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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

6.6.3.BASE

Description (partial)

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

The reason is that the backup path is not used.

Conditions:
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 100.1.0.1/32 detail 
Fri Aug 14 09:15:11.102 EDT
100.1.0.1/32, 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 1.1.1.1/32, recursive

   via 10.1.0.2/32, 3 dependencies, recursive, bgp-ext, bgp-best-ext, backup [flags 0x160]
    path-idx 0 NHID 0x0 [0x61ef9280 0x0]
    next hop 10.1.0.2/32 via 10.1.0.2/32


   via 1.1.1.1/32, 3 dependencies, recursive [flags 0x0]
    path-idx 1 NHID 0x0 [0x61ef93c0 0x0], Internal 0x62a880b0
    next hop 1.1.1.1/32 via 1.1.1.1/32

    Load distribution: 0 (refcount 1)

    Hash  OK  Interface                 Address
    0     Y   UNKNOWN intf 0x0000001c   10.3.0.2       

RP/0/0/CPU0:ios#
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