nanog mailing list archives

Re: 10G switch drops traffic for a split second


From: Michael Loftis <mloftis () wgops com>
Date: Tue, 29 Nov 2016 13:47:49 -0800

Yes it is absolutely possible to overrun the buffers.  Any kind of
backpressure (FC) from hosts, or 10G->1G transitions can easily cause
it.  Even if in a 10s window you're not over 1G if the 10G sender
attempts to back to back too many frames in a row (Like say sendfile()
API type calls) BOOM, dropping frames in the switch.

On Tue, Nov 29, 2016 at 1:28 PM, TJ Trout <tj () pcguys us> wrote:
Luke;

All l2, no l3. only 4 vlans. 2 peers trunked to a router which trunks back
to 2 devices (microwave backhauls).

Chuck;

All ports are 10g except the 2 peers are 1g and trunk back to a 10g port
for the router wan

No TCN's

Brian;

I have tried a IBM G8124 and a Ubiquiti ES-16-XG both show same exact drops
across all ports, makes me think it's a config issue. MTU, FC, something.

Andrew;

I have tried with FC disabled, but I will try that one more time.

Mikael;

Is it possible to over run the buffers of a 320gbps backplane switch with
only 1.5gbps traffic? I think the switch is rated for 140m PPS and I'm only
pushing 100k PPS


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