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In some cases, when administrators need to configure multiple BGP neighbors, to simplify the configuration, BGP neighbor groups are created and defined with the neighbor-range command.
As an example:
config router bgp
set as YYYY
set router-id z.z.z.z
set holdtime-timer 60
set ebgp-multipath enable
set ibgp-multipath enable
set additional-path enable
set graceful-restart enable
next
end
config neighbor-group
edit "test_1"
set capability-graceful-restart enable
set link-down-failover enable
set next-hop-self enable
set soft-reconfiguration enable
set remote-as XXXX
next
end
config neighbor-range
edit 1
set prefix 192.10.10.0 255.255.255.0
set neighbor-group "test_1"
next
end
Administrators usually also want to use the Graceful Restart feature to avoid network disruptions and packet loss in cases of a failover or a reboot of the cluster.
When using this 'neighbor-groups', during failover testing, packet loss can be seen.
Reverting the configuration to manually configured neighbors corrects the packet loss. This indicates a possible issue with Graceful Restart when using BGP neighbor groups defined with the neighbor-range command.
Conclusion:
Since neighbor-groups are passive and cannot trigger a re-connection, it's expected that neighbor-groups defined with neighbor-range can't perform Graceful Restart when it is the side that initiates a restart.
BGP graceful restart against dynamic BGP peers during a HA failover is not supported at this time in FortiOS.
In order to benefit fully from the Grace Restart feature, BGP configuration would need to be modified to manually configure neighbors instead of neighbor-groups defined with neighbor-range.
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