Re: [LARTC] Priotizing Bandwith but without Shaping the Bandwith

From: "Wingtung.Leung" <s965817@uia.ua.ac.be>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] Priotizing Bandwith but without Shaping the Bandwith
Date: Thu, 28 Jun 2001 20:09:07 +0000	[thread overview]
Message-ID: <marc-lartc-99375902020263@msgid-missing> (raw)
In-Reply-To: <marc-lartc-99367664430871@msgid-missing>

On Thu, 28 Jun 2001, Alexandra Alvarado wrote:

> Well, as i say before, a i need that all traffic udp has priority over
> tcp traffic, because i have to improve the voice quility over internet,
> well now i'm upgrading to Red Hat 7.1 (kernel 2.4) to use TOS field, but
> my question is if this sentence:
>
> iptables -t mangle -A PREROUTING -p udp -j TOS --set-tos
> Maximize-Throughput
>
> works or not, and how can i verify it?

I'm not sure, but I *think* this does *not* work.

> Until know i use CBQ, but with cbq i only asign specific bandwith to my
> clients using ip address, but i don't know how to prioritize traffic udp
> over tcp but without limiting the bandwith using CBQ.

A simple solution: attach 2 unbounded (!) classes to your interface, both
with a rather low transfer rate like 20kbit/s and give one a high
priority and the other one low priority. There is a priority parameter
when you create a class.

Now find a method to redirect both UDP and TCP traffic to the correct
class. An easy and lazy way is to mark the packets with iptables in the
mangle table. For example, mark UDP packets with 1 and TCP packets with 2.
Look at the iptables manpage for info about using it.

Use tc and install the fw filters which redirect the marked packets into
the correct classes. Redirect the packets marked with 1 to the low hi prio
class, and marked with 2 to the low prio class.

That should to it.

The low transfer rate is the minimum garantued rate for that class, all
bandwidth which is not allocated to a class, will be delivered to the
class with the highest priority.

I described a similar setup a few weeks/months ago, maybe reading the
archives gives you more hints.

Succes.

(Good that you type beneath the quote, the second step is cut irrelevant
parts from the quoted text. Signatures for example. And this small note
too. :-)

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