From owner-freebsd-hackers Tue Nov 12 16: 6: 5 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 21C6837B404 for ; Tue, 12 Nov 2002 16:06:04 -0800 (PST) Received: from ares.cs.Virginia.EDU (ares.cs.Virginia.EDU [128.143.137.19]) by mx1.FreeBSD.org (Postfix) with ESMTP id D925A43E77 for ; Tue, 12 Nov 2002 16:06:02 -0800 (PST) (envelope-from nicolas@cs.Virginia.EDU) Received: from h0060978f1c76.ne.client2.attbi.com (localhost [127.0.0.1]) by ares.cs.Virginia.EDU (8.9.3+Sun/8.9.2/UVACS-2000040300) with ESMTP id TAA13989 for ; Tue, 12 Nov 2002 19:06:01 -0500 (EST) Date: Tue, 12 Nov 2002 19:05:59 -0500 (EST) From: Nicolas Christin X-X-Sender: nc2y@localhost.localdomain To: freebsd-hackers@FreeBSD.ORG Subject: Re: [hackers] Re: Netgraph could be a router also. In-Reply-To: <3DD1865E.B9C72DF5@mindspring.com> Message-ID: Organization: University of Virginia - CS Dept. MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Tue, 12 Nov 2002, Terry Lambert wrote: > 100mbit/s / 200kp/s = 500 bytes per packet > > ...and that an absolute top end. Somehow, I think the packets are > smaller. Just for the record... Measurement studies[1] (and NLANR traces[2]) suggest that the average packet size on the Internet is between 400-500 bytes, depending on the backbone link you're monitoring. According to the same studies/traces, packet size distribution can be approximated relatively accurately by a tri-modal distribution, with about 40% ~40 to 44-byte packets, 20% ~572 to 576-byte packets, and 20% 1500-byte packets. The 20 remaining percent are more or less uniformly distributed between 40 and 4000 bytes. This is all of course a rather crude approximation (which is not helped by the fact I'm quoting these numbers off the top of my head - I'll post a correction if I'm blatantly wrong, but I think my memory still works ok), but it may be helpful to get a rough idea of the 'typical' packet size one can observe. The point is, 200 Kpps should be relatively close to what you should see on a 100 Mbps FDX link. [1] http://www.caida.org/outreach/resources/learn/packetsizes [2] http://pma.nlanr.net/PMA/ Best, -- Nicolas Christin Ph.D. Candidate, University of Virginia, Computer Science http://www.cs.virginia.edu/~nicolas To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message