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The protocol translation software attempts to provide transparent translation between systems running disparate protocols. The software fully supports two-way virtual terminal protocol translation between nodes running X.25, Local Area Transport (LAT), SLIP or PPP, and Telnet, a remote terminal protocol that is part of the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite.
To provide fully transparent protocol conversion, the router masquerades as two or more hosts on the same network. When a connection is made to the router, the router determines which host the connection is for and what protocol that host is using. The router then establishes a new network connection using the networking protocol required by that host. This network connection is more efficient and allows the router to act upon greater knowledge of the protocols in use because the router acts as a network connection rather than a terminal.
This chapter describes the commands used to configure protocol translation connections. For protocol translation configuration information and examples, refer to the chapter "Configuring Protocol Translation Sessions" earlier in this publication.
For information about protocol translation EXEC commands, such as the pad EXEC command, refer to the Cisco Access Connection Guide.
To view translation sessions that have been configured on a router, enter the following command in privileged EXEC mode:
show translateThis command has no arguments or keywords.
Privileged EXEC
The display from this command shows each translation session set up on the router. It shows the incoming device and virtual terminal protocol as well as the outgoing device and protocol.
The show translate output in this sample display is based on the following translate command configured on the router:
translate lat ramble ppp 172.21.10.10 0 keepalive
CS# show translate
Translate From: LAT ramble
To: PPP 172.21.10.10 keepalive 0
1/1 users active, 1 peak, 1 total, 0 failures
Table 11-1 describes fields shown in the display.
| Field | Description |
|---|---|
| Translate From: LAT ramble | The virtual terminal protocol (LAT) and hostname (ramble) of the incoming device. |
| To: PPP 172.21.10.10 | The virtual terminal protocol (PPP) and IP address (172.21.10.10) of the outgoing device. |
| keepalive 0 | Indicates that keepalive updates have been disabled for the current translation session. |
| 1/1 users active | Number of users active over the total number of users. |
| 1 peak | Maximum number of translate sessions up at any given time. |
| 1 total | Total number of translation sessions. |
| 0 failures | Number of failed translation attempts resulting from this configuration. |
To automatically convert incoming LAT, TCP, or X.25 requests for connections to a specified destination address or host name to the specified outgoing connection type, use the translate global configuration command.
translate protocol incoming-address [in-options] protocol outgoing-address [out-options]No default translation parameters
Global configuration
Table 11-2 provides a visual aid for understanding how to use the translate command. As the table illustrates, you define the protocol translation connections--both incoming and outgoing--by choosing a protocol keyword and supplying the appropriate address or service name. The protocol connection information is followed by optional features for that connection, also as appropriate. For example, the binary option is only appropriate with TCP/IP connections. The global options, in general, apply to all the connection types, but there are exceptions. The swap keyword, for example, is for X.25 to TCP translations only. See the examples for more explanations on how to enter this command.
| Incoming Protocol | Options | Outgoing Protocol | Options | Global Options | |
|---|---|---|---|---|---|
| translate | protocol incoming-address | [in-options] | protocol outgoing-address | [out-options] | [global-options] |
| lat service-name | unadvertised | lat service-name | node node-name | access-class number | |
| port port-name | max-users number | ||||
| local | |||||
| login | |||||
| x25 x.121-address | cud c-u-data | x25 x.121-address | cud c-u-data | quiet | |
| profile profile | profile profile | swap | |||
| accept-reverse | reverse | ||||
| printer | |||||
| pvc number | |||||
| tcp ip-address | port number | tcp ip-address | port number | ||
| binary | |||||
| stream | |||||
| printer | |||||
| slip ip-address | headercompressed [passive] | ||||
| routing | |||||
| keepalive number-of-seconds | |||||
| mtu bytes | |||||
| ppp ip-address | headercompressed [passive] | ||||
| routing | |||||
| keepalive number-of-seconds | |||||
| mtu bytes | |||||
| ppp authentication {pap | chap} | |||||
| ppp use-tacacs |
The following example illustrates a simple X.25 to TCP translation command. Packets coming in X.25 address 652365123 arrive via PVC 1 and are translated to TCP packets and transmitted out IP address 131.108.1.1.
translate x25 652365123 pvc 1 tcp 131.108.1.1
incoming option outgoing
The following example illustrates incoming LAT to outgoing TCP translations. The unadvertised keyword prevents broadcast of service advertisements to other servers. Outgoing translated packets are transmitted out IP address rubble via TCP port 4005.
