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tbaranski Sun, 02/22/2004 - 08:37
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Since it runs over Ethernet it can be considered layer 2.5. Protocols don't always map to the OSI model perfectly.

r.leutert Tue, 02/24/2004 - 04:21
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ARP is actually a layer 2 protocol as it is not routable (only bridges or Layer2 switches forward an ARP). But as it deals with layer 3 IP address resolution, you may see it as an utility protocol for layer 3. But ARP has not been designed for IP only (that's why you have the protocol field in the ARP header), it has been used by other protocols too,which have disapeared in the meantime (i.e. Chaosnet protocol). Regards Rolf

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