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ADM Project

ADM Project Presentation

Part I:SDH BasicsPart II:ADM Project Description

Part I Contents

PDH ExplanationPDH LimitationsSDH Explanation SDH BenefitsSTM FrameProtection Switching

Plesiochronous

PDH Bit Rates

ANSI ETSI64 Kbps1.5 Mbps6 Mbps45 Mbps140 Mbps

64 Kbps1.5 Mbps6 Mbps34 Mbps

140 Mbps

PDH Multiplexing Steps

PDH Multiplexing

PDH Limitations

Synchronous

SDH Bit Rates

Benefits of a Synchronous Digital HierarchySynchronous transmission overcomes the limitations experienced in a plesiochronous network. It allows the network to evolve to meet the new demand being placed upon it. Synchronous offers a number of benefits, both to telecoms, network operators, and to end users.

Network Simplification.Management and Supervision.Bandwidth On Demand.Standardization.

Benefits of a Synchronous Digital HierarchyNetwork Simplification:One of the main benefits seen by a network operator is the network simplification brought about through the use of synchronous equipment. A single synchronous multiplexer can perform the function of an entire plesiochronous “multiplexer mountain”, leading to significant reductions in the amount of equipment used. Lower operation costs will also result due to the reduction in required spare inventory, simplified maintenance, the reduction in floor space required by equipment and lower power consumption. The more efficient “drop and insert” of channels offered by an SDH network, together with its powerful network management capabilities, will lead to greater ease in provisioning of high bandwidth lines for new multimedia services, as well ubiquitous access to those services. Thus, the simplification of the network, and the new flexibility this brings, opens up the potential for the network operator to generate new revenues.

Benefits of a Synchronous Digital HierarchyManagement and Supervision:Provision of network management channels within the SDH frame struct-ure means that a synchronous network will be fully software controllable. Network management systems will not only perform traditional event management functions such as dealing with alarms in the network, but will also provide a host of other functions, like performance monitoring, configuration management, resource management, network security,inventory management, and network planning and design.The possibility of remote provisioning and centralized maintenance will result in a great saving in time spent by maintenance personnel in traveling to remote sites, and this of source corresponds to a reduction of expenses.

Benefits of a Synchronous Digital HierarchyBandwidth On Demand:In a synchronous network it will be possible to dynamically allocate net-work capacity, or bandwidth on demand. Users anywhere within the net-work will be able to subscribe at very short notice to any service offered over the network, some of which may require large amounts of bandwidth. An example of this is dial-up video-conferencing. Users will be able to obtain the required bandwidth for a video-conferencing link just by dialing the appropriate number, as opposed to the current situation where video-conferencing links must reserved days in advance.Many other new services become possible in a synchronous network. These will represent new sources of revenue for network operators, and provide increased conveniences for users. Some examples of such services are high speed packet switched services and LAN interconnection.

Benefits of a Synchronous Digital HierarchyStandardization:The SDH standards mean that for the first time, transmission equipment from different manufacturers can interwork on the same link. The ability to achieve this so-called “mid-fiber meet” which has come about as a result of standards which define fiber-to-fiber interfaces at the physical level. They determine the optical line rate, wavelength, power levels, pulse shapes and coding. Frame structure, overhead and payload mapp-ing are also defined.This standardization of equipment and interfaces in SDH means network operators have freedom to choose different equipment from different vendors, and be confident that it will interwork. This means operators can avoid the problems traditionally associated with being locked into proprietary solutions from a single vendor. SDH standards also facilitate interworking between North American and European transmission hierarchies.

SDH Multiplexing Steps

Benefits of a Synchronous Digital Hierarchy -The Impact Of Synchronous:In the short term, network operators will adopt synchronous transmission equipment due to its improvement in network quality and its reduction in operating costs compared to plesiochronous transmission. The long term vision of a flexible and efficient network, with full network management facilities will also make this attractive.Once widespread deployment of synchronous of transmission systemoccur, the way in which network are designed, operated, and managed will change completely. Currently, network complexity makes deployment of new services a difficult proposition. In a much simplified synchronous network, services providers will be freed from these complexities. As a result they will be able to offer a rich mixture of services.Thus,the SDH will eliminate the network complexity which currently restricts the growth of new services. Eventually a truly global telecomm.

