[Xorp-users] ARP problems with static routes in XORP

Vikram KAUL vkaul at research.telcordia.com
Wed Jun 7 08:47:07 PDT 2006


Allan,

 Thanks for your reply

allan>   It looks like your host may be doing the right thing, depending on how you have your default gateway set up. The host is sending an ARP for the destination IP address and the router (17.17.17.1) should reply with a proxy ARP if it has a route to 10.1.1.2. I'm assuming that this router has a directly connected route to 10.1.1.0/24.

The Router does get the arp request from the host, but there is no reply 
sent for that . I check that using tcpdump. 
Does something have to be enabled in XORP to reply arp requests for 
directly connected subnets ? I could not find that in the documentation. 

allan>
allan>I would make sure that:
allan>1) the host has a default gateway set to 17.17.17.1.  You can use netstat -r (Linux/Win) and check for the presence of a 0.0.0.0/0 route to 17.17.17.1.
allan>2) the router has a connected route to 10.1.1.0/24 (my assumption on your subnet mask)
allan>3) the router at 10.1.1.2 has a route (static or RIP derived) back to 17.17.17.0/24 (again, I'm assuming you're using a /24 here again).

I made sure of these when I was doing the test. 
Is there some hook/flag I can enable in XORP to see if the arps are being 
replied ?

Thanks
Vikram



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