SDH for Students

8/2/2019 SDH for Students

1/91

Synchronous

Average frequency of all

clocks in the system is the

same.

No multiplexing stages are

needed, any lower order

signal can be added to a

higher order signal easily.

No bit stuffing.

Asynchronous.

Eachterminal on thenetwork running on its own

clock. Uses multiple stages for

multiplexing, lower order(e.g. E1-2Mbs) signals areneeded to bring up to arange of higher order(e.g.E3-34Mbs) signal formultiplexing.

Bit stuffing technique is

use.

Introduction to

Synchronization


2/91

PDH


3/91

Older Networks were developed for point to point

transmission.

Supported manual approach to network management

& maintenance.

In PDH signal structures, no place for network

management & maintenance functions(i.e.no spare

signal capacity for improvement in signal transmission.

PDH cont


4/91

Development caused interconnection, difficult &

unreliable

(Result:Existing standards for point to point

communication became unsuitable)

PDH is stage by stage multiplexing based

on 64 Kb/s voice channels with different hierarchies in theworld & approved specs; covered up to 140 Mb/s (1920voice channels).

PDH cont


5/91

Lower order signal could not be accessed directlywithout de-multiplexing & multiplexing again (addedcost)

No common standards available above 140 Mb/s(Result:Vendor Dependency)

Customer circuits, Speed & B.W. limited.

No proper response to new customer services (Lessefficient, not cost effective, B.W control notpossible)

PDH cont


6/91

(HIERARCHIES)

PDH Hierarchies


7/91

1. InterfacesElectrical interfaces---only regional standards,

no universal standard.

2. Three rate hierarchies for PDH:European(2Mb/s) .

Japanese (1.5 Mb/s)

North American(1.5Mb/s).

3. Optical interfaces---no standards at all,

manufacturers develop at their will.

Difficult to inter-connect

Disadvantage of PDH


8/91

Multiplexing for PDH:

The location of low-rate signals in high-rate signals is not

regular nor predictable. So it is impossible to directly

add/drop low-rate signals from high-rate signals.

Where

did I putthe signals?

Disadvantage of PDH cont..


9/91

140Mb/s34Mb/s 34Mb/s

8Mb/s 8Mb/s

2Mb/s

140Mb/s

de-multiplexerde-multiplexer

de-multiplexer multiplexer

multiplexer

multiplexer

Low-rate signals have to be separated from high-rate signals

level by level. Multiple levels of multiplexing/de-multiplexingcause signals to deteriorate, it is not suitable for huge-volume

transmission.



10/91

OAM OAM function affects the maintenance cost.It is determined

by the number of overhead bytes(redundant bytes);

There are VERY few redundant byes available in PDH

signals which can be used as OAM purpose, so OAM in PDH

is very poor, it is unreliable either.

No universal network management interface.

It is hard to set up an integrated network management.

No way to form a universalTMN. PDH is inappropriate to transmit huge-volume signals, so

SDH came to play the part.



11/91


12/91

It's based on overlaying a synchronousmultiplexed signal onto a light stream

transmitted over fiber-optic cable.

SDH is also defined for use on radio relay links,satellite links, and at electrical interfacesbetween equipment.

Introduction to Synchronous Digital

Hierarchy cont


13/91

SDH

Asynchronous

E0 64 kbit/s One 64 kbit/sE1 2.048 Mbit/s 32 E0E2 8.448 Mbit/s 128 E0E3 34.368 Mbit/s 16 E1E4 139.264 Mbit/s 64 E1

Synchronous

STM-0 51 Mbit/s 21 E1STM-1 155 Mbit/s 63 E1 or 1 E4STM-4 622 Mbit/s 252 E1 or 4 E4STM-16 2.4 Gbit/s 1008 E1 or 16 E4STM-64 10 Gbit/s 4032 E1 or 64 E4

Transmission Hierarchies


14/91

All these factors & deficiencies

led to the birth of

S.D.H


15/91

Overheads

and Pointers

SDH

Overview

Frame

structure

and

multiplex-

ing

methods

Logical parts

of SDH

equipment

SDH Principle1


16/91

The principle is divided into 4 parts:

1- SDH OverviewTo have the basic concept of SDH

What is SDH? What are the differences?

Advantages and disadvantages of SDH system.

2- Frame structure and multiplexing method of SDH signalsThe functions of each part in SDH signal frame structure

Multiplexing the commonly encountered PDH signals

(2Mb/s, 34Mb/s,140Mb/s) into SDH signals?

