R2511-HP MSR Router Series Interface Configuration Guide(V5)

Figure 14 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 device

to channelized STM-1 interfaces on devices of other vendors, you should consider the possible

numbering differences due to different channel referencing methods.

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.

SDH provides a variety of overhead bytes, but only those involved in CPOS configuration are discussed

in this section.

SOH

The section overhead (SOH) is further classified into the regenerator section overhead (RSOH) and the

multiplex section overhead (MSOH).

The regeneration section trace message J0 is included in RSOH to repeatedly send the section access

point identifier, based on which 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 the networks of two

operators are involved, the sending and receiving devices at network borders must use the same J0 byte.

With the J0 byte, operators can detect and troubleshoot faults in advance or use less time to recover

networks.

POH

The payload of an STM-N frame includes the path overhead (POH), which monitors low-speed tributary

signals.

The SOH monitors the section layer, and the POH monitors the path layer. The POH is divided into the

higher-order path overhead and the lower-order path overhead.

Higher-order path overhead monitors paths at the VC-4/VC-3 level.

VC-4 TUG-3

TUG-3

TUG-2

TU-12

TUG-2

TU-12

TUG-2

TU-12