Cisco Cisco IOS Software Release 12.0(19)S
IP Services Engine Line Cards
Feature Overview
5
Cisco IOS Release 12.0(19)S
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STM-n:
STM-1 is the base level signal for a POS interface (155.52 Mbps). Multiple STM-n signals can be
multiplexed to form higher-capacity interfaces. For example, four STM-1 signals multiplexed
together form a STM-4 signal.
STM-1 is the base level signal for a POS interface (155.52 Mbps). Multiple STM-n signals can be
multiplexed to form higher-capacity interfaces. For example, four STM-1 signals multiplexed
together form a STM-4 signal.
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TUG-3:
Tributary Unit Group 3 controller used to carry DS-3 data over TUG-2.
Tributary Unit Group 3 controller used to carry DS-3 data over TUG-2.
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VC-3:
Virtual Container 3 used in SDH AU-4 framing to carry DS-3 or E3 serial data.
Virtual Container 3 used in SDH AU-4 framing to carry DS-3 or E3 serial data.
SDH STM-n Multiplexing Hierarchy
This section contains a technical description of the SDH STM-n multiplexing hierarchy as shown in
.
At the lowest level, PDH (plesiochronous digital hierarchy) signals are mapped into containers (C). The
mapping process uses bit stuffing to generate synchronous containers with a common bit rate. Overhead
bytes are then added to create virtual containers (VCs). The VCs are then aligned into tributary units
(TUs) where pointer processing operations are implemented. This allows the TUs to be synchronously
multiplexed into TU groups (TUGs). The TUGs are then multiplexed to become the payload of a High
Order VC (HOVC) that includes its own overhead bytes. The HOVC is aligned into administrative units
(AUs) by adding the AU pointer, then multiplexed into an AU group (AUG). Finally, the frame of a SDH
Synchronous Transport Module level (STM-n) is created by multiplexing n AUGs and adding the
multiplexer section and regenerator section overhead bytes (MSOH and RSOH).
mapping process uses bit stuffing to generate synchronous containers with a common bit rate. Overhead
bytes are then added to create virtual containers (VCs). The VCs are then aligned into tributary units
(TUs) where pointer processing operations are implemented. This allows the TUs to be synchronously
multiplexed into TU groups (TUGs). The TUGs are then multiplexed to become the payload of a High
Order VC (HOVC) that includes its own overhead bytes. The HOVC is aligned into administrative units
(AUs) by adding the AU pointer, then multiplexed into an AU group (AUG). Finally, the frame of a SDH
Synchronous Transport Module level (STM-n) is created by multiplexing n AUGs and adding the
multiplexer section and regenerator section overhead bytes (MSOH and RSOH).
The multiplexing hierarchy is the ITU-T SDH multiplexing hierarchy defined in ITU-T G.707.
Figure 1
SDH STM-n Multiplexing Hierarchy
Applications
This section describes applications of the ISE line cards in the 12000 series routers:
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VC-3
x1
TU-3
x1
C-3
x1
VC-3
Multiplexing
VC-4
TUG-3
STM-n
AUGxn
Aligning
Mapping
x1
x1
x1
x3
x3
x3
x3
AU-4
E3
34,368 kbps
34,368 kbps
DS-3
44,736 kbps
44,736 kbps
AU-3
6
6044