Linux shaping packet loss

Chris chris at
Tue Dec 8 09:14:01 CST 2009

Thanks, Steiner and everyone for the input. It's good to see the list is
still as friendly as ever.

There are two paths I'm trying to get my head round after someone offlist
helpfully suggested putting cburst and burst on all classes.

My thoughts are that any dropped packets on the parent class is a bad thing:

qdisc htb 1: root r2q 10 default 265 direct_packets_stat 448 ver 3.17
 Sent 4652558768 bytes 5125175 pkt (dropped 819, overlimits 10048800
requeues 0)
 rate 0bit 0pps backlog 0b 28p requeues 0

Until now I've had Rate and Ceil at the same values on all the classes but I
take the point about cburst and burst allowing greater levels of borrowing
so I've halved the Rate for all classes and left the Ceil the same.

I've gone done this route mainly because I really can't risk breaking things
with incorrect cburst and burst values (if anyone can please tell me on an
i686 box at, say, 10Mbps the ideal values I can translate them into higher
classes, TC seems to work them out as 1600b/8 mpu by default and the timing
resolution confuses me.)

Thanks again,


2009/12/8 <sthaug at>

> > Won't say I'm an expert with TC, but anytime I see packet loss on an
> > interface I always check the interface itself...10% packet loss is
> > pretty much what you would get if there was a duplex problem. I always
> > try to hard set my interfaces on both the Linux machines and Switches.
> Used to set everything hard five years ago. Nowadays auto works just
> fine most of the time.
> Steinar Haug, Nethelp consulting, sthaug at

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