X25 provides two different types of virtual circuit: switched virtual circuit (SVC) and permanent virtual circuit (PVC).
Abilis CPX is able to manage SVC channels through the SVC routings table, and PVC channels through the PVC connections table.
In order to properly work, communications ports must be correctly configured with respect to the connected devices. Particular attention must be paid to the logical channels (PVC, ISVC, BSVC, OSVC) numbering. For more detailed information refer to the section X25 Level 3 ports.
The following pictures show the differences between SVC and PVC connections.
|
A virtual call is a dynamically established virtual circuit (channel SVC) using a call setup and a call clearing procedure for every communication session.
Packet routing inside the network (and Abilis CPX) is made according to the data of the call, and to the SVC routings table.
|
A permanent virtual circuit is a permanent, network-assigned, virtual circuit (PVC).
Packets routing inside the network (and Abilis CPX) is made according to a "fixed" table. Routing can be changed only by modifying the configuration tables.
Whenever necessary, DTEs or the network can request to reset the connection trough the reset procedure provided for PVC channels.
Print this page