Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932455AbWCMUz5 (ORCPT ); Mon, 13 Mar 2006 15:55:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932457AbWCMUz4 (ORCPT ); Mon, 13 Mar 2006 15:55:56 -0500 Received: from mail.infrasupportetc.com ([66.173.97.5]:64576 "EHLO mail733.InfraSupportEtc.com") by vger.kernel.org with ESMTP id S932455AbWCMUzz convert rfc822-to-8bit (ORCPT ); Mon, 13 Mar 2006 15:55:55 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: Router stops routing after changing MAC Address Content-class: urn:content-classes:message X-MimeOLE: Produced By Microsoft Exchange V6.5 Date: Mon, 13 Mar 2006 14:57:04 -0600 Message-ID: <925A849792280C4E80C5461017A4B8A20321F5@mail733.InfraSupportEtc.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Router stops routing after changing MAC Address Thread-Index: AcZG3JFcaxxA2oPXRWKojNxFlJZu7wAAmu6g From: "Greg Scott" To: "linux-os \(Dick Johnson\)" , "Stephen Hemminger" Cc: "Chuck Ebbert" <76306.1226@compuserve.com>, "linux-kernel" , "David S. Miller" , , "Bart Samwel" , "Alan Cox" , "Simon Mackinlay" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1541 Lines: 35 But in a failover scenario you want two devices to have the same IEEE (station) Address (or MAC Address or hardware address). So many names for the same thing! When the primary unit fails, you want the backup unit to completely assume the failed unit's identity - right down to the MAC Address. The other way to do it using gratuitous ARPs is not good enough because some cheap router someplace with an ARP cache of several hours will not listen and will never update its own ARP cache. I like to think of this as bending the rules a little bit, not really breaking them. :) - Greg >Actually, it doesn't make any difference. Changing the IEEE station >(physical) address is not an allowed procedure even though hooks are >available in many drivers to do this. According to the IEEE 802 >physical media specification, this 48-bit address must be unique >and must be one of a group assigned by IEEE. Failure to follow this >simple protocol can (will) cause an entire network to fail. If you >don't care, then you certainly don't care about multicast bits either, >basically let them set it to all ones as well. >Cheers, >Dick Johnson >Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips). >Warning : 98.36% of all statistics are fiction, book release in April. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/