared access: TACACS, extended TACACS, or TACACS+, which is coupled with the Authentication, Authorization, and Accounting (AAA) model.

• Restrict login connections to specific users with a username authentication system.

• Control access on serial interfaces with Challenge Handshake Authentication Protocol (CHAP) and Password Authentication Protocol (PAP).

• Create access lists to filter traffic to and from specific destinations. Subsequent chapters that describe the routing protocols in detail define access lists. This section provides general guidelines for creating access lists.

• Create security labels for Internet Protocol (IP) datagrams using the Internet Protocol Security Option (IPSO), as described in the chapter entitled "IP Commands."

• Enable accounting for Internet Protocol (IP) access list violations and display the accounting data. For information on the IP accounting access-violations feature and commands, see the "Configuring IP" chapter of the Router Products Configuration Guide and the "IP Commands" chapter later in this publication.

Security management commands required to perform these tasks are described this chapter.

• Fault Management

To manage network faults, you need to discover, isolate, and fix the problems. You can discover problems with the system's monitoring commands, isolate problems with the system's test commands, and resolve problems with other commands, including debug.

This chapter describes general fault management commands. For detailed troubleshooting procedures and a variety of scenarios, see the Troubleshooting Internetworking Systems guide. For complete details on all debug commands, see the Debug Command Reference publication.

• System Performance Management

To manage system performance, you need to monitor and determine response time, error rates, and availability. Once these factors are determined, you can perform load-balancing and modify system parameters to enhance performance. For example, priority queuing allows you to prioritize traffic order. You can configure fast and autonomous switching to improve network throughput, as described in the "Configuring Interfaces" chapter of the Router Products Configuration Guide.

See the Internetwork Design Guide for additional information.

• Accounting Management

Accounting management allows you to track both individual and group usage of network resources. You can then reallocate resources as needed. For example, you can change the system timers and configure TCP keepalives. See also the IP accounting feature in the "Configuring IP" chapter of the Router Products Configuration Guide. Additionally, the AAA/TACACS+ aaa accounting command allows you to set start-stop accounting for any or all of the listed functions for this command.

For system management configuration tasks and examples, refer to the chapter entitled "Managing the System" in the Router Products Configuration Guide.

aaa accounting

To enable AAA accounting of requested services for billing or security purposes when using TACACS+, use the aaa accounting global configuration command. Use the no form of this command to disable accounting.

Syntax Description

Default

AAA accounting is not enabled.

Command Mode

Global configuration

Usage Guideline

The aaa accounting command allows you to set start-stop accounting for any or all of the functions listed in "Syntax Description." For minimal accounting control, issue the stop-only keyword, which sends a stop record accounting notice at the end of the requested user process. For additional accounting control, you can issue the start-stop command, where TACACS+ sends a start accounting notice at the beginning of the requested process and a stop accounting notice at the end of the process. You can further control access and accounting by issuing the wait-start command, which ensures that the start notice is received by the TACACS+ server before granting the user's process request. Accounting is done only to the TACACS+ server.

Examples

In the following example, accounting is set for outbound Telnet and rlogin, and both a start and stop accounting notice is sent to the TACACS+ server:

aaa accounting connection start-stop tacacs+

In the following example, accounting is set for privilege level 15 commands, with a wait-start restriction:

aaa accounting command 15 wait-start tacacs+

Related Commands

aaa authorization
aaa new-model

aaa authentication arap

To enable an AAA authentication method for AppleTalk Remote Access (ARA) users using TACACS+, use the aaa authentication arap global configuration command. Use the no form of this command to disable this authentication.

Syntax Description

Default

If the default list is not set, only the local user database is checked. This version has the same effect as the following command:

aaa authentication arap default local

Command Mode

Global configuration

Usage Guideline

The list names and default that you set with the aaa authentication arap command are used with the arap authentication command. These lists can contain up to four authentication methods that are used when a user tries to log in with ARA.

Create a list by entering the aaa authentication arap list-name method command, where list-name is any character string used to name this list, such as MIS-access. The method argument identifies the list of methods the authentication algorithm tries in the given sequence. You can enter up to four methods, which are described in Table 5-1.

To create a default list that is used if no list is specified in the arap authentication command, use the default keyword followed by the methods you wish to be used in default situations.

The additional methods of authentication are used only if the previous method returns an error, not if it fails.

Use the show running-config command to view lists of authentication methods.

Examples

The following example creates a list called MIS-access, which first tries TACACS+ authentication and then none:

aaa authentication arap MIS-access tacacs+ none

The following example creates the same list, but sets it as the default list that is used for all ARA protocol authentications if no other list is specified:

aaa authentication arap default tacacs+ none

Related Commands

aaa authentication local-override
aaa new-model
arap authentication

aaa authentication enable default

To enable AAA authentication to determine if a user can access the privileged command level with TACACS+, use the aaa authentication enable default global configuration command. Use the no form of this command to disable this authorization method.

Syntax Description

Default

If the default list is not set, only the enable password is checked. This version has the same effect as the following command:

aaa authentication enable default enable

On the console, the enable password is used if it exists. If no password is set, the process will succeed anyway.

Command Mode

Global configuration

Usage Guideline

Use the aaa authentication enable default command to create a series of authentication methods that are used to determine if a user can access the privileged command level. You can specify up to four authentication methods. Method keywords are described in Table 5-2. The additional methods of authentication are used only if the previous method returns an error, not if it fails. To specify that the authentication should succeed even if all methods return an error, specify none as the final method in the command line.

If a default authentication routine is not set for a function, the default is none and no authentication is performed. Use the show running-config command to view currently configured lists of authentication methods.

Example

The following example creates an authentication list that first tries to contact a TACACS+ server. If no server can be found, then AAA tries to use the enable password. If this attempt also returns an error (because no enable password is configured on the server), the user is allowed access with no authentication.

aaa authentication enable default tacacs+ enable none

Related Commands

aaa authentication local-override
aaa authorization
aaa new-model
enable password

aaa authentication local-override

To have the router check the local user database for authentication before attempting another form of authentication, use the aaa authentication local-override global configuration command. Use the no form of this command to disable the override.

Syntax Description

This command has no arguments or keywords.

Default

Override is disabled.

Command Mode

Global configuration

Usage Guideline

This command is useful when you want to configure an override to the normal authentication process for certain personnel such as system administrators.

When this override is set, the user is always prompted for the username. The system then checks to see if the entered username corresponds to a local account. If the username does not correspond to one in the local database, login proceeds with the methods configured with other aaa commands (such as aaa authentication login). Note when using this command that Username: is fixed as the first prompt.

Example

The following example enables AAA authentication override:

aaa authentication local-override

Related Commands

aaa authentication arap
aaa authentication enable default
aaa authentication login
aaa authentication ppp
aaa new-model

aaa authentication login

To set AAA authentication at login when using TACACS+, use the aaa authentication login global configuration command. Use the no form of this command to disable AAA authentication.

Syntax Description

Default

If the default list is not set, only the local user database is checked. This version has the same effect as the following command:

aaa authentication login default local

Command Mode

Global configuration

Usage Guideline

The default and optional list names that you create with the aaa authentication login command are used with the login authentication command.

Create a list by entering the aaa authentication list-name method command, where list-name is any character string used to name this list, such as MIS-access. The method argument identifies the list of methods the authentication algorithm tries, in the given sequence. Method keywords are described in Table 5-3.

To create a default list that is used if no list is assigned to a line with the login authentication command, use the default argument followed by the methods you want in default situations.

The additional methods of authentication are used only if the previous method returns an error, not if it fails. To ensure that the authentication will succeed even if all methods return an error, specify none as the final method in the command line.

If authentication is not specifically set for a line, the default is to deny access--no authentication is performed. Use the show running-config command to view currently configured lists of authentication methods.

Examples

The following example creates an AAA authentication list called MIS-access. This authentication first tries to contact a TACACS+ server. If no server is found, TACACS+ returns an error and AAA tries to use the enable password. If this attempt also returns an error (because no enable password is configured on the server), the user is allowed access with no authentication.

aaa authentication login MIS-access tacacs+ enable none

The following example creates the same list, but sets it as the default list that is used for all login authentications if no other list is specified:

aaa authentication login default tacacs+ enable none

Related Commands

aaa authentication local-override
aaa new-model
login authentication

aaa authentication ppp

To specify one or more AAA authentication methods for use on serial interfaces running Point-to-Point (PPP) when using TACACS+, use the aaa authentication ppp global configuration command. Use the no form of this command to disable authentication.

Syntax Description

Default

If the default list is not set, only the local user database is checked. This version has the same effect as the following command:

aaa authentication ppp default local

Command Mode

Global configuration

Usage Guideline

The lists that you create with the aaa authentication ppp command are used with the ppp authentication command. These lists contain up to four authentication methods that are used when a user tries to log in to the serial interface.

Create a list by entering the aaa authentication ppp list-name method command, where list-name is any character string used to name this list, such as MIS-access. The method argument identifies the list of methods the authentication algorithm tries in the given sequence. You can enter up to four methods. Method keywords are described in Table 5-4.

The additional methods of authentication are only used if the previous method returns an error, not if it fails. Specify none as the final method in the command line to have authentication succeed even if all methods return an error.

If authentication is not specifically set for a function, the default is none and no authentication is performed. Use the show running-config command to view lists of authentication methods.

Example

The following example creates an AAA authentication list called MIS-access for serial lines that use PPP. This authentication first tries to contact a TACACS+ server. If this action returns an error, the user is allowed access with no authentication.

aaa authentication MIS-access ppp tacacs+ none

Related Commands

aaa authentication local-override
aaa new-model
ppp authentication

aaa authorization

To set parameters that restrict a user's network access based on TACACS+ authorization, use the aaa authorization global configuration command. To disable authorization for a function, use the no form of this command.

Syntax Description

Default

Authorization is disabled for all actions (equivalent to the keyword none).

Command Mode

Global configuration

Usage Guideline

Use the aaa authorization command to create a list of one and up to four authorization methods that can be used when a user accesses the specified function.

The additional methods of authorization are only used if the previous method returns an error, not if it fails. Specify none as the final method in the command line to have authorization succeed even if all methods return an error.

If authorization is not specifically set for a function, the default is none and no authorization is performed.

The authorization command causes a request packet containing a series of attribute value pairs to be sent to the TACACS daemon as part of the authorization process. The daemon can:

• accept the request as is

• make changes to the request

• refuse the request, and hence, refuse authorization

Table 5-6 describes attribute value pairs associated with the aaa authorization command. Registered users can find more information about TACACS+ and attribute pairs on Cisco Information Online.

Examples

The following example specifies that TACACS+-style of authorization is used for all network-related requests. If this authorization method returns an error (if the TACACS+ server cannot be contacted), no authorization is performed and the request is successful.

aaa authorization network tacacs+ none

The following example specifies that TACACS+-style of authorization is run for level 15 commands. If this authorization method returns an error (if the TACACS+ server cannot be contacted), no authorization is performed and the request succeeds.

aaa authorization command 15 tacacs+ none

Related Commands

aaa accounting
aaa new-model

aaa new-model

To enable the AAA access control model that includes TACACS+, issue the aaa new-model global configuration command. Use the no form of this command to disable this functionality.

Syntax Description

This command has no arguments or keywords.

Default

AAA/TACACS+ is not enabled.

Command Mode

Global configuration

Usage Guideline

This command enables the AAA access control system and TACACS+. If you initialize this functionality and later decide to use TACACS or extended TACACS, issue the no version of this command and then enable the version of TACACS you want to use.

Example

The following example initializes AAA and TACACS+:

aaa new-model

Related Commands

aaa accounting
aaa authentication arap
aaa authentication enable default
aaa authentication local-override
aaa authentication login
aaa authentication ppp
aaa authorization

alias

To create a command alias, use the alias global configuration command. Use the no alias command to delete all aliases in a command mode or to delete a specific alias, and to revert to the original command syntax.

Syntax Description

Defaults

Default aliases are in EXEC mode as follows:

Command Mode

Global configuration

Usage Guidelines

You can use simple words or abbreviations as aliases. The aliases in the Default section are predefined. They can be turned off using the no alias command.

Table 5-7 shows the acceptable options for the mode argument in the alias global configuration command.

Router#lo?
*lo=logout  lock  login  logout 

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#alias exec device-mail telnet device.cisco.com 25
Router(config)# end
Router# device-mail?
*device-mail="telnet device.cisco.com 25" 

Router(config)#alias exec td trace device
Router(config)#^Z
Router#t?
*td="trace device"  telnet  terminal  test  tn3270
trace               

Router# t?
telnet  terminal  test  tn3270  trace

Router(config)# alias exec td telnet device
Router(config)# ^Z
Router#td ?
      /debug     Enable telnet debugging mode
      /line      Enable telnet line mode
      ...
      whois      Whois port
      <cr>
Router# telnet device

bones# t
% Ambiguous command:  "t"

Example

In the following example, the alias fixmyrt is created for the EXEC-mode command clear ip route 198.92.116.16.

alias exec fixmyrt clear ip route 198.92.116.16

Related Command

show aliases

arap authentication

To enable TACACS+ authentication for ARA on a line, use the arap authentication line configuration command. Use the no form of the command to disable authentication for an ARA line.

Caution If you use a list-name value that was not configured with the aaa authentication arap command, ARA protocol will be disabled on this line.

Syntax Description

Default

ARA protocol authentication uses the default set with aaa authentication arap command. If no default has been set, the local user database is checked.

