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Implementing IS-IS on Cisco IOS XR Software
How to Implement IS-IS on Cisco IOS XR Software
RC-93
Cisco IOS XR Routing Configuration Guide
Configuring Single Topology for IS-IS
After an IS-IS instance is enabled, it must be configured to compute routes for a specific network
topology.
This task explains how to configure the operation of the IS-IS protocol on an interface for an IPv4 or
IPv6 topology.
Restrictions
To enable the router to run in single-topology mode, configure each of the IS-IS interfaces with all of
the address families enabled and “single-topology” in the address-family IPv6 unicast in the IS-IS router
stanza. You can use either the IPv6 address family or both IPv4 and IPv6 address families, but your
configuration must represent the set of all active address families on the router. In addition, you should
explicitly enable single-topology operation by configuring it in the IPv6 router address family submode.
Exceptions to these instructions exist:
1. If the address-family stanza in the IS-IS process contains the adjacency-check disable command,
then an interface is not required to have the address family enabled.
2. If the interface is configured to Level 2 only. (This exception permits the running of IPv4 and IPv6
areas.)
3. The single-topology command is not valid in the ipv4 address-family submode.
Step 5
end
or
commit
Example:
RP/0/RP0/CPU0:router(config-isis)# end
or
RP/0/RP0/CPU0:router(config-isis)# commit
Saves configuration changes.
• When you issue the end command, the system prompts
you to commit changes:
Uncommitted changes found, commit them before
exiting(yes/no/cancel)?
[cancel]:
–
Entering yes saves configuration changes to the
running configuration file, exits the configuration
session, and returns the router to EXEC mode.
–
Entering no exits the configuration session and
returns the router to EXEC mode without
committing the configuration changes.
–
Entering cancel leaves the router in the current
configuration session without exiting or
committing the configuration changes.
• Use the commit command to save the configuration
changes to the running configuration file and remain
within the configuration session.
Step 6
show isis [instance
instance-id
] protocol
Example:
RP/0/RP0/CPU0:router# show isis protocol
(Optional) Displays summary information about the IS-IS
instance.
Command or Action Purpose