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Cisco Bug: CSCvh57750 - FRR gets delayed due to incorrect handling of AFI (v4/v6/mpls) updates during link flaps

Last Modified

Jul 25, 2019

Products (3)

  • Cisco Network Convergence System 5500 Series
  • Cisco Network Convergence System 5508
  • Cisco IOS XR Software

Known Affected Releases

6.1.3.BASE

Description (partial)

Symptom:
NCS5500 IOS-XR 6.1.3 with FRR (TE FRR or TI-LFA) enabled for fast convergence in a case of primary path failure.

After the link flap, traffic drop might be observed due to LFIB (Label Forwarding Information Base) on linecard is not synchronized with LFIB on RP:

RP/0/RP0/CPU0:NCS5500#show mpls for labels 103001
Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes
Label  Label       or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
103001 Exp-Null-v4 SR Pfx (idx 3001)  Te0/0/0/1/0  10.23.123.0     0
       104219      SR Pfx (idx 3001)  Te0/0/0/1/2  10.23.123.3     14737        (!)

RP/0/RP0/CPU0:NCS5500#show mpls for labels 103001 location 0/0/cpu0
Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes
Label  Label       or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
103001 Exp-Null-v4 SR Pfx (idx 3001)  Te0/0/0/1/2  10.23.123.0     0
       104219      SR Pfx (idx 3001)  Te0/0/0/1/2  10.23.123.3     14959

Conditions:
link flap and several thousand prefixes with backup route
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