BGP neighbourship is established between SRX and FortiGate (could be any other Vendor FW)

FortiGate reports BGP Warning : Unrecognized Capability Code 71

BGP neighbourship is UP/ESTABLISHED without any issue

BGP Peer (FortiGate) in this case reports Warning : Unrecognized Capability Code 71

No impact on operation due to this Warning

Unrecognized Capability Code 71 : Code 71 stands for the Long-Lived Graceful Restart (LLGR) Capability for BGP. During the initial phase of setting up a BGP session (the OPEN message state), routers/FWs negotiate a list of features they support.

If any feature/capability is not supported by the peer, a Warning message is logged flagging the same.

Long-Lived Graceful Restart (LLGR)

Standard Graceful Restart allows a router to hold onto routing tables for a few minutes if the BGP control plane restarts.

LLGR takes this a step further for non-critical or slow-converging networks where in it allows a peer to retain "stale" routes for a much longer period (potentially hours or days) but marks them with a lower priority attribute so they are only used as a last resort if no better path exists.

On Juniper devices (SRX in this case), LLGR is enabled by default.

We can explicitly disable this for the peer to address the Warning on the Peer device.

set protocols bgp group <group-name> neighbor <neighbour IP> graceful-restart long-lived receiver disable

Clear the BGP session on both ends and check for the warning messages on the peer.

https://www.juniper.net/documentation/us/en/software/cn-cloud-native23.4/cn-cloud-native-feature-guide/cn-cloud-native-network-feature/topics/topic-map/cn-cloud-native-graceful-restart-llgr.html