Troubleshooting DECnet

This chapter presents protocol-related troubleshooting information for DECnet Phase IV connectivity and performance problems. The procedures outlined apply only to environments in which DECnet routing is enabled on the router, not to environments in which DECnet is being bridged (that is, bridging is enabled on the router interfaces and EtherType 6003 is being passed).

This chapter does not discuss other Digital protocols, such as MOP, LAT, LAVC, and LAST.

Note For information about troubleshooting ISO CLNS (DECnet Phase V) problems, refer to the "Troubleshooting ISO CLNS" chapter.

The first section in this chapter, "Using DECnet in a Multiprotocol Environment," discusses possible problems when using DECnet in an internetwork running other protocols as well. The remaining sections describe specific DECnet symptoms, the problems that are likely to cause each symptom, and the solutions to those problems.

Note In some of the symptom discussions that follow, OPCOM messages are used to illustrate certain errors. These examples assume that OPCOM is running and event logging is enabled. For more information about event logging, see the section "Configuring a DECnet Node to Log DECnet Events" later in this chapter.

Using DECnet in a Multiprotocol Environment

It is important to remember that DECnet changes the MAC address of router interfaces. This behavior can cause problems for other protocols that are already enabled on the router.

If after enabling DECnet on a router interface other protocols (such as Novell IPX or XNS) experience connectivity loss due to address resolution problems, the problem is probably a result of DECnet changing the MAC address of the router interface.

As a rule, enable DECnet on router interfaces first, then enable other protocols. Otherwise, use the copy running-config startup-config command to save the router configuration and then reload the router.

Connections to DEC Hosts Fail over Router (End Node Problem)

Symptom: DECnet nodes cannot communicate when attempting to make connections over routers.

Note This section focuses on problems in end nodes. For router-related problems and solutions, see the section "Connections to DEC Hosts Fail over Router (Router Problem)" later in this chapter.

Table 9-1 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-1: DECnet: Connections to DEC Hosts Fail over Router (End Node Problem)

Possible Problem	Solution
Misconfigured end node	Step 1 Check the end node configuration using the show executor characteristics NCP command. Step 2 Make sure that the end node type (nonrouting Phase IV, routing Phase IV, area), node address, node name, and routing and link parameters are correctly specified. Step 3 Check the circuit characteristics using the show known circuit characteristics NCP command. Step 4 Make sure that the designated router, hello timer, router priority (if the node is a routing node), and other circuit characteristics are properly configured. Step 5 Reconfigure the end node if any of the end node or circuit characteristics are misconfigured. For information on configuring end nodes, refer to the vendor documentation.
Host access control rejects connection	With this problem, users will see the message "connect failed, access control rejected." This is typically a session layer problem. Step 1 Make sure that the following requirements are satisfied: User-supplied access control information is correct Proxy access is set up correctly Proxy database and proxy account are correct Step 2 Make sure that the user's security access matches the access specifications for the user on the remote systems. Step 3 If there are problems in any of these areas, make changes as necessary.
Unrecognized object	With this problem, users will see the message "connect failed, unrecognized object." Step 1 Use the tell NCP command to determine whether the object is defined on the target node. The syntax of the tell command is as follows: `tell target-node-name show known objects` Step 2 If the object is not defined, log in as superuser and run NCP to define the object with the set object NCP command, as follows: `set object object-id` Step 3 After the object is defined, use the tell NCP command to determine whether the object has a file specified, as follows: `tell target-node-name show object object-id character` Step 4 Exit NCP and determine whether the file specified for the object exists. Step 5 If the file for the requested object does not exist, create the file. Step 6 Make sure the permissions for the specified file are correct.
Insufficient resource error	With this problem, VMS users will see the following message: `% system-E-REMRSC, insufficient system resource at remote node` Note: This error message might not indicate a problem. These parameter values can be set intentionally to prevent network connections beyond a certain number. Try tuning the following DEC target system parameters: SYSGEN parameters: MAXPROCESSCNT NCP parameters: MAXIMUM LINKS ALIAS MAXIMUM LINKS AUTHORIZE parameters: MAXJOBS MAXACCTJOBS

Configuring a DECnet Node to Log DECnet Events

In addition to the diagnostic tools available on your router, DECnet environments provide a wealth of diagnostic information. DECnet nodes can use the DECnet Event Logging Facility (EVL) to track DECnet events. EVL allows you to monitor significant network events, such as lost packets and circuit failures.

