Network Interface Layer
The network interface layer is
responsible for placing data on
the network medium and receiving
data off the network medium.
This layer contains such
physical devices as network
cables and network adapters. The
network adapter has a unique
12-character hexadecimal number,
such as B5-50-04-22-D4-65, which
is known as the media access
control (MAC) address. The
network interface layer does not
contain the type of
software-based protocols that
are included in the other three
layers, but it does contain such
protocols as Ethernet and
asynchronous transfer mode
(ATM), which define how data is
transmitted on the network.
Identifying Applications
In a network, many applications
are in communication at the same
time. When multiple applications
are active on a single computer,
TCP/IP requires a method for
differentiating one application
from another. For this
purpose, TCP/IP uses a socket,
also known as an end point in
network communication, to
identify a specific application.
IP Address
To start a network
communication, the location of
the source and destination
computers in the network must be
known. The location is
identified by a unique number,
known as an IP address, which is
assigned to each computer on the
network. An example of an IP
address is 192.168.2.200.