3Com 10014299 Create the permanent virtual circuit PVC, Configure X.25 Datagram Transmission

Configure X.25 207

Configure X.25 Datagram Transmission

The configuration of X.25 datagram transmission includes:

■Create the mapping from the protocol address to X.121 address

■Create the permanent virtual circuit

In the most frequently used X.25 service, data is transmitted remotely between two hosts using the X.25 protocol via X.25 public packet network. As shown in the figure below, LAN A and LAN B are far apart, and X.25 packet switching network can be used to realize information exchange between them.

Figure 63 LAN interconnection via X.25

		Router B
LAN A	X.25	LAN B
	Router A

The datagram uses IP address to communicate data and information between LAN A and LAN B, whereas X.121 address is used inside X.25. Therefore, we setup correct mapping between the IP address and X.121 address.

1Create the mapping from the protocol address to X.121 address

An X.25 interface has its own X.121 address and inter-network protocol (such as IP protocol) address. When X.25 initiates a call through this interface, the source address (calling DTE address) it carries in the call request packet is the X.121 address of this interface.

For a datagram with a definite destination IP address, its corresponding X.121 destination address is located by the configured address mapping. The called destination, just like a calling source, also has its own protocol address and X.121 address. Establish the mapping between the destination protocol address and the X.121 address at the calling source, you can find the destination X.121 address according to the destination protocol address, and successfully initiate a call.

In the interface view, perform the following commands to create/delete an address mapping.

Table 246 Create/Delete the mapping from the protocol address to X.121 address

Operation	Command
Create the mapping from the destination	x25 map { ip ipx }
protocol address to X.121 address	protocol-address x121-address
	x.121-address [ option ]
Delete the mapping from the destination	undo x25 map protocol
protocol address to X.121 address	protocol-address

The protocol-address and x.121-address in the command line refer to the protocol address and X.121 address of the destination, not those of the source.

An address mapping should be created for every destination.

While creating an address mapping, specify its attributes with the option items. The meanings and specific content of these options will be described in subsequent sections.

2Create the permanent virtual circuit (PVC)

A permanent virtual circuit can be created for large-traffic and stable data transmission on leased line. Permanent virtual circuits (PVCs) do not need any call