Date: Tue, 13 Jan 2004 23:36:56 -0500 (EST) From: Robert Watson <rwatson@freebsd.org> To: Nielsen <nielsen@memberwebs.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Gratituous ARP and the em driver Message-ID: <Pine.NEB.3.96L.1040113233522.37309F-100000@fledge.watson.org> In-Reply-To: <20040112011942.C78B6840128@mail.npubs.com>
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On -1 xxx -1, Nielsen wrote: > When I change IP addresses on my 'em' gigabit NIC, ARP isn't sent > properly. This appears to be the problem in the following bug report, > however i'm using the 'fixed' version of the em driver (in FreeBSD 4.9). > > http://www.freebsd.org/cgi/query-pr.cgi?pr=54488 > > Does anyone have any tips on how to get around this? > > I'm building new systems with gigabit ethernet support and this problem > keeps cropping up. I have a failover system, and when moving an IP alias > between machines, the em NIC driver doesn't properly send out gratituous > ARP, resulting in the IP being inaccessible. > > - The problem does not occur when plugged into a 100BaseTX switch - > FreeBSD 4.9p1 / em version 1.7.16 - Tried various gigabit switches. - > One other odd thing is that when configuring the NIC (ifconfig) the > machine locks up for several seconds. If you run tcpdump on the machine to sniff the interface in question looking for arp packets, does tcpdump see the gratuitous arp? I'm guessing that it does, and the lack of sending the arp is a result of delays in negotiating on the wire. Does this problem turn up only the first time you raise the interface, or every time you change the IP address on the interface? Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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