Specifications

Implementing IS-IS on Cisco IOS XR Software
Information About Implementing IS-IS on Cisco IOS XR Software
RC-170
Cisco IOS XR Routing Configuration Guide
Key Features Supported in the Cisco IOS XR IS-IS Implementation
The Cisco IOS XR implementation of IS-IS conforms to the IS-IS Version 2 specifications detailed in
RFC 1195 and the IPv6 IS-IS functionality based on the Internet Engineering Task Force (IETF) IS-IS
Working Group draft-ietf-isis-ipv6.txt document.
The following list outlines key features supported in the Cisco IOS XR implementation:
• Single topology IPv6
• Multitopology
• Nonstop forwarding (NSF), both Cisco proprietary and IETF
• Three-way handshake
• Mesh groups
• Multiple IS-IS instances
• Configuration of a broadcast medium connecting two networking devices as a point-to-point link
• Fast-flooding with different threads handling flooding and shortest path first (SPF).
Note For information on IS-IS support for Bidirectional Forwarding Detection (BFD), see Cisco IOS XR
Interface and Hardware Configuration Guide and Cisco IOS XR Interface and Hardware Command
Reference.
IS-IS Configuration Grouping
Cisco IOS XR groups all of the IS-IS configuration in router IS-IS configuration mode, including the
portion of the interface configurations associated with IS-IS. To display the IS-IS configuration in its
entirety, use the show running router isis command. The command output displays the running
configuration for all configured IS-IS instances, including the interface assignments and interface
attributes.
IS-IS Configuration Modes
The following sections show how to enter each of the configuration modes. From a mode, you can enter
the ? command to display the commands available in that mode.
Router Configuration Mode
The following example shows how to enter router configuration mode:
RP/0/RP0/CPU0:router# configuration
RP/0/RP0/CPU0:router(config)# router isis isp
RP/0/RP0/CPU0:router(config-isis)#
Router Address Family Configuration Mode
The following example shows how to enter router address family configuration mode:
RP/0/RP0/CPU0:router(config)# router isis isp
RP/0/RP0/CPU0:router(config-isis)# address-family ipv6 unicast
RP/0/RP0/CPU0:router(config-isis-af)#