|
While network layer addresses are used to
get packets from source to destination, it is important to understand
that a different type of address is used to get packets from one
router to the next. For a packet to get from the source to the
destination, both Layer 2 and Layer 3 addresses are used. As shown in
Figure  , at
each interface, as the packet moves across the network, the routing
table is examined and the router determines the next hop. The packet
is then forwarded using the MAC address of that next hop. The IP
source and destination headers do not change, at any time.
The Layer 3 address is used to route
the packet from the source network to the destination network. The
source and destination IP addresses remain the same. The MAC address
changes at each hop or router. A data-link layer address is necessary
because delivery within the network is determined by the address in
the Layer 2 frame header, not the Layer 3 packet header.
| |
Interactive Media Activity
Drag and Drop: L2 and L3 Address
After completing this activity, the student will be able to identify L2 and
L3 addresses.
|
|
|
|
Web Links