Command Mode

Line configuration

Usage Guideline

This command is a per-line command that specifies the name of a list of AAA authentication methods to try at login. If no list is specified, the default list is used (whether or not it is specified in the command line). You create defaults and lists with the aaa authentication arap command. Entering the no version of arap authentication has the same effect as entering the command with the default argument.

Before issuing this command, create a list of authentication processes by using the aaa authentication arap global configuration command.

Example

The following example specifies that the TACACS+ authentication list called MIS-access is used on ARA line 7:

line 7
arap authentication MIS-access

Related Command

aaa authentication arap

buffers

Use the buffers global configuration command to make adjustments to initial buffer pool settings and to the limits at which temporary buffers are created and destroyed. Use the no form of this command to return the buffers to their default size.

Syntax Description

Default

The default number of buffers in a pool is determined by the hardware configuration and can be displayed with the EXEC show buffers command.

Command Mode

Global configuration

Usage Guidelines

Normally you need not adjust these parameters; do so only after consulting with technical support personnel. Improper settings can adversely impact system performance.

You cannot configure FDDI buffers.

Examples of Public Buffer Pool Tuning

In the following example, the system will try to keep at least 50 small buffers free:

buffers small min-free 50

In the following example, the permanent buffer pool allocation for big buffers is increased to 200:

buffers big permanent 200

Example of Interface Buffer Pool Tuning

A general guideline is to display buffers with the show buffers command, observe which buffer pool is depleted, and increase that one.

In the following example, the permanent Ethernet 0 interface buffer pool on a Cisco 4000 is increased to 96 because the Ethernet 0 buffer pool is depleted:

buffers ethernet 0 permanent 96

Related Commands

buffers huge size
show buffers

buffers huge size

Use the buffers huge size global configuration command to dynamically resize all huge buffers to the value you specify. Use the no form of this command to restore the default buffer values.

Syntax Description

Default

18024 bytes

Command Mode

Global configuration

Usage Guidelines

Use only after consulting with technical support personnel. The buffer size cannot be lowered below the default.

Example

In the following example, the system will resize huge buffers to 20000 bytes:

buffers huge size 20000

Related Commands

buffers
show buffers

calendar set

To set the system calendar for a Cisco 7000 system or a Cisco 4500 system, use the calendar set EXEC command.

Syntax Description

Command Mode

EXEC

Usage Guidelines

Once you set the Cisco 7000 calendar or the Cisco 4500 calendar, the system clock will be automatically set when the system is restarted or when the clock read-calendar EXEC command is issued. The calendar maintains its accuracy, even after a power failure or system reboot has occurred. The time specified in this command is relative to the configured time zone.

Example

In the following example, the system calendar is manually set to 1:32 p.m. on July 23, 1993:

calendar set 13:32:00 23 July 1993

Related Commands

clock read-calendar
clock set
clock summer-time
clock timezone
clock update-calendar

cdp enable

To enable Cisco Discovery Protocol (CDP) on an interface, use the cdp enable interface configuration command. Use the no form of this command to disable CDP on an interface.

Syntax Description

This command has no arguments or keywords.

Default

Enabled at the global level and on all supported interfaces.

Command Mode

Interface configuration

Usage Guidelines

CDP is enabled by default at the global level and on each interface in order to send or receive CDP information.

Example

In the following example, CDP is enabled on Ethernet interface 0:

interface ethernet 0
cdp enable

Related Command

cdp run

cdp holdtime

To specify the amount of time the receiving device should hold a CDP packet from your router before discarding it, use the cdp holdtime global configuration command. Use the no form of this command to revert to the default setting.

Syntax Description

Default

180 seconds

Command Mode

Global configuration

Usage Guidelines

CDP packets are sent with time-to-live, or hold time, that is nonzero after an interface is enabled and a hold time of 0 immediately before an interface is idled down.

The CDP hold time must be set to a higher number of seconds than the time between CDP transmissions, which is set using the cdp timer command.

Example

In the following example, the CDP packets being sent from your device should be held by the receiving device for 60 seconds before being discarded. You might want to set the hold time lower than the default setting of 180 seconds if information about your device changes often and you want the receiving devices to purge this information more quickly.

cdp holdtime 60

Related Commands

cdp timer
show cdp

cdp run

To enable CDP on your router, use the cdp run global configuration command. Use the no form of this command to disable CDP.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Global configuration

Usage Guidelines

CDP is enabled on your router by default, which means the Cisco IOS software will receive CDP information. CDP also is enabled on supported interfaces by default. To disable CDP on an interface, use the cdp enable interface configuration command.

Example

In the following example, CDP is disabled for the router:

no cdp run

Related Command

cdp enable

cdp timer

To specify how often your router will send CDP updates, use the cdp timer global configuration command. Use the no form of this command to revert to the default setting.

Syntax Description

Default

60 seconds

Command Mode

Global configuration

Usage Guidelines

The trade-off with sending more frequent transmissions is providing up-to-date information versus using bandwidth more often.

Example

In the following example, CDP updates will be sent from your router every 80 seconds, less frequently than the default setting of 60 seconds. You might want to make this change if you are concerned about preserving bandwidth.

cdp timer 80

Related Commands

cdp holdtime
show cdp

clear cdp counters

To reset CDP traffic counters to zero (0) on your router, use the clear cdp counters privileged EXEC command.

Syntax Description

This command has no arguments or keywords.

Command Mode

Privileged EXEC

Example

In the following example, the CDP counters have been cleared. The show cdp traffic output shows that all of the traffic counters have been reset to zero (0).

Router# clear cdp counters
Router# show cdp traffic

CDP counters:
        Packets output: 0, Input: 0
        Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
        No memory: 0, Invalid packet: 0, Fragmented: 0

Related Commands

clear cdp table
show cdp traffic

clear cdp table

To clear the table that contains CDP information about neighbors, use the clear cdp table privileged EXEC command.

Syntax Description

This command has no arguments or keywords.

Command Mode

Privileged EXEC

Example

In the following example, the CDP table is cleared. The output of the show cdp neighbors command shows that all information has been deleted from the table.

Router# clear cdp table 

CDP-AD: Deleted table entry for neon.cisco.com, interface Ethernet0
CDP-AD: Deleted table entry for neon.cisco.com, interface Serial0
Router# show cdp neighbors


Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP
 
Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID

Related Commands

clear cdp counters
show cdp neighbors

clock calendar-valid

To configure the Cisco 7000 series or the Cisco 4500 as a time source for a network based on its calendar, use the clock calendar-valid global configuration command. Use the no form of this command to set the router so that the calendar is not an authoritative time source.

Syntax Description

This command has no arguments or keywords.

Default

Neither the Cisco 7000 nor the Cisco 4500 are not configured as a time source.

Command Mode

Global configuration

Usage Guidelines

Use this command if no outside time source is available.

Example

In the following example, the Cisco 7000 is configured as the time source for a network based on its calendar:

clock calendar-valid

Related Commands

A dagger (⁺) indicates that the command is documented in another chapter.

ntp master
vines time use-system ⁺

clock read-calendar

To manually read the calendar into either the Cisco 7000 or the Cisco 4500 system clock, use the clock read-calendar EXEC command.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

When either the Cisco 7000 series or the Cisco 4500 calendar is rebooted, the calendar is automatically read into the system clock. However, you may use this command to manually read the calendar setting into the system clock. This command is useful if the calendar set command has been used to change the setting of the calendar.

Example

In the following example, the system clock is configured to set its date and time by the calendar setting:

clock read-calendar

Related Commands

calendar set
clock set
clock update-calendar
ntp update-calendar

clock set

To manually set the system clock, use the clock set EXEC command.

Syntax Description

Command Mode

EXEC

Usage Guidelines

Generally, if the system is synchronized by a valid outside timing mechanism, such as an NTP or VINES clock source, or if you have a Cisco 7000 with calendar capability, you do not need to set the system clock. Use this command if no other time sources are available. The time specified in this command is relative to the configured time zone.

Example

In the following example, the system clock is manually set to 1:32 p.m. on July 23, 1993:

clock set 13:32:00 23 July 1993

Related Commands

calendar set
clock read-calendar
clock summer-time
clock timezone

clock summer-time

To configure the system to automatically switch to summer time (daylight savings time), use one of the formats of the clock summer-time configuration command. Use the no form of this command to configure the router not to automatically switch to summer time.

Syntax Description

Default

Summer time is disabled. If clock summer-time zone recurring is specified without parameters, the summer time rules default to United States rules. Default of offset is 60.

Command Mode

Global configuration

Usage Guidelines

Use this command if you want to automatically switch to summer time (for display purposes only). Use the recurring form of the command if the local summer time rules are of this form. Use the date form to specify a start and end date for summer time if you cannot use the first form.

In both forms of the command, the first part of the command specifies when summer time begins, and the second part specifies when it ends. All times are relative to the local time zone. The start time is relative to standard time. The end time is relative to summer time. If the starting month is after the ending month, the system assumes that you are in the Southern Hemisphere.

Examples

In the following example, summer time starts on the first Sunday in April at 02:00 and ends on the last Sunday in October at 02:00:

clock summer-time PDT recurring 1 Sunday April 2:00 last Sunday October 2:00

If you live in a place where summer time does not follow the pattern in the first example, you could set it to start on October 12, 1993 at 02:00, and end on April 28, 1994 at 02:00, with the following example:

clock summer-time date 12 October 1993 2:00 28 April 1994 2:00

Related Commands

calendar set
clock timezone

clock timezone

To set the time zone for display purposes, use the clock timezone global configuration command. To set the time to Coordinated Universal Time (UTC), use the no form of this command.

Syntax Description

Default

UTC

Command Mode

Global configuration

Usage Guidelines

The system internally keeps time in UTC, so this command is used only for display purposes and when the time is manually set.

Example

In the following example, the timezone is set to Pacific Standard Time and is offset 8 hours behind UTC:

clock timezone PST -8

Related Commands

calendar set
clock set
clock summer-time
show clock

clock update-calendar

To set the Cisco 7000 or Cisco 4500 calendar from the system clock, use the clock update-calendar EXEC command.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

If the system clock and calendar are not synchronized, and the system clock is more accurate, use this command to update the Cisco 7000 series or Cisco 4500 calendar to the correct date and time.

Example

In the following example, the current time is copied from the system clock to the Cisco 7000 calendar:

clock update-calendar

Related Commands

clock read-calendar
ntp update-calendar

custom-queue-list

To assign a custom queue list to an interface, use the custom-queue-list interface configuration command. To remove a specific list or all list assignments, use the no form of the command.

Syntax Description

Default

No custom queue list is assigned.

Command Mode

Interface configuration

Usage Guidelines

Only one queue list can be assigned per interface. Use this command in place of the priority-list command (not in addition to it). Custom queuing allows a fairness not provided with priority queuing. With custom queuing, you can control the interfaces' available bandwidth when it is unable to accommodate the aggregate traffic enqueued. Associated with each output queue is a configurable byte count, which specifies how many bytes of data should be delivered from the current queue by the system before the system moves on to the next queue. When a particular queue is being processed, packets are sent until the number of bytes sent exceeds the queue byte count or until the queue is empty.

Use the show queuing custom and show interface commands to display the current status of the custom output queues.

Example

In the following example, custom queue list number 3 is assigned to serial interface 0:

interface serial 0
custom-queue-list 3

Related Commands

queue-list default
queue-list interface
queue-list protocol
queue-list queue byte-count
queue-list queue limit

downward-compatible-config

To have the router try to generate a configuration that is compatible with an earlier Cisco IOS release, use the downward-compatible-config global configuration command. To remove this feature, use the no form of this command.

Syntax Description

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

In Cisco IOS Release 10.3, the IP access list formats changed. Use this command to regenerate a configuration in the format prior to Release 10.3 if you are going to downgrade from a Release 10.3 or later to an earlier release. The earliest release this command accepts is 10.2.

When this command is configured, the router attempts to generate a configuration that is compatible with the specified version. Currently, this command affects only IP access lists.

Under some circumstances, the software might not be able to generate a fully backward-compatible configuration. In such a case, the software issues a warning message any time it writes a configuration that is not downward compatible.

Example

In the following example, the router will attempt to generate a configuration file compatible with Cisco IOS Release 10.2:

downward-compatible-config 10.2

Related Commands

A dagger (⁺) indicates that the command is documented in another chapter.

access-list (extended)⁺
access-list (standard)⁺

enable

To log onto the router at a specified level, use the enable EXEC command.

Syntax Description

Default

Level 15

Command Mode

EXEC

Usage Guidelines

The enable command is a privilege level 0 command. If you configure AAA authorization for a privilege level greater than 0, the enable command will not be included in the command set for the privilege level.

Example

In the following example, the user is logging on to privilege level 5 on the router:

enable 5

Related Commands

A dagger (⁺) indicates that the command is documented in another chapter.

privilege level
disable ⁺

enable last-resort

To specify what happens if the TACACS and extended TACACS servers used by the enable command do not respond, use the enable last-resort global configuration command. The no form of this command restores the default.

Syntax Description

Default

Default action is to fail.

Command Mode

Global configuration

Usage Guideline

The secondary authentication is used only if the first attempt fails. The secondary authentication does not occur if the first authentication is only unsuccessful.