translate lat pt-printer1 unadvertised tcp rubble port 4005
incoming option outgoing option
The following example illustrates a more complex configuration that calls an X.29 profile and swaps the default PAD operation of the router to that of an X.25 host.
x29 profile fullpackets 2:0 3:0 4:100 7:21
translate x25 217536124 profile fullpackets tcp rubble port 4006 swap
incoming option outgoing option global
The following example illustrates the use of the TCP incoming protocol option printer for an incoming TCP connection.
translate tcp 160.89.32.250 printer x25 5678
incoming option outgoing
The following example illustrates the use of the X.25 incoming protocol option printer for an incoming X.25 connection.
translate x25 55555 printer tcp 131.108.1.1
incoming option outgoing
The following example translates LAT on an incoming line to SLIP on an outgoing line. It uses header compression only if incoming TCP packets on the same interface are compressed.
translate lat rudolph slip 1.0.0.4 headercompressed
incoming outgoing option
The following example translates X.25 packets to PPP. It enables routing updates between the two connections.
translate x25 12345678 ppp 1.0.0.2 routing
incoming outgoing option
The following example first shows the command to disable keepalives on a PPP line, then shows sample output from the show translate command when keepalives have been turned off on the line.
translate lat ramble ppp 172.21.2.2 keepalive 0
.
.
.
router# show translate
Translate From: LAT ramble
To: PPP 172.21.2.2 no-keepalive
1/0 users active, 1 peak, 1 total, 0 failures
Use the x25 host global configuration command to define a static host name for address mapping. Use the no x25 host command to remove the host name.
x25 host name x.121-address [cud call-user-data]| name | Host name. |
| x.121-address | X.121 address. |
| cud call-user-data | (Optional) Specifies the Call User Data (CUD) field in the X.25 Call Request packet. |
No static address mapping is defined.
Global configuration
This command permits you to map an X.121 address to an easily recognizable name. You can later use this host name instead of the X.121 address when you issue the translate command for X.25.
The following example specifies a static address mapping:
x25 host Willard 4085551212
The following example removes a static address mapping:
no x25 host Willard
The following example specifies static address mapping from the X.121 address 12345678 to the host name masala. It then uses the name masala in the translate command in place of the X.121 address when translating from the X.25 host to the PPP host with address 1.0.0.2.
x25 host masala 12345678 translate x25 masala ppp 1.0.0.2 routing
translate
To limit access to the router from certain X.25 hosts, use the x29 access-list global configuration command. To delete an entire access list, use the no form of this command.
x29 access-list access-list-number {permit | deny} regular-expression| access-list-number | Number of the access list. It can be a value between 1 and 199. |
| deny | Denies access and clears call requests immediately. |
| permit | Permits access to the router. |
| regular-expression | Usually the X.121 address, with or without regular expression pattern-matching characters, with which to compare for access. |
No default access list is defined.
Global configuration
An access list can contain any number of access list items. The list are processed in the order in which you entered them, with the first match causing the permit or deny condition. If an X.121 address does not match any of the regular expression in the access list, access will be denied.
Access lists take advantage of the message field defined by Recommendation X.29, which describes procedures for exchanging data between two PADs or a PAD and a DTE device.
The UNIX-style regular expression characters allow for pattern matching of characters and character strings in the address. Various pattern-matching constructions are available that will allow many addresses to be matched by a single regular expressions. Refer to the appendix "X.3 PAD Parameters" later in this publication for more information.
The following example permits connections to hosts with addresses beginning with the string 31370:
x29 access-list 2 permit ^31370
To create a PAD profile script for use by the translate command, use the x29 profile global configuration command.
x29 profile name parameter:value [parameter:value]| name | Name of the PAD profile script. |
| parameter:value | (Optional) X.3 PAD parameter number and value separated by a colon. You can specify multiple parameter-value pairs. |
No default PAD profile script defined.
Global configuration
When an X.25 connection is established, the router acts as if an X.29 SET PARAMETER packet had been sent containing the parameters and values set by the x29 profile command and sets the router accordingly.
The following profile script turns local edit mode on when the connection is made and establishes local echo and line termination upon receipt of a Return. The name linemode is used with the translate global configuration command to effect use of this script.
x29 profile linemode 2:1 3:2 15:1
translate
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