Configuring X.25 SVCs

X.25 SVCs allow X.25 switching to multiple destinations using PANL. Each destination must be configured in the Passport 4400 units. SVCs can be configured between:

• A local physical X.25 port and a virtual X.25 port
• Two unique LCNs on a local X.25 port
• Two unique LCNs on a single virtual X.25 port

You can configure the unit to associate specific X.25 addresses or address prefixes to an outgoing physical or virtual X.25 port. Here is an example of an X.25 routing table:

The X.25 services do not have any requirements about the length of the called address. You can define whatever call addressing scheme meets the requirements of your network.

Upon receiving a call request, the X.25 services:

1. Searches the X.25 routing table for the best match.
2. If a destination is found (the best match), a call request message is sent to the destination.
3. If a destination is not found (no match), a clear request message is sent to the call originator.

The X.25 services call routing algorithm evaluates the called address against every row in the X.25 routing table. Each row receives a score, based on how closely it matches the called address, as follows:

• If the length of a row's called destination prefix is greater than the length of the called address, the row receives a score of 0.
• If any of the digits in the called destination prefix do not match the prefix digits of the called address, the row receives a score of 0.
• If neither of the previous conditions apply, then the row's score will be 2*(each digit in the row's prefix) + 1 for each wild-card in the row's prefix.

Here is an example where the called address is 3021123412345678:

The row with the highest score, which represents the best match, is in bold text.