sdh & pdh fundemantal
TRANSCRIPT
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SDH & PDH FundamentalSDH & PDH Fundamental
BY
Chief Engineer NEAMA AWAD JASIMHead of North West Communication Dept.
Ministry of Electricity / Iraq
SDH & PDH Fundamentalby
Chief Engineer neamah awad jasimHead of communication dept. in north west region
the general doctorate of control & operation
Ministry of Electricity – IRAQ
please see my whole profile at the URL :
830/56/a50 jasim/-awad-https://www.linkedin.com/pub/neamah
Or my page at the facebook:
https://www.facebook.com/neamah.jasim
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PrefaceHi guys, this slide show is basically depend on 2-week training course which i
have been done for teenager engineers & technicians in my dept. in
mosul/iraq. In deed i`m not so much satisfied about some articles in this
show that I have some issues prevent me from making the require
updating for this show , so I ask my readers the forgiveness for the lack in
this work. But by other hand I hope that this work will gave a basic
background knowledge about this revolutionary technology in the world
of communication. Also I think that some explanations should be added
to some items , but I hope in future to cover this issues in the next works .
Most of graphs in this show have been made personally depending on the
available resources in the web as mention in the next page .
For more information or any remarks about this work kindly you may mailing
@gmail.com70neamame via
.
The references :1-ALSTOM GRID e-DXC SDH MANUALS
2- The Fundamentals of SDH – by Telecommunications Techniques Corporation
(www.ttc.com)
)3- The Fundamentals of SDH-slide show by ( ERICSSON CO.
4- PDH & SDH Integration FOX 515-slide show by ABB CO.
5- Synchronous Digital Hierarchy slide show BY (ABB CO.)
6- SDH Telecommunications Standard Primer by (Tektronix Co.)
7- Course 13 SDH/SONET multiplexing strategy
8- SDH Next Generation by José M. Caballero9- Optical Fiber introduction by Patrick LANNUZEL (ALSTOM GRID CO.)
10- SDH Training document BY SEIMENS CO.
11- Synchronous Digital Hierarchy (SDH) Graphical Overview BY CISCO SYSTEMS
12- Synchronous Digital Hierarchy BY 2013 JDS Uniphase Corporation
13- WandelGoltermann_sdh1 REFERENCE BOOK
) BY the author at URL:ینقتیش تلايفمظناثیدحلا )-14االتص ال
8107http://www.kutub.info/library/book/
15- What is SDH ? By RAD data communication systems
16- Wikipedia .com
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PDH Tributaries (Low rate input/ output data)
-HSPDA: High Speed Packet Downlink Access
-ATM : Asynchronous Transfer Mode used for broad
band ISDN B-ISDN.
-E1 :The European Hierarchy Standard based on
32(64kb/s) channel frame with total rate
(2.o48Mb/s) .
-T1 : The American Hierarchy Standard based on
24(64kb/s) channel frame with total rate (1.5Mb/s)
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6.7
MULTIPLEXINGMULTIPLEXING
Whenever the bandwidth of a medium linking twoWhenever the bandwidth of a medium linking two
devices is greater than the bandwidth needs of thedevices is greater than the bandwidth needs of the
devices, the link can be shared. Multiplexing is the setdevices, the link can be shared. Multiplexing is the set
of techniques that allows the (simultaneous)of techniques that allows the (simultaneous)
transmission of multiple signals across a single datatransmission of multiple signals across a single data
link. As data and telecommunications use increases, solink. As data and telecommunications use increases, so
does traffic.does traffic.
Frequency-Division Multiplexing (FDM)
Wavelength-Division Multiplexing (WDM)
Time-Division Multiplexing (TDM)
TYPES OF MULTIPLEXINGTYPES OF MULTIPLEXING
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2-Wave length Division Multiplexing (WDM)
this method used the same channel or media but with manydifferent wavelength optic signals , it is used mainly with
fiber optics communication at very high rate levels.
OPGW stand for FIBER OPTIC OVERHEAD
GROUND WIRE
the usable band of light that used in fiber optic
communication
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High Density WDM (DWDM)
The Digital Transmission of Information
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THE PULSE CODE MODULATION (PCM) PRINCEBLEEach sample of analog signal represent by a digital code
i.e.;PAM.PPM.PDM..ETC.
