[192863] in North American Network Operators' Group
Re: 10G switch drops traffic for a split second
daemon@ATHENA.MIT.EDU (TJ Trout)
Tue Nov 29 16:53:28 2016
X-Original-To: nanog@nanog.org
In-Reply-To: <CAHDg04tYj=7pB2-CtvfDbfzB4XZ+vbGaSBtM1MQfPox8Hd7Sug@mail.gmail.com>
From: TJ Trout <tj@pcguys.us>
Date: Tue, 29 Nov 2016 13:53:23 -0800
To: Michael Loftis <mloftis@wgops.com>
Cc: nanog <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
I plan on disabling FC on everything tonight, I've done that before but I
want to be sure.
Anything that can be done about the 2 x 1G peers trunking to the 10G router
transition that can be fixed? should I be rate limiting the vlan for the
peers at 1G so the 10G router isn't trying to send more than 1G?
On Tue, Nov 29, 2016 at 1:47 PM, Michael Loftis <mloftis@wgops.com> wrote:
> 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
>