Example

In the following example, if the TACACS servers do not respond to the enable command, the user can enable by entering the privileged level password:

enable last-resort password

Related Command

A dagger (⁺) indicates that the command is documented in another chapter.

enable ⁺

enable password

To configure the enable password for a given level, use the enable password global configuration command. Use the no form of this command to remove the enable password for a given level.

Syntax Description

Default

No password is defined.

Command Mode

Global configuration

Usage Guidelines

Use this command with the level option to define a privilege level. Once the level and the password are specified, give the password to the users you want to have access at this level. Use the privilege level (global) configuration command to specify the commands that are accessible at the specified level.

You will not ordinarily enter an encryption type. Typically, you will only enter encryption type if you cut and paste a password that has already encrypted by the system back into this command.

Enable or disable password encryption with the service password-encryption command. If you enter a value for the encryption-type argument, but have not enabled encryption, the encryption type will be treated as part of the password.

An enable password can contain from 1 to 80 uppercase and lowercase alphanumeric characters, except that the first character cannot be a number. Some spaces are valid password characters; for example, "two words" is valid. Leading spaces are ignored, but trailing spaces are recognized. For example, " woolly" is interpreted as "woolly" (without the space ). On the other hand, "woolly " is interpreted as "woolly " (with the space). To create an enable password containing a question mark (?), precede the question mark with keystrokes Ctrl-V. For example, to create the password "abc?123", you enter the letters abc followed by Ctrl-V followed by ? followed by the numbers 123. When the system prompts you to enter the enable password, you do not need to precede the question mark with the Ctrl-V. For example, you can simply enter abc?123 at the password prompt.

Example

In the following example, the password pswd2 is enabled for privilege level 2:

enable password level 2 pswd2

Related Commands

A dagger (⁺) indicates that the command is documented in another chapter.

disable ⁺
enable ⁺
privilege level (global)
service password-encryption
show privilege

enable secret

To specify an additional layer of security over the enable password command, use the enable secret command. Use the no form of the command to turn off the enable secret function.

Syntax Description

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

The enable secret command is used in conjunction with the enable password command to provide an additional layer of security over the enable password. This process provides better security in two ways: first by enforcing the use of an additional password; second, by storing this second password using a non-reversible cryptographic function. This encryption method is especially useful in environments where the password crosses a network or is stored on a TFTP server.

If you use the same password for enable password and enable secret, you will receive an error message warning you that this practice is not recommended. The system will prompt you again for a password. You can reenter the password you use for enable password, and the system will accept it the second time. But if you do, you undermine the additional security that the enable secret command provides.

Examples

The following example specifies an enable secret password of gobbledegook:

enable secret gobbledegook

After specifying an enable secret password, users must enter this password to gain access. Any passwords set through enable password will no longer work.

Password: gobbledegook

Related Command

enable
enable password

enable use-tacacs

To enable use of the TACACS to determine whether a user can access the privileged command level, use the enable use-tacacs global configuration command. Use the no form of this command to disable TACACS verification.

Caution If you use the enable use-tacacs command, you must also use the tacacs-server authenticate enable command, or else you will be locked out of the router.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

When you add this command to the configuration file, the EXEC enable command prompts for a new username and password pair. This pair is then passed to the TACACS server for authentication. If you are using extended TACACS, it also will pass any existing UNIX user identification code to the server.

Example

The following example sets TACACS verification on the privileged EXEC-level login sequence:

enable use-tacacs
tacacs-server authenticate enable

Related Command

tacacs-server authenticate enable

fair-queue

To enable weighted fair queueing for an interface and to set the congestion threshold after which messages for high-bandwidth conversations are dropped, use the fair-queue interface configuration command. To disable weighted fair queueing for an interface, use the no form of this command.

Syntax Description

Default

Fair queueing is enabled by default for physical interfaces whose bandwidth is less than or equal to 2.048 megabits per second (Mbps) and that do not use Link Access Procedure, Balanced (LAPB), X.25, PPP, or Synchronous Data Link Control (SDLC) encapsulations. (Fair queuing is not an option for these protocols.) However, if custom queueing or priority queueing is enabled for a qualifying link, it overrides fair queueing, effectively disabling it. Additionally, fair queuing is automatically disabled if you enable autonomous or SSE switching.

Fair queueing is disabled automatically on interfaces configured with the ppp multlilink command. If the no ppp multilink command is configured, you must enable fair queuing manually on the interface.

The congestive-discard threshold is 64 messages.

Command Mode

Interface configuration

Usage Guidelines

When enabled for an interface, weighted fair queueing provides traffic priority management that automatically sorts among individual traffic streams without requiring that you first define access lists. Enabling weighted fair queueing requires use of this command only.

Weighted fair queuing can manage duplex data streams, such as those between pairs of applications, and simplex data streams such as voice or video. From the perspective of weighted fair queueing, there are two categories of sessions: high-bandwidth sessions and low-bandwidth sessions. Low-bandwidth traffic has effective priority over high-bandwidth traffic, and high-bandwidth traffic shares the transmission service proportionally according to assigned weights.

When weighted fair queuing is enabled for an interface, new messages for high-bandwidth traffic streams are discarded after the configured or default congestive-messages threshold has been met. However, low-bandwidth conversations, which include control-message conversations, continue to enqueue data. As a result, the fair queue may occasionally contain more messages than its configured threshold number specifies.

Weighted fair queuing uses a traffic data stream discrimination registry service to determine which traffic stream a message belongs to. For each forwarding protocol, Table 5-8 shows the attributes of a message that are used to classify traffic into data streams.

It is important to note that IP precedence, congestion in Frame Relay switching, and discard eligibility flags affect the weights used for queuing.

IP precedence, which is set by the host, is a number in the range of 0 to 7. Data streams of precedence number are weighted so that they are given an effective bit rate of number+1 times as fast as a data stream of precedence 0, which is normal.

In Frame Relay switching, message flags for congestion (FECN and BECN) and discard eligible (DE) message flags cause the algorithm to select weights that effectively impose reduced queue priority, providing the application with "slow down" feedback and sorting traffic, giving the best service to applications within their Committed Information Rate.

Fair queueing is supported for all LAN and line (WAN) protocols except those that use LAPB, which are listed in "Default." Because tunnels are software interfaces that are themselves routed over physical interfaces, fair queueing is not supported for tunnels. If fair queueing is configured for an interface, the default of no fair-queue is applied for these links and tunnels on the interface and appears in the configuration script for them.

Example

The following example enables use of weighted fair queuing on Serial 0, with a congestive discard threshold of 300. This means that messages will be discarded from the queuing system only when 300 or more messages have been queued and the message is in a data stream that has more than one message in the queue. The transmit queue limit is set to 1, based on the 384-kilobit (kb) line set by the bandwidth command:

interface serial 0
bandwidth 384
fair-queue 300

hostname

To specify or modify the host name for the network server, use the hostname global configuration command. The host name is used in prompts and default configuration filenames. The setup command facility also prompts for a host name at startup.

Syntax Description

Default

The factory-assigned default host name is router.

Command Mode

Global configuration

Usage Guidelines

The order of display at startup is banner message-of-the-day (MOTD), then login and password prompts, then EXEC banner.

Do not expect case to be preserved. Upper- and lowercase characters look the same to many internet software applications (often under the assumption that the application is doing you a favor). It may seem appropriate to capitalize a name the same way you might do in English, but conventions dictate that computer names appear all lowercase. For more information, refer to RFC 1178, Choosing a Name for Your Computer.

The name must also follow the rules for ARPANET host names. They must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphens. Names must be 63 characters or fewer. For more information, refer to RFC 1035, Domain Names--Implementation and Specification.

Example

The following example changes the host name to sandbox:

hostname sandbox

ip bootp server

To access the BOOTP service available from hosts on the network, use the ip bootp server global configuration command. Use the no form of the command to disable these services.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Global configuration

Usage Guidelines

By default, the BOOTP server is enabled.

When you disable the BOOTP server, access to the BOOTP ports cause the Cisco IOS software to send an "ICMP port unreachable" message to the sender and discard the original incoming packet.

Example

The following example disables the BOOTP service on the router:

no ip bootp server

load-interval

To change the length of time for which data is used to compute load statistics, use the load-interval interface configuration command. Use the no form of this command to revert to the default setting.

Syntax Description

Default

300 seconds (or 5 minutes)

Command Mode

Interface configuration

Usage Guidelines

If you want load computations to be more reactive to short bursts of traffic, rather than averaged over five-minute periods, you can shorten the length of time over which load averages are computed.

If the load interval is set to thirty seconds, new data is used for load calculations over a thirty-second period. This data is used to compute load statistics, including input rate in bits and packets per second, output rate in bits and packets per second, load, and reliability.

Load data is gathered every five seconds on the router. This data is used for a weighted average calculation in which more-recent load data has more weight in the computation than older load data. If the load interval is set to thirty seconds, the average is computed for the last thirty seconds of load data.

The load-interval command allows you to change the default interval of five minutes to a shorter or longer period of time. If you change it to a shorter period of time, the input and output statistics that are displayed when you use the show interface command will be more current, and based on more instantaneous data, rather than reflecting a more average load over a longer period of time.

This command is often used for dial backup purposes, to increase or decrease the likelihood of a backup interface being implemented, but it can be used on any interface.

Example

In the following example, the default five-minute average is set it to a thirty-second average. A burst in traffic that would not trigger a dial backup for an interface configured with the default five-minute interval might trigger a dial backup for this interface that is set for a shorter, thirty-second interval.

interface serial 0
load-interval 30

Related Command

A dagger (⁺) indicates that the command is documented in another chapter.

show interfaces ⁺

logging

To log messages to a syslog server host, use the logging global configuration command. The no form of this command deletes the syslog server with the specified address from the list of syslogs.

Syntax Description

Default

No messages are logged to a syslog server host.

Command Mode

Global configuration

Usage Guidelines

This command identifies a syslog server host to receive logging messages. By issuing this command more than once, you build a list of syslog servers that receive logging messages.

Example

The following example logs messages to a host named johnson:

logging johnson

Related Commands

logging trap
service timestamps

logging buffered

To log messages to an internal buffer, use the logging buffered global configuration command. The no form of this command cancels the use of the buffer and writes messages to the console terminal, which is the default.

Syntax Description

Default

The router displays all messages to the console terminal.

Command Mode

Global configuration

Usage Guidelines

This command copies logging messages to an internal buffer instead of writing them to the console terminal. The buffer is circular in nature, so newer messages overwrite older messages after the buffer is filled.

To display the messages that are logged in the buffer, use the EXEC command show logging. The first message displayed is the oldest message in the buffer.

Do not make the buffer size too large because the router could run out of memory for other tasks. You can use the show memory EXEC command to view the free processor memory on the router; however, this is the maximum available and should not be approached.

Example

The following example illustrates how to enable logging to an internal buffer:

logging buffered

logging console

To limit messages logged to the console based on severity, use the logging console global configuration command. The no form of this command disables logging to the console terminal.

Syntax Description

Default

debugging

Command Mode

Global configuration

Usage Guidelines

Specifying a level causes messages at that level and numerically lower levels to be displayed at the console terminal.

The EXEC command show logging displays the addresses and levels associated with the current logging setup, as well as any other logging statistics.

The effect of the log keyword with the IP access list (extended) command depends on the setting of the logging console command. The log keyword takes effect only if the logging console level is set to 6 or 7. If you change the default to a level lower than 6 and specify the log keyword with the IP access list (extended) command, no information is logged or displayed.

Example

The following example changes the level of messages displayed to the console terminal to alerts, which means alerts and emergencies are displayed:

logging console alerts

Related Commands
A dagger (⁺) indicates that the command is documented in another chapter.

logging facility
access-list (extended)⁺

logging facility

To configure the syslog facility in which error messages are sent, use the logging facility global configuration command. To revert to the default of local7, use the no form of this command.

Syntax Description

Default

local7

Command Mode

Global configuration

Usage Guidelines

Table 5-10 describes the acceptable options for the facility-type keyword.

Example

The following example configures the syslog facility to kernel:

logging facility kern

Related Command

logging console

logging monitor

To limit messages logged to the terminal lines (monitors) based on severity, use the logging monitor global configuration command. This command limits the logging messages displayed on terminal lines other than the console line to messages with a level at or above level. The no form of this command disables logging to terminal lines other than the console line.

Syntax Description

Default

debugging

Command Mode

Global configuration

Usage Guidelines

Specifying a level causes messages at that level and numerically lower levels to be displayed to the monitor.

Example

The following example specifies that only messages of the levels errors, critical, alerts, and emergencies be displayed on terminals:

logging monitor errors

Related Command

A double dagger (⁺⁺) indicates that the command is documented in the Cisco Access Connection Guide.

terminal monitor ⁺⁺

logging on

To control logging of error messages, use the logging on global configuration command. This command enables or disables message logging to all destinations except the console terminal. The no form of this command enables logging to the console terminal only.

Syntax Description

This command has no arguments or keywords.

Default

The router logs messages to the console terminal.

Command Mode

Global configuration

Example

The following example shows how to direct error messages to the console terminal only:

no logging on

logging synchronous

Syntax Description

Defaults

This feature is turned off by default.

If you do not specify a severity level, the default value of 2 is assumed.

If you do not specify the maximum number of buffers to be queued, the default value of 20 is assumed.

Command Mode

Line configuration

Usage Guidelines

When synchronous logging of unsolicited messages and debug output is turned on, unsolicited router output is displayed on the console or printed after solicited router output is displayed or printed. Unsolicited messages and debug output is displayed on the console after the prompt for user input is returned. This is to keep unsolicited messages and debug output from being interspersed with solicited router output and prompts. After the unsolicited messages are displayed, the console displays the user prompt again.