Synchronous Transmission descriptionSTM –1 Element :

CONTAINER Cn: (n=1-4)The basic element of the STM signal consisting of a group of bytes allocated to carry the transmission rates in G.702 (i.e. 1.5 Mbit/ sec & 2Mbit/ sec transmission hierarchies)

VIRTUAL CONTAINER VC-n :( n=1-4)Built up from the container plus additional capacity to carry the path overhead (POH) .The path overhead provides end-to-end path control and monitoring information.For a VC-3 or VC-4 the payload maybe a number of TUs or TUGs.


Synchronous Transmission descriptionTRIBUTARY UNIT TU –n: (n= 1-3)The tributary unit consists of a Virtual Containers plus a Tributary Unit Pointer .The position of the VC within TU is not fixed , However the position of TU pointer is fixed with relation of the next step of the multiplex structure , and indicates the start of the VC.

TRIBUTARY UNIT GROUP TUG This is formed by a group of identical TUs .

ADMINISTRATION UNIT AU –n:(n=3,4)This consists of a VC plus a AU pointer .The phase alignment of the AU pointers are fixed with the relation to the STM-1 frame as a whole and indicate the positions of the VC .


Synchronous Transmission descriptionSYNCHRONOUS TRANSPORT MODULE: LEVEL N (STM-1)

This is the basic element of the SDH .It is formed from a payload (made up of the AU) and additional bytes to from a section overhead (SOH) . The section overhead (SOH) .The section overhead allows control information to be passed between adjacent synchronous network elements .Within an STM-1 frame , information type repeats every 270 bytes .Thus , the STM-1 frame is often considered as a 270 byte x 9 line structure ,asshown in the figure below .the first 9 columns of this structure constitutes the “Section Overhead “ area , while the remaining 261 columns “Payload”area .


Synchronous Transmission description

SYNCHRONOUS TRANSPORT MODULE: LEVEL N (STM-N)

Formed by combining lower level STM signals using byte interleavingThe basic transmission rate defined in the SDH standards is 155.520Mbits/ s (STM-1) .Given that an STM-1 frame consists of 2430 8-bit bytes , this corresponds to a frame duration of 125microseconds .Two higher bit rates are also defined : 622.08 Mbit/ s ( STM-4) & 2,488.320 Mbit/ s (STM-16)

STM Frame

STM Frame Description

C2G1

B3J1

F2H4Z3Z4Z5

RSOH

MSOHC-4

AU-4

AU-4 Pointer

PayloadSTM-1 VC-4 POH VC-4

261

261 9 270Columnsrows

3

1

5


SDH Network Layers


STM Frame DescriptionSECTION OVERHEAD

E2Z2Z2Z2Z1Z1Z1

D12D11D10

D9D8D7

D6D5D4

K2K1B2B2B2

AU POINTER

D3D2D1

F1E1B1

C1A2A2A2A1A1A1

MSOH

RSOH


STM Frame DescriptionThe section overhead (SOH) bytes are used for communication between adjacent pieces of synchronous equipment .As well as being used for frame synchronization , they perform variety of management and administration facilities .The purpose of individual bytes is detailed below :A1 , A2 : Framing B1 , B2 : This bytes are simple parity checks for error detection C1 : Identifies an STM-1 in an STM-N frame .D1 , D12 : Data Communication Channel used for network managementE1 ,E2 : Order wire Channels F1 : User channelK1 , K2 : Automatic protection switching (APS) ChannelZ1 , Z2 :Reserved bytes for national use

Pointer

SDH Multiplexing

SDH Benefits

Protection Switching

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