This article describes the effect of enabling or disabling graceful-restart on existing BGP sessions under global and configured routing-instance.
After configuring set routing-options graceful-restart disable, BGP sessions flapped. However, the BGP session under routing-instance remains stable.
The following configuration was done under global instance on the router:
set routing-options graceful-restart enable
or
set routing-options graceful-restart
or
set routing-options graceful-restart disable
or
delete/deactivate set routing-options graceful-restart
This re-establishes the BGP session to advertise the graceful-restart capability. The BGP sessions under configured routing-instnace (L3VPN) will not be affected due to the above configuration change.
lab@MX> show bgp summary
Groups: 2 Peers: 2 Down peers: 0
Table Tot Paths Act Paths Suppressed History Damp State Pending
inet.0
0 0 0 0 0 0
inet.2
0 0 0 0 0 0
bgp.l3vpn.0
10 10 0 0 0 0
bgp.l3vpn.2
0 0 0 0 0 0
bgp.mvpn.0
738 738 0 0 0 0
Peer AS InPkt OutPkt OutQ Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
1.2.1.4 45543 771 589 0 1 28:35 Establ
inet.0: 0/0/0/0
inet.2: 0/0/0/0
bgp.l3vpn.0: 10/10/10/0
bgp.l3vpn.2: 0/0/0/0
bgp.mvpn.0: 738/738/738/0
L3VPN-IPTV.inet.0: 3/10/10/0
L3VPN-IPTV.mvpn.0: 498/498/498/0
30.30.30.201 100 4 6 0 0 41 Establ
L3VPN-IPTV.inet.0: 0/0/0/0
lab@MX# set routing-options graceful-restart disable
[edit]
lab@MX# commit and-quit
commit complete
Exiting configuration mode
lab@MX> show bgp summary
Groups: 2 Peers: 2 Down peers: 1
Table Tot Paths Act Paths Suppressed History Damp State Pending
inet.0
0 0 0 0 0 0
inet.2
0 0 0 0 0 0
bgp.l3vpn.0
0 0 0 0 0 0
bgp.l3vpn.2
0 0 0 0 0 0
bgp.mvpn.0
0 0 0 0 0 0
Peer AS InPkt OutPkt OutQ Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
27.2.192.4 45543 0 0 0 0 4 Active
30.30.30.201 100 5 8 0 0 1:08 Establ <<< This session which is under routing-instance L3VPN-IPTV did not flap
L3VPN-IPTV.inet.0: 0/0/0/0
Graceful-restart is configured on a per instance basis. If BGP is configured under default global instance, such as under [routing-options], it will take effect only for this main instance. If the graceful-restart is applied to the specific routing-instance under [routing-instance <instance-name> routing-options], then it will take effect on that specific instance. Hence, any changes done related to graceful-restart under one routing-instance will not affect BGP sessions in other routing-instances.
This is the expected behavior in Junos.