[j-nsp] UDLD packets not traversing MX-80

[Ankur Mittal]

Has anyone out there experienced Cisco UDLD packets not traversing BGP signaled L2VPNs transparently. We are a service provider and have a Juniper MPLS core (MX-80s used as PE routers and MX-480 and T-640 as P routers). 
 
Recently, we upgraded the MX-80s from 10.3R2.11 to 11.1R6 and noticed that the customers started complaining about UDLD packets not traversing our network. This is really bizarre given that we deploy a CPE that does q-in-q so when the frames get to upstream Juniper MX-80, it’s already tagged and as such should be dumped into the L2VPN without any further inspection. Moreover L2VPNs don't learn MAC addresses and as such should not be blocking well known MAC addresses. 
 
We provide transparent services so it’s really crucial that we transport all these Layer 2 control protocols through our network. We have always been able to transparently pass these L2TP in the previous software versions (except 11.1 onwards). 
 
Can anyone shed any light on the similar experience and the workarounds. 
 
Thanks a lot in advance.