The following steps outline the basic tasks required to enable event logging on a VMS system:

Step 1 Determine whether the Operator Communication Manager (OPCOM) process is running:

$ show system

Step 2 If OPCOM does not appear in the list of running processes, enter the following command to start it:

$ @sys$system:STARTUP.com OPCOM

Step 3 Use the Network Control Protocol (NCP) to enable event logging:

$ MCR NCP

NCP> SET logging MONITOR KNOWN Events

NCP> DEFINE logging MONITOR KNOWN Events

NCP> SET logging MONITOR STATE ON

NCP> DEFINE logging MONITOR STATE ON

Step 4 Exit NCP:

NCP> Exit

Step 5 To monitor network events from a console terminal, enter the following command at the VMS system prompt:

$ REPLY/ENABLE = NETWORK

(This command is equivalent to the terminal monitor privileged EXEC command.)

Connections to DEC Hosts Fail over Router (Router Problem)

Symptom: DECnet nodes cannot communicate when attempting to make connections over routers.

Note This section focuses on problems in the router. For end node-related problems and solutions, see the section "Connections to DEC Hosts Fail over Router (End Node Problem)" earlier in this chapter.

Table 9-2 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-2: DECnet: Connections to DEC Hosts Fail over Router (Router Problem)

Possible Problem	Solution
DECnet is not enabled on router	Step 1 Use the show decnet interface privileged EXEC command to see on which interfaces, if any, DECnet is enabled. Step 2 If the output shows that DECnet is not enabled, use the show running-config privileged EXEC command to view the router configuration. Determine whether DECnet global and interface command specifications are configured on the router. Step 3 Enable DECnet routing on the appropriate routers and interfaces. For detailed information on configuring DECnet, refer to the Cisco IOS Network Protocols Configuration Guide, Part 2.
Missing decnet cost command	Step 1 Make sure that there is a cost configured on DECnet interfaces. Check the configuration for a decnet cost cost-value interface configuration command entry. Step 2 If the command is not present, add the decnet cost command for each interface on which DECnet is enabled.
End nodes and router area number mismatch	Step 1 Check the configuration of end nodes and routers on the network segment. Check the area address specified on end nodes and routers. Step 2 If an end node is not in the same area as a router on the segment, you must either change the address of the end node to be the same as a router on the segment, or you must reconfigure a router on the segment with the same area number as the end node.
Actual cost to the destination area is more than the configured cost	Step 1 Use the show decnet interface EXEC command to determine the configured maximum cost to the destination area. Step 2 Use the show decnet route EXEC command to determine the actual cost to the destination area. Step 3 If the actual cost is more than the configured maximum cost, increase the maximum cost configured on the router. On Level 1 routers, use the decnet max-cost global configuration command to increase the area maximum cost. On Level 2 routers, use the decnet area-max-cost global configuration command to increase the area maximum cost.
Actual number of hops to the destination is more than the configured maximum number of hops	Step 1 Use the show decnet interface command to determine the maximum number of hops allowed for intra-area routing. Step 2 Use the show decnet route EXEC command to determine the actual number of hops to the destination as shown in the DECnet routing table. Step 3 If the actual number of hops is more than the configured maximum allowed hops, increase the maximum hops configured on the router. On Level 1 routers, use the decnet max-hops global configuration command to increase the maximum hops. On Level 2 routers, use the decnet area-max-hops global configuration command to increase the maximum number of hops.
Access list is misconfigured	Step 1 Use the show decnet access-list privileged EXEC command to determine whether there are DECnet access lists configured on the router. Step 2 If there are access lists applied to router interfaces, use the debug decnet connects privileged EXEC command to determine whether important packets are being forwarded properly. Step 3 If packets are being dropped, disable all access lists on the router using the no decnet access-group interface configuration command. Step 4 Determine whether connections to hosts are now possible. If connections are made successfully, a misconfigured access list is probably the problem. Step 5 Enable access lists on the router using the decnet access-group interface configuration command. Enable the lists one at a time until connectivity is lost, at which point you have found the problem access list. Step 6 Modify the access list as necessary. Make sure to include explicit permit statements for traffic that you want to be forwarded normally. Step 7 If problems persist, continue the process until you have isolated all problem access lists.
Node address out of range	Step 1 Use the show running-config privileged EXEC command to view router configurations. Check to see if the decnet max-address global configuration command has been configured. This command sets the highest DECnet node number allowed in the area. Note: The decnet max-address command specifies the highest node number allowed in an area, `not` the maximum number of node addresses allowed in an area. For example, if you configure the command decnet max-address 1000 on a router and you configure a node with a node address of 1001, the address is out of range. Step 2 The default maximum address is 1023. However, if another value is configured, the node address might be more than the configured value. If this is the case, increase the maximum address value using the decnet max-address command.
Partitioned area	Make sure the network topology has no discontiguous areas. If any discontiguous areas exist, reconfigure the topology by changing area addresses or by creating a path (with a router) to create a contiguous network.
Media problem	For information on troubleshooting serial lines, refer to the "Troubleshooting Serial Line Problems" chapter. For information on troubleshooting LAN media, refer to the "Troubleshooting LAN Media Problems" chapter.

