Virtual Circuit Topology; Introduction; Figure 277 Virtual Circuit Topology - ZyXEL Communications Vantage CNM User Manual

Introduction

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:
• Virtual Channel: Logical connections between ATM switches
• Virtual Path: A bundle of virtual channels
• Virtual Circuit: A series of virtual paths between circuit end points

Figure 277 Virtual Circuit Topology

Think of a virtual path 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; a
VCI (Virtual Channel Identifier) identifies a channel within a virtual path.
The VPI and VCI identify a virtual path, that is, termination points between ATM switches. A
series of virtual paths make up a virtual circuit.
Your ISP (Internet Service Provider) should supply you with VPI/VCI numbers.
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Virtual Circuit Topology

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