ZyXEL Communications Prestige 642R Series, User Manual, Page: 158 / 163

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:
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.
Diagram 3 VPI's & VCI's