An Overview of X.25 Addressing

A Simple Addressing Scheme

The X.121 specification applies only to addressing on public data networks; there are no rules regarding addressing on private data networks.

The addressing scheme that is used on a private data network depends totally on how the manufacturer has designed the switch. Sometimes the manufacturer imposes a particular addressing scheme; other times, as Netrix does, a flexible addressing scheme using any number of digits up to the maximum of 15 can be used.

A simple addressing scheme that could be used in the Netrix network could consist of a two-digit node number followed by the CM & DIN numbers of the place where the equipment is connected.

For example, a host computer connected to the first CM (01) on a V.35 card in DIN slot 09 of node #30 would have its address assigned as 300109.

This is a simple and workable system for networks with fewer than 100 nodes and that provides a unique address for every possible connection (since node numbers must be unique).

Although the 6-digit addressing scheme that was illustrated is a simple one that can be easily implemented in your Netrix network, you can set up any addressing scheme you want.

Before assigning addresses in your network, you should think carefully about how you want to set up your addressing scheme.

You will want an address format that meets your needs, provide unique addresses throughout the network, and can be used relatively easily with the Netrix address translation mechanism that will be explained in the rest of this course.