Date: Wed, 18 Feb 1998 01:08:30 +0000 From: Brian Somers <brian@Awfulhak.org> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> 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 Message-ID: <199802180108.BAA24538@awfulhak.org> In-Reply-To: Your message of "Tue, 17 Feb 1998 21:10:57 %2B0100." <199802172010.VAA01212@labinfo.iet.unipi.it>
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> > > * "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 <brian@Awfulhak.org>, <brian@FreeBSD.org>, <brian@OpenBSD.org> <http://www.Awfulhak.org>; 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
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