HP HSR6800 Configuration Manual page 76

Figure 18 Process of multiplexing four STM-1 frames into an STM-4 frame
The recipient will demultiplex a received STM-4 frame into four STM- 1 frames. During the multiplexing
process, the A1, A2, J0, Z0, B1, E1, F1, D1, D2, and D3 fields in the RSOH of the first frame are
multiplexed into the STM-4 frame while those of the rest three frames are treated as invalid. The other
fields of each frame are multiplexed into the STM-4 frame separately.
Figure 19 Process of demultiplexing an STM-16 frame in the SDH frame format
Rate hierarchy of SONET/SDH
SDH frames at different rates are identified in the form of STM-N (N equals 1, 4, 16, 64, and so on,
indicating that the frame is formed through multiplexing and interleaving N STM- 1 frames). SONET
frames at different rates are identified in the form of STS-N (N equals 1, 3, 12, 48, and so on, indicating
that the frame is formed through multiplexing and interleaving N STS- 1 frames.
hierarchies of SONET and SDH.
Table 2 Rate hierarchy of SONET/SDH
SONET
STS-1
STS-3
SDH
N/A
STM-1
71
Table 2 lists the rate
Rate
51.840 Mbps
155.52 Mbps