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According to the Law FS ≥2W (Nyguist law)Where FS is Sampling frequency & W is the common bandwidth of Human
Sound (4KHz) Thin FS= 2*4= 8 KHZ 8000 sample / sec.
Each sample represent by
8-bit then 2 EXP 2 = 128
level & as the Sound is
alternative signal so it
should be 128
Quantization Levels in each
direction
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3-Time Division Multiplexing (TDM)
TDM is a digital multiplexing technique for combiningseveral low-rate digital channels into one high-rate one.
This method of Multiplexing mainly used with PDH
Hierarchies T1& E1
Time Division Multiplexing –Bit
Interleaving This method of
Multiplexing mainly used
with PDH
Hierarchies T1& E1
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Plesiosynchronous Multiplexer use bit interleaved
Mechanism due that the incoming signal bits came in different
width or periods so the MUX.add some justification bits (Mappingmethod) to get the synchronization of different rate tributaries of
the incoming steams.
InterleavingThe process of taking a group of bits from each input line for
multiplexing is called interleaving. We interleave bits (1 - n)
from each input onto one output.
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This method used
in SDH & S0NET
Time Division Multiplexing –Byte
Interleaving This method usedin SDH & S0NET
Byte interleaving takes advantage of technology
develo ed for com uters and reserves b te timin
SSSynchronization
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Synchronization Pattern or
Framing bits( This Technique used in American PDH
Hierarchy standard T1 While in European
standard there are a channel for this purposes)
The Communication Era before SDHThe development of digital transmission systems started In the early70s , and was based on the Pulse Code Modulation (PCM) method.
In the early 80's digital systems became more and more complex , yetthere was huge demand for some features that were not supportedby the existing systems. The demand was mainly to high ordermultiplexing through a hierarchy of increasing bit rates up to 140Mbps or 565 Mbps in Europe. The problem was the high cost ofbandwidth and digital devices. The solution that wascreated then , was a multiplexing technique , allowed for thecombining of slightly non synchronous rates, referred to as
plesiochronous*, which lead to the term plesiochronous digitalhierarchy (PDH).
*plesiochronous - "almost synchronous , because bits are stuffed intothe frames as padding and the calls location varies slightly - jitters -from frame to frame".
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The Most Common PDH Hierarchies
1-The American standard of digital transmission ( T1)
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This standard used Mainlyin north America & in
Japan with some
modifications
T-1 line for multiplexing telephone lines
T-1 frame structure
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Digital hierarchy
The Most Common PDH Hierarchies2-The European Standard (E1)This standard used in Europe & other world Countries
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This Happen when
we used the
channels for data
only not for speech
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European PDH Hierarchy (ITU-T G.702)
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The PDH Standards in the World
PDH Add(Insert)/Drop Functionby
Stepper MULTIPLEXING/DEMULTIPLEXING
EASTWEST
LTE :LINE TERMINAL
EQUIBMENT
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TheAdd/ Drop Scheme regard as the main disadvantage scheme of
PDH compare with SDH that there is ability to add(insert)/ drop
different rates of Tributaries along the a path while in PDH it
should be multiplex/demultiplex till to reach the appropriate lower
rate carrier
SDH (Synchronous Digital Hierarchy)
IS AN ITU-T STANDARD FOR A HIGH CAPACITY TELECOM NETWORK.
SDH IS A SYNCHRONOUS DIGITAL TRANSPORT
SYSTEM, AIM TO PROVIDE A SIMPLE, ECONOMICAL
AND FLEXIBLE TELECOM INFRASTRUCTURE .ATTEMPTS TO FORMULATE
STANDARDS FOR TRANSMISSION OF SYNCHRONOUS SIGNALS
BEGAN IN U.S. AT THE BEGINNING OF 1984, BY ANSI ACCREDITED
T1X1 COMMITTEE.IN 1985 ‘SONET’ STANDARD WAS BORN.IN 1986
CCITT BECAME INTERESTED IN SONET STANDARD.CCITT PROPOSED
CHANGES TO ‘T1X1’COMMITTEE TO ACCOMMODATE BOTH
AMERICAN AND EUROPEAN HIERARCHIES. FINAL AGREEMENT WAS
REACHED IN 1988 AND CCITT WORKING GROUP-XVIII CAME OUT
WITH RECOMMENDATIONS ON SDH
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SDH (Synchronous DigitalHierarchy)so SDH is an international standard for high speedtelecommunication over optical/electical networkswhich can transport digital signalsin variable capacities. It is a synchronous systemwhich intend to provide a more flexible , yet simplenetwork infrastructure.
