10G switch drops traffic for a split second

Michael Loftis mloftis at wgops.com
Tue Nov 29 21:47:49 UTC 2016

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 at 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

More information about the NANOG mailing list