netdev - route problem

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Message-ID: <B97B134FACB2024DB45F524AB0A7B7F2058B01D4@XMB-BGL-419.cisco.com>
Date:	Wed, 18 Jan 2012 14:47:50 +0530
From:	"Prashant Batra (prbatra)" <prbatra@...co.com>
To:	<netdev@...r.kernel.org>
Subject: route problem

Hi,

I have added a route for an external ip via a gateway which is available
on the same machine.
I want to capture the packets going to this external IP using PF_PACKET
socket.

#route 
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
192.168.101.0   *               255.255.255.0   U     0      0        0
eth1
172.16.60.0     192.168.101.10  255.255.255.0   UG    0      0        0
eth1

So, when a packet is sent to 172.16.60.*, kernel should send arp request
for this gw IP 192.168.101.10. As gw IP is locally reachable, 
It should send its mac address in arp-response and kernel should send
the packet via that interface.

But what I am seeing is that instead of asking the gateway IP, kernel
sends a arp request for destingation ip(172.16.60.*)

#tcpdump -I eth1
04:12:45.334966 arp who-has 172.16.60.2 tell 192.168.101.20
04:12:46.334839 arp who-has 172.16.60.2 tell 192.168.101.20
04:12:48.334584 arp who-has 172.16.60.2 tell 192.168.101.20
04:12:49.334457 arp who-has 172.16.60.2 tell 192.168.101.20
04:12:50.335329 arp who-has 172.16.60.2 tell 192.168.101.20
04:12:52.335075 arp who-has 172.16.60.2 tell 192.168.101.20
04:12:53.334947 arp who-has 172.16.60.2 tell 192.168.101.20
04:12:54.334821 arp who-has 172.16.60.2 tell 192.168.101.20


Is my understanding correct?

Regards,
Prashant

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