SDH multiplex structure

 Synchronous Digital Hierarchy (SDH) is a CCITT standard for a hierarchy of optical transmission rates. Synchronous Optical Network (SONET) is an ANSI (American National Standards Institute) standard for North America, that is largely equivalent to SDH.

Both are widely spread technologies for very high speed transmission of voice and data signals across the numerous world-wide fiber-optic networks.SDH and SONET are point-to-point synchronous networks that use TDM multiplexing across a ring or mesh physical topology.

The main difference between both standards are the some header/pointer informations and the transmission rates.The base transport module of SDH is the synchronous transport module with a transmission rate of 155,52mbps (STM-1), SONET uses OC-1 (~51mbs) as base module.

SDH/SONET transmission rates

 PDH

(USA)PDH

(Europe)SDH SONET

Bit Rate (Mbps)

Name Name Container Transport Container Transport

40000       STM-256   STS/OC-768

10000       STM-64   STS/OC-192

2500       STM-16   STS/OC-48

622       STM-4   STS/OC-12

155       STM-1   STS/OC-3

140   E4 VC4      

51           STS/OC-1

45 DS-3/T3       STS-1 SPE  

34   E3 VC3      

8   E2        

6 DS-2/T2      VT6 (not really used)

 

2   E1 VC12      

1,5 DS-1/T1       VT1.5  

0,064 DS-0/T0 E0/D64S        

 SDH multiplex structure

 The SDH multiplex structure shown in the picture is defined in ITU-T G.707 and describes how low order signals are multiplexed into higher multiplex levels.

KLM values

Imagine you have a large number of E1 customer aggregated on a PA-MC-STM-1SMI (Cisco) or a PE-1CHSTM1-SMIR-QPP   (Juniper).The low order signal is transported over an SDH network, through the númerous multiplex levels, and is terminated on your channelized STM-1 card.For configuring the customers interface on the aggregation device, you need to know in which timeslot the customers E1 resides.

–> This position is specified by the KLM values.

K describes TUG-3 group (1-3) L describes a TUG-2 group inside a TUG-3 (1-7) M describes a TU-12/VC12/E1 inside a TUG-2 (1-3)

Here’s an overview for the KLM values of a STM-1:

Timeslot TUG-3 TUG-2 VC-12 (–> E1) KLM1 1 1 1 1.1.12 1 1 2 1.1.23 1 1 3 1.1.34 1 2 1 1.2.15 1 2 2 1.2.26 1 2 3 1.2.37 1 3 1 1.3.18 1 3 2 1.3.29 1 3 3 1.3.310 1 4 1 1.4.1

11 1 4 2 1.4.212 1 4 3 1.4.313 1 5 1 1.5.114 1 5 2 1.5.215 1 5 3 1.5.316 1 6 1 1.6.117 1 6 2 1.6.218 1 6 3 1.6.319 1 7 1 1.7.120 1 7 2 1.7.221 1 7 3 1.7.322 2 1 1 2.1.123 2 1 2 2.1.224 2 1 3 2.1.325 2 2 1 2.2.126 2 2 2 2.2.227 2 2 3 2.2.328 2 3 1 2.3.129 2 3 2 2.3.230 2 3 3 2.3.331 2 4 1 2.4.132 2 4 2 2.4.233 2 4 3 2.4.334 2 5 1 2.5.135 2 5 2 2.5.236 2 5 3 2.5.337 2 6 1 2.6.138 2 6 2 2.6.239 2 6 3 2.6.340 2 7 1 2.7.141 2 7 2 2.7.242 2 7 3 2.7.343 3 1 1 3.1.144 3 1 2 3.1.245 3 1 3 3.1.346 3 2 1 3.2.147 3 2 2 3.2.248 3 2 3 3.2.349 3 3 1 3.3.150 3 3 2 3.3.251 3 3 3 3.3.352 3 4 1 3.4.1

53 3 4 2 3.4.254 3 4 3 3.4.355 3 5 1 3.5.156 3 5 2 3.5.257 3 5 3 3.5.358 3 6 1 3.6.159 3 6 2 3.6.260 3 6 3 3.6.361 3 7 1 3.7.162 3 7 2 3.7.263 3 7 3 3.7.3