Modifying Active BGP neighbor-group

bjberginz · ‎07-15-2014

If you modify a BGP neighbor-group that is apllied to established BGP neighbors, does that reset the neighbors that are using the group?

bhnegi · ‎07-20-2014

I don't think so.

When you modify the neighbor group it will only take action on the next session establishment. New parameters are considered only during session setup.

Please eloborate the behavior you are seeing.

Best Regards,

Bheem

bjberginz · ‎07-23-2014

So modifying the neighbor group doesn't impact an extablished session and will only take effect when the sessin is dropped and re-established? I'm not seeing any behavior, I just have a lot of peers associated with a neighbor group that I want to modify, and am trying to avoid chaos if possible.

bhnegi · ‎07-23-2014

That is correct but since this is production network I would suggest doing it during a MW.

I quickly tried it in lab and I don't see any issue.. I am removing update-source from neighbor-group. You can see the ibgp peer don't flap and uptime is incrementing.

RP/0/0/CPU0:IOSxr2#sh bgp vpnv4 unicast summary
Wed Jul 23 23:50:35.236 UTC
BGP router identifier 6.6.6.6, local AS number 25159
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0x0 RD version: 0
BGP main routing table version 18
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.

Process RcvTblVer bRIB/RIB LabelVer ImportVer SendTblVer StandbyVer
Speaker 18 18 18 18 18 18

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer InQ OutQ Up/Down St/PfxRcd
3.3.3.3           0 25159      22      16       18    0    0 00:09:41          6
5.5.5.5           0 25159      19      16       18    0    0 00:09:52          4
7.7.7.7           0 25159      22      16       18    0    0 00:09:51          6

RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#conf t
Wed Jul 23 23:50:38.285 UTC
RP/0/0/CPU0:IOSxr2(config)#router bgp 25159
RP/0/0/CPU0:IOSxr2(config-bgp)#neighbor-group IBGP-PEER
RP/0/0/CPU0:IOSxr2(config-bgp-nbrgrp)# remote-as 25159
RP/0/0/CPU0:IOSxr2(config-bgp-nbrgrp)#no update-source Loopback0
RP/0/0/CPU0:IOSxr2(config-bgp-nbrgrp)#commit
Wed Jul 23 23:51:13.553 UTC
RP/0/0/CPU0:IOSxr2(config-bgp-nbrgrp)#end
RP/0/0/CPU0:IOSxr2#sh clock
Wed Jul 23 23:51:17.413 UTC
23:51:17.453 UTC Wed Jul 23 2014
RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#sh bgp vpnv4 unicast summary
Wed Jul 23 23:51:22.132 UTC
BGP router identifier 6.6.6.6, local AS number 25159
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0x0 RD version: 0
BGP main routing table version 18
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.

Process RcvTblVer bRIB/RIB LabelVer ImportVer SendTblVer StandbyVer
Speaker 18 18 18 18 18 18

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer InQ OutQ Up/Down St/PfxRcd
3.3.3.3           0 25159      23      17       18    0    0 00:10:28          6
5.5.5.5           0 25159      20      17       18    0    0 00:10:38          4
7.7.7.7           0 25159      23      17       18    0    0 00:10:38          6

RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#sh clock
Wed Jul 23 23:51:27.962 UTC
23:51:28.002 UTC Wed Jul 23 2014
RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#
RP/0/0/CPU0:IOSxr2#sh bgp vpnv4 unicast summary
Wed Jul 23 23:51:30.122 UTC
BGP router identifier 6.6.6.6, local AS number 25159
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0x0 RD version: 0
BGP main routing table version 18
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.

Process RcvTblVer bRIB/RIB LabelVer ImportVer SendTblVer StandbyVer
Speaker 18 18 18 18 18 18

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer InQ OutQ Up/Down St/PfxRcd
3.3.3.3           0 25159      23      17       18    0    0 00:10:36          6
5.5.5.5           0 25159      20      17       18    0    0 00:10:46          4
7.7.7.7           0 25159      23      17       18    0    0 00:10:46          6

RP/0/0/CPU0:IOSxr2#

Best Regards,

Bheem

bjberginz · ‎07-24-2014

Thanks for the testing results, it may be the type of change to the neighbor-group or software version, but I got different results in my testing. I changed an address family in a neighbor-group to 'route reflector client' and it immediately reset the neighbor that used the group when committed.

srikant · ‎06-14-2018

Even I faced the similar problem, all the BGP session using a neighbor-group got reset when I edited the neighbor-group.

smilstea · ‎06-14-2018

What parameter did you change?

What is your configuration for BGP?

Thanks,

Sam

srikant · ‎06-21-2018

I have removed IPv6 config from the neighbor-group config.