IP/Network

  

 

 

 

Network : SONET / SDH

 

SONET stands for Synchronous Optical Network and SDH stands for Synchronous Digital Hierarchy. Basically these two are almost same. The difference is the organization that defines the technology. SONET is defined by ANSI(American National Standard Institute) and SDH is defined by ITU-T(International Telecommunication Union-Telecommunication Standardization Sector). Putting it another way, SONET is a kind of regional spec used in US and SDH is a kind of global specification.

 

 

Frame Structure

 

Data in SONET is transferred in frame structure defined as shown below.

 

 

 

OC (Optical Carrier) level and Data Rate

 

SONET Data Rate is defined as a special category called OC (Optical Carrier) followed by a number. The fundamental data rate is OC-1 and OC-1 data rate can be calculated as below (this calculation is based on the frame structure shown in previous section).

 

Data rate for other OC level is derived by multiplying OC-1 data rate as shown below.

 

OC Level

Data Rate

OC-1

51.84 Mbps (51.84 x 1)

OC-3

155.52 Mbps (51.84 x 3)

OC-9

466.56 Mbps (51.84 x 9)

OC-12

622.08 Mbps (51.84 x 12)

OC-15

777.6 Mbps (51.84 x 15)

OC-18

933.12 Mbps (51.84 x 18)

OC-24

1244.16 Mbps (51.84 x 24)

OC-36

1866.24 Mbps (51.84 x 36)

OC-48

2488.32 Mbps (51.84 x 48)

OC-192

9953.28 Mbps (51.84 x 192) = 10 G

OC-256

13271.04 Mbps (51.84 x 256)

OC-768

39813.12 Mbps (51.84 x 768) = 40 G

OC-1920

99532.8 Mbps (51.84 x 1920) = 100 G

OC-3840

199065.6 Mbps (51.84 x 3840) = 200 G