System information

Troubleshooting ISO CLNS 12-283
ISO CLNS: Users Cannot Make Connections over Parallel Path
Possible Problem Solution
Routing has not
converged
Step 1 Use the show clns route privileged exec command to view the CLNS routing table.
Examine the table for routes listed as “possibly down.” This indicates that the routing
protocol has not converged.
Step 2 Wait for the routing protocol to converge. Use the show clns route command again to
see whether the routes are now up.
Note: ISO-IGRP does load balancing only for domain prefix routes. If you are doing Level 1
or Level 2 routing in ISO-IGRP, only a single path is maintained. If that path goes down, you
must wait for the network to converge before the alternate path is available.
Misconfigured
access list
Step 1 Use the trace exec command to determine the path taken to reach remote hosts.
Step 2 If you discover a router that is stopping traffic, use the show access-lists privileged
exec command to see whether any access lists are configured on the router.
Step 3 Disable all access lists on the router using no access-group interface configuration
commands on the appropriate interfaces.
Step 4 Determine whether hosts can now use the protocol in question. If traffic can get
through, it is likely that an access list is blocking protocol traffic.
Step 5 Make sure the access list does not filter traffic from ports that are used by the protocol
in question. Configure explicit permit statements for traffic that you want the router
to forward normally.
Step 6 Enable the access list and verify that the protocol still functions correctly. If problems
persist, continue isolating and analyzing access lists on all routers in the path from
source to destination.
Hardware or
media problem
For information on troubleshooting hardware problems, see Chapter 3, “Troubleshooting
Hardware and Booting Problems.” For information on troubleshooting media problems, refer
to the media troubleshooting chapter that covers the media type used in your network.