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Tech Note #22: Asynchronous Transfer Mode (ATM)  Addresses
©
1998 Bionic Buffalo Corporation; All Rights Reserved.
       14 September 1998
http://www.tatanka.com
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Node A
Node B
Node C
Node D
A1
A2
B1
B2
B4
B5
D1
C1
D1
B3
9
:
;
8
7
7
8
9
:
;
virtual channel
virtual path
A virtual channel may exit one virtual path, which terminates within a node, and then enter a
different virtual path terminating at the node, to proceed thereby to another node. (Channel X
illustrates this.)
A VPI and VCI are meaningful only in the context of a specific connection and node. As a cell
passes through the network, the network may give the cell a different VPI and VCI as it passes
through each node. However, the VCI and VPI do not change between nodes, since (of course)
there is no way to renumber them in transit.
If a node has more than one connection or link, then each link may number VPIs
independently. In other words, two different VPs with the same VPI may found in a single
node. These diagrams do not emphasize this point.
VPI
=44
VPI
=21
VPI
=20
VPI
=45
VPI
=45
VPI
=44
VPI
=20
VPI
=21
VPI=33
VPI=33
VCI=15
VCI=28
VCI=28
VCI=89
VCI=29
VCI=29
VCI=28
VCI=29
VCI=89
VCI=15
VCI=90
VCI=90
VCI=28
VCI=29