Here's how my current setup looks like:
$ ifconfig eth4
eth4 Link encap:Ethernet HWaddr 74:fe:48:04:e7:eb
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
...
$
ifconfig eth5
eth5 Link encap:Ethernet HWaddr 74:fe:48:04:e7:e6
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
...
$ ip route show
default via 192.168.1.2 dev eth4
192.168.1.0/24 dev eth4 proto kernel scope link src 192.168.1.1
192.168.1.0/24 dev eth5 proto kernel scope link src 192.168.1.2
I've deliberately added a default gateway to 192.168.1.2 (so that the
ARP response is routed back through it).
$ip neigh show
(there's no neighbor entries)
cat /proc/sys/net/ipv4/conf/all/rp_filter
0
cat /proc/sys/net/ipv4/conf/all/arp_filter
1
cat /proc/sys/net/ipv4/conf/eth4/rp_filter
0
cat /proc/sys/net/ipv4/conf/eth4/arp_filter
1
cat /proc/sys/net/ipv4/conf/eth5/rp_filter
0
cat /proc/sys/net/ipv4/conf/eth5/arp_filter
1
Even with these settings, ARP for 192.168.1.2, via eth4 (192.168.1.1)
interface fails.
On Mon, Jan 19, 2015 at 5:31 PM, Mandeep Sandhu
<[email protected]> wrote:
>> You'd mentioned earlier that your setup was this:
>>
>> xeth0 - 192.168.2.1
>> xeth2 - 192.168.2.2
>>
>> That looks to me like two network interfaces on the same subnet, though
>> that's my guess since you don't show the prefix lengths. I'm guessing the
>> subnet on both is 192.168.2/24.
>
> Correct. Netmask is /24.
>
>>
>> Unless things have changed since the last time I looked into this, for IPv4
>> Linux implements what's referred to as the "weak" address binding model
>> where IP addresses are considered to belong to the host not the interface.
>> That means your host may be transmitting an ARP response, but not out the
>> interface you expect, particularly if in fact you have the same subnet
>> assigned to more than one interface.
>>
>> You might want to tcpdump on all interfaces when you do this.
>
> I actually did that (after some googling) but there's no ARP response
> being transmitted out of either of the interfaces. As I mentioned
> before, this problem happens even with regular ethernet interfaces and
> not specifically with my custom hardware related ones, so looks like a
> routing (mis)configuration issue.
>
>>
>> Also, you might want to include the output of the following in future posts:
>>
>> ip addr show
>> ip route show
>> ip neigh show
>
> I'll now test with 2 "regular" ethernet interfaces on my test machine
> (eth0,eth1) and send the o/p of these commands.
>
> Thanks!
>
>>
>> Jeff Haran
>>
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