[j-nsp] QSFP28 oddities between Arista and QFX after upgrade

[Jason Lixfeld]

Hey,

I have a QFX5110 in the lab which I upgraded from 17.something to 18.4 to resolve some ISIS weirdness.  ISIS weirdness resolved, but now the previously working link between this QFX and an Arista 7280SR no longer comes up, despite light levels on both sides being within norms.  I went from 18.4 to 19.1 just for the hell of it, and still no bueno.

The QSFP28 in the QFX comes up if it’s looped to itself, as does the QSFP28 in the Arista.  The Arista QSFP28 links to another Arista, or an MX204.  The QFX QSFP28 links to the same MX204 as well (no other QSFP28 gear to test with otherwise) so it seems to be a weird compatibility issue between the Arista and the QFX?

Does this sort of thing smell familiar to anyone?  I’ve had pretty good luck with 100G compatibility in general so far, so I’m not overly familiar with any knobs to work around any compatibility issues that may creep up here or there, so happily accept some pointers if anyone has some clue.

Thanks!