S3031BH0 AMCC [Applied Micro Circuits Corporation], S3031BH0 Datasheet - Page 2

• Manufacturer Part Number: S3031BH0
• Description: E4/STM-1/OC-3 ATM TRANSCEIVER
• Manufacturer: AMCC [Applied Micro Circuits Corporation]

SONET/SDH OVERVIEW
Synchronous Optical Network (SONET) is a standard
for connecting one fiber system to another at the op-
tical level. SONET, together with the Synchronous
Digital Hierarchy (SDH) administered by the ITU-T,
form a single international standard for fiber intercon-
nect between telephone networks of different coun-
tries. SONET is capable of accommodating a variety
of transmission rates and applications.
The SONET standard is a layered protocol with four
separate layers defined. These are:
Figure 2 shows the layers and their functions. Each
of the layers has overhead bandwidth dedicated to
administration and maintenance. The photonic layer
simply handles the conversion from electrical to opti-
cal and back with no overhead. It is responsible for
Figure 2. SONET Structure
2
Table 1. SONET Signal Hierarchy
S3031B
• Photonic
• Section
• Line
• Path
Elec.
STS-1
STS-3
STS-12
STS-24
STS-48
Payload to
SPE mapping
Maintenance,
protection,
switching
Functions
Scrambling,
framing
Optical
transmission
End Equipment
STM-16
STM-1
STM-4
ITU-T
Photonic layer
Section layer
Path layer
Line layer
Optical Data Rate (Mbps)
OC-1
OC-3
OC-12
OC-24
OC-48
Fiber Cable
Photonic layer
Section layer
1244.16
2488.32
Line layer
Path layer
155.52
622.08
51.84
End Equipment
(Embedded Ops
Layer Overhead
Channel)
576 Kbps
192 Kbps
0 bps
transmitting the electrical signals in optical form over
the physical media. The section layer handles the
transport of the framed electrical signals across the
optical cable from one end to the next. Key functions
of this layer are framing, scrambling, and error moni-
toring. The line layer is responsible for the reliable
transmission of the path layer information stream
carrying voice, data, and video signals. Its main func-
tions are synchronization, multiplexing, and reliable
transport. The path layer is responsible for the actual
transport of services at the appropriate signaling rates.
Data Rates and Signal Hierarchy
Table 1 contains the data rates and signal designa-
tions of the SONET hierarchy. The lowest level is the
basic SONET signal referred to as the synchronous
transport signal level-1 (STS-1). An STS- N signal is
made up of N byte-interleaved STS-1 signals. The
optical counterpart of each STS- N signal is an optical
carrier level- N signal (OC- N ). The S3031B supports
OC-3 rates (155.52 Mbps).
Frame and Byte Boundary Detection
The SONET/SDH fundamental frame format for STS-3
consists of nine transport overhead bytes followed by
Synchronous Payload Envelope (SPE) bytes. This pat-
tern of 9 overhead and 261 SPE bytes is repeated
nine times in each frame. Frame and byte boundaries
are detected using the A1 and A2 bytes found in the
transport overhead. (See Figure 3.)
For more details on SONET operations, refer to the
Bellcore SONET standard document.
Figure 3. STS-3/OC Frame Format
Rows
9
1 A
1 B
D
H
2 B
D
D
D
1 S
E4/STM-1/OC-3 ATM TRANSCEIVER
1
1
4
7
0 1
1 A
*
*
H
2 B
*
*
*
1 Z
1
Transport Overhead
1 A
*
*
H
2 B
*
*
*
1 Z
1
9 Columns
2 A
1 E
D
H
1 K
D
D
D
2 Z
2
2
5
8
1 1
2 A
*
*
H
*
*
*
*
2 Z
2
2 A
*
*
H
*
*
*
*
M
2
1
0 J
1 F
D
H
2 K
D
D
D
2 E
3
3
6
9
2 1
125 sec
August 19, 1999 / Revision D
0 Z
*
*
H
*
*
*
*
*
3
0 Z
*
*
H
*
*
*
*
*
3
Synchronous Payload
261 Columns
Envelope
2349 bytes
9 x 261 =