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Cisco Bug: CSCvu92233 - Primary i-BGP backup e-bgp resulting 4sec of convergence

Last Modified

Sep 03, 2020

Products (3)

  • Cisco ASR 9000 Series Aggregation Services Routers
  • Cisco IOS XR Software
  • Cisco IOS XR for Third Party Hardware

Known Affected Releases


Description (partial)

Traffic loss is larger than expected, after primary path goes down.

The reason is that the backup path is not used.

BGP PIC prefix has one primary path, and one backup path, which has 'bgp-best-ext' flag

Sample show output,

RP/0/0/CPU0:ios#show cef detail 
Fri Aug 14 09:15:11.102 EDT, version 9, internal 0x1000001 0x0 (ptr 0x61ef9008) [1], 0x0 (0x0), 0x0 (0x0)
 Updated Aug 14 09:14:09.471
 Prefix Len 32, traffic index 0, precedence n/a, priority 0
  gateway array (0x626080f8) reference count 1, flags 0x102010, source rib (7), 0 backups
                [1 type 3 flags 0x48441 (0x6266c650) ext 0x0 (0x0)]
  LW-LDI[type=0, refc=0, ptr=0x0, sh-ldi=0x0]
  gateway array update type-time 1 Aug 14 09:14:09.471
 LDI Update time Aug 14 09:14:09.498

  Level 1 - Load distribution: 0
  [0] via, recursive

   via, 3 dependencies, recursive, bgp-ext, bgp-best-ext, backup [flags 0x160]
    path-idx 0 NHID 0x0 [0x61ef9280 0x0]
    next hop via

   via, 3 dependencies, recursive [flags 0x0]
    path-idx 1 NHID 0x0 [0x61ef93c0 0x0], Internal 0x62a880b0
    next hop via

    Load distribution: 0 (refcount 1)

    Hash  OK  Interface                 Address
    0     Y   UNKNOWN intf 0x0000001c       

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