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arp who-has on multiple subnet

Posted on 2010-11-26
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Last Modified: 2012-05-10

Hi,

I have some questions about the protocol ARP. One of my device send a "who has" arp packet to a other device. But the second device are in other subnet.

If I understand well a "who has" query is a broadcast, so it is normal that the second device don't reply the "who has" query since is not in the same subnet. is it? But why the first device send "who has" query?

Maybe I just don't understand how is working.

Here are the packet:

2.835165 wlan in arp who-has 192.168.10.40 tell 192.168.6.2
0x0000       ffff ffff ffff 0002 2d66 1bd2 0806 0001      ........-f......
0x0010       0800 0604 0001 0002 2d66 1bd2 c0a8 0602      ........-f......
0x0020       0000 0000 0000 c0a8 0a28                                          .........(

and no more reply after that.



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Question by:Vbourbeau
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guitar7man earned 1000 total points
ID: 34218594
If a node needs to get to a device on a different subnet, it's not going to send out an ARP for its MAC address, it's going to ARP for its gateway (if needed) because it knows the intended destination is not on the layer 2 network. Do you have your subnet mask correct on the host?
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by:Vbourbeau
ID: 34218781

This is what I think. For the subnet mask I'm pretty sure is set correctly but I can't check for now.

My doubts are on the device himself maybe an frimware update will help.

Thank you
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