ZyXEL Communications 642R Series Manuel D’Utilisation
Prestige 642R Series ADSL Router
H
Virtual Path and Channels
Appendix B
Virtual Paths and Channels
VPI & VCI
ATM is a connection-oriented technology, meaning that it sets up virtual circuits over which end systems
communicate. The terminology for virtual circuits is as follows:
ATM is a connection-oriented technology, meaning that it sets up virtual circuits over which end systems
communicate. The terminology for virtual circuits is as follows:
z
VC (virtual channel)
Logical connections between end stations
z
VP (virtual path)
A bundle of VCs
Think of a VP as a cable that contains a bundle of wires. The cable connects two points, and wires within
the cable provide individual circuits between the two points. In an ATM cell header, a VPI (Virtual Path
Identifier) identifies a link formed by a virtual path and a VCI (Virtual Channel Identifier) identifies a
channel within a virtual path. The VPI and VCI are identified and correspond to termination points at ATM
switches as shown. Your telephone company should supply you with these numbers.
the cable provide individual circuits between the two points. In an ATM cell header, a VPI (Virtual Path
Identifier) identifies a link formed by a virtual path and a VCI (Virtual Channel Identifier) identifies a
channel within a virtual path. The VPI and VCI are identified and correspond to termination points at ATM
switches as shown. Your telephone company should supply you with these numbers.
Diagram 3 VPI's & VCI's