SDH Principle


17/91

3- Overhead and Pointers

Layered monitoring mechanism of SDHOverheads

Directly add/drop lower-rate signals in SDHPointers

4- Logical composition of SDH equipment

Common network elements of SDH network

Logical function blocks of SDH equipment

SDH Principle Curriculum


18/91

Where it can be

usedDisadvantages

of SDH

Background

of SDHAdvantages

of SDH

SDH Overview


19/91

1. What is SDH.

2. What are the differences.

3. Where it can be used.

4. Advantages & Disadvantages of SDH

Background of SDH


20/91

New Digital Hierarchy

155.52 Mb/s, 622.08 Mb/s, 2488.32 Mb/s etc.

Existing PDH and future ATM signals are

carried over the SDH system

Very basic functions are same as PDH.

Multiplex low bit rate digital signals to

higher bit rate and transmit large informationefficiently.

What is SDH ?


21/91

SDH is a STANDARD for high speed

High capacity telecommunication networks

More specifically it is a SYNCHRONOUS DIGITAL

TRANSPORT SYSTEM designed for providing a more

simple, economic & Flexible telecommunication network

infrastructure.

What is SDH ? cont


22/91

What are differences?Synchronous Network All network elements work on the same clock.

Abundant Overhead Bits

To carry large information for Network

Management

Unified Interface and Multiplexing specifications Common to Europe, North America and Japan

digital hierarchies.

Standard optical interfaces.


23/91

What are differences? cont.. Simple multiplexing process

Easy access to tributary signals in a multiplexed

high bit rate signal.

ADD/DROP ----------------- distribution

RING ---------------------- survivability

CROSS CONNECT --------- capacity management

band width management protection route

diversity.


24/91

In all traditional N/W application areas, providing

interconnection between three major

telecommunication networks.

Where S.D.H is used?


25/91

Multi-vender Environment

International Connection

Realization of highly advanced Network Management System.

Fault management.

Configuration management. Performance management.

Security management.

Accounting management.

What are benefits ?


26/91

Interfaces

Electrical interfaces:standard rate hierarchy

(transmission speed level).

Optical interfaces:only scramble the electrical

signals.

Advantages of SDH


27/91

SDH Signals Bit rate(Mb/s)

STM-1 155.520 or 155M

STM-4 622.080 or 622M

STM-16 2488.320 or 2.5G

STM-64 9953.280 or 10G

The basic rate level is called Synchronous

Transfer Module(STM-1), the other rate

levels are the multiple of STM-1.

Advantages of SDH cont


28/91

STM-1155Mb/s

STM-4622Mb/s

STM-162.5Gb/s

STM-6410Gb/s

10Gb/s

4 4

4

WDM

SDH:4STM-1=STM-44STM-4=STM-16



29/91

Multiplexing methods:

low-rate SDHhigh-rate SDH(e.g.:4 STM-1STM-4).

Uses byte interleaved multiplexing method.

STM-1

STM-1

STM-1

STM-1

STM-4

Byte

interleaved

multiplexing



30/91

Other signalsSDH:Using pointers to align the low-rate signals in SDH frame

,so the receivers can directly drop low-rate signals.E.g.:

P

D

H

Packing P

kg

Alignment

PKG

a

PKG

b

STM-1



31/91

OAM More bytes in SDH frame structure are used for

OAM purpose, about 5% of total bytes. SDH boasts

of high capability of OAM.

Compatibility SDH is compatible with the existing PDH system.

SDH allows new types of equipment to be used,

allows broadband access, such as ATM.



32/91

STM-N STM-N

PDH, ATM

FDDI signals

packing

packagePackage

packing transmit

SDH

network

unpacking

PDH, ATM

FDDI signalsSDH compatibility schematics

transmit transmit



33/91

1. Low bandwidth utilization ratio--- contradictionbetween efficiency and reliability.

2. Mechanism of pointer adjustment is complex, it can

cause pointer adjustment jitters

3. Large-scale application of software makes SDH system

vulnerable to viruses or mistakes.

140M

34M

2M

1140M=642M

334M=482M

632M

STM-1(155M)

Disadvantages of SDH


34/91

Components

and functions

Multiplexing

Procedure

Frame Structure and Multiplexing

methods

140M

34M

2M

STM-N

2


35/91

1. Components &Functions


36/91

I must

understand the functions

of different parts

of SDH frame


37/91

9270N bytes

SOH

SOH

AU-PTR

1

345

9

STM-Npayload

(including POH)

9N 261N

270N

columns

Transmission

direction Transmit

left to rightup to down

STM-N frame structure


38/91

Block frame in units of bytes(8bit),

Transmission---from left to right, from top to bottom,

Frame frequency constant---8000 frames/s,

frame period 125us.