End Nodes Cannot Find Designated Router

Symptom: End nodes cannot find a designated router. End nodes cannot access nodes that are on different LANs, but other nodes connected to the same LAN are accessible.

Table 9-3 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-3: DECnet: End Nodes Cannot Find Designated Router

Possible Problem	Solution
DECnet not enabled on router	Step 1 Use the show running-config privileged EXEC command to view the router configuration. Determine whether DECnet global configuration and interface command specifications are configured on the router. Step 2 Enable DECnet routing on the appropriate routers and interfaces. For detailed information on configuring DECnet, refer to the Cisco IOS `Network Protocols Configuration Guide, Part 2`.
End nodes and router area number mismatch	Step 1 Check the configuration of end nodes and routers on the network segment. Check the area address specified on end nodes and routers. Step 2 If an end node is not in the same area as a router on the segment, you must either change the address of the end node to be the same as a router on the segment, or you must reconfigure a router on the segment with the same area number as the end node.
Hello packets are not being exchanged	Step 1 Use the debug decnet adj privileged EXEC command to determine whether the router is sending hello packets and whether hellos are being received. Step 2 If no exchange is occurring, use the show interfaces EXEC command to determine whether the interface input and output queues are full. A full input queue is indicated by a value of 75/75, and a full output queue is indicated by a value of 40/40. Step 3 If the queues are full and no hello packets are being exchanged, contact your technical support representative. Step 4 If routers are sending hello packets, check end nodes to determine why end nodes are rejecting hello packets.
Media problem	For information on troubleshooting serial lines, refer to the "Troubleshooting Serial Line Problems" chapter. For information on troubleshooting LAN media, refer to the "Troubleshooting LAN Media Problems" chapter.

Router or End Node Sees Incorrect Designated Router

Symptom: Routers and end nodes see an incorrect or an unexpected designated router. If your network requires a specific router to be elected the designated router, allowing another router to become a designated router can cause unpredictable network behavior and can block connectivity in and out of the area.

Table 9-4 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-4: DECnet: Router or End Node Sees Incorrect Designated Router

Possible Problem	Solution
Priority of the expected designated router is not configured correctly	Step 1 Use the show decnet interface EXEC command to determine which router is the designated router. Note the priority of the router that is shown in the command output. Step 2 If the designated router identified in the output is not the correct router, use the show decnet interface command on the expected designated router and the actual designated router. Step 3 Compare the priority of the actual designated router with that of the expected designated router. The router that you want to be the designated router should have the highest priority. Step 4 If necessary, use the decnet router-priority interface configuration command to give a higher priority to a router so that it will be elected the designated router.
Multiple routers have the same router priority	Step 1 Use the show decnet interface command to determine which router is the designated router. Note the priority of the router that is shown in the command output. Step 2 Use the show decnet interface command on the expected designated router and compare the priorities of the actual and the expected designated routers. Step 3 If the routers have the same priority, use the decnet router-priority interface configuration command to configure a higher priority on the router that should be elected the designated router. Note: If two routers are configured with the same priority, the router with the higher node number will become the designated router.
Adjacency between nodes is not bidirectional	Step 1 Use the show decnet route EXEC command to see if the adjacency with the expected designated router is in a "down" or "initializing" state. Step 2 Use the debug decnet adj privileged EXEC command to determine whether hello packets are being exchanged. Step 3 If a router is not sending hello packets, use the show interfaces command to determine whether the interface input and output queues are full. A full input queue is indicated by a value of 75/75, and a full output queue is indicated by a value of 40/40. Step 4 If the queues are full, and no hello packets are being exchanged, contact your router technical support representative. Step 5 If routers are sending hello packets, contact end-node administrators to determine why end nodes are rejecting hello packets.

Possible Problem

Solution

Priority of the expected designated router is not configured correctly

Step 1 Use the show decnet interface EXEC command to determine which router is the designated router. Note the priority of the router that is shown in the command output.

