After IS-IS configuration one might want to verify if everything works as it should. Cisco IOS offers a few commands that help accomplish this task:

The first (non IS-IS specific) command that can be used is:

Router# show ipv6 protocols [summary]

It displays the parameters and current state of the active IPv6 routing processes.

To view a list of all connected routers running IS-IS in all or specific areas use the following
command:

Router# show isis [area-tag] [ipv6 | *] topology

The show clns command is used to display end system (ES), intermediate system (IS) and multitopology IS-IS (M-ISIS) neighbours.

Router# show clns [area-tag] neighbors \\
                                     [interface-type interface-number] [area] [detail]

The same command may also be used to display adjacency information for IS-IS neighbours:

Router# show clns area-name is-neighbors [type number] [detail]

To display a log of significant events during an IS-IS SPF computation, use the debug isis spfevents
command.

Router# debug isis spf-events

Examples

a) In the following example output information about the parameters and current state of that active IPv6 routing process is displayed using the show ipv6 protocols EXEC command: