SONET and SDH Data Rates

 

 

OC  vs  STS  vs  STM  Data Rates

Optical Carrier

Level

Data Rate
(Line Rate)

Transport

Overhead Rate

Payload-SONET (SPE)
(Data Rate – Transport

Overhead)

User Data Rate (Mbps)

(SPE – Path Overhead)

SONET
STS
(ANSI)

SDH
STM
(CCITT)

OC-1

51.84 Mbps

1.728 Mbps

50.112 Mbps

49.536

STS-1

--

OC-3

155.52 Mbps

5.184 Mbps

150.336 Mbps

148.608

STS-3

STM-1

OC-9

466.56 Mbps

 

451.044 Mbps

445.824

STS-9

STM-3

OC-12

622.08 Mbps

20.736 Mbps

601.344 Mbps

594.824

STS-12

STM-4

OC-18

933.12 Mbps

 

902.088 Mbps

891.648

STS-18

STM-6

OC-24

1244.16 Mbps

 

1202.784 Mbps

1188.864

STS-24

STM-8

OC-36

1866.24 Mbps

 

1804.176 Mbps

1783.296

STS-36

STM-12

OC-48

2488.32 Mbps

82.944 Mbps

2.4 Gbps

2377.728

STS-48

STM-16

OC-192

9953.28 Mbps

331.776

9.6 Gbps

9510.912

STS-192

STM-64

OC-768

40Gbit/s

1327.104

38.5 Gbps

-

STS-768

STM-256

OC-3072

160Gbit/s

 

-

-

STS-3072

STM-1024

SONET and SDH Data Rates

*** all use the same frame rate of 8000 frames/sec ***

 

SDH/SONET  Conversion 

STM-n = STS-3n = OC-3n

For example:  STM-1 =  STS-3 = OC-3 = 155.52 Mbps

 

Unused Data Rates - other rates (OC-9, OC-18, OC-24, OC-36, OC-96) are referenced in some of the standards documents but were never widely implemented. It is possible other higher rates (e.g. OC-3072) may be defined in in the future.

The "line rate" refers to the raw bit rate carried over the optical fiber. A portion of the bits transferred over the line are designated as "overhead". The overhead carries information that provides OAM&P (Operations, Administration, Maintenance, and Provisioning) capabilities such as framing, multiplexing, status, trace, and performance monitoring. The "line rate" minus the "overhead rate" yields the "payload rate" which is the bandwidth available for transferring user data such as packets or ATM cells.

The SONET/SDH level designations sometimes include a "c" suffix (such as "OC-48c"). The "c" suffix indicates a "concatenated" or "clear" channel. This implies that the entire payload rate is available as a single channel of communications (i.e. the entire payload rate may be used by a single flow of cells or packets). The opposite of concatenated or clear channel is "channelized". In a channelized link the payload rate is subdivided into multiple fixed rate channels. For example, the payload of an OC-48 link may be subdivided into four OC-12 channels. In this case the data rate of a single cell or packet flow is limited by the bandwidth of an individual channel.

 

SONET vs SDH