SDH (and its American variant- SONET) emerged from
standard bodies somewhere around 1990.these two standards create a revolution in the
communication networks based on opticalinfibers their cost and performance.
why using SDH ?Although PDH was A breakthrough in the digital transmissionsystems , it has a lot of weaknesses :
- No world standard on digital format (three incompatibleregional standards - European, North American andJapanese).
- No world standard for optical interfaces. Networking isimpossible at the optical level.
- Rigid asynchronous multiplexing structure.
- Limited management capability.
- Because of PDH disadvantages, It was obvious That a newmultiplexing method is needed.The new method was called SDH.
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SDH has a lot of advantages
First world standard in digital format.
First optical Interfaces.
Transversal compatibility reduces networking cost.Multivendor environment drives price down
Flexible synchronous multiplexing structure .
Easy and cost-efficient traffic add-and-drop and cross connectcapability.
Reduced number of back-to-back interfaces improve networkreliability and serviceability.
Powerful management capability.New network architecture. Highly flexible and survivable selfhealing rings available.
Backward and forward compatibility: Backward compatibilityto existing PDHForward compatibility to future B-ISDN, etc.
Standards of SDH
SDH has been standardized by ITU-T in 1988.
In November 1988 the first SDH standards were approved.
In 1989 , the CCITT (International Consultative Committee on Telephony & Telegraphy)had published in its "Blue book" recommendations G.707 , G.708 & G.709 coveringthe SDH standards.
G.702 - Digital Hierarchy Bit RatesG.703 - Physical/Electrical Characteristics of Hierarchical Digital
Interfaces
G.707 - SDH Bit RatesG.708 - Network Node Interface for the SDHG.709 - Synchronous Multiplexing StructureG.773 - Protocol Suites for Q Interfaces for Management of
Transmission SystemsG.781 - (Formerly G.smux-1) Structure of Recommendations on
Multiplexing Equipment for the SDHG.782 - (Formerly G.smux-2) Types and General Characteristics
of SDH Multiplexing EquipmentG.783 - (Formerly G.smux-3) Characteristics of SDH Multiplexing
Equipment Functional BlocksG.784 - (Formerly Gsmux-4) SDH Management
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Compare between SDH & SONET speed
rates
SONET &SDH are almost the same, but the SONET for American standard ,Japan and SDH for
Europe & rest of the world
SDH Hierarchy compare with SONET
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2.175mb/s
The SDH have some version according to the needs of
customers
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Elements of SDH Multiplexing
1- The Containers C
The Container (C)
– Basic packaging unit for tributary signals (PDH)
– Synchronous to the STM-1
– Bitrate adaptation is done via a positive stuffing
procedure
– Adaptation of synchronous tributaries by fixedstuffing bits
– Bit by bit stuffing
OR Container-n( n=1-4 ): is the information structure
which forms the network synchronous information
payload for a virtual container
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2-Virtual Containers VC
The Virtual Container (VC)
– Formation of the Container by adding of a POH
(Path Overhead)
– Transport as a unit through the network (SDH)
– A VC containing several VCs has also a pointer area
Virtual Container-n(VC-n):It is the informationstructure used to support path layer connections in
the SDH. There are Two types of VCs: Lower order
VC-n(n=1,2) & Higher order Vc-n(n=3,4)
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Virtual Containers(VC)
The Virtual Container is obtained after adding POH to The
Containers
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3-Administrative Units (AU)
It is an information structure which provides adaptation
between two
layers: -Between lower and higher order path layers for TU
-Between higher order path layer and section layer for AU
4-Tributary Unit (TU)
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The Tributary Unit (TU)
– Is formed via adding a pointer to the VC• The Tributary Unit Group (TUG)
– Combines several TUs for a new VC
• The Administrative Unit (AU)
– Is shaped if a pointer is allocated to the VC formed atlast
• The Synchronous Transport Module Level 1 (STM- 1)
– Formed by adding a Section Overhead (SOH) to AUs
– Clock justification through positive-zero-negativestuffing
in the AU pointer area
– byte by byte stuffing
Structure of the administrative units and of the
tributary units used in the SDH system
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5-Tributary Unit Group (TUG)
6-Adminstrative Unit Group (AUG)
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LO-POH have two forms
The Mapping process in SDH system
(HO-POH) have also two forms
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HO-POHit is the 10 columns of the STM-1 Structure ,
consist of 9 bytes determine the boundaries of VC-4
Details of J1 & B3 of Higher Order POH• J1 - Higher-Order VC-N path trace byte
This user-programmable byte repetitively transmits a 15-byte string
plus 1-byte CRC-7. A 64-byte free-format string is also permitted for
this Access Point Identifier. This allows the receiving terminal in a
path to verify its continued connection to the intended transmitting
terminal.
