
Configuring ATM Services
2-6 114056 Rev. A
Although we use raw bandwidth to describe line rates, inherent overhead within
the media limits maximum bandwidth for the line. Use Table 2-1 to determine the
maximum bandwidth for the media you are using.
ATM Layer
The B-ISDN protocol reference model, on which ATM is based, consists of four
layers. Each layer communicates only with the layers directly above it or directly
below it. Figure 2-4 shows the B-ISDN ATM protocol reference model.
Figure 2-4. B-ISDN ATM Protocol Reference Model
Table 2-1. Maximum Bandwidth
Media
Raw
Bandwidth (Mb/s)
Maximum
Bandwidth (Mb/s)
Maximum
Cells/s
OC-3 SONET/SDH 155 149.76 353207
DS-3 44.736 40.704 96000
E-3 (G.832 Framing) 34.368 33.920 80000
E-3 (G.751 Framing) 34.368 30.528 72000
Higher Protocol Layer
ATM
adaptation
layer
(AAL)
Convergence sublayer (CS)
Segmentation and reassembly sublayer (SAR)
ATM Layer
Transmission convergence sublayer
Physical medium dependent sublayer (PMD)
Physical
layer
(PHY)
ATM0003A
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