Characteristics of SDH signals


39/91

1. Payload

It is where we put all the information in STM-N

frame structure. All kinds of effective info, such

as 2M, 34M ,140M are first packed before

being stored here. Then they are carried by STM-

N signals over the SDH network.

Composition of SDH signals


40/91

If we should consider STM-N signal to be a truck, theninfo payload would be the carriage of the truck. In order to

monitor the transmission status of the goods during

transportation, POH are added to each information package.

Pkg

Pkg Pkg

PkgPkg

Payload

PkgLow-rate signals 1

Low-rate signalsn

loading

POH

POH

packing

packing

STM-N

loading

Composition of SDH signals cont


41/91

2. Section Overhead Accomplishes monitoring of STM-N signal streams. To check

whether the goods in STM-N carriage is damaged or not.

Regenerator Section Overhead(RSOH): monitor the overall

STM-N signals.

Multiplex Section Overhead(MSOH): monitor each STM-1

in STM-N signal.

RSOH, MSOH and POH set up SDH layered monitoring

mechanism.



42/91

. SDH

Section signal(SOH)

Low-rate signal 1

Low-rate signal 2

Low-rate signal n

low-rate path signal(POH)

Sections and Paths



43/91

3. Administrative Unit Pointer(AU-PTR)

Indicates the location of low-rate signals in STM-N

frame(payload), makes the location of low-rate

signals in high-rate signals predictable.



44/91

Sending:AU-PTR indicates the first

info package

Receiving:According to the value ofAU-PTR, get the first info

package, through the

regularity of byte interleaved

multiplexing, get the other

packages

(SDH transmission

network)



45/91

2M

34MTU-PTR

Primary alignment

AU-PTRSecondary alignment

For low-rate signals such as 2M, 34M. We need two-levelsof pointers to align.

First, small information goods is packed into middle information

goods. Tributary unit pointer(TU-PTR) is used to align the

location of small goods in middle goods.

Then these middle goods are packed into big goods, AU-PTR is

to align the location of middle info package.



46/91

low-rate SDHhigh-rate SDH:

byte interleaved multiplexing, 4 into 1.

PDH signalsSTM-N: synchronous multiplexing:140MSTM-N

34M STM-N

2MSTM-N

Multiplexing is based on the multiplexing route diagram.

ITU-T defines several different multiplexing routes, but for

any country or region, the method is unique.

2. Multiplexing Procedure of SDH


47/91

STM-16 AU-4-16c C-4-16cVC-4-16c

E1: 2.048Mb/s

E4: 139.264Mb/s

STM-4

STM-1

AU-4-4c

AU-4

AU-3

VC-4-4c

VC-4

C-4-4c

C-4

C-3

C-2

C-12

C-11

VC-3

VC-2

VC-12

VC-11

TUG-3

TUG-2

DS1:1.544Mb/s

E3: 34.368Mb/sDS3: 44.736Mb/s

DS2:6.312 Mb/s

VC-3

TU-3

TU-11

TU-12

TU-2

x4

x3

x1

x7x7

x3x3

564.992Mb/s

2259.968Mb/s

VC-n

AU-n

AUG

STM-n Synchronous Transport Module

Administrative Unit Group: One or more

AU(s)

Administrative Unit: VC + pointers

Virtual Container: payload + path overhead

STM-64 AU-4-64c VC-4-64cC-4-64c

AUG

x16

x4

x4x64

x16

x4

9039.872Mb/s

Containers of Base Signal(Low Order Payloads)

High Order Payloads

Multiplexing Procedure of SDH cont...


48/91

Regenerator

Section OH

Multiplex

Section OH

9 bytes

3

1

5

261 bytes

VC-4 Payload:

C4 or TUG-3 mapped

J1

B3

C2

G1

F2

H4

F3

K3

N1

H1

H2H3

H1

H2H3

H1

H2H3

C-3

Payload

J1

B3

C2

G1

F2

H4

F3

K3

N15 bytes

Higher Order

Path OH

AU Pointer

TUG-3

TUG-2/VC12

Muxed

C-3

Payload

J1

B3

C2

G1

F2

H4

F3

K3

N1

V

C

1

2

Vx

ptr

Low Order Path

OH

Multiplexing /Mapping of Signals cont...