• B3 - Path Bit Interleaved Parity code (Path BIP-8) byte
This is an even-parity code, used to determine if a transmissionerror has occurred over a path. Its value is calculated over all the
bits of the previous virtual container before scrambling and placed in
the B3 byte of the current frame. (BIP-8 is calculated on the 8 bit
blocks of the nth frame and placed on the (n+1) the frame of VC3/
VC4.)
• C2 - Path signal label byte – This byte specifies whether the virtualcontainer is equipped or not and the mapping type in therespective virtual container.
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What is BIP?
• Bit Interleaved Parity
• Error monitoring in SDH uses a CRC with a
polynomial, xn+x0, called Bit Interleaved Parity (BIP-
n).
• The signal to be monitored is divided in to small
blocks with n-bit size. The even parity check is
applied to each bit of all the blocks in the signal, fro
m 1st to nth bit independently.
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Used with C-4 /C-3
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Comparison of POH in Higher and Lower
Orders
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8-Pointers is an indicator whose value defines the
frame offset of a VC with respect to the frame reference of
the transport entity on which it is supported .
The Role of AU-Pointers in SDH system, is performing AU
units in Process called Adaption OR Aligning
the rest of AU-MATRIX is commonly filled with stuffing or
justification bits .Also AU- pointer determine the starting of
pay load or VC within the STM structure .
The pointer consist of three bytes (H1,H2,H3) as
follows :
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Application of Pointer – A Pointer is used to address a particular locationwithin an AU or a TU structure. There are mainly 2
types of pointers
1. AU Pointers: used to point at Higher Order VC’s (VC-4,3) in
an STM frame
2. TU Pointers: used to point at Lower Order VC’s (VC-12) in
higher order VC
Each of these pointers carry the offset number (address) at
which the 1st byte of the payload is located, within the frame.The offset numbering of AU4, TU3, TU12, frames are shown
in slide # 66, 68, 71. The offset numbering of TUs/AUs will be
according to the CCITT Rec. G.707.
Functions of a Pointer1. Minimization of multiplexing Delay
– This is the main advantage of pointers. Normally signals from different originatingpoints differ in theirphases, because of different transmission length and
different clock generation. In the usual multiplexing process, to align them, eachsignal has to be written into memories and read out using a
new phase of the frame to be multiplexed. Thus, it is inevitable to cause additionaldelay of half of theframe time in average and one frame time at maximum. Also,
it requires large capacity memories.
– To avoid above inconveniences, this pointer method was introduced into themultiplexing of SDH signal. A pointer is assigned to each VC to be multiplexed andit indicates relative phase shift between the VC and the new frame by using theaddress number in the new frame. As a matter of course, every VC
has different pointer value. The pointer is renewed at every multiplexing process, soit is not necessary to introduce undesirable additional delays.
arrival speed
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What is Justification• Imagine 2 compartments of a train. It is connected with
a pair of buffers and flexible chain.
• If the first moving compartment going faster the next.
The chain will pull the next compartment. This is
equivalent to ‘Positive Justification.’
• If the first compartment is moving slower than the next
the buffers will collide and slow down the next one. This
is equivalent to ‘Negative Justification’.
• In this example, the first moving compartment is
analogous to higher order tributary and the next is
equivalent to primary tributary.
