Date: Wed, 30 Apr 2003 09:08:05 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: netgeek@speakeasy.net Cc: freebsd-questions@freebsd.org Subject: Re: arp moved from [mac address] to [mac address] Message-ID: <20030430080805.GC58116@happy-idiot-talk.infracaninophi> In-Reply-To: <20030430054852.8267.qmail@webmail.speakeasy.net> References: <20030430054852.8267.qmail@webmail.speakeasy.net>
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--9Ek0hoCL9XbhcSqy Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Apr 29, 2003 at 10:48:52PM -0700, netgeek@speakeasy.net wrote: > The Internet connection is through AT&T Broadband, using DHCP. When I boo= t, the DHCP connection is up correctly and all works. Within five minutes a= series of messages like >=20 > pi /kernel: arp: 66.41.23.107 moved from 00:02:dd:30:0a:00 to 00:02:dd:30= :4a:e2 on dc0 > pi /kernel: arp: 66.41.23.107 moved from 00:02:dd:30:4a:e2 to 00:02:dd:30= :0a:00 on dc0 >=20 > (The IP and MAC addresses are not accurate, sorry.) >=20 > As soon as this happens I cannot access anything on the Internet (IP or d= omain name), but the link lights stay on and ifconfig reports no change. >=20 > Are these related, and if so what is the fix? >=20 > This isn't my computer, and I'm 40 minutes away from it, so if this quest= ion needs information it might be slow in coming. This is probably some sort of redundant fail-over system used by AT&T -- which is all very well unless it interferes with the working of your system. Since the address is flipping between the interfaces so frequently as every five minutes that's going to be a significant degradation of your service. So long as the IP address in question is not configured on one of your machines' own interfaces this shouldn't have any direct effect on you -- the log message is just your system acknowledging that the IP number has moved to a different MAC address. However, if you have certain types of networking kit between your machine and the rest of the net, it may not respond very quickly to the arp change. Cisco switches are a case in point: they can take an appreciable amount of time to respond to this sort of arp change. FreeBSD in my experience is very good at recognizing such changes quickly and responding to them. This is something that should be able to be sorted out by configuration changes in the networking kit --- contact the service provider to see if they have any advice: chances are this is a problem that many people have run into before. Search the web as well. Cheers, Matthew PS. To identify the manufacturer of the kit whose IP number is being affected you can look up the 3-byte prefix of a MAC address at http://standards.ieee.org/regauth/oui/index.shtml (Nb. you have to separate the octets with '-' rather than ':', vis 00-02-dd) Doesn't help much in this case though, unless 'Bromax Communications, Ltd.' means anything to you. --=20 Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks Savill Way PGP: http://www.infracaninophile.co.uk/pgpkey Marlow Tel: +44 1628 476614 Bucks., SL7 1TH UK --9Ek0hoCL9XbhcSqy Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (FreeBSD) iD8DBQE+r4RldtESqEQa7a0RApP/AJwNr37P/ODpk62buNS4gzBTNmSYnACfa5nl VfrcQdNMh6WQ0WswbvJJ4aE= =j6n6 -----END PGP SIGNATURE----- --9Ek0hoCL9XbhcSqy--
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