Linux shaping packet loss

Nickola Kolev nikky at mnet.bg
Tue Dec 8 13:09:57 CST 2009


On Tue, 8 Dec 2009 13:13:03 +0000
Chris <chris at ghostbusters.co.uk> wrote:

> Hi All,
> 
> It would be appreciated if anyone using TC on Linux for shaping could please
> help with an intermittent problem on an egress interface.

Well, it's unbelievable, but almost 5 hours and 11 mails later not even
one of them has mentioned something different than L2
incompatibilities! And this, IMHO, has nothing to do with Chris
problems.

I'd really expect more from the guys that make the Internet run...
Anyway... :)

> I'm seeing about ten per cent of packet loss for all classes at seemingly
> quiet times and random parts of the day using about forty classes and
> 250Mbps. I've isolated it to the egress HTB qdisc.

I'd start with a careful revisit of each class and the classifier that
goes with it. I'd pay special attention to go with u32/hash classifiers
(filters), and not with iptables.

You can try to visualize the number of packets in each class
(queued,dropped), and that way you will probably could see where the
problem is.

> Any TC experts out there have a spare minute please ? Any thoughts on the
> RED qdisc ?

As for this, I'd suggest to take a look at:

[1] http://lartc.org/howto/lartc.adv-qdisc.red.html
[2] http://www.opalsoft.net/qos/DS-26.htm

> Thanks very much,
> 
> Chris


-- 
Best regards,
Nickola





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