When specifying a severity level number, consider that for the logging system, low numbers indicate greater severity and high numbers indicate lesser severity.

When a terminal line's message-queue limit is reached, new messages are dropped from the line, although these messages might be displayed on other lines. If messages are dropped, the notice "%SYS-3-MSGLOST number-of-messages due to overflow" follows any messages that are displayed. This notice is displayed only on the terminal that lost the messages. It is not sent to any other lines, any logging servers, or the logging buffer.

Caution By configuring abnormally large message-queue limits and setting the terminal to "terminal monitor" on a terminal that is accessible to intruders, you expose yourself to "denial of service" attacks. An intruder could carry out the attack by putting the terminal in synchronous output mode, making a Telnet connection to a remote host, and leaving the connection idle. This could cause large numbers of messages to be generated and queued, and these messages would consume all available RAM. Although unlikely to occur, you should guard against this type of attack through proper configuration.

Example

The following example identifies line 4 and enables synchronous logging for line 4 with a severity level of 6. Then the example identifies another line, line 2, and enables synchronous logging for line 2 with a severity level of 7 and specifies a maximum number of buffers to be 70000:

line 4
logging synchronous level 6
line 2
logging synchronous level 7 limit 70000

Related Command

A dagger (⁺) indicates that the command is documented in another chapter.

line⁺

logging trap

To limit messages logged to the syslog servers based on severity, use the logging trap global configuration command. The command limits the logging of error messages sent to syslog servers to only those messages at the specified level. The no form of this command disables logging to syslog servers.

Syntax Description

Default

informational

Command Mode

Global configuration

Usage Guidelines

The EXEC command show logging displays the addresses and levels associated with the current logging setup. The command output also includes ancillary statistics.

Table 5-9 lists the syslog definitions that correspond to the debugging message levels. Additionally, there are four categories of messages generated by the software, as follows:

• Error messages about software or hardware malfunctions at the LOG_ERR level.

• Output for the debug commands at the LOG_WARNING level.

• Interface up/down transitions and system restarts at the LOG_NOTICE level.

• Reload requests and low process stacks are at the LOG_INFO level.

Use the logging and logging trap commands to send messages to a UNIX syslog server.

Example

The following example logs messages to a host named johnson:

logging johnson
logging trap notifications

Related Command

logging

login authentication

To enable TACACS+ authentication for logins, use the login authentication line configuration command. Use the no form of this command to return to the default.

Caution If you use a list-name value that was not configured with the aaa authentication login command, you will disable login on this line.

Syntax Description

Default

Uses the default set with aaa authentication login.

Command Mode

Line configuration

Usage Guideline

This command is a per-line command used with AAA that specifies the name of a list of TACACS+ authentication methods to try at login. If no list is specified, the default list is used (whether or not it is specified in the command line). You create defaults and lists with the aaa authentication login command. Entering the no version of login authentication has the same effect as entering the command with the default argument.

Before issuing this command, create a list of authentication processes by using the global configuration aaa authentication login command.

Examples

The following example specifies that the default AAA authentication is to be used on line 4:

line 4
login authentication default

The following example specifies that the AAA authentication list called MIS-access is to be used on line 7:

line 7
login authentication MIS-access

Related Command

aaa authentication login

ntp access-group

To control access to the system's Network Time Protocol (NTP) services, use the ntp access-group global configuration command. To remove access control to the system's NTP services, use the no form of this command.

Syntax Description

Default

No access control (full access granted to all systems)

Command Mode

Global configuration

Usage Guidelines

The access group options are scanned in the following order from least restrictive to most restrictive:

1. peer
   
   
2. serve
   
   
3. serve-only
   
   
4. query-only
   

Access is granted for the first match that is found. If no access groups are specified, all access is granted to all sources. If any access groups are specified, only the specified access is granted. This facility provides minimal security for the time services of the system. However, it can be circumvented by a determined programmer. If tighter security is desired, use the NTP authentication facility.

Example

In the following example, the system is configured to allow itself to be synchronized by a peer from access list 99. However, the system restricts access to allow only time requests from access list 42.

ntp access-group peer 99
ntp access-group serve-only 42

Related Command

A dagger (⁺) indicates that the command is documented in another chapter.

access-list ⁺

ntp authenticate

To enable Network Time Protocol (NTP) authentication, use the ntp authenticate global configuration command. Use the no form of this command to disable the feature.

Syntax Description

This command has no keywords or arguments.

Default

No authentication

Command Mode

Global configuration

Usage Guidelines

Use this command if you want authentication. If this command is specified, the system will not synchronize to a system unless it carries one of the authentication keys specified in the ntp trusted-key command.

Example

The following example enables NTP authentication:

ntp authenticate

Related Commands

ntp authentication-key
ntp trusted-key

ntp authentication-key

To define an authentication key for Network Time Protocol (NTP), use the ntp authentication-key global configuration command. Use the no form of this command to remove the authentication key for NTP.

Syntax Description

Default

No authentication key is defined for NTP.

Command Mode

Global configuration

Usage Guidelines

Use this command to define authentication keys for use with other NTP commands in order to provide a higher degree of security.

Example

The following example sets authentication key 10 to aNiceKey:

ntp authentication-key 10 md5 aNiceKey

Related Commands

ntp authenticate
ntp peer
ntp server
ntp trusted-key

ntp broadcast

To specify that a specific interface should send Network Time Protocol (NTP) broadcast packets, use the ntp broadcast interface configuration command. Use the no form of this command to disable this capability.

Syntax Description

Default

Disabled

Command Mode

Interface configuration

Example

In the following example, Ethernet interface 0 is configured to send NTP version 2 packets:

interface ethernet 0
ntp broadcast version 2

Related Commands

ntp broadcast client
ntp broadcastdelay

ntp broadcast client

To allow the system to receive NTP broadcast packets on an interface, use the ntp broadcast client command. Use the no form of this command to disable this capability.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

Use this command to allow the system to listen to broadcast packets on an interface-by-interface basis.

Example

In the following example, the router synchronizes to NTP packets broadcasted on Ethernet
interface 1:

interface ethernet 1
ntp broadcast client

Related Commands

ntp broadcast
ntp broadcastdelay

ntp broadcastdelay

To set the estimated round-trip delay between the router and a Network Time Protocol (NTP) broadcast server, use the ntp broadcastdelay global configuration command. Use the no form of this command to revert to the default value.

Syntax Description

Default

3000 microseconds

Command Mode

Global configuration

Usage Guidelines

Use this command when the router is configured as a broadcast client and the round-trip delay on the network is other than 3000 microseconds.

Example

In the following example, the estimated round-trip delay between the router and the broadcast client is set to 5000 microseconds:

ntp broadcastdelay 5000

Related Commands

ntp broadcast
ntp broadcast client

ntp clock-period

Caution Do not enter this command; it is documented for informational purposes only. The system automatically generates this command as Network Time Protocol (NTP) determines the clock error and compensates.

As NTP compensates for the error in the system clock, it keeps track of the correction factor for this error. The system automatically saves this value into the system configuration using the ntp clock-period global configuration command. The system uses the no form of this command to revert to the default.

Syntax Description

Default

17179869 (4 milliseconds)

Command Mode

Global configuration

Usage Guidelines

If a copy running-config startup-config command is entered to save the configuration to NVRAM, this command will automatically be added to the configuration. It is a good idea to perform this task after NTP has been running for a week or so; this will help NTP synchronize more quickly if the system is restarted.

ntp disable

To prevent an interface from receiving Network Time Protocol (NTP) packets, use the ntp disable interface configuration command. To enable receipt of NTP packets on an interface, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Interface configuration

Usage Guidelines

This command provides a simple method of access control.

Example

In the following example, Ethernet interface 0 is prevented from receiving NTP packets:

interface ethernet 0
ntp disable

ntp master

To configure the router as a Network Time Protocol (NTP) master clock to which peers synchronize themselves when an external NTP source is not available, use the ntp master global configuration command. To disable the master clock function, use the no form of this command.

Caution Use this command with extreme caution. It is very easy to override valid time sources using this command, especially if a low stratum number is configured. Configuring multiple machines in the same network with the ntp master command can cause instability in timekeeping if the machines do not agree on the time.

Syntax Description

Default

By default, the master clock function is disabled. When enabled, the default stratum is 8.

Command Mode

Global configuration

Usage Guidelines

Since our implementation of NTP does not support directly attached radio or atomic clocks, the router is normally synchronized, directly or indirectly, to an external system that has such a clock. In a network without Internet connectivity, such a time source may not be available. The ntp master command is used in such cases.

If the system has ntp master configured, and it cannot reach any clock with a lower stratum number, the system will claim to be synchronized at the configured stratum number, and other systems will be willing to synchronize to it via NTP.

Example

In the following example, the router is configured as an NTP master clock to which peers may synchronize:

ntp master 10

Related Command

clock calendar-valid

ntp peer

To configure the router's system clock to synchronize a peer or to be synchronized by a peer, use the
ntp peer global configuration command. To disable this capability, use the no form of this command.

Syntax Description

Default

No peers are configured by default. If a peer is configured, the default NTP version number is 3, no authentication key is used, and the source IP address is taken from the outgoing interface.

Command Mode

Global configuration

Usage Guidelines

Use this command if you want to allow this machine to synchronize with the peer, or vice versa. Using the prefer keyword will reduce switching back and forth between peers.

If you are using the default version of 3 and NTP synchronization does not occur, try using NTP version number 2. Many NTP servers on the Internet run version 2.

Example

In the following example, the router is configured to allow its system clock to be synchronized with the clock of the peer (or vice versa) at IP address 131.108.22.33 using NTP version 2. The source IP address will be the address of Ethernet 0.

ntp peer 131.108.22.33 version 2 source ethernet 0

Related Commands

ntp authentication-key
ntp server
ntp source

ntp server

To allow the router's system clock to be synchronized by a time server, use the ntp server global configuration command. To disable this capability, use the no form of this command.

Syntax Description

Default

No peers are configured by default. If a peer is configured, the default NTP version number is 3, no authentication key is used, and the source IP address is taken from the outgoing interface.

Command Mode

Global configuration

Usage Guidelines

Use this command if you want to allow this machine to synchronize with the specified server. The server will not synchronize to this machine.

Using the prefer keyword will reduce switching back and forth between servers.

If you are using the default version of 3 and NTP synchronization does not occur, try using NTP version number 2. Many NTP servers on the Internet run version 2.

Example

In the following example, the router is configured to allow its system clock to be synchronized with the clock of the peer at IP address 128.108.22.44 using NTP version 2:

ntp server 128.108.22.44 version 2

Related Commands

ntp authentication-key
ntp peer
ntp source

ntp source

To use a particular source address in Network Time Protocol (NTP) packets, use the ntp source global configuration command. Use the no form of this command to remove the specified source address.

Syntax Description

Default

Source address is determined by the outgoing interface.

Command Mode

Global configuration

Usage Guidelines

Use this command when you want to use a particular source IP address for all NTP packets. The address is taken from the named interface. This command is useful if the address on an interface cannot be used as the destination for reply packets. If the source keyword is present on an ntp server or ntp peer command, that value overrides the global value.

Example

In the following example, the router is configured to use the IP address of Ethernet 0 as the source address of all outgoing NTP packets:

ntp source ethernet 0

Related Commands

ntp peer
ntp server

ntp trusted-key

If you want to authenticate the identity of a system to which Network Time Protocol (NTP) will synchronize, use the ntp trusted-key global configuration command. Use the no form of this command to disable authentication of the identity of the system.

Syntax Description

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

If authentication is enabled, use this command to define one or more key numbers (corresponding to the keys defined with thentp authentication-key command) that a peer NTP system must provide in its NTP packets, in order for this system to synchronize to it. This provides protection against accidentally synchronizing the system to a system that is not trusted, since the other system must know the correct authentication key.

Example

In the following example, the system is configured to synchronize only to systems providing authentication key 42 in its NTP packets:

ntp authenticate
ntp authentication-key 42 md5 aNiceKey
ntp trusted-key 42

Related Commands

ntp authenticate
ntp authentication-key

ntp update-calendar

To periodically update the Cisco 7000 calendar from Network Time Protocol (NTP), use the ntp update-calendar global configuration command. Use the no form of this command to disable this feature.

Syntax Description

This command has no arguments or keywords.

Default

The Cisco 7000 calendar is not updated.

Command Mode

Global configuration

Usage Guidelines

If a Cisco 7000 is synchronized to an outside time source via NTP, it is a good idea to periodically update the calendar with the time learned from NTP. Otherwise, the calendar will tend to gradually lose or gain time. The calendar will be updated only if NTP has synchronized to an authoritative time server.

Example

In the following example, the system is configured to periodically update the calendar from the system clock:

ntp update-calendar

Related Commands

clock read-calendar
clock update-calendar

ping (privileged)

Use the ping (packet internet groper) privileged EXEC command to diagnose basic network connectivity on Apollo, AppleTalk, Connectionless Network Service (CLNS), DECnet, IP, Novell IPX, VINES, or XNS networks.

Syntax Description

Command Mode

Privileged EXEC

Usage Guidelines

The ping program sends an echo request packet to an address, then awaits a reply. Ping output can help you evaluate path-to-host reliability, delays over the path, and whether the host can be reached or is functioning.

