Re: [Cerowrt-devel] trying to make sense of what switch vendors say wrt buffer bloat

["Toke Høiland-Jørgensen" <toke@toke.dk>]

Eric Johansson <esj@eggo.org> writes:

> Buffer bloat was a relevant on 10/100M switches, not 10Gb switches. At
> 10Gb we can empty the queue in ~100ms, which is less than the TCP
> retransmission timers, therefore no bloat. Buffer bloat can happen at
> slower speeds, but not an issue at the speeds we have on our switches.

100 ms of buffering at 10 Gbps? Holy cow!

There's no agreed-upon definition of what exactly constitutes 'bloat',
and it really depends on the application. As such, I'm not surprised
that this is the kind of answer you get if you ask "do your switches
suffer from bufferbloat". A better question would be "how much buffer
latency can your switches add to my traffic" - which they offer here.

If I read the answer right, anytime you have (say) two ingress ports
sending traffic at full speed out one egress port, that traffic will be
queued for 100 ms. I would certainly consider that broken, but well,
YMMV depending on what you need them for...

-Toke