Step 2 If the designated router identified in the output is not the correct router, use the show decnet interface command on the expected designated router and the actual designated router.

Step 3 Compare the priority of the actual designated router with that of the expected designated router. The router that you want to be the designated router should have the highest priority.

Step 4 If necessary, use the decnet router-priority interface configuration command to give a higher priority to a router so that it will be elected the designated router.

Multiple routers have the same router priority

Step 1 Use the show decnet interface command to determine which router is the designated router. Note the priority of the router that is shown in the command output.

Step 2 Use the show decnet interface command on the expected designated router and compare the priorities of the actual and the expected designated routers.

Step 3 If the routers have the same priority, use the decnet router-priority interface configuration command to configure a higher priority on the router that should be elected the designated router.

Note: If two routers are configured with the same priority, the router with the higher node number will become the designated router.

Adjacency between nodes is not bidirectional

Step 1 Use the show decnet route EXEC command to see if the adjacency with the expected designated router is in a "down" or "initializing" state.

Step 2 Use the debug decnet adj privileged EXEC command to determine whether hello packets are being exchanged.

Step 3 If a router is not sending hello packets, use the show interfaces command to determine whether the interface input and output queues are full. A full input queue is indicated by a value of 75/75, and a full output queue is indicated by a value of 40/40.

Step 4 If the queues are full, and no hello packets are being exchanged, contact your router technical support representative.

Step 5 If routers are sending hello packets, contact end-node administrators to determine why end nodes are rejecting hello packets.

Routers Not Establishing Adjacencies

Symptom: Routers do not establish adjacencies with other routers on the same LAN.

Table 9-5 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-5: DECnet: Router Not Establishing Adjacencies

Possible Problem	Solution
More than 32 routers on the network	DECnet limits the number of adjacencies that can be established by a router to 32. Step 1 Enable the debug decnet events privileged EXEC command to determine whether the adjacency is being rejected. Enable this command on one router at a time. Step 2 If the adjacency is being rejected, reduce the number of adjacent routers or increase the priority of a router that you want to be adjacent so that it has a higher priority than one of the other neighboring routers. An adjacency will be established with the router you want instead of with a router assigned a lower priority.
Node address out of range	Step 1 Use the show running-config privileged EXEC command to view router configurations. Check to see if the decnet max-address global configuration command has been configured. This command sets the highest DECnet node number allowed in the area. Note: The decnet max-address command specifies the highest node number allowed in an area, `not` the maximum number of node addresses allowed in an area. For example, if you configure the command decnet max-address 1000 on a router and you configure a node with a node address of 1001, the address is out of range. Step 2 The default maximum address is 1023. However, if another value is configured, the node address might be more than the configured value. If this is the case, increase the maximum address value using the decnet max-address command.
Router area number is higher than configured decnet max-area	If the area number of a DECnet node (such as a router) is higher than the configured decnet max-area value, the adjacency will be reset. Step 1 Use the show running-config privileged EXEC command to view the router configuration. Look for decnet max-area global configuration command entries. This command sets the DECnet maximum area number for the router. Note: The decnet max-area command specifies the highest area value allowed in the network, `not` the maximum number of areas configurable. For example, if you configure the command decnet max-area 60 and you configure a node with area number 61, the node's area address is out of range. Step 2 Use the show running-config privileged EXEC command to find the area number configured on other DECnet routers. Compare the value configured by the decnet max-area command to the area numbers of other routers. Step 3 If a router's area number is higher than the value configured by the decnet max-area global configuration command, reconfigure the decnet max-area command so that the DECnet maximum area is higher than the area number of all routers.
Adjacency between routers is not bidirectional	Step 1 Use the show decnet route EXEC command to see if the adjacency with the expected designated router is in a "down" or "initializing" state. Step 2 If you are troubleshooting a nonbroadcast multiaccess network (such as Frame Relay or X.25), make sure that map statements are properly configured. Step 3 Use the debug decnet adj privileged EXEC command to determine whether hello packets are being exchanged. Step 4 If a router is not sending hello packets, use the show interfaces command to determine whether the interface input and output queues are full. A full input queue is indicated by a value of 75/75, and a full output queue is indicated by a value of 40/40. Step 5 If the queues are full, and no hello packets are being exchanged, contact your router technical support representative.