49/91

Section

Overhead

Overhead

Overhead and Pointers

Pointers

Path

OverheadAU-PTR TU-PTR

3


50/91

Overhead

SOH

RSOH MSOH

POH

VC4

POH

VC12

POH

(HPOH)(LPOH)

OVERHEAD


51/91

STM-N

RSOH

STM-1

MSOH

VC4

HO-POHVC12

LO-POH

Layered Monitoring


52/91

A1 A1 A1 A2 A2 A2 J0

B1

D1

B2

D4

D7

D10S1

B2 B2 K1

D5

D8

D11M1 E2

D12

D9

D6

K2

F1

D3

E1

D2

AU-PTR

* *

*

RSOH

MSOH

Bytes reserved for domestic use

Marked bytes are not scrambled

1 2 3 4 5 6 7 8 9

1

2

3

45

6

7

89

* * * ****

SOH (Section Over Head)


53/91

SDH Networking


54/91

I want to masterthe common NEs

and the functions

of logical blocks


55/91

TM: Terminal Multiplexer

ADM: Add/Drop Multiplexer

REG: Regenerator

DXC: Digital Cross Connect

Network Element


56/91

Common NEs in SDH Network

TM ADM REG DXC


57/91

TMSTM-N

2M 34M 140M STM-M Note: (M


58/91

ADMSTM-N

2M 34M 140M

(Optical interface)

(Tributary Interface)

Application ofADM in chain network

TMTM ADM

STM-N ew

Multiplexing, cross-connection

(Optical interface)

STM-M Note: (M


59/91

REGSTM-N

TMTM REG

STM-N ew

ADMADM

Regeneration, amplification and relaying

(Optical interface)(Optical interface)

Application ofREG in chain network

REG (Regenerator)


60/91

DXC

Core function is cross-connection

Used at hub station

(Optical interface)(Optical interface)

DXC (Digital Cross Connect)


61/91

Chain Network

Star Network

Ring Network

Basic Networks


62/91

A B C D E

All the nodes are connected one after another

Both ends open

Not easy to provide protection

Chain Network


63/91

A

A special node connected directly with

other nodes

No direct connection with other nodes

Easy and flexible to manage

E

DC

B

Star Network


64/91

A

Connect the end nodes of chain network

Easy to provide protection

Widely used network

C

B

E

D

Ring Network


65/91

Protection


66/91

SDH need to be highly reliable.

Down-time should be minimal (less than 50 msec)

So systems must repair themselves (no time for manual intervention)

Upon detection of a failure (dLOS, dLOF, high BER)

the network must reroute traffic (protection switching)from working channel to protection channel

The Network Element that detects the failure (tail-end NE)initiates the protection switching

The head-end NE must change forwarding or to send duplicate traffic

Protection switching is unidirectionalProtection switching may be revertive (automatically revert to working channel)

head-end NE tail-end NE

working channel

protection channel

What is Protection?


67/91

Head-end and tail-end NEs have bridges (muxes)

Head-end and tail-end NEs maintain bidirectional signaling channel

Signaling is contained in K1 and K2 bytes ofprotection channel

K1 tail-end status and requests

K2 head-end status

head-end bridge tail-end bridge

working channel

protection channel signaling channel

How Does it works ?


68/91

Types of Protection? Linear 1+1 Protection (SNCP)

Linear 1+N Protection

Two Fiber or Four Fiber Protection

Unidirectional & Bidirectional Protection

UPSR & BLSR (MS-SPRing)


69/91

Simplest form of protection

Can be at STM-n level (different physical fibers) or at STM/VC

level (called Sub Network Connection Protection)

working channel

protection channel

extra traffic

Linear 1+1 Protection


70/91

In order to save BW

we allocate 1 protection channel for every N

working channels

working channels

protection channel

Linear 1+N Protection


71/91

1 + 1 protection

1 : n protection

Bridge Switching

XWorking Line/PathProtection Line/Path

Working Line/Path

Protection Line/PathX

Line : STM-N line, Path : VCn path

1+1 & 1+ N Protection


72/91


73/91

Unidirectional routing

working channel B-A same direction (e.g. clockwise) as A-Bmanagement simplicity: A-B and B-A can occupy same timeslotsInefficient: waste in ring BW and excessive delay in one direction

Bidirectional routingA-B and B-1 are opposite in direction

both using shortest routespatial reuse: timeslots can be reused in other sections

A

BA-B

B-A

A

B

B-A

A-B

C

B-C

C-B

Unidirectional & Bidirectional Protection

UPSR & BLSR (MS SPRi )


