Hi, I am testing OpenBGPD as a route-reflector, with a view to replacing our existing route reflectors. I have a test environment where I have multiple vendors equipment peered with OpenBGPD to ensure it can handle our use-cases.
I noticed that our Cisco IOS-XE devices have unstable BGP sessions and are dropping with the OpenBGPD log message: "sending notification: error in UPDATE message, optional attribute error" Upon further inspection, when the Cisco router issues an NLRI update and withdraw's a VPNv4 prefix OpenBGPD drops the session. I found a report of a similar issue, but with a Juniper MX router from Hendrik Meyburgh back in 2012, where the problem was with the vrf-table-label command on JunOS. I checked our configuration and IOS-XE is configured with: "mpls label mode all-vrfs protocol bgp-vpnv4 per-vrf" which assigns a single label per VRF table, rather than a label per prefix. I suspect that this is causing the NLRI updates to be formatted in a way that OpenBGPD does not like. I took a packet capture of the UPDATE causing the session to be terminated, there are two instances of it being dropped in the pcap available at https://mergesync.btg.co.nz/index.php/s/rvc8mc9RCpTR1Lg Is there anything we can do to stop OpenBGPD from dropping the session? Running per-VRF label's is default on all Juniper platforms, and is common on Cisco as well. Regards, Andrew