Effects of Justification• Assume secondary tributary speed fs
• Assume primary tributary speed fp
• If fs > fp, Positive Justification, the effect will be to read one
information bit of primary as two information bits of secondary.
Hence, in secondary one bit has to be inhibited.
• If fs < fp, Negative Justification, the effect will be to lose one
information bit of primary in the secondary. Hence, in secondaryone bit has to be introduced.
• If fs = fp, Zero Justification, the ideal situation but difficult torealize in practice.
• In SDH, all the above 3 justifications will be achieved byintroduction of a pointer in addition to the information andpath overhead bits
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2. Frequency Justification – Generally this function is not required in an SDH network since all network
elements are synchronized to a single clock. But if the VC’s are transported overdifferent networks, and if a network element is in an abnormal condition, justification is necessary to absorb any frequency differences between payloadand the frames.
There are 2 types of justification in SDH:a. Positive Justification: If the frame speed of the STM is higher than the payloadarrival speed.
b. Negative justification: If the frame speed of the STM is lower than the payload
Positive justification
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Positive justification
Negative justification
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Mu tip exing steps o 2M s E1 into
STM-1 SignalDue that there are multi rate tributaries like (ATM,GFP(2.114Mb/s)or the rate of E1signal (2.048Mb/s) is not always in regular speed so the concept of multi-frame isintroduced for the convenience of rate adaptation used in multiplexing 2Mb/sinto STM-1signal , i.e. four C-12 basic frames form a multi-frame , each basic C-12frame represent by 9×4-2 matrix (notched matrix )
Since the frame frequency of the C-12 basic frame is 8000-frame per second, theframe frequency of the C-12 multi-frame will be 2000-frame per second.
-if E1 signals have a standard rate of 2.048Mb/s, each basic frame willaccommodate 32-byte (256-bit) which a integer value.
--- While when E1 signals rate of 2.046Mb/s are accommodated into a C-12 basicframe, the average number of bits loaded in each frame is: (2.046 x106b/second)/(8000-frame/second)=255.75 bits. Because this number is not an
integer so if a multi-frame of four basic frames is used, the number of bits can beloaded in the multi-frame is: (2.046 x 106b/second)/(2000-frame/second)=1023
bits. Each of the first three basic frames accommodates 256-bit (32-byte) payloadand the fourth accommodates 255-bit payload.
--A multi-frame can accommodate payloads at the rate ranging from C-12 Multiframe max to C-12 Multi-frame min, as follows:
C-12 Multi-frame max=(1023+1+1)x 2000=2.050Mb/s
C-12 Multi-frame min=(1023+0+0)x 2000=2.046Mb/s while
Mapping 2M to THE SDH streamFirst step is mapping E1 signal into SDH Container (creating
containers) ,
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C-12 Containers as in each of tow
ma in methods
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Multiplexing steps (E1 to STM-1)
First step is mapping E1 signal into SDH Container (creating Containers)
E1 PDH stream is interleaved into multi frame stream
1-Creating C-12 multi framethe regular rate of E1 signal is 2.o48Mb/s & the Max`m rate of C-12 is (2.176Mb/s)
So that each basic C-12 can handle the maximum rate of E1
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The rest of C-12 Used AS Overhead for E1 AS follows
2-Creation of VC-12 Multi frameTo monitor on a real-time basis the performance of each 2Mb/spath signal during transmission on SDH network, C-12 mustbe further packed ---- adding corresponding path overhead(lower order overhead)---- to form a VC-12 informationstructure. the LP-POH (lower order path overhead) is addedto the notch in the top left corner of each basic frame. Eachmulti-frame has a set of lower order path overhead
composed of total 4 bytes: V5, J2, N2 and K4. Since the VCcan be regarded as an independent entity, dispatching of2Mb/s services later is conducted in unit of VC-12.
A set of path overhead monitors the transmission status of thewhole multi-frame on a network. How many frames of 2Mb/ssignals does a C-12 multi-frame accommodate? One C-12multi-frame accommodates 4 frames of PCM30/32 signals.Therefore a set of LP-POH monitors the transmission status of4 frames of PCM30/32 signals.
