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Re: [LARTC] RED to use ECN (or work at all?)

To: Daniel Schaffrath <daniel.schaffrath@mac.com>
Subject: Re: [LARTC] RED to use ECN (or work at all?)
From: Andy Furniss <lists@andyfurniss.entadsl.com>
Date: Tue, 26 Jun 2007 22:44:26 +0100
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Daniel Schaffrath wrote:
Dear Community,

sorry for the somewhat dumb question. Maybe someone has any pointer to how to setup the RED queue to mark pakets with ECN. In particular what are appropriate parameter settings for limit, min, max, etc.

I have never really played with red - but I wouldn't start by putting it on lo - I don't think you will get a backlog. Even on root of an eth there will be quite big buffer to fill before it gets any backlog.

You are best using it as a child of something that rate limits tbf/hfsc/htb. There is a rate parameter which I guess you should use - but it's not to actually do the rate limiting.

As for ECN, it's off by default on Linux, so I don't think it will be much use unless you have control over the network. I just turned it on on two of my PCs -

echo 1 > /proc/sys/net/ipv4/tcp_ecn

and did a test with red and it does work and save some drops.

Andy.
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