From owner-freebsd-current Tue Feb 17 17:19:34 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id RAA09998 for freebsd-current-outgoing; Tue, 17 Feb 1998 17:19:34 -0800 (PST) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from awfulhak.org (awfulhak.demon.co.uk [158.152.17.1]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id RAA09983 for ; Tue, 17 Feb 1998 17:19:16 -0800 (PST) (envelope-from brian@Awfulhak.org) Received: from gate.lan.awfulhak.org (localhost [127.0.0.1]) by awfulhak.org (8.8.7/8.8.7) with ESMTP id BAA24538; Wed, 18 Feb 1998 01:08:31 GMT (envelope-from brian@gate.lan.awfulhak.org) Message-Id: <199802180108.BAA24538@awfulhak.org> X-Mailer: exmh version 2.0.1 12/23/97 To: Luigi Rizzo cc: eivind@yes.no (Eivind Eklund), plm@xs4all.nl, freebsd-current@FreeBSD.ORG Subject: Re: cvs commit: src/usr.sbin/ppp command.c datalink.c datalink.h defs.h vars.c vars.h In-reply-to: Your message of "Tue, 17 Feb 1998 21:10:57 +0100." <199802172010.VAA01212@labinfo.iet.unipi.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 18 Feb 1998 01:08:30 +0000 From: Brian Somers Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > > * "preemption" . > > > I don't think ppp allows this, but perhaps it could be possible to > > > implement preemption of long packets (or transfer them in smaller > > > 'cells') so that interactive traffic does not suffer exceedingly > ... > > I'm not certain how this can be handled. A possibility might be to > > fragment the packets for just that connection, ie, in effect lower the > > MTU for just part of the use. > > > > I believe some smart heuristics would be necessary to make this work well. > > the idea would be that the (non-standard) PPP link can be treated > to transfer cells of a fixed max size, each cell tagged with the > flow it belongs to. The sender does the fragmentation so the FQ > algorithm uses cells instead of packets. > > The whole things could be (probably) optimized if we can make use of > some unused ppp escape sequence to mark a preemption point, rather than > always fragment packets. At the moment, ppp has four queues. Two IP queues and two modem queues. The IP queues are `interactive' and `normal', and the modem queues are `fast' and `normal'. LCP and `interactive IP' traffic goes into the `fast' modem queue. `fast' data gets delivered first. Wouldn't this be best approached by just having a dynamic MTU - one that varies based on the number of packets in the interactive queue ? > cheers > luigi > -----------------------------+-------------------------------------- > Luigi Rizzo | Dip. di Ingegneria dell'Informazione > email: luigi@iet.unipi.it | Universita' di Pisa > tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) > fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ > _____________________________|______________________________________ -- Brian , , Don't _EVER_ lose your sense of humour.... To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message