Page 118 - Optical Switching And Networking Handbook

05_200023_CH04/Batesx 1/17/01 8:18 AM Page 103

Synchronous Digital Hierarchy 103

SDH Model OSI Model
Figure 4-13
SDH layer model
contrasted with
OSI IP Network Layer 3

POTS/ISDN AAL PPP

Data Link Layer 2
VC-12 layer ATM

Virtual Container-4 layer

Multiplexer Section

Repeater Section Physical Layer 1

Physical interface

Photonic sub-layer

Figure 4-14
Path mapping
of SDH
ATM ATM
PDH SDH SDH PDH
MUX Digital R R Digital MUX
IP Cross- Cross- IP
Connect Connect

Figure 4-14 shows the mapping of the payloads at the SDH mul-
tiplexer, whereby the next portions of the circuit are added. This is
shown in the path description.