When using Cisco router IOS-XR 6.5.x or 7.0.x, as BGP Link State speaker, BGP session crash when decoding unknown Link State TLV.

First, LinkAttributesParser warn about valid link attribute (in fact about attribute it is not able to decode). This produce a BGPDocumentedException in bgp-parser. After that, BGP session crashes and ODL attempt to re-open the BGP session. However, the BGP session has not been properly close i.e. the Cisco Router doesn't see that the BGP session close. Thus, in turn to the new BGP Open message, the Router close it with a CEASE=6 reason (which is normal as the router feel that the peer try to re-open an on-going BGP session). After that, ODL enter in a loop where it try to open the BGP session, and the Router to close it with the CEASE=6 reason.

2020-07-15T19:31:47,720 | WARN  | epollEventLoopGroup-7-1 | LinkAttributesParser             | 215 - org.opendaylight.bgpcep.bgp-linkst
ate - 0.13.1 | TLV 1173 is not a valid link attribute, ignoring it                                                                      
2020-07-15T19:31:47,989 | ERROR | epollEventLoopGroup-7-1 | BGPDocumentedException           | 223 - org.opendaylight.bgpcep.bgp-parser
-api - 0.13.1 | Error = MALFORMED_ATTR_LIST

[...]

2020-07-15T19:31:58,217 | INFO  | epollEventLoopGroup-7-3 | BGPSessionImpl                   | 229 - org.opendaylight.bgpcep.bgp-rib-im
pl - 0.13.1 | Closing session: BGPSessionImpl

Unknown macro: {channel=[id}

                                                                                                                                  
2020-07-15T19:31:58,217 | INFO  | epollEventLoopGroup-7-3 | BGPPeer                          | 229 - org.opendaylight.bgpcep.bgp-rib-im
pl - 0.13.1 | Session with peer 10.194.77.240 terminated: BGPTerminationReason{error=CEASE}                                             
2020-07-15T19:31:58,218 | INFO  | epollEventLoopGroup-7-3 | BGPPeer                          | 229 - org.opendaylight.bgpcep.bgp-rib-im
pl - 0.13.1 | Closing session with peer

The only way to stop this behavior is to stop ODL or delete BGP peer.

Here, the unknown TLV is a valid one i.e. MSD TLV

The expected behavior is to raise only a warning message without the BGPDocumentedException

The expected