VPI dan VCI pada DSLAM

Buat yang baru pasang speedy pasti bertanya - tanya, apa sih VPI dan VPI itu ? terus kenapa nilainya berbeda - beda tergantung dengan DSLAM yang digunakan ? Nah berikut ini penjelasan mengenai VPI dan VCI versi wikipedia :

VPI = Virtual Path Identifier
Virtual Path Identifier refers to an 8-bit (user to network packets) or 12-bit (network-network packets) field within the header of an Asynchronous Transfer Mode packet. The VPI, together with the VCI (Virtual Channel Identifier) is used to identify the next destination of a cell as it passes through a series of ATM switches on its way to its destination. VPI is useful to reduce the switching table for some Virtual Circuits which have common path.

VCI = Virtual channel identifier
A Virtual Channel Identifier (VCI) is a unique identifier which indicates a particular virtual circuit on a network. It is a 16-bit field in the header of an ATM cell. The VCI, together with the VPI (Virtual Path Identifier) is used to identify the next destination of a cell as it passes through a series of ATM switches on its way to its destination.

ATM switches use the VPI/VCI fields to identify the virtual channel link {VCL} of the next network that a cell needs to transit on its way to its final destination. The function of the VCI is similar to that of the data-link connection identifier DLCI in Frame Relay and the Logical Channel Number & Logical Channel Group Number in X.25.