Routing Node Adjacencies Toggle Up and Down

Symptom: Routing adjacencies toggle up and down. Output such as the following appears repeatedly on the DEC system console:

%%%%%%%%%%% OPCOM 30-JUN-1993 1:25:07.45 %%%%%%%%%%%%
Message from user DECNET on The Bay
DECnet event 4.16, adjacency rejected
From NODE 12.1 (The Bay), 30-JUN-1993 1:25:07.45
Circuit UNA-0, Adjacent node = 1.101 (Vax1)
%%%%%%%%%%% OPCOM 30-JUN-1993 1:25:07.46 %%%%%%%%%%%%
Message from user DECNET on The Bay
DECnet event 4.15, adjacency up
From NODE 12.1 (The Bay), 30-JUN-1993 1:25:07.46
Circuit UNA-0, Adjacent node = 1.12 (Vax2)

This output indicates that routers are constantly being added and removed from the routing table. The OPCOM messages specify DECnet events 4.16 (adjacency rejected) and 4.15 (adjacency up) for specific routing nodes.

Table 9-6 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-6: DECnet: Routing Node Adjacencies Toggle Up and Down

Possible Problem	Solution
Total number of routing nodes on network segment is more than 32	DECnet limits the number of adjacencies that can be established by a router to 32. Step 1 Enable the debug decnet events privileged EXEC command to determine whether the adjacency is being rejected. Enable this command on one router at a time. Step 2 If the adjacency is being rejected, reduce the number of adjacent routers on the segment.
Hardware problem	Check the error message output to identify the routing node or nodes that are causing the adjacency to toggle. Follow the procedures outlined in the "Troubleshooting Hardware and Booting Problems" chapter.

Possible Problem

Solution

Total number of routing nodes on network segment is more than 32

DECnet limits the number of adjacencies that can be established by a router to 32.

Step 1 Enable the debug decnet events privileged EXEC command to determine whether the adjacency is being rejected. Enable this command on one router at a time.

Step 2 If the adjacency is being rejected, reduce the number of adjacent routers on the segment.

Hardware problem

Check the error message output to identify the routing node or nodes that are causing the adjacency to toggle.

Follow the procedures outlined in the "Troubleshooting Hardware and Booting Problems" chapter.

No Phase IV Connectivity over Phase V Backbone

Symptom: Communication between DECnet Phase IV areas separated by a ISO CLNS (Phase V) backbone fails. Phase IV nodes cannot communicate with other Phase IV nodes across a Phase V cloud. However, nodes can communicate with one another within the same Phase IV cloud.

Note For more information about troubleshooting DECnet /OSI internetworks, see the "Troubleshooting ISO CLNS" chapter.

Table 9-7 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-7: DECnet: No DECnet Phase IV Connectivity over Phase V Backbone

Possible Problem	Solution
Misconfigured addresses	Step 1 Use the show interfaces command to confirm that CLNS and DECnet Phase IV are both configured on ISO CLNS backbone routers. Step 2 Make sure that the decnet conversion global configuration command is configured on backbone routers to allow DECnet Phase IV-to-ISO CLNS conversion. Step 3 Use the show running-config privileged EXEC command on backbone routers to verify that DECnet addresses agree with CLNS addresses. These addresses are easily misconfigured: DECnet addresses are specified in decimal, and CLNS (NSAP) addresses are specified in hexadecimal. For more information, refer to the section "DECnet Phase IV and ISO CLNS Addresses" later in this chapter. Step 4 If the area addresses do not agree, confirm the address specifications and reconfigure the DECnet and CLNS addresses on the router. For detailed information on configuring DECnet Phase IV, CLNS, and conversion, refer to the Cisco IOS `Network Protocol Configuration Guide, Part 2`.
ISO CLNS or DECnet not enabled on appropriate interfaces	Step 1 On Phase IV routers bordering the backbone, use the show clns interface and the show decnet interface commands to see which interfaces are running which protocols. Verify that DECnet and ISO CLNS are enabled on backbone router interfaces where conversion will occur. Step 2 If DECnet is not configured on the correct interfaces, enable it. Make sure you specify the decnet cost interface configuration command to assign a cost to the interface. If ISO CLNS routing is not configured on the correct interfaces, use the clns router interface configuration command. For detailed information on configuring DECnet Phase IV and ISO CLNS, refer to the Cisco IOS `Network Protocol Configuration Guide, Part 2`.

Possible Problem

Solution

Misconfigured addresses

Step 1 Use the show interfaces command to confirm that CLNS and DECnet Phase IV are both configured on ISO CLNS backbone routers.

Step 2 Make sure that the decnet conversion global configuration command is configured on backbone routers to allow DECnet Phase IV-to-ISO CLNS conversion.

