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208 CHAPTER 16: CONFIGURING LAPB AND X.25
process and it always exists. An address mapping will be created implicitly while a
permanent virtual circuit is created.
To create/delete a permanent virtual circuit, perform the following tasks in
interface view.
Table 247 Create/Delete permanent virtual circuit
The format of this command shows that while a permanent virtual circuit is
created, an address mapping is also created for it. Similarly, the protocol-address
and x.121-address in the command also refer to the destination address. While
creating a permanent virtual circuit, some attributes of the PVC can also be
selected via the option. This [option] is a subset of [option] in the command "
x25
map
...... [option]".
For configuration example of permanent virtual circuit, refer to subsequent
sections.
Configure Additional
Parameters of X.25
Datagram Transmission
The Configuration additional parameters of X.25 datagram transmission includes:
■ Specify the maximum idle time of SVC
■ Specify the maximum number of SVCs that is associated with the same address
mapping
■ Specify the pre-acknowledgement of packet
■ Configure X.25 user facility
■ Set the length of virtual circuit queue
■ Broadcast via X.25
■ Restrict the use of address mapping
■ Configure the interface with the standby center
The X.25 of the 3Com Router series allows adding some additional characteristics,
including a series of optional user facilities stipulated in ITU-T Recommendation
X.25.
This section shows how to configure such additional characteristics, including the
options in the two commands of "
x25 map ......" and "x25 pvc......". Please
select and configure these additional characteristics according to the actual needs,
X.25 network structure and the services provided by service provider.
1 Configure SVC maximum idle time
Specify a time period, and if SVC is idle within this period (no packet interaction),
then X.25 of the 3Com Router series will automatically clear this SVC to avoid
unnecessary expenses. Before the data packet is sent next time, this SVC will be
reestablished. So the activation of this characteristic will not affect data
transmission.
In the interface view, this task can be accomplished in two different ways. For
details, refer to the table as follows.
Operation Command
Create a permanent virtual circuit x25 pvc pvc-number protocol
protocol-address x121-address
x.121-address [ option ]
Delete a permanent virtual circuit undo x25 pvc pvc-number