7.2 Configuring X.25
7.2.1 Interface tasks
When you select X.25 as a WAN protocol, you must set appropriate interface parameters. Interface tasks are as follows:
  • Define the X.25 encapsulation (DTE is the default).
  • Assign the X.121 address (usually supplied by the PDN service provider).
  • Define map statements to associate X.121 addresses with higher-level protocol addresses.

Other configuration tasks can be performed to control data throughput and to ensure compatibility with the X.25 network service provider. Commonly used parameters include the number of VCs allowed and packet size negotiation.

X.25 is a flow-controlled protocol. The default flow-control parameters must match on both sides of a link. Mismatches because of inconsistent configurations can cause severe internetworking problems.

Note: Before configuring X.25 parameters, you must enter interface configuration mode and assign a higher-layer address, such as an IP address to the interface.