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From: Chris Wilson <chris@netservers.co.uk>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] problem with prio qdisc and TOS
Date: Thu, 30 Jan 2003 14:07:09 +0000	[thread overview]
Message-ID: <marc-lartc-104393644000392@msgid-missing> (raw)
In-Reply-To: <marc-lartc-104393326828670@msgid-missing>

Hi Andreas,

I hope I have this right, based on my limited understanding of Linux QoS. 
If I'm wrong then I hope someone will correct me =)

>  If I just attach a PRIO qdisc on eth1(outgoing) will I be able to
> prioritise packets based on the TOS value.

You don't even need to do that, the default qdisc is pfifo_fast which also 
prioritises by TOS flags.

> The TOS value is set by a test application.

It can also be overridded by a Netfilter rule, if you want to force or 
change priority for certain types of packets.

> At very high data rates will the data stream with lower
> priority TOS value be starved because it cannot send out of packets from
> its band on eth1 interface?.

Yes, if there is not enough capacity to send on eth1 then lower-priority 
packets will be starved, will queue up until the queue is full and then 
get dropped.

> Does something be set in linux kernel so that kernel sets priority for
> packets according to TOS value.I guess this priorty will be used by PRIO
> qdisc(by default) to decide which band the packet belongs.

Yes, it happens by default, with the pfifo_fast qdisc.

Cheers, Chris.
-- 
   ___ __     _
 / __// / ,__(_)_  | Chris Wilson -- UNIX Firewall Lead Developer |
/ (_ / ,\/ _/ /_ \ | NetServers.co.uk http://www.netservers.co.uk |
\ _//_/_/_//_/___/ | 21 Signet Court, Cambridge, UK. 01223 576516 |

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  reply	other threads:[~2003-01-30 14:07 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-01-30 13:26 [LARTC] problem with prio qdisc and TOS Andreas Wright
2003-01-30 14:07 ` Chris Wilson [this message]
2003-02-03 10:22 ` Andreas Wright

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