Tech Note #22: Asynchronous Transfer Mode (ATM) Addresses
1998 Bionic Buffalo Corporation; All Rights Reserved.
14 September 1998
5 of 12
The ATM layer of these protocol stacks translates the VPI and VCI numbers, as the cell moves
through the network. Other functions of the ATM layer include cell header process, cell
multiplexing and demultiplexing, and some flow control. If a cell passes through a single
intermediate node while going from one connection point to another, the associated protocol
stack might have the following configuration:
physical layer (1st link)
ATM layer (does VPI/
physical layer (2nd link)
In the most complex and interesting cases, however, the VPI and VCI numbers are assigned
dynamically as part of the routing and switching process, as connections are established and
broken down. Adding these functions requires increasing the complexity of the architecture, as
explained in the next section.