This issue is seen starting 202411.
2025 Feb 24 19:54:55.980637 MSN-2700 INFO bgp#bgpcfgd: The 'set src' configuration with Loopback0 ip 'FC00:1::32' has been scheduled to be added
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel1017|FC00::29/126', 'SET', (('state', 'ok'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel105|FC00::9/126', 'SET', (('state', 'ok'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel1017', 'SET', (('vrf', ''),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel1011|10.0.0.12/31', 'SET', (('state', 'ok'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel1023|10.0.0.28/31', 'SET', (('state', 'ok'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel1014|10.0.0.16/31', 'SET', (('state', 'ok'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel108', 'SET', (('vrf', ''),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('Loopback0|10.1.0.32/32', 'SET', (('state', 'ok'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 INFO bgp#bgpcfgd: The 'set src' configuration with Loopback0 ip '10.1.0.32' has been scheduled to be added
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel1014', 'SET', (('vrf', ''),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('PortChannel1023|FC00::39/126', 'SET', (('state', 'ok'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('Loopback0', 'SET', (('NULL', 'NULL'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('Loopback0|FC00:1::32/128', 'SET', (('NULL', 'NULL'),))'
2025 Feb 24 19:54:55.980637 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('Loopback0|10.1.0.32/32', 'SET', (('NULL', 'NULL'),))'
2025 Feb 24 19:54:55.996435 MSN-2700 DEBUG bgp#bgpcfgd: Received message : '('fc00::42', 'SET', (('asn', '64001'), ('holdtime', '10'), ('keepalive', '3'), ('local_addr', 'fc00::41'), ('name', 'ARISTA01T0'), ('nhopself', '0'), ('rrclient', '0')))'
We find it rarely that this logic doesn't result in set src being set with loopback ip address
route-map RM_SET_SRC6 permit 10
exit
!
route-map RM_SET_SRC permit 10
exit
2025 Feb 24 19:54:48.685582 MSN-2700 NOTICE bgp#zebra[34]: [V98V0-MTWPF] client 52 says hello and bids fair to announce only bgp routes vrf=0
2025 Feb 24 19:54:59.978720 MSN-2700 ERR bgp#zebra[34]: [HSYZM-HV7HF] Extended Error: Carrier for nexthop device is down
2025 Feb 24 19:54:59.978720 MSN-2700 ERR bgp#zebra[34]: [WVJCK-PPMGD][EC 4043309093] netlink-dp (NS 0) error: Network is down, type=RTM_NEWNEXTHOP(104), seq=34, pid=3716991302
2025 Feb 24 19:54:59.978720 MSN-2700 ERR bgp#zebra[34]: [X5XE1-RS0SW][EC 4043309074] Failed to install Nexthop (18[if 4 vrfid 0]) into the kernel
2025 Feb 24 19:55:00.080107 MSN-2700 ERR bgp#zebra[34]: [HSYZM-HV7HF] Extended Error: Carrier for nexthop device is down
2025 Feb 24 19:55:00.080182 MSN-2700 ERR bgp#zebra[34]: [WVJCK-PPMGD][EC 4043309093] netlink-dp (NS 0) error: Network is down, type=RTM_NEWNEXTHOP(104), seq=45, pid=3716991302
Checking on swss rec. the intf_table for loopback is only set later in time than bgpcfg processing
2025-02-24.19:55:06.815196|INTF_TABLE:Loopback0|SET|NULL:NULL|mac_addr:00:00:00:00:00:00
2025-02-24.19:55:06.815219|INTF_TABLE:Loopback0:10.1.0.32/32|SET|scope:global|family:IPv4
2025-02-24.19:55:06.815511|INTF_TABLE:Loopback0:FC00:1::32/128|SET|scope:global|family:IPv6
Hence it is not clear if this is an FRR issue or bgpcfgd issue. Currently there are no logs or records for the commit command in bgpcfgd. I recommend adding one which can be helpful in debug
This issue is seen starting 202411.
bgpcfgd has logic to apply set src command when receiving loopback interface
sonic-buildimage/dockers/docker-fpm-frr/frr/zebra/zebra.set_src.conf.j2
Line 5 in a1e2c1f
We find it rarely that this logic doesn't result in set src being set with loopback ip address
During this time, there is no indication of any error from zebra
Checking on swss rec. the intf_table for loopback is only set later in time than bgpcfg processing
Hence it is not clear if this is an FRR issue or bgpcfgd issue. Currently there are no logs or records for the commit command in bgpcfgd. I recommend adding one which can be helpful in debug
Tech support logs
frr.running_config