packet is handed to the protocol listed in the Ether-Type field--it's
given to IP.
the packet's destination address doesn't match any of the addresses
configured on the receiving router itself, the router will look up the
destination IP network address in its routing table.
the packet will be discarded immediately and an ICMP message will
be sent back to the originating device with a "destination network
unavailable" message.
the packet is switched to the exit interface--in this example, interface
Ethernet 1.
tination host and first checks the ARP cache. If the hardware address
of Host B has already been resolved, then the packet and the hardware
address are handed down to the Data Link layer to be resolved.
an ARP request looking for the hardware address of 172.16.20.2.
tion hardware address are both sent to the Data Link layer for framing.
hardware address, Ether-Type field, and FCS field at the end of the
frame. The frame is handed to the Physical layer to be sent out on
the physical medium one bit at a time.
matches what's in the FCS field, the hardware destination address is
then checked. If the host finds a match, the Ether-Type field is then
checked to determine protocol where the packet should be handed to
at the Network layer--IP, in this example.
nation address. Since there's finally a match made, the protocol field
is checked to find out whom the payload should be given to.