> The arp request is in the form of 'who has ip 192.168.0.1'.  If that
> host 192.168.0.1 is on the network segment then it will reply with its
> mac address.  This is then added to the arp table and the packet is
> encapsulated with the layer 2 frame with the destination mac it just
> learnt.

Yes.

> If the destination host is via a router then the router will respond
> with its mac address and the packet is encapsulated with that mac
> address and the router takes care of it.

You should only send an ARP request for IP addresses where the
network number (IP address AND'ed with net mask) matches your
own network number (on a per-interface basis).  If you want to
send a packet to an IP address which has a different network
number, then you do an ARP request for your default route's IP
address and forward the packet there for onward transmission.
(It's a little more complex if you have complex routing tables,
but this suffices for an end node with a single interface.)

						Lee Jones

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