Nortel Networks 8000 - Manual (Page 224)

Nortel Secure Router 8000 Series
Configuration -WAN Access 7 LAPB and X.25 configuration
Configuring the attributes related to the address code set in the call packet or call
accept packet
As specified in the X.25 protocol, the call packet must carry the information set of
both the calling DTE address (source address) and the called DTE address
(destination address). This address information set is called the address code set.
For call receiving packets, however, some networks require that both (the calling
DTE address and the called DTE address) be carried, some networks require that only
one of the two be carried, and some other networks require that neither should be
carried. X.25 in the SR8000 enables the user to make choices according to the
requirement of specific networks.
Configuring the default upper layer protocol
A Call User Data (CUD) field is contained in an X.25 call request packet to identify
the upper layer protocol carried by the X.25 protocol.
Whenever the router receives an X.25 call, it examines the CUD field in the packet. If
it finds that the CUD field of the packet is unidentifiable, it does not accept it. But, an
upper layer protocol can be specified as the default protocol carried on the X.25 of
the SR8000. When the X.25 of the SR8000 receives a call with an unrecognizable
CUD, it treats it as the default upper layer protocol specified by the user.
7.3.4 Configuring an X.25 sub-interface
Do as follows on the routers.
Step 1 Run:
system-view
The system view appears.
Step 2 Run
interface serial interface-number
The interface view appears.
Step 3 Run:
link-protocol x25
The command configures the link layer protocol of the interface as X.25.
Step 4 Run:
quit
Return to the system view.
Step 5 Run:
interface serial interface-number.subinterface-number [ p2mp | p2p ]
The command creates an X.25 sub-interface.
Step 6 Choose one of the following steps to configure the address mapping or PVC of the interface
as required.
• Run the x25 map { compressedtcp protocol-address | ip protocol-address } *
x121-address x.l21-address [ option ] command to configure the address mapping.
Issue 5.3 (30 March 2009) Nortel Networks Inc. 7-21