Re: constant FEC errors juniper mpc10e 400g

[Tom Beecher <beecher () beecher cc>]

> We've seen the same between Juniper and Arista boxes in the same rack
> running at 100G, despite cleaning fibres, swapping optics, moving ports,
> moving line cards, e.t.c. TAC said it's a non-issue, and to be expected,
> and shared the same KB's.
 Just for extra clarity off those KB, probably has nothing to do with
vendor interop as implied in at least one of those.

You will see some volume of FEC corrected on 400G FR4 with the same router
hardware and transceiver vendor on both ends, with a 3m patch. Short of
duct taping the transceivers together, not going to get much more optimal
than that.

As far as I can suss out from my reading and what Smart People have told
me, certain combinations of modulation and lamda are just more susceptible
to transmission noise, so for those FEC is required by the standard. PAM4
modulation does seem to be a common thread, but there are some PAM2/NRZs
that FEC is also required for. ( 100GBASE-CWDM4 for example. )



On Thu, Apr 18, 2024 at 8:15 AM Mark Tinka <mark@tinka.africa> wrote:

> On 4/17/24 23:24, Aaron Gould wrote:
>
> > Well JTAC just said that it seems ok, and that 400g is going to show
> > 4x more than 100g "This is due to having to synchronize much more to
> > support higher data."
>
> We've seen the same between Juniper and Arista boxes in the same rack
> running at 100G, despite cleaning fibres, swapping optics, moving ports,
> moving line cards, e.t.c. TAC said it's a non-issue, and to be expected,
> and shared the same KB's.
>
> It's a bit disconcerting when you plot the data on your NMS, but it's
> not material.
>
> Mark.