[j-nsp] Autonegotiation woes with EX-3400

[Anthony Johnson]

I have run into this before using 1 Gigabit SFP optics in the uplink module
on EX switches. We disabled auto-negotiation on the uplink and didn't an
issue. See https://kb.juniper.net/InfoCenter/index?page=content&id=KB34060

It's definitely not my preferred way of handling the situation, but it
worked, and as long as it's documented it shouldn't become an problem in
the future.

On Tue, May 5, 2020 at 11:55 AM Norman Elton <normelton at gmail.com> wrote:

> 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
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-- 
- Anthony

http://www.linkedin.com/in/anthonyjohnson