[j-nsp] Autonegotiation woes with EX-3400

[Norman Elton]

Hello!

We've got a sizable deployment of EX-3400s on campus, and have noticed
that after a reboot, some switches fail to bring their uplink
connection online. Connections between two EX switches tend to work
fine, connections between an EX-3400 and an MX or SRX fail much more
frequently. In some cases, it fails every single time. In all cases,
we can down the interface, bring it back up, and things are fine. It
seems to only fail immediately after a reboot. We've tried changing
fiber, changing SFPs, etc. Nothing.

We've worked with JTAC, and our account team, on a resolution. In both
cases, the answer from engineering is that this is a hardware chipset
problem, and not resolvable in software. The workaround is to disable
autonegotiation on uplink interfaces.

Has anyone else experienced this phenomenon? If it's a chipset issue,
I would think it's present in other vendor's products?

We've long standardized on running autonegotiation, everywhere. Do
others actually disable autonegotiation on "managed" connections,
where you're configuring both ends of the link?

Thanks!

Norman