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2-Creation of VC-12 Multi frame
2-Creation of VC-12 Multi frame
500 µ second
E1
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3-Creation of TU-12 Multi frame
For correct aligning of VC-12 frames in the receiving end, a four-byteTU-PTR (Pointer)is added to the four notches of the VC-12 multi-
frame. Then the information structure of the signal changes into TU-
12 with 9 rows x 4 columns. The TU-PTR indicates the specific
location of the start point of the first VC-12 within the multi-
frame.The First two pointers used for these purposes.
The Structure of VC-12 POH
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3-Creation of TU-12 Multi frame
3-Creation of TU-12 Multi frame
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The construction of TU-12 multi frame
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4-Creation of tributary Unit group-2
Three TU-12 forms a TUG-2 via byte interleaved multiplexing. TheTUG-2 has the frame structure of 9 rows by 12 columns .
So ,According to (Rec. G.709)TUG-2 Unification low
rate tributaries belong to US,CEPT Standards Like
E1(C-12),T1(C11), T2..etc.
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5-Creation of Tributary Unit Group -3
(TUG-3)Seven TUG-2 can be multiplexed into a TUG-3 information
structure via byte interleaved multiplexing. Note that this
information structure formed by the 7 x TUG-2 is 9-row by
84-column. Two rows of fixed stuff bits shall be added in
front of the structure, as illustrated in slide -------- . The
multiplexing structure for the TUG-2 via the TUG-3 is
depicted in slides ------ . The TUG-3 is a 9-row by 86-
column structure with the first two columns of fixed stuff.
5-Creation of TUG-3
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In the first column of the TUG3 unit there are reserved positions for the
VC3 pointer – due to the fact that it is a fixed phase relation between
the TUG2 and the TUG3 unit it is not necessary a pointer; thepositions for the pointer are occupied by a null pointer indicator (NPI
– Null Pointer Indicator).
5-Creation of TUG-3
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5-Creation of TUG-3
Highest multiplexing point has been introduced by SDH to
accommodate high rate European 140 Mbps and to
accommodate lower bit speed tributaries, So,TUG-3 role is
like TUG-2, Unification of High Tributaries of US & CEPT
standards Hierarchies
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Creation of TUG-3
Fixed
Stuffs
The Anatomy of TUG-3 is depend on the rate of tributary So,When we
start with 2Mb/s input then TUG3 became as shown below but if we
start multiplexing with higher rate tributary then this is another story .
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While here
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6- Creation of Container -4 (C-4)Three TUG-3 can be multiplexed into the C-4 signal structure viabyte interleaved multiplexing method. The arrangement ofthree TUG-3s multiplexed in the VC-4. The TUG-3 is a 9-rowby 86-column structure. The VC-4 consists of one column ofVC-4 POH, two columns of fixed stuff and a 258-columnpayload structure. The three TUG-3s are byte interleaved intothe 9-row by 258-column VC-4 payload structure and have a
fixed phase with respect to the VC-4. The phase of the VC-4with respect to the AU-4 is given by the AU-4 pointer.
Since the TUG-3 is an information structure of 9 rows x 86columns, the information structure composed of three TUG-3via byte interleaved multiplexing is a block frame structure of9 rows x 258 columns. While C-4 is a block frame structure of9 rows x 260 columns. Two columns of stuffed bits are addedto the front of the composite structure of 3 x TUG-3 to form aC-4 information structure. shows the frame structure of oneC-4.
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6- Multiplexing of Container -4 (C-4)
7-Creation of Virtual Container -4 by
mapping or adding (HO-POH)
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SDH Section Over Head (SOH) & SSMThese bytes(91 bytes) lies between columns (1 to 9) in the STM-1
structure, each byte of them has particular role like signaling, control
,alarms ,multiplexing demultiplexing…etc. , some bytes of them are
media dependent bytes, while others spare for future applications.