To abnormally terminate a ping session, type the escape sequence--by default, Ctrl-^ X. You type the default by simultaneously pressing and releasing the Ctrl, Shift, and 6 keys, and then pressing the X key.

Table 5-11 describes the test characters that the ping facility sends.

Example

After you enter the ping command in privileged mode, the system prompts for one of the following keywords: appletalk, clns, ip, novell, apollo, vines, decnet, or xns. The default protocol is IP.

If you enter a host name or address on the same line as the ping command, the default action is taken as appropriate for the protocol type of that name or address.

While the precise dialog varies somewhat from protocol to protocol, all are similar to the ping session using default values shown in the following display.

Router# ping
Protocol [ip]:
Target IP address: 192.31.7.27
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.31.7.27, timeout is 2 seconds:
!!!!!
Success rate is 100 percent, round-trip min/avg/max = 1/2/4 ms

Table 5-12 describes the default ping fields shown in the display.

Related Command

ping (user)

ping (user)

Use the ping (packet internet groper) user EXEC command to diagnose basic network connectivity on AppleTalk, CLNS, IP, Novell, Apollo, VINES, DECnet, or XNS networks.

Syntax Description

Command Mode

EXEC

Usage Guidelines

The user-level ping feature provides a basic ping facility for users who do not have system privileges. This feature allows the router to perform the simple default ping functionality for a number of protocols. Only the nonverbose form of the ping command is supported for user-level pings.

If the system cannot map an address for a host name, it will return an "%Unrecognized host or address" error message.

To abnormally terminate a ping session, type the escape sequence--by default, Ctrl-^ X. You type the default by simultaneously pressing and releasing the Ctrl, Shift, and 6 keys and then pressing the X key.

Table 5-13 describes the test characters that the ping facility sends.

Example

The following display shows sample ping output when you ping the IP host named donald:

Router> ping donald
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.31.7.27, timeout is 2 seconds:
!!!!!
Success rate is 100 percent, round-trip min/avg/max = 1/3/4 ms

Related Command

ping (privileged)

ppp authentication

To enable Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) and to enable an AAA authentication method on an interface, use the ppp authentication interface configuration command. Use the no form of this command to disable this authentication.

Caution If you use a list-name value that was not configured with the aaa authentication ppp command, you will disable PPP on this interface.

Syntax Description

Default

PPP authentication is not enabled.

Command Mode

Interface configuration

Usage Guidelines

Once you have enabled CHAP or PAP, the local router requires a password from remote devices. If the remote device does not support CHAP or PAP, no traffic is passed to that device.

If you are using autoselect on a TTY line, you will probably want to use the ppp authentication command to turn on PPP authentication for the corresponding interface.

If you specify the if-needed option, PPP authentication is not required when the user has already provided authentication. This option is useful if you are using the autoselect command, but it cannot be used with AAA/TACACS+.

The list-name argument can be used only when AAA/TACACS+ is initialized and cannot be used with the if-needed argument.

Example

The following example enables CHAP on asynchronous interface 4, and uses the authentication list MIS-access:

interface async 4
encapsulation ppp
ppp authentication chap MIS-access

Related Commands

A dagger (⁺) indicates that the command is documented in another chapter.

aaa authentication ppp
aaa new-model
autoselect ⁺
encapsulation ppp
ppp use-tacacs
username

ppp use-tacacs

To enable TACACS for PPP authentication, use the ppp use-tacacs interface configuration command. Use the no form of the command to disable TACACS for PPP authentication.

Syntax Description

Default

TACACS is not used for PPP authentication.

Command Mode

Interface configuration

Usage Guidelines

This is a per-interface command. Use this command only when you have set up an extended TACACS server. This command requires the new extended TACACS server.

When CHAP authentication is being used, the ppp use-tacacs command with the single-line option specifies that if a username and password are specified in the username, separated by an asterisk (*), then a standard tacacs login query is performed using that username and password. If the username does not contain an asterisk, then normal CHAP authentication is performed using TACACS.

This feature is useful when integrating TACACS with other authentication systems that require a clear-text version of the user's password. Such systems include one-time password systems, token card systems, kerberos, and others.

Caution Normal CHAP authentications prevent the clear-text password from being transmitted over the link. When you use the single-line option, passwords will cross the link in the clear.

If the username and password are contained in the CHAP password, then the CHAP secret is not used by the Cisco system. Because most PPP clients will require that a secret be specified, you can use any arbitrary string; the Cisco system will ignore it.

Examples

In the following example, asynchronous serial interface 1 is configured to use TACACS for CHAP authentication.

interface async 1
ppp authentication chap
ppp use-tacacs

In the following example, asynchronous serial interface 1 is configured to use TACACS for PAP authentication.

interface async 1
ppp authentication pap
ppp use-tacacs

Related Commands

A dagger (⁺) indicates that the command is documented in another chapter.

ppp authentication⁺
ppp authentication⁺
tacacs-server extended
tacacs-server host

priority-group

To assign the specified priority list to an interface, use the priority-group interface configuration command. Use the no form of this command to remove the specified priority group assignment.

Syntax Description

Default

None

Command Mode

Interface configuration

Usage Guidelines

Only one list can be assigned per interface. Priority output queueing provides a mechanism to prioritize packets transmitted on an interface.

Use the show queuing priority and show interface commands to display the current status of the output queues.

Example

The following example causes packets on interface serial 0 to be classified by priority list 1:

interface serial 0
priority-group 1

Related Commands

priority-list
priority-list interface
priority-list queue-limit
priority-list stun

priority-list default

To assign a priority queue for those packets that do not match any other rule in the priority list, use the priority-list default global configuration command. Use the no form of this command to return to the default or assign normal as the default.

Syntax Description

Default

The normal queue is assumed if you use the no form of the command.

Command Mode

Global configuration

Usage Guidelines

When using multiple rules, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol or interface type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.

Example

The following example sets the priority queue for those packets that do not match any other rule in the priority list to a low priority:

priority-list 1 default low

Related Commands

priority-group
show queueing

priority-list interface

To establish queuing priorities on packets entering from a given interface, use the priority-list interface global configuration command. Use the no form of this command with the appropriate arguments to remove an entry from the list.

Syntax Description

Default

No queuing priorities are established.

Command Mode

Global configuration

Usage Guidelines

When using multiple rules, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol or interface type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.

Example

The following example sets any packet type entering on Ethernet interface 0 to a medium priority:

priority-list 3 interface ethernet 0 medium

Related Commands

priority-group
show queueing

priority-list protocol

Syntax Description

Default

No queuing priorities are established.

Command Mode

Global configuration

Usage Guidelines

When using multiple rules, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol or interface type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.

The decnet_router-l1 keyword refers to the multicast address for all level-1 routers, which are intra-area routers, and the decnet_router-l2 keyword refers to all level 2 routers, which are interarea routers.

Use Table 5-14, Table 5-15, and Table 5-16 to configure the queuing priorities for your system.

Use the no priority-list global configuration command followed by the appropriate list-number argument and the protocol keyword to remove a priority list entry assigned by protocol type.

Examples

The following example assigns 1 as the arbitrary priority list number, specifies DECnet as the protocol type, and assigns a high-priority level to the DECnet packets transmitted on this interface:

priority-list 1 protocol decnet high

The following example assigns a medium-priority level to every DECnet packet with a size greater than 200 bytes:

priority-list 2 protocol decnet medium gt 200

The following example assigns a medium-priority level to every DECnet packet with a size less than 200 bytes:

priority-list 4 protocol decnet medium lt 200

The following example assigns a high-priority level to traffic that matches IP access list 10:

priority-list 1 protocol ip high list 10

The following example assigns a medium-priority level to Telnet packets:

priority-list 4 protocol ip medium tcp 23

The following example assigns a medium-priority level to UDP Domain Name service packets:

priority-list 4 protocol ip medium udp 53

The following example assigns a high-priority level to traffic that matches Ethernet type code access list 201:

priority-list 1 protocol bridge high list 201

Related Commands

priority-group
show queueing

priority-list queue-limit

To specify the maximum number of packets that can be waiting in each of the priority queues, use the priority-list queue-limit global configuration command.The no form of this command selects the normal queue.

Syntax Description

Default

The default queue limit arguments are listed in Table 5-17.

Command Mode

Global configuration

Usage Guidelines

If a priority queue overflows, excess packets are discarded and quench messages can be sent, if appropriate, for the protocol.

Example

The following example sets the maximum packets in the priority queue to 10:

priority-list 2 queue-limit 10 40 60 80

Related Commands

priority-group
show queueing

privilege level (global)

To set the privilege level for a command, use the privilege level global configuration command. Use the no form of this command to revert to default privileges for a given command.

Syntax Description

Defaults

Level 15 is the level of access permitted by the enable password.

Level 1 is normal EXEC-mode user privileges.

Command Mode

Global configuration

Usage Guidelines

Table 5-7 in the description of the alias command shows the acceptable options for the mode argument in the privilege level global configuration command.

The password for the privilege level defined using the privilege level global configuration mode is configured using the enable passwordcommand.

Level 0 can be used to specify a more-limited subset of commands for specific users or lines. For example, you can allow user "guest" to only use the show users and exit commands.

If you set a command to a privilege level, all commands that have a syntax that is a subset of the syntax of that command will also be set to that level. For example, if you set the command show ip route to level 15, if you do not set show commands and show ip commands to a different level, they will also be at privilege level 15.

Example

In the following example, the configure command in global configuration mode is assigned a privilege level of 14. Only users who know the level 14 password will be able to use the configure command.

privilege exec level 14 configure
enable password level 14 pswd14

Related Commands

enable password
privilege level (line)

privilege level (line)

To set the default privilege level for a line, use the privilege level line configuration command. Use the no form of this command to restore the default user privilege level to the line.

Syntax Description

Defaults

Level 15 is the level of access permitted by the enable password.

Level 1 is normal EXEC-mode user privileges.

Command Mode

Line configuration

Usage Guidelines

The privilege level that is set using this command can be overridden by a user logging in to the line and enabling a different privilege level. The user can lower the privilege level by using the disable command. If they know the password to a higher privilege level, they can use that password to enable the higher privilege level.

Level 0 can be used to specify a more limited subset of commands for specific users or lines. For example, you can allow user "guest" to only use the show users and exit commands.

You might specify a high level of privilege for your console line if you are able to restrict who uses that line.

Example

In the following example, the auxiliary line is configured for privilege level 5. Anyone who is using the auxiliary line will have privilege level 5 by default.

line aux 0
privilege level 5

Related Commands

enable password
privilege level (line)

prompt

To customize the router prompt, use the prompt global configuration command. To revert to the default router prompt, use the no form of this command.

Syntax Description

Default

The default router prompt is either Router or the router name defined with the hostname global configuration command, followed by an angle bracket (>) for EXEC mode or a pound sign (#) for privileged EXEC mode.

Command Mode

Global configuration

Usage Guidelines

You can include escape sequences when specifying the router prompt. All escape sequences are preceded by a percent sign (%). Table 5-18 lists the valid escape sequences.

Examples

The following example changes the EXEC prompt to include the TTY number, followed by the router name and a space:

prompt TTY%n@%h%s%p

The following are examples of user and privileged EXEC prompts that result from the previous command:

TTY17@Router1 >
TTY17SRouter1 #

Related Command

hostname

queue-list default

Syntax Description

Default

Queue number 1

Command Mode

Global configuration

Usage Guidelines

Queue number 0 is a system queue. It is emptied before any of the other queues are processed. The system enqueues high-priority packets, such as keepalives, to this queue.

When using multiple rules, remember that the system reads the queue-list commands in order of appearance. When classifying a packet, the system searches the list of rules specified by queue-list commands for a matching protocol or interface type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.

Example

In the following example, the default queue for list 10 is set to queue number 2:

queue-list 10 default 2

Related Commands

custom-queue-list
show queueing

queue-list interface

Syntax Description

Default

No queuing priorities are established.

Command Mode

Global configuration

Usage Guidelines

When using multiple rules, remember that the system reads the queue-list commands in order of appearance. When classifying a packet, the system searches the list of rules specified by queue-list commands for a matching protocol or interface type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.

Example

In the following example, queue list 4 established queuing priorities for packets entering on interface tunnel 3. The queue number assigned is 10.

queue-list 4 interface tunnel 3 10

Related Commands

custom-queue-list
show queueing

queue-list protocol

Syntax Description

Default

No queuing priorities are established.

Command Mode

Global configuration

Usage Guidelines

When using multiple rules, remember that the system reads the queue-list commands in order of appearance. When classifying a packet, the system searches the list of rules specified by queue-list commands for a matching protocol or interface type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.

The decnet_router-l1 keyword refers to the multicast address for all level-1 routers, which are intra-area routers, and the decnet_router-l2 keyword refers to all level 2 routers, which are interarea routers.

The rsrb keyword refers only to RSRB direct encapsulation.

Use Table 5-14, Table 5-15, and Table 5-16 from the priority-list protocol command to configure custom queuing for your system.

