IS-IS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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IS-IS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Static IS-IS BGP tracking

Updated: June 9, 2026

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Explains static IS-IS BGP status concepts, supporting users in monitoring and managing the relationship between IS-IS and BGP protocols.

The static IS-IS BGP tracking feature is a routing capability that

  • integrates static IS-IS neighbor advertisement with BGP peer state monitoring

  • enables conditional advertisement of static IS-IS links based on BGP neighbor status, and

  • improves topology accuracy and operational reliability by dynamically controlling static neighbor advertisement.

Feature Name

Release Information

Description

Static IS-IS BGP status

 Release 26.1.1

Introduced in this release on: Fixed Systems (8200, 8700); Centralized Systems (8600); Modular Systems (8800 [LC ASIC: Q100, Q200, P100])

You can now boost network accuracy and reliability with the static IS-IS BGP tracking feature. It only advertises static IS-IS neighbors when the matching BGP peer is up, using a simple route-policy to track their status. Two-way connectivity checks are turned off for static neighbors to avoid false failures, and IS-IS extended TLVs make sure these neighbors are clearly shown in IS-IS LSPs for accurate network mapping.

Two-way connectivity checks

Two-way connectivity check mechanisms ensure link reliability by checking connectivity in both directions. For static neighbors, since the remote device does not run IS-IS, Two-way connectivity check mechanism is disabled to avoid false negatives. This suppression allows the network controller to accurately represent the topology without expecting a two-way handshake on links where IS-IS is not active on the remote end.

IS-IS extended TLVs and their role in static neighbor representation

IS-IS extended TLVs are iS-IS protocol elements that carry link state information for adjacencies. You rely on IS-IS Extended TLVs to represent static neighbors seamlessly within iS-IS LSPs. This ensures that controllers receive consistent and accurate topology information without needing to understand new or different link types, maintaining interoperability and simplifying network management.

Best practices for static IS-IS neighbor advertisement and connectivity

Follow these best practices for static IS-IS neighbor advertisement and connectivity to maintain accurate and reliable network topology information.

  • Always configure a route policy that tracks the state of the BGP neighbor associated with a static IS-IS link. This ensures you advertise the static neighbor only when the BGP peer is operational.

  • Suppress two-way connectivity check (TWCC) for static neighbors where the remote device does not run IS-IS. This avoids false negatives and maintains accurate topology representation.

  • Use IS-IS extended TLVs to advertise static neighbors identically to real IS-IS adjacencies. This enables seamless distribution of topology information without requiring protocol changes.

Configure IS-IS static neighbor tracking

Configure static IS-IS neighbors and enable conditional advertisement for enhanced topology accuracy and reliable link status.

Use this task when setting up static neighbors in an IS-IS network to maintain precise topology representation and dependable connectivity.

Before you begin

  • Ensure you have access to the network controller and the necessary permissions to configure IS-IS settings.

  • Ensure of these information:

    • IS-IS System-ID of the static neighbor

    • Either or both remote IPv4 and IPv6 addresses

    • Affinity link to advertise

  • Enable logging static neighbor advertisement changes

Follow these steps to perform static IS-IS neighbor advertisement and connectivity:

Procedure

1.

Configure IS-IS static neighbor by using the static-neighbor command.

Example:

Router(config)# router isis 1
Router(config-isis)# interface GigabitEthernet0/2/0/7
Router(config-isis-if)# static-neighbor
Router(config-isis-static-nbr)# system-id 0001.0002.0007
Router(config-isis-static-nbr)# remote ipv4 address 10.2.2.2
Router(config-isis-static-nbr)# affinity RED
Router(config-isis-static-nbr)#log-advertisement-changes
2.

View the running configuration using the show running-config command.

Example:

router isis 1
 interface GigabitEthernet0/2/0/7
  static-neighbor
   system-id 0001.0002.0007
   remote ipv4 address 10.2.2.2
   affinity RED
   log-advertisement-changes
  !
 !
!
3.

Configure a static neighbor explicitly to define a peer for the routing protocol on an interface, thereby bypass the dynamic adjacency discovery process. Despite this, the routing protocol remains active on the interface, and the local IP subnet will still be advertised to the statically configured neighbor. Enable conditional static neighbor advertisement based on the BGP session state.

Example:

Router(config)# router isis 1
Router(config-isis)# affinity-map RED bit-position 7
Router(config-isis)# interface GigabitEthernet0/2/0/7
Router(config-isis-if)# point-to-point
Router(config-isis-if)# static-neighbor
Router(config-isis-static-nbr)# system-id 0001.0002.0007
Router(config-isis-static-nbr)# remote ipv4 address 10.1.1.2
Router(config-isis-static-nbr)# Remote ipv6 address: 2001:DB8::1
Router(config-isis-static-nbr)# advertise route-policy isis-bgp
Router(config-isis-static-nbr)# exit
Router(config-isis-static)# address-family ipv4 unicast
Router(config-if)# exit
Router(config-if)# address-family ipv6 unicast
Router(config-if)# exit
4.

Configure a track object to monitor the state of a BGP neighbor for the IPv4 unicast address family by entering global configuration mode and specifying the neighbor’s IP address.

Example:

Router(config)# track track-bgp-neighbors
Router(config-track)# type bgp neighbor address-family state
Router(config-track-bgp-nbr-af)# address-family ipv4 unicast
Router(config-track-bgp-neighbor)# neighbor 10.2.35.1 
Router(config-track-af)# exit
Router(config-track)# exit
5.

Configure a route policy named isis-bgp that permits advertisement of a static IS-IS neighbor only when the associated BGP neighbor is up.

Example:

Router(config)# route-policy isis-bgp
Router(config-rpl)# if bgp-nbr is up then
Router(config-rpl-if)# pass
Router(config-rpl-if)# else
Router(config-rpl-if)# drop
Router(config-rpl-if)# endif
Router(config-rpl)# end-policy
6.

Use show isis static-neighbors command to verify the status of the static neighbors.

Example:

Router# show isis static-neighbors 
Fri Sep  6 05:32:18.889 PDT

IS-IS 1 static neighbors:

System Id          Interface        State
0001.0002.0007     Gi0/2/0/7        Up            

  Remote IPv4 Address: 10.1.1.2
  Remote IPv6 Address: 2001:DB8::1
  Affinity: RED
  Route-policy: isis-bgp
  Level-1:
    Advertised in MT (Standard (IPv4 Unicast)): Yes
    Last Transition in MT (Standard (IPv4 Unicast)): 07:55:35.177
    Advertised in MT (IPv6 Unicast): Yes
    Last Transition in MT (IPv6 Unicast): 09:06:41.918
  Level-2:
    Advertised in MT (Standard (IPv4 Unicast)): Yes
    Last Transition in MT (Standard (IPv4 Unicast)): 07:55:35.183
    Advertised in MT (IPv6 Unicast): Yes
    Last Transition in MT (IPv6 Unicast): 09:06:41.917

The show output shows that the static IS-IS neighbor advertisement is controlled by the configured route policy named isis-bgp

The show output also shows that the static IS-IS neighbor is currently being advertised in the IS-IS Multi-Topology (MT) instance for the standard IPv4 unicast address family. This confirms that the route policy condition was met, that is the BGP neighbor is up, and the static neighbor is actively included in the IS-IS topology for IPv4 unicast routing.