[j-nsp] EX4550 apparently dropping IPv6 RA

[John Neiberger]

I was paged to take a look at an interesting problem this morning. We have
an MX960 connected to an EX4550 via a trunk carrying multiple VLANs. The
EX4550 is, in turn, connected to a second switch. I don't recall what model.

The second switch used to be connected to something else and was moved over
to the EX4550 yesterday, I believe. Some time overnight, some devices on
the second switch lost IPv6 connectivity. They had no default gateway.
Quite a bit of troubleshooting by the on-shift engineers and JTAC show that
the EX4550 appears to have stopped forwarding IPv6 Router Advertisements.
It is passing ND and NS, but there does not seem to be any RA or RS between
the two switches.

The EX4550 is just layer two. There is no routing configured on it, so it
should just be passing the RAs from the router to the hosts on the second
switch, but that doesn't seem to be happening.

I don't recall ever seeing anything quite like this and it certainly makes
no sense. JTAC is recommending that we restart some process on the switch.
I can't recall the name of the process, but it was something like "sbit".

Have any of you ever seen anything quite like this?

Thanks,
John