Examples

The following example assigns 1 as the custom queue list, specifies DECnet as the protocol type, and assigns 3 as a queue number to the packets transmitted on this interface:

queue-list 1 protocol decnet 3

The following example assigns DECnet packets with a size greater than 200 bytes to queue number 2:

queue-list 2 protocol decnet 2 gt 200

The following example assigns DECnet packets with a size less than 200 bytes to queue number 2:

queue-list 4 protocol decnet 2 lt 200

The following example assigns traffic that matches IP access list 10 to queue number 1:

queue-list 1 protocol ip 1 list 10

The following example assigns Telnet packets to queue number 2:

queue-list 4 protocol ip 2 tcp 23

The following example assigns UDP Domain Name service packets to queue number 2:

queue-list 4 protocol ip 2 udp 53

The following example assigns traffic that matches Ethernet type code access list 201 to queue number 1:

queue-list 1 protocol bridge 1 list 201

Related Commands

custom-queue-list
show queueing

queue-list queue byte-count

Syntax Description

Default

1500 bytes

Command Mode

Global configuration

Example

In the following example, queue list 9 establishes the byte-count as 1400 for queue number 10:

queue-list 9 queue 10 byte-count 1400

Related Commands

custom-queue-list
show queueing

queue-list queue limit

To designate the queue length limit for a queue, use the queue-list queue limit global configuration command. To return the queue length to the default value, use the no form of the command.

Syntax Description

Default

20 entries

Command Mode

Global configuration

Example

In the following example, the queue length of queue 10 is increased to 40:

queue-list 5 queue 10 limit 40

Related Commands

custom-queue-list
show queueing

scheduler allocate

To guarantee CPU time for processes, use the scheduler allocate global configuration command on the Cisco 7200 series and Cisco 7500 series. The no form of this command restores the default.

Syntax Description

Default

Approximately 5 percent of the CPU is available for process tasks.

Command Mode

Global configuration

Usage Guidelines

This command applies to the Cisco 7200 series and Cisco 7500 series.

Caution Cisco recommends that you do not change the default values.

Example

The following example makes 20 percent of the CPU available for process tasks:

scheduler allocate 2000 500

Related Command

scheduler interval

scheduler interval

To control the maximum amount of time that can elapse without running system processes, use the scheduler interval global configuration command. The no form of this command restores the default.

Syntax Description

Default

High-priority operations are allowed to use as much of the central processor as needed.

Command Mode

Global configuration

Usage Guidelines

The normal operation of the network server allows the switching operations to use as much of the central processor as is required. If the network is running unusually heavy loads that do not allow the processor the time to handle the routing protocols, give priority to the system process scheduler. High-priority operations are allowed to use as much of the central processor as needed.

On the Cisco 7200 series and Cisco 7500 series, use the scheduler allocate global configuration command.

Example

The following example changes the low-priority process schedule to an interval of 750 milliseconds:

scheduler interval 750

Related Command

scheduler allocate

service exec-wait

To delay the startup of the EXEC on noisy lines, use the service exec-wait global configuration command. Use the no form of this command to disable this feature.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

This command delays startup of the EXEC until the line has been idle (no traffic seen) for 3 seconds. The default is to enable the line immediately on modem activation.

This command is useful on noisy modem lines or when a modem attached to the line is configured to ignore MNP or V.42 negotiations, and MNP or V.42 modems may be dialing in. In these cases, noise or MNP/V.42 packets may be interpreted as usernames and passwords, causing authentication failure before the user gets a chance to type a username/password. The command is not useful on non-modem lines or lines without some kind of login configured.

Example

The following example delays the startup of the EXEC:

service exec-wait

service finger

To allow Finger protocol requests (defined in RFC 742) to be made of the network server, use the service finger global configuration command. This service is equivalent to issuing a remote show users command. The no form of this command removes this service.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Global configuration

Example

The following is an example of how to disable the Finger protocol:

no service finger

service hide-telnet-address

To hide addresses while trying to establish a Telnet session, use the service hide-telnet-address global configuration command. Use the no form of this command to remove this service.

Syntax Description

This command has no arguments or keywords.

Default

Addresses are displayed.

Command Mode

Global configuration

Usage Guidelines

When you attempt to connect to a device, the router displays addresses and other messages (for example, Trying router1 (171.69.1.154, 2008)...). With the hide feature, the router suppresses the display of the address (for example, Trying router1 address #1...). The router continues to display all other messages that would normally display during a connection attempt, such as detailed error messages if the connection was not successful.

The hide feature improves the functionality of the busy-message feature. When you configure only the busy-message command, the normal messages generated during a connection attempt are not displayed; only the busy-message is displayed. When you use the hide and busy features together you can customize the information displayed during Telnet connection attempts. When you configure the service hide-telnet-address command and the busy-message command, the router suppresses the address and displays the message specified with the busy-message command if the connection attempt is not successful.

Example

The following example shows how to hide Telnet addresses:

service hide-telnet-address

Related Command

A dagger (⁺) indicates that the command is documented outside this chapter.

busy-message ⁺

service nagle

To enable the Nagle congestion control algorithm, use the service nagle global configuration command. Use the no form of this command to disable this feature.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

When using a standard TCP implementation to send keystrokes between machines, TCP tends to send one packet for each keystroke typed. On larger networks, many small packets use up bandwidth and contribute to congestion.

John Nagle's algorithm (RFC 896) helps alleviate the small-packet problem in TCP. In general, it works this way: The first character typed after connection establishment is sent in a single packet, but TCP holds any additional characters typed until the receiver acknowledges the previous packet. Then the second, larger packet is sent, and additional typed characters are saved until the acknowledgment comes back. The effect is to accumulate characters into larger chunks, and pace them out to the network at a rate matching the round-trip time of the given connection. This method is usually a good for all TCP-based traffic. However, do not use the service nagle command if you have XRemote users on X Window sessions.

Example

The following example enables the Nagle algorithm on the router:

service nagle

service password-encryption

To encrypt passwords, use the service password-encryption global configuration command. Use the no form of this command to disable this service.

Syntax Description

This command has no arguments or keywords.

Default

No encryption

Command Mode

Global configuration

Usage Guidelines

The actual encryption process occurs when the current configuration is written or when a password is configured. Password encryption can be applied to both the privileged command password and to console and virtual terminal line access passwords.

When password encryption is enabled, the encrypted form of the passwords is displayed when a show startup-config command is entered.

Example

The following example causes password encryption to take place:

service password-encryption

service tcp-keepalives

To generate keepalive packets on idle network connections, use the service tcp-keepalives global configuration command. The no form of this command with the appropriate keyword disables the keepalives.

Syntax Description

Default

Disabled

Command Mode

Global configuration

Example

The following example generates keepalives on incoming TCP connections:

service tcp-keepalives in

service tcp-small-servers

To access minor TCP/IP services available from hosts on the network, use the service tcp-small-servers command. Use the no form of the command to disable these services.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Global configuration

Usage Guidelines

By default, the TCP servers for Echo, Discard, Chargen, and Daytime services are enabled.

When you disable the minor TCP/IP servers, access to the Echo, Discard, Chargen, and Daytime ports cause the Cisco IOS software to send a TCP RESET packet to the sender and discard the original incoming packet.

Example

The following example enables minor TCP/IP services available from the network:

service tcp-small-servers

service telnet-zero-idle

To set the TCP window to zero (0) when the Telnet connection is idle, use the service telnet-zero-idle global configuration command. Use the no form of this command to disable this feature.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

Normally, data sent to noncurrent Telnet connections is accepted and discarded. When service telnet-zero-idle is enabled, if a session is suspended (that is, some other connection is made active or the EXEC is sitting in command mode), the TCP window is set to zero. This action prevents the remote host from sending any more data until the connection is resumed. Use this command when it is important that all messages sent by the host be seen by the users and the users are likely to use multiple sessions.

Do not use this command if your host will eventually time out and log out a TCP user whose window is zero.

Example

The following example sets the TCP window to zero when the Telnet connection is idle:

service telnet-zero-idle

Related Command

resume

service timestamps

To configure the system to timestamp debugging or logging messages, use one of the service timestamps global configuration commands. Use the no form of this command to disable this service.

Syntax Description

Default

No timestamping.

If service timestamps is specified with no arguments or keywords, default is service timestamps debug uptime.

The default for service timestamps type datetime is to format the time in UTC, with no milliseconds and no time zone name.

The command no service timestamps by itself disables timestamps for both debug and log messages.

Command Mode

Global configuration

Usage Guidelines

Timestamps can be added to either debugging or logging messages independently. The uptime form of the command adds timestamps in the format HHHH:MM:SS, indicating the time since the system was rebooted. The datetime form of the command adds timestamps in the format
MMM DD HH:MM:SS, indicating the date and time according to the system clock. If the system clock has not been set, the date and time are preceded by an asterisk (*) to indicate that the date and time are probably not correct.

Examples

The following example enables timestamps on debugging messages, showing the time since reboot:

service timestamps debug uptime

The following example enables timestamps on logging messages, showing the current time and date relative to the local time zone, with the time zone name included:

service timestamps log datetime localtime show-timezone

Related Commands

clock set
debug (Refer to the Debug Command Reference publication.)
ntp

service udp-small-servers

To access minor User Datagram Protocol (UDP) services available from hosts on the network, use the service udp-small-servers command. Use the no form of the command to disable these services.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Global configuration

Usage Guidelines

By default the UPD servers for Echo, Discard, and Chargen services are enabled.

When you disable the servers, access to Echo, Discard, and Chargen ports causes the Cisco IOS software to send an "ICMP port unreachable" message to the sender and discard the original incoming packet.

Example

The following example disables minor UDP services on the router:

no service udp-small-servers

show aliases

To display all alias commands, or the alias commands in a specified mode, use the show aliases EXEC command.

Syntax Description

Command Mode

EXEC

Usage Guidelines

All of the modes listed in Table 5-7 have their own prompts, except for the null interface mode. For example, the prompt for interface configuration mode is Router(config-if).

Sample Display

The following is sample output from the show aliases exec commands. The aliases configured for commands in EXEC mode are displayed.

Router# show aliases exec
Exec mode aliases:
  h                     help
  lo                    logout
  p                     ping
  r                     resume
  s                     show
  w                     where

Related Command

alias

show buffers

Use the show buffers EXEC command to display statistics for the buffer pools on the network server.

Syntax Description

Command Mode

EXEC

Sample Displays

The following is sample output from the show buffers command with no arguments, showing all buffer pool information:

Router#show buffers
Buffer elements:
     398 in free list (500 max allowed)
     1266 hits, 0 misses, 0 created
 
Public buffer pools:
Small buffers, 104 bytes (total 50, permanent 50):
     50 in free list (20 min, 150 max allowed)
     551 hits, 0 misses, 0 trims, 0 created
Middle buffers, 600 bytes (total 25, permanent 25):
     25 in free list (10 min, 150 max allowed)
     39 hits, 0 misses, 0 trims, 0 created
Big buffers, 1524 bytes (total 50, permanent 50):
     49 in free list (5 min, 150 max allowed)
     27 hits, 0 misses, 0 trims, 0 created
VeryBig buffers, 4520 bytes (total 10, permanent 10):
     10 in free list (0 min, 100 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
Large buffers, 5024 bytes (total 0, permanent 0):
     0 in free list (0 min, 10 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
Huge buffers, 18024 bytes (total 0, permanent 0):
     0 in free list (0 min, 4 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
          
Interface buffer pools:
Ethernet0 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
Ethernet1 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
Serial0 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
Serial1 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
TokenRing0 buffers, 4516 bytes (total 48, permanent 48):
     0 in free list (0 min, 48 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
TokenRing1 buffers, 4516 bytes (total 32, permanent 32):
     32 in free list (0 min, 48 max allowed)
     16 hits, 0 fallbacks
0 failures (0 no memory)

Table 5-19 describes significant fields shown in the display.

Router#show buffers Ethernet 0
Ethernet0 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache

Router#show buffers alloc
Buffer elements:
     398 in free list (500 max allowed)
     1266 hits, 0 misses, 0 created
 
Public buffer pools:
Small buffers, 104 bytes (total 50, permanent 50):
     50 in free list (20 min, 150 max allowed)
     551 hits, 0 misses, 0 trims, 0 created
Middle buffers, 600 bytes (total 25, permanent 25):
     25 in free list (10 min, 150 max allowed)
     39 hits, 0 misses, 0 trims, 0 created
Big buffers, 1524 bytes (total 50, permanent 50):
     49 in free list (5 min, 150 max allowed)
     27 hits, 0 misses, 0 trims, 0 created
VeryBig buffers, 4520 bytes (total 10, permanent 10):
     10 in free list (0 min, 100 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
Large buffers, 5024 bytes (total 0, permanent 0):
     0 in free list (0 min, 10 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
Huge buffers, 18024 bytes (total 0, permanent 0):
     0 in free list (0 min, 4 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
          
Interface buffer pools:
Ethernet0 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
Ethernet1 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
Serial0 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
Serial1 buffers, 1524 bytes (total 64, permanent 64):
     16 in free list (0 min, 64 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
TokenRing0 buffers, 4516 bytes (total 48, permanent 48):
     0 in free list (0 min, 48 max allowed)
     48 hits, 0 fallbacks
     16 max cache size, 16 in cache
TokenRing1 buffers, 4516 bytes (total 32, permanent 32):
     32 in free list (0 min, 48 max allowed)
     16 hits, 0 fallbacks
0 failures (0 no memory)
Address  PakAddr  Data     Off Data  Pool  Ref Link Enc     Flags Output  Input
                  Area     set Size        Cnt Type Type    (Hex) Idb     Idb
--------------------------------------------------------------------------------
604B37A0 604B37C0 40004A38  62    60 Big     1   65    3        0 Et0          
604C6DA0 604C6DC0 40007038  84     0 Ether   1    0    0        0              
604C6F60 604C6F80 400076E4  84     0 Ether   1    0    0        0              
604C7120 604C7140 40007D90  84     0 Ether   1    0    0        0              
604C72E0 604C7300 4000843C  84     0 Ether   1    0    0        0              
604C74A0 604C74C0 40008AE8  84     0 Ether   1    0    0        0              
604C7660 604C7680 40009194  84     0 Ether   1    0    0        0              
604C7820 604C7840 40009840  84     0 Ether   1    0    0        0              
.
.
.

show calendar

To display the calendar hardware setting for the Cisco 7000 or Cisco 4500, use the show calendar EXEC command:

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

You can compare the time and date shown with this command with the time and date listed via the show clock command to verify that the calendar and system clock are in sync with each other. The time displayed is relative to the configured time zone.

