[120114] in North American Network Operators' Group
Re: Linux shaping packet loss
daemon@ATHENA.MIT.EDU (Chris)
Thu Dec 10 07:50:57 2009
X-IP-MAIL-FROM: chris@ghostbusters.co.uk
In-Reply-To: <20091209091817.44a72d8a.nikky@mnet.bg>
From: Chris <chris@ghostbusters.co.uk>
Date: Thu, 10 Dec 2009 12:49:33 +0000
To: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Thanks to all that replied.
Trial and error it is ... I'm now waiting (22 hours later) for it to break
again after I changed the priority on the "default" catch-all class. It
lasted five days before.
I'm looking at CBQ but it's not at all friendly relative to HTB.
If I'm forced to go down the proprietary traffic-shaping route. What's good
for really cheap gigabit, redundant, high throughput (including during
64-byte UDP attacks) shapers ? Suggestions appreciated.
Chris
2009/12/9 Nickola Kolev <nikky@mnet.bg>
> =D0=9D=D0=B0 Wed, 09 Dec 2009 06:38:31 +0000
> gordon b slater <gordslater@ieee.org> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=
=B0:
>
> > On Wed, 2009-12-09 at 08:02 +0200, Bazy wrote:
> >
> > > Hi Chris,
> > >
> > > Try setting txqueuelen to 1000 on the interfaces and see if you
> > > still get a lot of packet loss.
> > >
> >
> > Yes, good point and well worth a try. Rereading Chris's post about
> > "250Mbps" and "forty queues", the "egress" could well be bumping the
> > end of a default fifo line.
> >
> > If 1000 is too high for your kit try pushing it upwards gradually from
> > the default of 100 (?) but back off if you get drops or strangeness in
> > ifconfig output on the egress i/f.
>
> The default *is* 1000. From the ifconfig man page:
>
> txqueuelen length
>
> Set the length of the transmit queue of the device. It is useful to
> set this to small values for slower devices with a high atency (modem
> links, ISDN) to prevent fast bulk transfers from disturbing interactive
> traffic like telnet too much.
>
> So, if you should touch it if and only if you want to have (supposedly)
> finer grained control on queueing, as the hardware device also does
> some reordering before it puts the data on the wire.
>
> > I append grep-ped ifconfig outputs into a file every hour on a cron
> > job until I'm happy that strangeness doesn't happen, they never do
> > when you're watching sadly.
> >
> > TC problems aren't always about the TC itself, the physical interfaces
> > are inherently part of the "system", as my long rambling 5am+
> > up-all-night-over-ssh post about reseating NICs was trying to hint
> > at.
> >
> > Nice one Bazy
> >
> > Gord
> >
> >
> >
> >
> >
>
>
> --
> Regards,
> Nickola
>
>
