Organization of the Network layer

There are two possible internal organizations of the network layer: datagram and virtual circuits.

Datagram Organization

The datagram organization has been very popular in computer networks. Datagram-based network layers include IPv4 and IPv6 in the global Internet, CLNP defined by the ISO, IPX defined by Novell or XNS defined by Xerox.

This organization is connectionless and hence each packet contains:

• The network layer address of the destination host.
• The network layer address of the sender.
• The information to be sent.

To understand the datagram organization, let’s consider the slides below. A network layer address represented by a letter, has been assigned to each host and router. Host A wishes to send some information to host J.