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Cisco Bug: CSCuo99941 - Autoroute-announce never retries after failure

Last Modified

Jul 20, 2018

Products (8)

  • Cisco Carrier Routing System
  • Cisco NCS 6008 - 8-Slot Chassis
  • Cisco IOS XR Software
  • Cisco ASR 9922 Router
  • Cisco ASR 9010 Router
  • Cisco ASR 9006 Router
  • Cisco ASR 9001 Router
  • Cisco ASR 9912 Router

Known Affected Releases

4.1.1.MPLS 4.2.3.MPLS 4.3.2.MPLS

Description (partial)

Symptom:

After a tail router has been replaced in the network, autoroute-announced tunnels to that node are no longer announced to the IGP after recovery, and therefore do not appear in the RIB.

Conditions:

This issue has only been observed when removing a tunnel destination router from a network and replacing it with another running, identically-configured router. 

To trigger this issue, is is necessary that:
 - a destination node be removed from the network in such a way that its TE router LSA is not withdrawn
 - the node be replaced before the stale router LSA times out and is purged from the network
 - all tunnels to the destination are configured with FRR

The exact sequence of events that must occur at the tunnel head for this issue to be observed is:
 - a stale router LSA originated by the tail router exists in the topology while the tail is down
 - an adjacency is formed to the tail that results in a valid path for the tunnel
 - a Path message for the tunnel is sent
 - the stale LSA is removed from the topology
 - the Resv message for the tunnel is sent
 - the refreshed LSA for the tail node is added to the topology.

Note that this issue has not been observed during (and is not expected to be triggered by) a simple node reload.

The issue has only been observed in an OSPF network, but could in principle also be observed with ISIS.
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