They are divided into three parts as follows:
1-Regenerator Section Overhead (RSOH)
2-AU-Pointer
3- Multiplex Section Over Head (MSOH)
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AU Pointer
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AU-4 Pointer
AU-4 Pointer offset numbering
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RSOH
RSOH
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MSOH
8-Multiplexing Administrative Unit-4 (AU-4) with
Regenerator Section Over Head (RSOH)
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9-Multiplexing AUG-1 with Multiplexing
Section Over Head(MSOH)
TU3 Pointer
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10-the last step –getting Synchronous Transmission
Module1 (STM-1) by multiplexing MSOH
SDH Signal STM-N (Synchronous Transport
Module)frame structure
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So the structure of STM-1 is look like this blocks
when it multiplexed from C-12 tributary
Thus each STM-1 Containsabout 2M×3×7×3=63×2M b/s data
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While The payload of STM-1 with C-4 tributary will be one
single block of data (about 150 Mb/s) , this happen in cases
look like HD video broadcasting …etc.
While we have Here the payload of STM-1
With 3 VC-3
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Here are the
Addressing of
American
tributary T1 WithKLM addressing
( C-11 tributary)
The addressing of VC`s at STM-1 Block (KLM addressing )
The KLM addressing concept with
C-12 tributaries
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High order of SDH
STM-4
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STM-16
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The Broadband Communication
Architecture
The OSI(Open Source Internetworking) Model
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Logical &Physical network segments
The Various transport segments in SDH
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Another example of Layers networks in
SDH with different Elements
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SDH Equipments
The terminal multiplexer(TM)
•is used to multiplex local tributaries LOW RATE (STM-M ) to HIGH
ORDER (STM-N) aggregate where(M less than N) OR/AND Mapping
low rate (PDH tributaries into HIGH RATE STM-N aggregate . The
(TM) is used in the chain topology as an end element. TM IS TYPE OF
MULTILEVEL MUX./DEMUX. TM should handle RSOH in
STM-N frames &MSOH for
ADD/DROP PDH tributaries
to STM-N purposes
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The Add And Drop Multiplexer (ADM)The function of (ADM) is to cross multiplex/de-multiplex the low rate tributary signal
(PDH,STM-M) to the High rate STM-N signal in east or west lines & STM-N signalcross connect west or east line port ( M less than N) . Also it include the cross
connect of the STM-N SIGNAL between the sides of the W/E line. ADM is equivalent
to two TMs, ADM is used in transfer stations of SDH network.
The REGENATOR (REG)is used to regenerate the (high rate) STM-N in case that the
distance between two sites is longer than the transmitter can carry.
REG needs only to handle RSOH in the STM-N frame to reproduce the
The STM-N frames.
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Digital Cross- Connect (DXC)
SDH Topologies
1-the chain topology
The linear bus (chain) topology used when there is no need
for protection and the demography of the sites is linear.
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2-Point to Point Topology
3-Point to Multipoint Topology
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6-The mesh topology
allows even the most paranoid network manager to sleepwell at nights because of the flexibility and redundancy
that it gives.
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7-The Star topology
is used for connecting far and less important sites
to the network.
Usage of SDH elements in SDH Topologies
The Terminal multiplexer can be used to connect two sites in a high rate connection .
The Add And Drop Multiplexer (ADM) is used to build the chain topologies in the
above picture. At the ends of the chain usually a Terminal Multiplexer is connected.
The Add And Drop Multiplexer (ADM) is used to build the ring topology .AT each site
we have the ability to add & drop certain tributaries.
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SDH ProtectionThe SDH gives the ability to create topologies with protection for the data
transferred. Following are some examples for protected ring topologies.
At this picture we can see Dual
Unidirectional Ring . The normal
data flow is according to ring A
(red). Ring B (blue) carriesunprotected data which is lost
in case of breakdown or it
carries no data at all.
In case of breakdown rings A & B become one ring without
the broken segment.
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The Bi-directional Ring allows data flow in both directions. For
example if data from one of the sites has to reach a site which is next
to the left of the origin site it willflow to the left instead of doing awhole cycle to the right.
In case of breakdown some of the data is lost and the important data
is switched. For example if data from a site should flow to its
destination through the broken segment, it will be switched to the
other side instead.
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Protection Methods
Protection Methods
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Automatic Protection Switching (APS)
• Automatic Protection Switching (APS) is the
capability of a transmission system to detect a
failure on a working facility and to switch to a
standby facility to recover the traffic.
• This capability has a positive effect on theoverall system availability.
• Two modes of APS are provided:
– 1+1 protection switching
– 1:N protection switching.
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Another samples of protection switching
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What is in the future