Re: [Codel] hardware multiqueue in fq_codel?

[Sebastian Moeller <moeller0@gmx.de>]

Hi there,


On Jul 12, 2013, at 17:13 , Eric Dumazet <eric.dumazet@gmail.com> wrote:

> On Fri, 2013-07-12 at 11:34 +0200, Jesper Dangaard Brouer wrote:
> 
>> I also think of "fq_codel" as a good replacement for pfifo_fast.  As
>> the 3-PRIO bands in pfifo_fast is replaced with something smarter in
>> "fq_codel". (IMHO please don't try to add a prio_fq_codel, just be because
>> pfifo_fast had prio bands, people can just enable a prio qdisc if they
>> really need it).
> 
> Nope. Its really easy for an attacker to flood your fq_codel with say
> UDP messages on all available hash slots.

	Question, what stops the same attacker to also fudge the TOS bits (say to land in priority band 0)? Just asking...

> 
> Some people really want the high prio packets to be sent before any
> med/low prio packets. Not everybody uses a separate ethernet port for
> management and heartbeats.
> 
> If we want to replace pfifo_fast as the default qdisc, we want some
> integrated qdisc with 3 bands.
> 
> I presume something really simple like :
> 
> a fifo for band 0 messages
> a fq_codel for band 1 messages
> a fifo for band 2 messages
> 
> Would be more than enough, and this also should use device txqueue len
> as the (dynamic) limit, because some existing scripts expect to control
> qdisc limit using "ifconfig eth0 txqueuelen 100", not a tc script.
> 
> 
> 
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Best
	Sebastian