AIS AI2524 user manual Configure Clns over WANs, Example ISO Clns over

Chapter 9: AI2524 OSI/CLNP Configuration Steps

Configure CLNS over WANs

This section provides general information about running ISO CLNS over WANs.

You can use CLNS routing on serial interfaces with HDLC, PPP, LAPB, X.25, Frame Relay, DDR, or SMDS encapsulation. To use HDLC encapsulation, you must have a router at both ends of the link. If you use X.25 encapsulation, and if IS-IS or ISO IGRP is not used on an interface, you must manually enter the NSAP-to-X.121 address mapping. The LAPB, SMDS, Frame Relay, and X.25 encapsulations interoperate with other vendors.

Both ISO IGRP and IS-IS can be configured over WANs.

X.25 is not a broadcast medium and, therefore, does not broadcast pro- tocols (such as ES-IS) that automatically advertise and record map- pings between NSAP/NET (protocol addresses) and SNPA (media addresses). (With X.25, the SNPAs are the X.25 network addresses, or the X.121 addresses. These are usually assigned by the X.25 network provider.) If you use static routing, you must configure the NSAP-to X.121 address mapping with th x25 map command.

Configuring a serial line to use CLNS over X.25 requires configuring the general X.25 information and the CLNS-specific information. First, configure the general X.25 information. Then, enter the CLNS static mapping information.

You can specify X.25 nondefault packet and window sizes, reverse charge information, and so on. The X.25 facilities information that can be specified is exactly the same as in the x25 map interface configu- ration command.

Example: ISO CLNS over X.25

In this example, serial interface 1 on Router A acts as a DTE for X.25. It permits broadcasts to pass through. Router B is an IS, which has CLNS address of 49.0001.bbbb.bbbb.bbbb.00 and an X.121 address of 31102. Router A has a CLNS address of 49.0001.aaaa.aaaa.aaaa.00 and an address of 31101. Figure 9-12 illustrates this configuration.

August 1997	Page 9-51
2524UM