Cisco Bug: CSCum05295 - BGP multipath entry in uRIB does not get updated after attribute change
May 11, 2020
- Cisco Nexus 7000 Series Switches
- Cisco Nexus 7000 10-Slot Switch
- Cisco Nexus 7000 18-Slot Switch
- Cisco Nexus 7000 9-Slot Switch
Known Affected Releases
Symptom: There are two symptoms that can be seen for this bug. 1. The following error message can be seen in syslog and IGP redistributing BGP routes may fail. 2013 Dec 13 01:21:58 PTAINTS410 %OSPF-3-RPM_LIB_API_FAILED: bgp_lookup_ext_attr() - failed in rpm_acquire_bgp_shmem_lock() 2. A route with a stale metric in the routing table exists `DC1-CORE-3# sho ip bgp 10.10.63.0 BGP routing table information for VRF default, address family IPv4 Unicast BGP routing table entry for 10.10.63.0/25, version 127677 Paths: (6 available, best #1) Flags: (0x00001a) on xmit-list, is in urib, is best urib route Multipath: eBGP iBGP <snip> Path type: internal, path is valid, received and used, not best reason: Router Id, multipath AS-Path: NONE, path sourced internal to AS 188.8.131.52 (metric 101) from 184.108.40.206 (220.127.116.11) Origin IGP, MED 409, localpref 100, weight 0 <====== MED 409 should match routing table DC1-CORE-3# sho ip route 10.10.63.0 IP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] '%<string>' in via output denotes VRF <string> 10.10.63.0/25, ubest/mbest: 5/0 *via 18.104.22.168, [200/409], 00:10:12, bgp-65001, internal, tag 65001 *via 22.214.171.124, [200/409], 00:43:22, bgp-65001, internal, tag 65001 *via 126.96.36.199, [200/409], 00:43:22, bgp-65001, internal, tag 65001 *via 188.8.131.52, [200/409], 00:43:22, bgp-65001, internal, tag 65001 *via 184.108.40.206, [200/409], 00:43:22, bgp-65001, internal, tag 65001 via 220.127.116.11, [200/65940], 00:15:17, bgp-65001, internal, tag 65001 <<======= OLD MED 409 not updated Conditions: 1. IGP (e.g., OSPF) redistributes BGP routes. 2. The redistribution uses route-map to evaluate community associated with the routes. 3. Maximum-paths command is configured. 4. BGP receives paths with only attribute (e.g., AS-PATH,MED) change.
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