From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: txqueuelen has wrong units; should be time
Date: Wed, 02 Mar 2011 17:50:44 +0100
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Cc: Stephen Hemminger <shemminger@vyatta.com>,
	John Heffner <johnwheffner@gmail.com>,
	Bill Sommerfeld <wsommerfeld@google.com>,
	Hagen Paul Pfeifer <hagen@jauu.net>,
	Albert Cahalan <acahalan@gmail.com>,
	Jussi Kivilinna <jussi.kivilinna@mbnet.fi>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	netdev@vger.kernel.org
To: Mikael Abrahamsson <swmike@swm.pp.se>
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Le mercredi 02 mars 2011 =C3=A0 17:41 +0100, Mikael Abrahamsson a =C3=A9=
crit :
> On Tue, 1 Mar 2011, Stephen Hemminger wrote:
>=20
> > Also WRED is not default on faster links because it can't be done f=
ast=20
> > enough.
>=20
> Before this propagates as some kind of truth. Cisco modern core route=
rs=20
> have no problems doing WRED at wirespeed, the above statement is not =
true.
>=20

looking at cisco docs you provided
( <http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/12stbwr.html=
>
 )
, it seems the WRED time limits (instead of bytes/packets limits) are
internaly converted to bytes/packets limits


quote :=20

When the queue limit threshold is specified in milliseconds, the number
of milliseconds is internally converted to bytes using the bandwidth
available for the class.=20


So it seems its only a facility provided, and queues are still managed
with bytes/packets limits...

WRED is able to prob drop a packet when this packet is enqueued. At tim=
e
of enqueue, we dont know yet the time of dequeue, unless bandwidth is
known.