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ForeRunner
ATM Switch Network Configuration Manual
Configuring PVCs
The VCI value of cells does not change as the cell is switched through the ATM network via a
virtual path. Each virtual path must originate at a switch fabric, pass through zero or more
switch fabrics and terminate at another switch fabric. The origination and termination points
are referred to as originating and terminating paths. Virtual paths are switched through switch
fabrics via through paths. Virtual paths are made up of an originating path, zero or more
through paths, and a terminating path.
Figure 1.4 -
Composition of a Virtual Path
1.2.1 Through Paths
Through paths route an entire virtual path through an ATM switch fabric. When a cell is
received by a switch fabric on a through path, the VPI is examined to determine the output
port and VPI. The VCI component of the ATM header remains unchanged and can have any
value. So, all of the channels within the through path are switched correctly without altering
the VCI value of cells on these channels.
Four parameters are needed to define a through path on a ForeRunner switch fabric: input
port, input VPI, output port, and output VPI. Through paths are represented as follows:
<iport> <ivpi> <oport> <ovpi>
The VCI value remains unchanged when cells are switched via a through path. For example,
the through path A4|10 -> B4|20 maps cells received on port A4 with VPI: 10 and any VCI to
port B4 with VPI: 20 and the same VCI.
Through Path
Virtual Path
Terminating Path
Originating Path
ForeRunner
ATM Switch
ForeRunner
ATM Switch
ForeRunner
ATM Switch
Summary of Contents for forerunner series
Page 6: ......
Page 16: ...TOC 10 ForeRunner ATM Switch Network Configuration Manual Table of Contents ...
Page 20: ...LOF 4 ForeRunner ATM Switch Network Configuration Manual List of Figures ...
Page 22: ...LOT 2 ForeRunner ATM Switch Network Configuration Manual List of Tables ...
Page 30: ...viii ForeRunner ATM Switch Network Configuration Manual Preface ...
Page 144: ...3 58 ForeRunner ATM Switch Network Configuration Manual Configuring an Emulated LAN ...
Page 180: ...6 12 ForeRunner ATM Switch Network Configuration Manual ATM Forum PNNI ...
Page 220: ...9 6 ForeRunner ATM Switch Network Configuration Manual Configuring Timing ...
Page 300: ...D 24 ForeRunner ATM Switch Network Configuration Manual Configuring FramePlus Modules ...
Page 308: ...Acronyms 8 ForeRunner ATM Switch Network Configuration Manual Acronyms ...
Page 346: ...Glossary 38 ForeRunner ATM Switch Network Configuration Manual Glossary ...
Page 352: ...Index 6 ForeRunner ATM Switch Network Configuration Manual Index ...