SONETSDH

1
Chapter 20
SONET/SDH (Synchronous Optical Network/ Synchronou
s Digital Hierarchy)
2
SONET/SDH General

• Standard Organization
• SONET ANSI
• SDH ITU-T
• A single clock is used to handle the timing of
  transmissions and equipment across the entire
  network.

3
Figure 20-1
A SONET System

• Synchronous transport signal (STS)
• Refer Table 20.1 SONET/SDH rates

4
Figure 20-2
An Example of a SONET Network
5
Figure 20-3
SONET Layers

• O/E conversion
• MUX/DEMUX
• Encap/Decap

• Line layer overhead
• is added to the frame.

• Framing, scrambling,
• and error control

• Physical specification
• - optical fiber channel
• - sensitivity of the receiver
• - multiplexing functions
• - and so on.

6
Figure 20-4
Device-Layer Relationship in SONET
7
Figure 20-5
Data Encapsulation in SONET

• SONET inserts overhead at a variety of locations
  in the middle of the frame.

8
Figure 20-6
STS-1 Frame
9
Figure 20-7
STS-1 Frame Overhead

• Synchronous payload envelope (SPE)

10
Figure 20-8
STS-1 Frame Section Overhead

• A1 (0b11110110), A2 (0b00101000) Framing and
  synchronization
• C1 Carrier Identifier (STS-1, -3, -9, -12, etc)
• B1 64kbps channel
• (used for communication between regenerators, or
  between terminals and regenerators)
• E1 64kbps channel (reserved for user needs at
  the section level)
• D1, D2, D3 operation, administration, and
  maintenance (OAM) signaling

11
Figure 20-9
STS-1 Frame Line Overhead

• H1, H2, H3 used in frame alignment
• and frequency adjustment of payload data
• K1, K2 128kbps channel
• (used for automatic detection of problems
• in line-terminating equipment)
• Z1, Z2 Reserved

12
Figure 20-10
Payload Pointers
13
Figure 20-11
STS-1 Frame Path Overhead

• P1 64kbps channel (used for tracking the path)
• C2 used to identify different higher-level
  protocols
• (FDDI or SMDS)
• G1 sent by the receiver to communicate its
  status to the sender.
• F2 64kbps channel (reserved for user needs)
• H4 indicates payloads that cannot fit into a
  single frame

14
Figure 20-12
Virtual Tributaries
15
Figure 20-13
VT Types
16
Figure 20-14
STS-n

• A column of path overhead is included in the
  payload,
• which is not necessarily in the first available
  column position.
• The line overhead contains a pointer that
  indicates
• where the path overhead starts.

17
Figure 20-15
STS Multiplexing
18
Figure 20-16
ATM in an STS-3 Envelope
19
Summary

• SONET/SDH
• A SONET System
• STS Multiplexer
• Regenerator
• Add/Drop Multiplexer