Chapter 9: AI2524 OSI/CLNP Configuration Steps
August 1997 Page 9-51
2524UM
Configure CLNS over WANs This section provides general infor mation 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 t he 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 C LNS-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 facilitie s 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.aa aa.a aa a .a aaa.00
and an address of 31101. Figure 9-12 illustrates this configuration.