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

[Mike Horn]

Hi Vikram,

To help you troubleshoot, can you provide a few pieces of information:

1. What OS are the hosts and Routers?

2. Can you send the interface configuration from all the devices (ifconfig
or equivalent).

3. Can you send the routing table output from all the devices.  You can use
"netstat -rn" from the unix shell or you can use XORP command "show route
table ipv4 unicast final".

Proxy ARP won't work in your setup, the HostA should only be ARP'ing for the
nexthop address on the local connected subnet, in this case 17.17.17.1.  The
traffic bound for 10.1.1.2 should be sent to 17.17.17.1 who should then
forward it to 10.1.1.2.

-mike

-----Original Message-----
From: xorp-users-bounces at xorp.org [mailto:xorp-users-bounces at xorp.org] On
Behalf Of Vikram KAUL
Sent: Wednesday, June 07, 2006 9:47 AM
To: Allan Leinwand
Cc: xorp-users at xorp.org
Subject: Re: [Xorp-users] ARP problems with static routes in XORP


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 
allan>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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