We ran into a lot of quirkiness with Linux when we started rolling out Linux-based CPE with XORP as a routing engine. I've thrown some sane defaults you might want to consider into a text file at: http://soucy.org/xorp/xorp-1.7-pre/TUNING Specifically, you prob. want option 2 instead of 1 for arp_ignore, otherwise you'll see funkiness with ARPs coming from the wrong IP in a multi-interface configuration. ----8<---- ARP_IGNORE values: 0 - Reply for any local address. 1 - Reply only if the target IP is configured on the receiving interface. 2 - Like 1, but the source IP (sender's address) must belong to the same subnet as the target IP. 3 - Reply only if the scope of the target IP is not the local host (e.g., that address is not used to communicate with other hosts). 4-7 - Reserved. 8 - Do not reply.
8 - Unknown value; accept request. ----8<----
Hope this helps, On Mon, Jan 30, 2012 at 7:09 PM, William Herrin <bill@herrin.us> wrote:
On Mon, Jan 30, 2012 at 6:24 PM, Joe Maimon <jmaimon@ttec.com> wrote:
Golden. Thank you, William.
Hi Joe,
You're welcome. The flip side of Linux's arp funkiness is that you can get it to do some nifty stuff. For example, a /32 ethernet looks more or less like this:
ifconfig lo:1 198.51.100.1 netmask 255.255.255.255 ifconfig eth1 192.168.0.1 netmask 255.255.255.252 ip route add 198.51.100.44/32 dev eth1 src 198.51.100.1 arptables --out-interface eth1 -j mangle -s 192.168.0.1 --mangle-ip-s 198.51.100.1
The implicit proxy arp takes care of the rest with the machine hanging off the interface thinking that it's part of a /24.
This sort of thing is how I'm using all 17 of the IP addresses in my Cox /28. :-)
Regards, Bill Herrin
-- William D. Herrin ................ herrin@dirtside.com bill@herrin.us 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004
-- Ray Soucy Epic Communications Specialist Phone: +1 (207) 561-3526 Networkmaine, a Unit of the University of Maine System http://www.networkmaine.net/