[c-nsp] TwinAx cables

Tom Hill tom at ninjabadger.net
Wed Jun 29 20:05:12 EDT 2016

On 29/06/16 13:01, Christina Klam wrote:
> A few years back we moved to using twinax cables for our 10G uplinks in
> our DataCenters.  We are now seeing input/output/CRC errors to many of
> our FEX and servers.
> Has anyone experienced twinax cables failing after only 2-3 years?  If
> this is common, the cost benefits of using twinax definitely decreases.

I have not found them to be terribly reliable, and quality between
vendors seemed to vary greatly (not as predictable as you might imagine).

You should also not rule out a few things:

1. Output CRCs on lots of ports simultaneously is probably due to one
port receiving CRCs and doing cut-thru switching, instead of dropping them

2. Don't underestimate the strange behaviour of server NICs (and their
drivers) - they can, and have, in my case, suddenly started causing CRC
errors until reset.

But in general, I'm a little wary of DACs. A little. The peace of mind
in short (1-3m) lengths of 10GBASE-SR has been enjoyable. 10GBASE-T has
been a happy situation so far, too (again, 1-3m only).



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