Date: Wed, 18 Sep 2002 14:55:32 -0400 (EDT) From: "Jim" <sitenet@siteplus.net> To: <cjc@FreeBSD.ORG> Cc: <questions@FreeBSD.ORG> Subject: Re: arplookup xx.xxx.xx.xxx failed: host is not on local network Message-ID: <2033.68.59.219.194.1032375332.squirrel@siteplus.net> In-Reply-To: <20020917223014.GB3323@blossom.cjclark.org> References: <F738a3s875qIOjsnK7L0001ad5a@hotmail.com> <20020917223014.GB3323@blossom.cjclark.org>
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This is a very good explanation, however I have this identical scenario with one of my co-los. I have gone round and round with the administrator for over a year now with no solution. You make the statement below that these two machines can't communicate, however I can ping and tracroute the offending machines, and they can do the same in reverse. On traceroute, the traffic definitely travels through the router as it should, but I still see these out of network ARP requests. I know I'm confused :( Jim > [Inappropriate cross-post to -stable removed.] > > On Sun, Sep 15, 2002 at 02:08:51PM -0500, Chris Byrnes wrote: >> My /var/log/messages is being filled, non-stop, by these errors >> looped: >> >> Sep 15 13:41:28 servername /kernel: arplookup xx.xxx.xx.xxx failed: >> host is not on local network >> Sep 15 13:41:28 servername /kernel: arplookup xx.xxx.xx.xxx failed: >> host is not on local network >> >> After doing some reading, I've already issued, "sysctl -w >> net.link.ether.inet.log_arp_wrong_iface=0" thinking that would fix the >> problem. Unfortunately, it has not. >> >> Any ideas? > > This is a netmask problem, but not really the one that other people have > described. This is how it usually works. Your troubled machine above, > "servername," receives an ARP who-has from another machine on the LAN > called "clientname." However, the IP address that clientname gives as a > source does not match up to any local networks that > servername knows about. > > For example, say servername has an address of 192.0.2.10/25. The other > machine has 192.0.2.210/24. When servername gets an ARP (which is > broadcast so servername gets it fine), > > who-has 192.0.2.10 tell 192.0.2.210 > > It gets confused. 192.0.2.210 is not local (as far as it is concerned) > so it logs an error. > > Note that this is not a harmless error. These two machine cannot talk to > each other. > > The fix, of course, is to make sure all machines on the same LAN have > the same netmask. > -- > Crist J. Clark | cjclark@alum.mit.edu > | cjclark@jhu.edu > http://people.freebsd.org/~cjc/ | cjc@freebsd.org > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-stable" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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