Sample Display

In the following sample display, the hardware calendar indicates the timestamp of 12:13:44 p.m. on Friday, January 1, 1993:

Router# show calendar
12:13:44 PST Fri Jan 1 1993

Related Command

show clock

show cdp

To display global CDP information, including timer and hold-time information, use the show cdp privileged EXEC command.

Syntax Description

This command has no arguments or keywords.

Command Mode

Privileged EXEC

Sample Display

The following is sample output from the show cdp command. Global CDP timer and hold-time parameters are set to the defaults of 60 and 180 seconds, respectively.

Router# show cdp

Global CDP information:
        Sending CDP packets every 60 seconds
        Sending a holdtime value of 180 seconds

Related Commands

cdp holdtime
cdp timer
show cdp entry
show cdp neighbors

show cdp entry

To display information about a neighbor device listed in the CDP table, use the show cdp entry privileged EXEC command.

Syntax Description

Command Mode

Privileged EXEC

Sample Displays

The following is sample output from the show cdp entry command with no limits. Information about the neighbor device.cisco.com is displayed, including device ID, address and protocol, platform, interface, hold time, and version.

Router# show cdp entry device.cisco.com

Device ID: device.cisco.com
Entry address(es): 
  IP address: 198.92.68.18
  CLNS address: 490001.1111.1111.1111.00
  DECnet address: 10.1
Platform: AGS,  Capabilities: Router Trans-Bridge 
Interface: Ethernet0,  Port ID (outgoing port): Ethernet0
Holdtime : 155 sec
 
Version :
GS Software (GS3), Experimental Version 10.2(10302) [asmith 161]
Copyright (c) 1986-1994 by cisco Systems, Inc.
Compiled Mon 07-Nov-94 14:34

The following is sample output from the show cdp entry privilege command. Only information about the protocols enabled on neon-cisco.com is displayed.

Router# show cdp entry device.cisco.com protocol
Protocol information for device.cisco.com :
  IP address: 198.92.68.18
  CLNS address: 490001.1111.1111.1111.00
  DECnet address: 10.1

The following is sample output from the show cdp entry version command. Only information about the version of software running on device.cisco.com is displayed.

Router# show cdp entry device.cisco.com version 
 
Version information for device.cisco.com :
  GS Software (GS3), Experimental Version 10.2(10302) [asmith 161]
Copyright (c) 1986-1994 by cisco Systems, Inc.
Compiled Mon 07-Nov-94 14:34

Related Command

show cdp neighbors

show cdp interface

To display information about the interfaces on which CDP is enabled, use the show cdp interface command.

Syntax Description

Command Mode

Privileged EXEC

Sample Displays

The following sample output form the show cdp interface command. Status information and information about CDP timer and hold time settings is displayed for all interfaces on which CDP is enabled.

Router# show cdp interface

Serial0 is up, line protocol is up, encapsulation is SMDS
  Sending CDP packets every 60 seconds
  Holdtime is 180 seconds
Ethernet0 is up, line protocol is up, encapsulation is ARPA
  Sending CDP packets every 60 seconds
  Holdtime is 180 seconds

The following is sample output from the show cdp interface command with an interface specified. Status information and information about CDP timer and holdtime settings is displayed for Ethernet interface 0 only.

Router# show cdp interface ethernet 0

Ethernet0 is up, line protocol is up, encapsulation is ARPA
  Sending CDP packets every 60 seconds
  Holdtime is 180 seconds

show cdp neighbors

To display information about neighbors, use the show cdp neighbors privileged EXEC command.

Syntax Description

Command Mode

Privileged EXEC

Sample Displays

The following is sample output from the show cdp neighbors command. Device ID, interface type and number, holdtime settings, capabilities, platform, and port ID information about the router's neighbors is displayed.

Router# show cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP
 
Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
device.cisco.com      Eth 0          151         R T        AGS       Eth 0
device.cisco.com      Ser 0          165         R T        AGS       Ser 3

The following is sample output from the show cdp neighbors detail command. Additional detail is shown about the router's neighbors, including network address, enabled protocols, and software version:

Router# show cdp neighbors detail 
Device ID: device.cisco.com
Entry address(es): 
  IP address: 198.92.68.18
  CLNS address: 490001.1111.1111.1111.00
  DECnet address: 10.1
Platform: AGS,  Capabilities: Router Trans-Bridge 
Interface: Ethernet0,  Port ID (outgoing port): Ethernet0
Holdtime : 143 sec
 
Version :
GS Software (GS3), Experimental Version 10.2(10302) [asmith 161]
Copyright (c) 1986-1994 by cisco Systems, Inc.
Compiled Mon 07-Nov-94 14:34

Related Command

show cdp entry

show cdp traffic

To display traffic information from the CDP table, use the show cdp traffic privileged EXEC command.

Syntax Description

This command has no arguments or keywords.

Command Mode

Privileged EXEC

Sample Display

The following is sample output from the show cdp traffic command.

Router# show cdp traffic
CDP counters :
        Packets output: 94, Input: 75
        Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
        No memory: 0, Invalid packet: 0, Fragmented: 0

In this example, traffic information is displayed including the numbers of packets sent, the number of packets received, header syntax, checksum errors, failed encapsulations, memory problems, and invalid and fragmented packets is displayed. Header syntax indicates the number of packets CDP receives with that have an invalid header format.

show clock

To display the system clock, use the show clock EXEC command:

Syntax Description

Command Mode

EXEC

Usage Guidelines

The system clock keeps an "authoritative" flag that indicates whether or not the time is authoritative (believed to be accurate). If system clock has been set by a timing source (Cisco 7000 calendar, NTP, VINES, and so forth), the flag is set. If the time is not authoritative, it will be used only for display purposes. Until the clock is authoritative and the "authoritative" flag is set, the flag prevents the router from causing peers to synchronize to itself when the router time is invalid.

The symbol that precedes the show clock display indicates the following:

An asterisk (*) indicates not authoritative

A blank space indicates authoritative

A period (. ) indicates authoritative, but NTP is not synchronized.

Sample Display

The following sample output shows that the current clock is authoritative and that the time source is NTP:

Router# show clock detail
15:29:03.158 PST Mon Mar 1 1993
Time source is NTP
Router#

Related Commands

clock set
show calendar

show context

Use the show context EXEC command to display information stored in NVRAM when the router crashes. This command only works on the Cisco 7000 series, Cisco 7200 series, and Cisco 7500 series platforms.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

The display from the show context command includes the following information:

• Reason for the system reboot

• Stack trace

• Software version

• The signal number, code, and router uptime information

• All the register contents at the time of the crash

This information is of use only to your technical support representative in analyzing crashes in the field. It is included here in case you need to read the displayed statistics to an engineer over the phone.

Sample Display

The following is sample output from the show context command following a system failure:

Router> show context
System was restarted by error - a Software forced crash, PC 0x60189354
GS Software (RSP-PV-M), Experimental Version 11.1(2033) [ganesh 111]
Compiled Mon 31-Mar-97 13:21 by ganesh
Image text-base: 0x60010900, data-base: 0x6073E000
Stack trace from system failure:
FP: 0x60AEA798, RA: 0x60189354
FP: 0x60AEA798, RA: 0x601853CC
FP: 0x60AEA7C0, RA: 0x6015E98C
FP: 0x60AEA7F8, RA: 0x6011AB3C
FP: 0x60AEA828, RA: 0x601706CC
FP: 0x60AEA878, RA: 0x60116340
FP: 0x60AEA890, RA: 0x6011632C
Fault History Buffer:
GS Software (RSP-PV-M), Experimental Version 11.1(2033) [ganesh 111]
Compiled Mon 31-Mar-97 13:21 by ganesh
Signal = 23, Code = 0x24, Uptime 00:04:19
$0 : 00000000, AT : 60930120, v0 : 00000032, v1 : 00000120
a0 : 60170110, a1 : 6097F22C, a2 : 00000000, a3 : 00000000
t0 : 60AE02A0, t1 : 8000FD80, t2 : 34008F00, t3 : FFFF00FF
t4 : 00000083, t5 : 3E840024, t6 : 00000000, t7 : 11010132
s0 : 00000006, s1 : 607A25F8, s2 : 00000001, s3 : 00000000
s4 : 00000000, s5 : 00000000, s6 : 00000000, s7 : 6097F755
t8 : 600FABBC, t9 : 00000000, k0 : 30408401, k1 : 30410000
gp : 608B9860, sp : 60AEA798, s8 : 00000000, ra : 601853CC
EPC : 60189354, SREG : 3400EF03, Cause : 00000024

Related Commands

show processes
show stacks

show environment

Use the show environment EXEC command to display temperature and voltage information on the AGS+, Cisco 7000 series, and Cisco 7500 series console.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

Once a minute a routine is run that gets environmental measurements from the CSC-ENVM card and stores the show environment output into a buffer. This buffer is displayed on the console when show environment is invoked.

If a measurement exceeds desired margins, but has not exceeded fatal margins, a warning message is printed to the system console. The system software queries the CSC-ENVM card for measurements once a minute, but warnings for a given testpoint are printed at most once every four hours. If a measurement is out of line within a four-hour period, an automatic warning message appears on the console. As noted, you can query the CSC-ENVM using the show environment command at any time to determine whether a measurement is at the warning tolerance.

Sample Displays

The following is sample output from the show environment command on the AGS+:

Router# show environment
Environmental controller firmware version 2.0
   	Serial number is 00220846, calibrated on 2-14-92, by technician rma
   	Internal temperature measured 34.3(C), shuts down at 43.0(C)
   	Air flow appears good.
   	+5 volt line measured at 5.061(V)
   	+12 volt line measured at 12.120(V)
   	-12 volt line measured at -11.936(V)
   	-5 volt line measured at -4.986(V)

Table 5-20 describes significant fields shown in the display.

Router#
ENVIRONMENTAL WARNING: Air flow appears marginal.

Router#
ENVIRONMENTAL WARNING: Internal temperature measured 41.3(C)

Router#
ENVIRONMENTAL WARNING:  +5 volt testpoint measured 5.310(V)     

Router#
SHUTDOWN: air flow problem

Router> show environment
Environmental Statistics
  Environmental status as of 13:17:39 UTC Thu Oct 22 1992 
  Data is 7 second(s) old, refresh in 53 second(s)
  All Environmental Measurements are within specifications

Table 5-21 describes the show environment display fields on the Cisco 7000.

show environment all

Use the show environment all EXEC command to display temperature and voltage information on the Cisco 7000 series and Cisco 7500 series console.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Displays

The following is sample output from the show environment all command on the Cisco 7000 when there are no warning conditions in the system:

7000> show environment all
Environmental Statistics
  Environmental status as of 13:17:39 UTC Thu Oct 22 1992
  Data is 11 second(s) old, refresh in 49 second(s)
  All Environmental Measurements are within specifications
  Lower Power Supply: 700W, ON     Upper Power Supply: Not Installed
  No Intermittent Powerfails
  +12 volt measured at  12.05(V)
   +5 volt measured at   4.92(V)
  -12 volt measured at -12.00(V)
  +24 volt measured at  23.80(V)
Airflow 	temperature measured at 30(C)
Inlet 	temperature measured at 25(C)

In the following example, there have been two intermittent power failures since the router was turned on, and the lower power supply is not functioning. The last intermittent power failure occurred on Sunday, October 25, 1992, at 11:07 p.m.

7000# show environment all
Environmental Statistics
  Environmental status as of 23:19:47 UTC Sun Oct 25 1992 
  Data is 6 second(s) old, refresh in 54 second(s)
  WARNING: Lower Power Supply is NON-OPERATIONAL
  Lower Power Supply:700W, OFF     Upper Power Supply: 700W, ON
  Intermittent Powerfail(s): 2     Last on 23:07:05 UTC Sun Oct 25 1992 
  +12 volts measured at  12.05(V)
   +5 volts measured at   4.96(V)
  -12 volts measured at -12.05(V)
  +24 volts measured at  23.80(V)
  Airflow temperature measured at 38(C)
  Inlet temperature measured at 25(C)

Table 5-22 describes the show environment all display fields.

7010# show environment all
Environmental Statistics
  Environmental status as of Fri 11-5-1993 19:10:41
  Data is 31 second(s) old, refresh in 29 second(s)
 All Environmental Measurements are within specifications
  Power Supply: 600W AC
  No Intermittent Powerfails
  +12 volts measured at  12.00(V)
   +5 volts measured at   5.02(V)
  -12 volts measured at -12.05(V)
  +24 volts measured at  23.70(V)
  Airflow temperature measured at 35(C)
  Inlet   temperature measured at 26(C)

Table 5-23 describes the fields shown in the display.

