Functional Overview
CTS850 SDH/PDH Test Set User Manual
2–31
Figure 2–21: SDH Multiplexing Hierarchy
Table 2–3: SDH Multiplexing Structure
Term
Contents
Description
C–n
n = 1 to 4
payload at lowest multiplexing level
VC–n
n = 1,2
single C–n plus VC POH
VC–n
n = 3,4
C–n, TUG–2s or TU–3s, plus POH for
the specific level
TU–n
n = 1 to 3
VC plus tributary unit pointer
TUG–2
(TU–n) = 1,3,4
various TU–n s
TUG–3
TU–3, 7 TUG–2s
TU–3, 7 TUG–2s
AU–n
n = 3,4
VCs plus AU pointer
STM–n
n = 1, 3 AUGs
n synchronously– multiplexed STM–1
signals
POH = Path Overhead; C = Container; TU = Tributary Unit; AU =
Administrative Unit; VC = Virtual Container; TUG = Tributary Unit
Group; STM = Synchronous Transport Module
Difference in Telecommunications Terms
Three sets of terms are listed here because it is important to see that
they are not equivalent terms, which is how they get used in normal
discussions. They are:
Add/ Drop
The process where a part of the information carried in a transmission
system is extracted (dropped) at an intermediate point and different
information is inserted (added) for subsequent transmission. The
remaining traffic passes straight through the multiplexer without
additional processing.
Summary of Contents for CTS 850
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