From owner-freebsd-net Sat Oct 9 13:52:22 1999 Delivered-To: freebsd-net@freebsd.org Received: from verdi.nethelp.no (verdi.nethelp.no [158.36.41.162]) by hub.freebsd.org (Postfix) with SMTP id DA97014C26 for ; Sat, 9 Oct 1999 13:52:11 -0700 (PDT) (envelope-from sthaug@nethelp.no) Received: (qmail 63644 invoked by uid 1001); 9 Oct 1999 20:52:08 +0000 (GMT) To: aron@cs.rice.edu Cc: freebsd-net@freebsd.org, justin@apple.com, alc@cs.rice.edu, wollman@khavrinen.lcs.mit.edu Subject: Re: arp errors on machines with two interfaces From: sthaug@nethelp.no In-Reply-To: Your message of "Sat, 9 Oct 1999 11:50:51 -0500 (CDT)" References: <199910091650.LAA08261@cs.rice.edu> X-Mailer: Mew version 1.05+ on Emacs 19.34.2 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Date: Sat, 09 Oct 1999 22:52:08 +0200 Message-ID: <63642.939502328@verdi.nethelp.no> Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > Garrett is correct, and sarcasm doesn't help. You can't have more > > than one interface on a given wire, with the same subnet address, > > using IP. Them's the protocol rules. > > Actually I am using different subnet addresses on the two interfaces. One is > 128.42.3.77 and the other is 192.168.3.77. There are other machines in the > dept running Solaris and other OS's that are connected in similar fashions. > However, the Ethernet is switched and any broadcast by anyone is going to be > seen by all interfaces connected to it. What you are doing is not supported by the standard TCP/IP model of communication. The fact that it (partly) works for you should be regarded as incidental. Try to think of it in terms of a traditional coax-based Ethernet, and having two NICs on one host connected to the same physical Ethernet cable. Would you expect this to work? (You shouldn't.) > I don't have control over the hardware. But here's a possibility - wouldn't > it be better if this error message generation in FreeBSD is turned off if > the packet is an arp broadcast ? Like I showed in my earlier mail, the > problem only happens due to arp broadcasts. No, the problem happens due to the fact that you are connecting two Ethernet NICs to the same segment. This is not supported. Why should the error message be turned off just to please you, when you're using an unsupported configuration? Steinar Haug, Nethelp consulting, sthaug@nethelp.no To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message