7500#show environment all
Arbiter type 1, backplane type 7513 (id 2) 
Power supply #1 is 1200W AC (id 1), power supply #2 is removed (id 7) 
Active fault conditions: none
Fan transfer point: 100%
Active trip points: Restart_Inhibit
15 of 15 soft shutdowns remaining before hard shutdown 
                        1
              0123456789012
Dbus slots:   X     XX    X
card        inlet      hotpoint      exhaust
RSP(6)     35C/95F     47C/116F      40C/104F
RSP(7)     35C/95F     43C/109F      39C/102F
Shutdown temperature source is 'hotpoint' on RSP(6), requested RSP(6) 
+12V measured at 12.31
+5V measured at 5.21
-12V measured at -12.07
+24V measured at 22.08
+2.5 reference is 2.49
PS1 +5V Current      measured at 59.61 A (capacity 200 A) 
PS1 +12V Current     measured at 5.08 A (capacity 35 A) 
PS1 -12V Current     measured at 0.42 A (capacity 3 A) 
PS1 output is 378 W

Table 5-24 describes the fields shown in the display.

show environment last

If a shutdown occurs due to detection of fatal environmental margins, the AGS+, Cisco 7000 series, or Cisco 7000 series router logs the last measured value from each of the six test points to internal nonvolatile memory. Only one set of measurements may be stored at any one time.

Use the show environment last EXEC command to display these test points.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Displays

The following is sample output from the show environment last command on the AGS+:

Router# show environment last
Environmental controller firmware version 2.0
   	Serial number is 3232, calibrated on 2-14-92, by technician rma
   	Internal temperature measured 24.1(C), shuts down at 43.0(C)
	   Air flow appears good.
	   +5 volt line measured at 4.988(V)
	   +12 volt line measured at 12.044(V)
	   -12 volt line measured at -11.787(V)
   	-5 volt line measured at -4.939(V)
LAST Environmental Shutdown Measurements:
   	Internal temperature was 24.0(C)
	   Air flow sensor was good
	   +5 volt line was 4.990(V)
	   +12 volt line was 9.900(V)*
	   -12 volt line was -11.719(V)
	   -5 volt line was -4.926(V)

As the display shows, the first block of data is equivalent to show environment, in that it displays the current measurements. The second block shows all the testpoint values at the time of the LAST environmental shutdown. An asterisk suffixes the testpoint that caused the failure. In this example, the +12 volt testpoint dropped to 9.900(V) to cause the shutdown.

The following example is for the Cisco 7000. The router retrieves the environmental statistics at the time of the last shutdown. In this example, the last shutdown was Tuesday, May 19, 1992 at 12:40p.m., so the environmental statistics at that time are displayed.

Router# show environment last
Environmental Statistics
  Environmental status as of 14:47:00 UTC Thu May 21 1992 
  Data is 6 second(s) old, refresh in 54 second(s)
  WARNING: Upper Power Supply is NON-OPERATIONAL
LAST Environmental Statistics
  Environmental status as of 12:40:00 UTC Tues May 19 1992 
  Lower Power Supply: 700W, ON     Upper Power Supply: 700W, OFF
  No Intermittent Powerfails
  +12 volts measured at  12.05(V)
   +5 volts measured at   4.98(V)
  -12 volts measured at -12.00(V)
  +24 volts measured at  23.80(V)
  Airflow temperature measured at 30(C)
  Inlet   temperature measured at 23(C)

Table 5-25 describes the show environment last display fields.

7500#show environment last
 RSP(4) Inlet       previously measured at 37C/98F
 RSP(4) Hotpoint    previously measured at 46C/114F
 RSP(4) Exhaust     previously measured at 52C/125F
 +12 Voltage        previously measured at 12.26
 +5 Voltage         previously measured at 5.17
 -12 Voltage        previously measured at -12.03
 +24 Voltage        previously measured at 23.78

Table 5-26 describes the fields shown in the display

show environment table

Use the show environment table EXEC command to display environmental measurements and a table that lists the ranges of environment measurement that are within specification. This command is available on the Cisco 7000 and Cisco 7500 series.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following sample output for the Cisco 7000 shows the current environmental status in tables that list voltage and temperature parameters. There are three warning messages; one each about the lower power supply, the airflow temperature, and the inlet temperature. In this example, voltage parameters are shown to be in the normal range, airflow temperature is at a critical level, and inlet temperature is at the warning level.

Router> show environment table
Environmental Statistics
  Environmental status as of Mon 11-2-1992 17:43:36
  Data is 52 second(s) old, refresh in 8 second(s)
  WARNING: Lower Power Supply is NON-OPERATIONAL
  WARNING: Airflow temperature has reached CRITICAL level at 73(C)
  WARNING: Inlet temperature has reached WARNING level at 41(C)
Voltage Parameters:
 SENSE        CRITICAL                NORMAL                CRITICAL
-------|--------------------|------------------------|--------------------
+12(V)                    10.20      12.05(V)      13.80
 +5(V)                     4.74       4.98(V)       5.26
-12(V)                   -10.20     -12.05(V)     -13.80
+24(V)                    20.00      24.00(V)      28.00
Temperature Parameters:
 SENSE     WARNING      NORMAL      WARNING      CRITICAL      SHUTDOWN
-------|-------------|------------|-------------|--------------|--------------
Airflow            10           60           70    73(C)   88
Inlet              10           39    41(C)  46            64

Table 5-27 describes the show environment table display fields.

7500#show env table
Sample Point      LowCritical    LowWarning     HighWarning    HighCritical   
RSP(4) Inlet                                    44C/111F       50C/122F       
RSP(4) Hotpoint                                 54C/129F       60C/140F       
RSP(4) Exhaust                                                                
+12 Voltage       10.90          11.61          12.82          13.38          
+5 Voltage        4.61           4.94           5.46           5.70           
-12 Voltage       -10.15         -10.76         -13.25         -13.86         
+24 Voltage       20.38          21.51          26.42          27.65          
2.5 Reference                    2.43           2.51                          
Shutdown boards at           70C/158F
Shutdown power supplies at   76C/168F
Restart after shutdown below 40C/104F

Table 5-28 describes the fields shown in the display.

show logging

Use the show logging EXEC command to display the state of logging (syslog).

This command displays the state of syslog error and event logging, including host addresses, and whether console logging is enabled. This command also displays Simple Network Management Protocol (SNMP) configuration parameters and protocol activity.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following is sample output from the show logging command:

Router# show logging
Syslog logging: enabled
     	Console logging: disabled
     	Monitor logging: level debugging, 266 messages logged.
     	Trap logging: level informational, 266 messages logged.
     	Logging to 131.108.2.238
SNMP logging: disabled, retransmission after 30 seconds
    0 messages logged

Table 5-29 describes significant fields shown in the display.

show memory

Use the show memory EXEC command to show statistics about the router's memory, including memory free pool statistics.

Syntax Description

Command Mode

EXEC

Usage Guidelines

The show memory command displays information about memory available after the system image decompresses and loads.

Sample Displays

The following is sample output from the show memory command:

Router# show memory
               Head   Total(b)    Used(b)    Free(b)  Lowest(b) Largest(b)
Processor    B0EE38    5181896    2210036    2971860    2692456    2845368
          Processor memory
Address   Bytes Prev.    Next     Ref  PrevF   NextF   Alloc PC  What
B0EE38     1056 0        B0F280     1                  18F132    List Elements
B0F280     2656 B0EE38   B0FD08     1                  18F132    List Headers
B0FD08     2520 B0F280   B10708     1                  141384    TTY data
B10708     2000 B0FD08   B10F00     1                  14353C    TTY Input Buf
B10F00      512 B10708   B11128     1                  14356C    TTY Output Buf
B11128     2000 B10F00   B11920     1                  1A110E    Interrupt Stack 
B11920       44 B11128   B11974     1                  970DE8    *Init*
B11974     1056 B11920   B11DBC     1                  18F132    messages
B11DBC       84 B11974   B11E38     1                  19ABCE    Watched Boolean 
B11E38       84 B11DBC   B11EB4     1                  19ABCE    Watched Boolean 
B11EB4       84 B11E38   B11F30     1                  19ABCE    Watched Boolean 
B11F30       84 B11EB4   B11FAC     1                  19ABCE    Watched Boolean 
Router#

The following is sample output from the show memory free command:

Router# show memory free
               Head   Total(b)    Used(b)    Free(b)  Lowest(b) Largest(b)
Processor    B0EE38    5181896    2210076    2971820    2692456    2845368
          Processor memory
Address  Bytes Prev.    Next     Ref  PrevF   NextF   Alloc PC  What
             24    Free list 1
CEB844       32 CEB7A4   CEB88C     0  0       0       96B894    SSE Manager
             52    Free list 2
             72    Free list 3
             76    Free list 4
             80    Free list 5
D35ED4       80 D35E30   D35F4C     0  0       D27AE8  96B894    SSE Manager
D27AE8       80 D27A48   D27B60     0  D35ED4  0       22585E    SSE Manager
             88    Free list 6
            100    Free list 7
D0A8F4      100 D0A8B0   D0A980     0  0       0       2258DA    SSE Manager
            104    Free list 8
B59EF0      108 B59E8C   B59F84     0  0       0       2258DA    (fragment)

The display of show memory free contains the same types of information as the show memory display, except that only free memory is displayed, and the information is displayed in order for each free list.

The first section of the display includes summary statistics about the activities of the system memory allocator. Table 5-30 describes significant fields shown in the first section of the display.

The second section of the display is a block-by-block listing of memory use. Table 5-31 describes significant fields shown in the second section of the display.

Router# show memory io
Address   Bytes Prev.   Next     Ref  PrevF   NextF   Alloc PC  What
6132DA0   59264 6132664 6141520  0    0      600DDEC  3FCF0     *Packet Buffer*
600DDEC     500 600DA4C 600DFE0  0   6132DA0 600FE68 0 
600FE68     376 600FAC8 600FFE0  0   600DDEC 6011D54 0 
6011D54     652 60119B4 6011FEO  0   600FE68 6013D54 0 
614FCA0     832 614F564 614FFE0  0   601FD54 6177640 0 
6177640 2657056 6172E90 0        0   614FCA0 0       0 
Total: 2723244

Router# show memory sram
Address   Bytes Prev.   Next     Ref  PrevF   NextF   Alloc PC  What
7AE0      38178 72F0    0        0    0       0       0
Total     38178 

Router# show memory
               Head   Total(b)    Used(b)    Free(b)  Lowest(b) Largest(b)
Processor    49C724   28719324    1510864   27208460   26511644   15513908
      I/O   6000000    4194304    1297088    2897216    2869248    2896812
     SRAM      1000      65536      63400       2136       2136       2136
Address   Bytes Prev.   Next     Ref  PrevF   NextF   Alloc PC  What
1000       2032 0       17F0       1                  3E73E     *Init*
17F0       2032 1000    1FE0       1                  3E73E     *Init*
1FE0        544 17F0    2200       1                  3276A     *Init*
2200         52 1FE0    2234       1                  31D68     *Init*
2234         52 2200    2268       1                  31DAA     *Init*
2268         52 2234    229C       1                  31DF2     *Init*
72F0       2032 6E5C    7AE0       1                  3E73E     Init
7AE0      38178 72F0    0          0    0      0      0         
Router#

The following is a partial sample output from the show memory summary command. This command shows the size, blocks, and bytes allocated. Bytes equal the size multiplied by the blocks. For a description of the other fields, see Table 5-30 and Table 5-31.

router# show memory summary
               Head   Total(b)    Used(b)    Free(b)  Lowest(b) Largest(b)
Processor    B0EE38    5181896    2210216    2971680    2692456    2845368
          Processor memory
Alloc PC        Size     Blocks      Bytes    What
0x2AB2           192          1        192    IDB: Serial Info
0x70EC            92          2        184    Init
0xC916           128         50       6400    RIF Cache
0x76ADE         4500          1       4500    XDI data
0x76E84         4464          1       4464    XDI data
0x76EAC          692          1        692    XDI data
0x77764          408          1        408    Init
0x77776          116          1        116    Init
0x777A2          408          1        408    Init
0x777B2          116          1        116    Init
0xA4600           24          3         72    List
0xD9B5C           52          1         52    SSE Manager
.......................
0x0                0       3413    2072576    Pool Summary
0x0                0         28    2971680    Pool Summary (Free Blocks)
0x0               40       3441     137640    Pool Summary(All Block Headers)
0x0                0       3413    2072576    Memory Summary
0x0                0         28    2971680    Memory Summary (Free Blocks)

Related Command

show processes memory

show ntp associations

To show the status of Network Time Protocol (NTP) associations, use the show ntp associations EXEC command.

Syntax Description

Command Mode

EXEC

Sample Displays

Detailed descriptions of the information displayed by this command can be found in the NTP specification (RFC 1305).

The following is sample output from the show ntp associations command:

Router# show ntp associations
     address         ref clock     st  when  poll reach  delay  offset    disp
 ~160.89.32.2      160.89.32.1       5    29  1024  377     4.2   -8.59     1.6
+~131.108.13.33    131.108.1.111     3    69   128  377     4.1    3.48     2.3
*~131.108.13.57    131.108.1.111     3    32   128  377     7.9   11.18     3.6
* master (synced), # master (unsynced), + selected, - candidate, ~ configured
Router#

Table 5-32 describes significant fields shown in the display.