SDH STRUCTURE

1. 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

2. 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) KLM
1 1 1 1 1.1.1
2 1 1 2 1.1.2
3 1 1 3 1.1.3
4 1 2 1 1.2.1
5 1 2 2 1.2.2

3. 6 1 2 3 1.2.3
7 1 3 1 1.3.1
8 1 3 2 1.3.2
9 1 3 3 1.3.3
10 1 4 1 1.4.1
11 1 4 2 1.4.2
12 1 4 3 1.4.3
13 1 5 1 1.5.1
14 1 5 2 1.5.2
15 1 5 3 1.5.3
16 1 6 1 1.6.1
17 1 6 2 1.6.2
18 1 6 3 1.6.3
19 1 7 1 1.7.1
20 1 7 2 1.7.2
21 1 7 3 1.7.3
22 2 1 1 2.1.1
23 2 1 2 2.1.2
24 2 1 3 2.1.3
25 2 2 1 2.2.1
26 2 2 2 2.2.2
27 2 2 3 2.2.3
28 2 3 1 2.3.1
29 2 3 2 2.3.2
30 2 3 3 2.3.3
31 2 4 1 2.4.1
32 2 4 2 2.4.2
33 2 4 3 2.4.3
34 2 5 1 2.5.1
35 2 5 2 2.5.2
36 2 5 3 2.5.3
37 2 6 1 2.6.1
38 2 6 2 2.6.2
39 2 6 3 2.6.3
40 2 7 1 2.7.1
41 2 7 2 2.7.2
42 2 7 3 2.7.3
43 3 1 1 3.1.1

4. 44 3 1 2 3.1.2
45 3 1 3 3.1.3
46 3 2 1 3.2.1
47 3 2 2 3.2.2
48 3 2 3 3.2.3
49 3 3 1 3.3.1
50 3 3 2 3.3.2
51 3 3 3 3.3.3
52 3 4 1 3.4.1
53 3 4 2 3.4.2
54 3 4 3 3.4.3
55 3 5 1 3.5.1
56 3 5 2 3.5.2
57 3 5 3 3.5.3
58 3 6 1 3.6.1
59 3 6 2 3.6.2
60 3 6 3 3.6.3
61 3 7 1 3.7.1
62 3 7 2 3.7.2
63 3 7 3 3.7.3