المساعد الشخصي الرقمي

مشاهدة النسخة كاملة : What is VPI and VCI?



A7med Baraka
04-15-2009, 08:46 PM
ATM is a connection orientated protocol and as such there is a
connection identifier in every cell header which explicitly associates a cell
with a given virtual channel on a physical link. The connection identifier
consists of two sub-fields, the Virtual Channel Identifier (VCI) and the
Virtual Path Identifier (VPI). Together they are used in multiplexing,
demultiplexing and switching a cell through the network. VCIs and VPIs are
not addresses. They are explicitly assigned at each segment (link between ATM
nodes) of a connection when a connection is established, and remain for the
duration of the connection. Using the VCI/VPI the ATM layer can
asynchronously interleave (multiplex) cells from multiple connections.