[c-nsp] ASR920 randomly loosing layer-2 on a port

[Shawn L]

I have a strange one.  I have a ASR-920-4SZ ( 2 copper ports, 4 10-gig sfp
ports all licensed).

In one of the 10gig sfp ports I have a cisco copper SFP.  The
interface configuration is really basic

interface TenGigabitEthernet0/0/4
 description P2P Connection to XXXX
 no ip address
 no negotiation auto
 service instance 58 ethernet
    encapsulation untagged
    bridge-domain 58

It's a point-to-point (really just a vlan) to another site.  When we turned
it up, it didn't want to work right away -- I could see mac addresses from
the remote side, but not the local.  Nothing I did seemed to make it want
to learn mac addresses.  Shut/no-shut, plugging a laptop into it, verifying
SFP was supported and worked in another router, etc.  In all cases the link
would come up, but no layer-2 traffic.

The last thing that I did was to add the no negotiation auto to the
interface thinking SFP-strangeness, toggle what you can, whatever.  At that
point we got side-tracked and when we looked at it again an hour later it
was all working correctly.  So we left it as it was.

A day or 2 ago, the connection dropped and we're back to the same situation
again.  Link is up, but not learning mac addresses from te0/0/4.  Nothing
has changed (which we verified) since we got the circuit working the first
time.  Bouncing the interface, going back to auto negotiate, etc. doesn't
seem to help.

Wondering if anyone's seen this before or has any ideas.  I know the asr920
is 'fun' and a 1-gig sfp in a 1-gig/10-gig slot isn't the greatest idea
(thinking of replacing it with something with more copper ports), but I'm
trying to figure out why it worked before and suddenly stopped in the
meantime.


Thanks