74/91

Of all the possible combinations, only a few are in use

Unidirectional Path Switched Ringsprotects tributariesextension of 1+1 to ring topology

Bidirectional Line Switched Rings (two-fiber and four-fiber versions)

called Multiplex Section Shared Protection Ring in SDHsimultaneously protects all tributaries in STMextension of 1:1 to ring topology

Path switchingLine switching

Two-fiberFour-fiber

UnidirectionalBidirectional

UPSR

BLSR

UPSR & BLSR (MS-SPRing)

UPSR


75/91

SDH/SONET Optical Ring

Working Ring(WR)

Fiber Cut

ProtectionRing(PR)

X 2:1 Switch1:2 Bridge

UPSR

BLSR (MS SP Ring)


76/91

BLSR/2F: Bidirectional Line Switched Ring /N-Fiber

SDH/SONET Optical Ring

Working Channel

Fiber Cut

Protection Channel

Node 4

Node 3

Node 1T2,1

Node 2

T2,1 T1,4

XLooping

Looping

BLSR (MS-SP Ring)

UPSR & BLSR (MS SPRing) cont


77/91

Working channel is in one direction

protection channel in the opposite direction

Two-fiber versionhalf of OC-N capacity devoted to protectiononly half capacity available for traffic

Four-fiber versionfull redundant OC-N devoted to protectiontwice as many NEs as compared to two-fiber

Example

recovery from unidirectional fiber cut

UPSR & BLSR (MS-SPRing) cont


78/91

NGSDH(Next Generation SDH)


79/91

SDH legacy technology is improving and adopting

data-friendly features.

Three technologies are central to Next-Generation

SDH.

Virtual Concatenation: VCAT

Link Capacity Adjustment Scheme: LCAS

Generic Framing Procedure: GFP

Next Generation SDH


80/91

Purpose of GFP

New ITU-T standard, G.7041 describes a

Generic Framing Procedure (GFP) which may beused for efficiently mapping client signals into

and transporting them over SONET/SDH or

G.709 links.


81/91

Generic Framing Procedure (GFP) Overview

GFP defines a mapping of client data signals into SDH

payloads in order to allow SDH to transport non-TDM traffic

more efficiently. GFP defines two types of client signals:

Frame-mapped GFP for PDU-oriented signals such as IP/ PPPor Ethernet MAC.

Transparent-mapped GFP for block-oriented signals such as

Fiber Channel.

Benefits of GFP

GFP provides major benefits. It gives one uniform mechanism

to transport any data type over SDH.

Purpose of GFP


82/91

VCAT


83/91

Payloads that dont fit into standard VT/VC sizes can be accommodated

by concatenating of several VTs / VCs

For example, 10 Mbps doesnt fit into any VT or VC

so w/o concatenation we need to put it into an STS-1 (48.384 Mbps)

the remaining 38.384 Mbps can not be used

We would like to be able to divide the 10 Mbps among7 VT1.5/VC-11 s = 7 * 1.600 = 11.20 Mbps or

5 VT2/VC-12 s = 5 * 2.176 = 10.88 Mbps

Concatenation


84/91

Virtual Concatenation (VCAT G.707)

payload split over multiple STSs / STMs

fragments may follow different routes

requires support only at path terminations

requires buffering and differential delay alignment

Virtual Concatenation


85/91

VCAT is an inverse multiplexing mechanism (round-robin)

VCAT members may travel along different routes in SONET/SDH network

Intermediate network elements dont need to know about VCAT

(unlike contiguous concatenation that is handled by all intermediate nodes)

H4

Virtual Concatenation


86/91

Using VCAT increases efficiency to close to100% !

Rate Mb/s w/o VCAT efficiency with VCAT efficiency

10 STS-1 21% VT2-5v

VC-12-5v

92%

100 STS-3c

VC-4

67% STS-1-2v

VC-3-2v

100%

1000 STS-48c

VC-4-16c

42% STS-3c-7v

VC-4-7v

95%

Efficiency Comparison


87/91

Link Capacity AdjustmentScheme


88/91

LCAS is defined in G.7042

LCAS extends VCAT by allowing dynamic BW changes.

Benefits of LCAS

The use of LCAS provides an effective way for the Service Provider to change

the bandwidth

allocated. Provisioning quickly the right bandwidth at any time is a major

operations management goal of Service Providers.

LCAS


89/91


90/91

THANKS


91/91

Any Question?

Date post:	05-Apr-2018
Category:	Documents
Upload:	david-olayinka-mosaku
View:	219 times
Download:	0 times

SDH for Students

Documents