The ATM Cell Header
Figure 20.5 shows the format of an ATM cell header for a cell that is sent between an endpoint system and its adjacent ATM switch.
Figure 20.5. Cell header sent between an endpoint system and an ATM switch.
Currently, the first 4 bits are unused. Recall that a virtual circuit is identified by its Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI). The VPI occupies the next 8 bits. When expressed as a decimal number, the VPI value can range from 0 to 255.
The VCI occupies 16 bits. Hence, when expressed as a decimal number, the VCI value can range from 0 to 65,535. In all, there are 16,777,216 possible (VPI, ...
Get Local Area High Speed Networks now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