Step 3 Use the show running-config privileged EXEC command on backbone routers to verify that DECnet addresses agree with CLNS addresses.

These addresses are easily misconfigured: DECnet addresses are specified in decimal, and CLNS (NSAP) addresses are specified in hexadecimal.

For more information, refer to the section "DECnet Phase IV and ISO CLNS Addresses" later in this chapter.

Step 4 If the area addresses do not agree, confirm the address specifications and reconfigure the DECnet and CLNS addresses on the router.

For detailed information on configuring DECnet Phase IV, CLNS, and conversion, refer to the Cisco IOS Network Protocol Configuration Guide, Part 2.

ISO CLNS or DECnet not enabled on appropriate interfaces

Step 1 On Phase IV routers bordering the backbone, use the show clns interface and the show decnet interface commands to see which interfaces are running which protocols.

Verify that DECnet and ISO CLNS are enabled on backbone router interfaces where conversion will occur.

Step 2 If DECnet is not configured on the correct interfaces, enable it. Make sure you specify the decnet cost interface configuration command to assign a cost to the interface. If ISO CLNS routing is not configured on the correct interfaces, use the clns router interface configuration command.

For detailed information on configuring DECnet Phase IV and ISO CLNS, refer to the Cisco IOS Network Protocol Configuration Guide, Part 2.

DECnet Phase IV and ISO CLNS Addresses

Address conversion between DECnet Phase IV and ISO CLNS (Phase V) requires that Network Service Access Point (NSAP) addresses be Phase IV-compatible. If an address can be converted to a valid Phase IV address, it is Phase IV-compatible.

To be compatible, the OSI area number must be between 1 and 63 (when converted to decimal) and the OSI station ID must be of the format "AA00.0400.xxxx." In addition, the OSI area and the DECnet area (calculated from the OSI station ID) must match. This allows the DECnet Phase IV address to be properly extracted from the NSAP.

Table 9-8 shows addresses and their equivalent DECnet Phase IV addresses, and indicates whether the NSAP address is Phase IV-compatible and why.

Table 9-8: OSI NSAP-to-DECnet Phase IV Address Conversion

OSI NSAP Address (Hex)	OSI Area	DECnet Address (Decimal)	Phase-IV Compatible
49.1111.0012.AA00.0400.0149.20	18	18.257	Yes
49.1111.0009.AA00.0400.BC04.20	9	1.188	No--OSI area does not match the DECnet area
49.1111.0041.AA00.0400.FFFF.20	65	63.1023	No--OSI area is greater than 63.
49.1111.000E.AA00.0400.0000.20	14	0.0	No--DECnet address in NSAP station ID is invalid
49.1111.0009.0800.2B05.8297.20	9	-	No--NSAP station ID is not in the proper format ("AA00.0400.`xxxx`")

Poor Performance

Symptom: Performance in a DECnet network is slow or unreliable. Connections to hosts over one or more routers are periodically inaccessible or drop unexpectedly.

Table 9-9 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 9-9: DECnet: Poor Performance

Possible Problem	Solution
DECnet traffic problem	Step 1 Use the show decnet traffic EXEC command and check the Received and Forwarded field in the output. In most cases, the values in these fields should match. Step 2 If the values do not match, check the Returned, Converted, Access Control Failed, No Route, and Encapsulation Failed fields to see what is causing the performance problem. Step 3 If the problem cannot be isolated or solved, contact your technical support representative for assistance.
Timer mismatch	Step 1 Use the show decnet interface EXEC command on all routers in the network. Verify that the values configured for hello timers and routing update timers are consistent among all routers in the network. `C4500#show decnet interface` `[...]` `Ethernet0 is up, line protocol is up, encapsulation is ARPA` `Interface cost is 50, priority is 64, DECnet network: 0` `We are the designated router` `Sending HELLOs every 15 seconds, routing updates 40 seconds` `[...]` Step 2 If timer values are inconsistent, bring routers into conformance using the decnet hello-timer and the decnet routing-timer interface configuration commands. The hello timer can be restored to its default of 15 seconds by using the no form of the command.
Media problem	Step 1 Use the show interfaces EXEC command and look for CRCs in the output. Step 2 If there are CRCs, there is probably a media problem. Refer to the "Troubleshooting Serial Line Problems" chapter or the "Troubleshooting LAN Media Problems" chapter for more information.
Buffer drops	Step 1 Use the show interfaces EXEC command to check the input and output queues. Look for drops. Step 2 If drops are occurring, contact your technical support representative for assistance.

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