Information Technology Reference
In-Depth Information
Table 12-6 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table12-6 ISO CLNS: Connections Fail Using Certain Protocols
Possible Problem
Solution
Host is not
configured to
support the
service
Verify that the needed protocols are correctly installed and
configured on the host system. Consult your vendor's
documentation for information on configuring hosts.
Misconfigured
access list
1.
Use the
trace
exec command to determine the path taken to
reach remote hosts.
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.
3.
Disable all access lists on the router using
no access-group
interface configuration commands on the appropriate
interfaces.
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.
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.
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.
ISO CLNS: Users Cannot Make Connections over Parallel Path
Symptom:
In environments with multiple paths between networks, when one link goes down,
connections across a parallel link are not possible.
IS-IS has equal-cost load balancing for both Level 1 and Level 2 routes. If there are parallel
paths in an IS-IS network and one goes down, the other should serve as a backup that is
ready to be used immediately.
Note
