Troubleshooting "Optional attribute error"

[Daniel Suchy]

On 05/06/2011 01:50 AM, Ondrej Zajicek wrote:
> There are (AFAIK) only two things that may generate such error - malformed
> NLRI or its next hop attribute. Also NLRI of unexpected kind (like IPv4 in
> bird6). Perhaps the other side sends both IPv4 and IPv6 in one session?

Just a note - we had similar issue caused by IPv6 prefix originated
somewhere (we also have full BGP). In our setup, BGP communities was not
filtered and additionaly, metric was set. If there was high ammount of
the communities and metric was set, in this case Cisco router malformed
update packet - there was empty NLRI sent out...

In our case, Quagga on the remote side was failing processing malformed
update and it was resetting the peer. Maybe this is similar issue (as
this is expected behavior stated in RFC). Bug was confirmed by Cisco -
but is not fixed yet on all platforms.

Our workaround was removal of the metric statement from the route-map or
striping/reducing number of the communities on the peer. This must be
done on the Cisco side.

Daniel