Overhead Byte - 3Com MSR 50 Series Configuration Manual

542 C 29: CPOS I
HAPTER
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Overhead Byte

n
C
NTERFACE ONFIGURATION
The two TU-12s are called adjacent, if they have the same TUG-3 number and
TUG-2 number but different TU-12 numbers with a discrepancy of 1.
The numbers in the aforementioned formula refer to the location numbers in a
VC-4 frame. TUG-3 can be numbered in the range 1 to 3; TUG-2 in the range 1 to
7 and TU-12 in the range 1 to 3. TU-12 numbers indicate the order in which the
63 TU-12s in a VC-4 frame are multiplexed, that is, E1 channel numbers.
Figure 153 Order of TUG-3s, TUG-2s, and TU-12s in a VC-4 frame
1
VC-4 TUG-3
2
TUG-3
3
TUG-3
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 1 to 63
or 1 to 84. When connecting your device to channelized STM-1 interfaces on
devices of other vendors, you should consider the possible numbering differences
result from different channel referencing approaches.
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.
SDH provides a variety of overhead bytes, but only those involved in CPOS
configuration are discussed in this section. For more information about overhead
bytes, refer to related books.
SOH
■
Section overhead (SOH) consists of regenerator section overhead (RSOH) and
multiplex section overhead (MSOH).
The regeneration section trace message J0 is included in RSOH to send the section
access point identifier repeatedly. Based on the identifier, the receiver can make
sure that it is in continuous connection with the sender. This byte can be any
character in the network of the same operator. If networks of two operators are
TU-12
1
TUG-2 TU-12
TU-12
TU-12
2
TUG-2 TU-12
.
TU-12
.
.
TU-12
7
TUG-2
TU-12
TU-12
1
2
3
1
2
3
1
2
3