R3303-HP HSR6800 Routers Interface Configuration Guide

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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.
Figure 13 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 13, w
hen 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.
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 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.