Complete Protocol dictionary, glossary and reference
VPI: Virtual Path Identifier
Virtual Path Identifier (VPI) is a routing label used in the Asynchronous Transfer Mode (ATM) header. The VPI, together with the Virtual Channel Identifier (VCI), identifies the next destination of a cell as it passes through a series of ATM switches on its way to its destination. VPI field has 8 to 12 bits: 8 in the case of user-network interface and 12 in the case of network-network interface. The 4 extra bits in the network-network interface allows support for an expanded number of VPC internal to the network, which can be used for network management. A VPI of 0 indicates that this PVC is a virtual channel connection (VCC). A nonzero value indicates that this is a virtual path connection (VPC).