H3C Technologies H3C SR8800 - Manual (Page 39)

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Figure 9 Order of TUG-3s, TUG-2s, and TU-12s in a VC-4 frame
You can calculate TU-12 numbers in the same way when the AU-3 path is used.
When 63 E1 channels or 84 T1 channels are configured on a CPOS interface, you can reference E1 or
T1 channels by referencing the numbers in the range of 1 to 63 or 1 to 84. When connecting your router
to channelized STM-1 interfaces on routers of other vendors, you should consider the possible numbering
differences due to different channel referencing approaches.
Figure 10 Order of TUG-3, VC-3, and C-3 in a VC-4 frame
The channel number calculation for E3/T3 channels is simpler than that for E1/T1 channels. As shown
in Figure 10 , when the AU-4 multiplexing path is used, as TUG-3 and VC-3 are not divided into
lower-order paths, the E3/T3 channel numbers are the TUG-3 numbers. When the AU-3 multiplexing
path is used, you can get the E3/T3 channel numbers in the same way.
Overhead bytes
SDH provides layered monitoring and management of precise division.
It provides monitoring at section and channel levels, where sections are subdivided into regenerator and
multiplex sections, and channels are subdivided into higher-order and lower-order paths. These
monitoring functions are implemented using overhead bytes.
NOTE:
SDH provides a variety of overhead bytes, but only those involved in CPOS configuration are discussed in
this section.
VC-4 TUG-3
TUG-3
TUG-3
TUG-2
TU-12
TU-12
TU-12
TUG-2
TU-12
TU-12
TU-12
TUG-2
TU-12
TU-12
TU-12
1
2
3
1
2
7
.
.
.
1
2
3
1
2
3
1
2
3
VC-4 TUG-3 TU-3 VC-3 C-3
TUG-3
TUG-3
TU-3
TU-3
VC-3
VC-3
C-3
C-3
1
2
3