From owner-freebsd-net Tue Jun 1 11:41:55 1999 Delivered-To: freebsd-net@freebsd.org Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by hub.freebsd.org (Postfix) with SMTP id 2694714ED3 for ; Tue, 1 Jun 1999 11:41:50 -0700 (PDT) (envelope-from luigi@labinfo.iet.unipi.it) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id SAA01772; Tue, 1 Jun 1999 18:12:04 +0200 From: Luigi Rizzo Message-Id: <199906011612.SAA01772@labinfo.iet.unipi.it> Subject: Re: dummynet & bridging To: avalon@coombs.anu.edu.au (Darren Reed) Date: Tue, 1 Jun 1999 18:12:04 +0200 (MET DST) Cc: net@FreeBSD.ORG In-Reply-To: <199906010236.MAA27249@cheops.anu.edu.au> from "Darren Reed" at Jun 1, 99 12:36:35 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Content-Length: 1287 Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > Has anyone run a system using dummynet with bridging in place and running > at 100MBps ? i.e. briding two 100BaseT segments running at full speed. > If so, what sort of performance problems (if any) did you see ? bridging just throws away unwanted packets before passing through the firewall, and generally does not make additional copies of the packets (except perhaps for an m_pullup() which is also needed by the ip_fw code). So if a given machine can receive at full speed from one (or more) interfaces, while at the same time send at full speed on another one, then it can also bridge at full speed. dummynet overhead is constant per-packet, and i think the biggest part is the ipfw overhead. I once measured it on an old P90 (with slow memory) as some 4-6us entry time plus some 0.5us per rule. cheers luigi -----------------------------------+------------------------------------- Luigi RIZZO, luigi@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL/FAX: +39-050-568.533/522 . via Diotisalvi 2, 56126 PISA (Italy) http://www.iet.unipi.it/~luigi/ngc99/ ==== First International Workshop on Networked Group Communication ==== -----------------------------------+------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message