From owner-freebsd-stable Sun Apr 1 13:36:48 2001 Delivered-To: freebsd-stable@freebsd.org Received: from stargate.compuware.com (stargate.compuware.com [166.90.248.158]) by hub.freebsd.org (Postfix) with SMTP id D478937B718 for ; Sun, 1 Apr 2001 13:36:45 -0700 (PDT) (envelope-from driehuis@playbeing.org) Received: from [199.186.16.12] by stargate.compuware.com via smtpd (for hub.freebsd.org [216.136.204.18]) with SMTP; 1 Apr 2001 20:36:45 UT Received: from bh1.compuware.com (compuware.com [172.22.1.239]) by cwus-dtw-mr02.compuware.com (Postfix) with ESMTP id 4D2CE74C41; Sun, 1 Apr 2001 16:36:45 -0400 (EDT) Received: from trashcan.nl.compuware.com ([172.16.16.52]) by bh1.compuware.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id HWM0ZB67; Sun, 1 Apr 2001 16:36:44 -0400 Received: from c1111.nl.compuware.com (c1111.nl.compuware.com [172.16.16.36]) by trashcan.nl.compuware.com (Postfix) with ESMTP id BB5F7145A4; Sun, 1 Apr 2001 22:36:43 +0200 (CEST) Date: Sun, 1 Apr 2001 22:36:43 +0200 (CEST) From: Bert Driehuis X-Sender: bertd@c1111.nl.compuware.com To: "Jason T. Luttgens" Cc: freebsd-stable@freebsd.org Subject: RE: Network performance question In-Reply-To: <000001c0bae7$d315d910$0200010a@lucky> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Sun, 1 Apr 2001, Jason T. Luttgens wrote: > >Send a predictable load to the device under test (say, include a > >sequence number) and use that to determine packet loss (and, also > >interesting, packet loss patterns). > > Well, I thought that I was doing this by using a known set of data from the > tcpdump I captured earlier and was replaying. Each time it replays, it is > the same number of packets and payload content. The network I am testing on > is isolated (not connected to anything else but these two computers). > > I'm not sure I see the difference between what you describe and what I did. > What do I need to do to create the environment you mention? Number the packets sequentially, and read the tcpdump recording on the receiving end. There is a huge difference between a driver crapping out halfway through or one dropping every twelfth packet. I've seen Ethernet drivers shut down for an X amount of time until a deadman timer restarts it, and finding gaps in the data is an indication of that. Cheers, -- Bert -- Bert Driehuis -- driehuis@playbeing.org -- +31-20-3116119 If the only tool you've got is an axe, every problem looks like fun! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message