Ok, riddle me this:

/kernel: arplookup WWW.XXX.YYY.10 failed: host is not on local network

I've been seeing these messages in the messages log, so I've done some additional tests and am now hunting for answers.

The curious part is, the host technically *is* on the local network. It's a /24 subnet; the address of the local machine is WWW.XXX.YYY.25 and the other host is WWW.XXX.YYY.10. As I mentioned, this is a /24, and so I've confirmed that both hosts are configured with the subnet mask of 0xffffff00 (

I can repeat the error message as often as I want by generating arp who-has requests (I've been using `arping' to accomplish these tests):

tcpdump output when running arping:

arp who-has WWW.XXX.YYY.10 tell WWW.XXX.YYY.25
arp reply WWW.XXX.YYY.10 is-at 0:e0:81:2:15:59

At the same time, my messages log fills up with arplookup errors.

/kernel: arplookup WWW.XXX.YYY.10 failed: host is not on local network

Now, I must add a necessary development to this, which is almost definitely the cause of the problem. These two hosts each have two interfaces on them. The primary interface on each is connected to WWW.XXX.YYY.0/24 as shown above. The secondary interface on each is assigned RFC1918 addresses on the subnet, and are directly connected with a crossover cable. The last octet used in the IP addresses for the secondary interfaces mirror the last octet used for the IP on the primary interfaces. Static routes have been added to force all communication *between* these two hosts to use the secondary interfaces:

WWW.XXX.YYY.25's static route:
        route add WWW.XXX.YYY.10

WWW.XXX.YYY.10's static route:
        route add WWW.XXX.YYY.25

The static routes work as they should - traffic destined for either host's IP on the WWW.XXX.YYY.0/24 subnet goes through the secondary interfaces instead. However, both machines are receiving the arplookup errors because of this, and I'd like to know if there is a solution besides disabling the sysctl variable that causes these errors to be logged.


-David Fuchs

[EMAIL PROTECTED] mailing list
To unsubscribe, send any mail to "[EMAIL PROTECTED]"

Reply via email to