Contents-• Introduction• SDH• Use of SDH• Benefits of SDH• Advantages of SDH• Services
Continued..• When to SDH• SDH frame Structure• Elements of frame Structure
Introduction• SDH provides transmission network with vendor independent environment.• (SDH) signals the beginning of a new phase in evolution of the world‘s telecommunication network.
Continued..• The network operator will experience significant cost savings associated with reduced amount of hardware in the network and increased efficiency and reliability of the network.• Designed to support future services such as Metropolitan Area Network (MAN), Broadband ISDN etc
What is SDH?• The SDH is a hierarchical set of digital transport structures, standardized for the transport of payloads over physical transmission networks.• ITU-t recommendations - STM-1 155Mbps, - STM-4 622 Mbps - STM-16 2.4 Gbps - STM64 10 Gbps
Benefits of SDH-• Network Simplification -performs the function of the entire Plesiochronous multiplexer mountain‘ hence reduces no of equipment used . Simplified maintenance, reduction in floor space required by equipment and lower power consumption.
Continued..• Survivability -deployment of optical fiber makes end to end monitoring and maintenance possible. The failure of links or even nodes to be identified immediately. Uses self-healing ring architecture, the network will be automatically reconfigured , re- routed as the faulty section has been repaired. As a result, failures will not disrupt services.
Continued..• Software Control -fully software controllable. Other functions such as performance monitoring, configuration management, resource management, network security etc. Remote provisioning and centralized maintenance will mean a great saving in time .Reduces expenses.• Bandwidth on Demand -possible to dynamically allocate network capacity or bandwidth on demand.
Continued..• Future-proof Networking -ideal platform for services ranging form POTS, ISDN and mobile radio through to data communications (LAN, WAN etc.). Handles latest services like video on demand and digital video broadcasting via ATM. Selected as the bearer network for the next generation of telecommunication network.
Advantages of the SDH system• First world standard in digital format.• First optical Interfaces.• Transversal compatibility reduces networking cost. Multi vendor environment drives price down• Flexible synchronous multiplexing structure.• Easy and cost-efficient traffic add-and-drop and cross connect capability.• Reduced number of back-to-back interfaces improves network reliability and serviceability.
Continued..• Powerful management capability.• New network architecture. Highly flexible and survivable self healing rings available.• Backward and forward compatibility: Backward compatibility to existing PDH• Forward compatibility to future B-ISDN, etc.
Services supported are -• Low/High speed data.• Voice• Interconnection of LAN• Computer links• Feature services like H.D.T.V.• Broadband ISDN transport (ATM transport)
When to use SDH?• Networks need increased transmission capacity.• Networks need to provide improve flexibility (quick response)• Networks need to provide improve survivability.• Networks need to reduce operation costs.
Continued..• Number of rows in a frame : 9• Number of columns in a frame : 9 + 261 = 270• Number of bytes/frame : 9 x 270• Number of bits /frame : 9 x 270 x 8• Number of bits per second : 9 x 270 x 8 x 8000• = 15552000 or 155.52 Mbps
Elements of frame StructureFrame structure consists of –• SOH -SOH bytes are used for communication between adjacent pieces of synchronous equipment.• RSOH –RSOH is used for the needs of the regenerator section• MSOH –MSOH is used for the needs of the multiplex section.• Pointer -defines frame offset of a VC with respect to• the frame reference
Continued..• POH-POH consists of 9 bytes denoted J1, B3, C2, G1,F2, H4, F3, K3 and N1• Payload – It contains information. POH + Payload= VC
Contents• Mapping In SDH• Alignment In SDH• Multiplexing In SDH• Principle of SDH Multiplexing• SDH Multiplexing Structure• PDH Signal to STM frame conversion• Multiplexing of 140Mbps Signal• Multiplexing of 34Mbps Signal• Multiplexing of 2Mbps Signal
What is Mapping• This is the procedure by which tributaries are adapted into virtual container.• Container of C-11, C-12, C-2, C-3, C-4 type are filled with plesiochronous signal.• Mapping is the first step in creation of STM-N frame
What is Alignment• This is the procedure by which the frame offset information is incorporated into the Tributary unit or Administrative unit.• Alignment applied after the complition of Mapping.• It is the process in which Virtual Container is adapted to TU or AU.
What is Multiplexing• It is a process in which multiple Higher order path layer signals are Adapted into a Multiplex section.• Also if the multiple Lower order path layer signals Adapted to Higher order path layer signals.• With multiplexing STM-N frame is completed.
Principle of SDH Multiplexing• Depending upon the PDH bit rates, various VCs are formed.• VC-1, VC-3 and VC-4 are formed for European PDH bit rates 2 Mbps, 34 Mbps and 140 Mbps respectively.• STM-N frame is fully synchonized, but the location of VCs within a STM-N frame are not be fixed with time.• Multiplexing scheme allows each container of any size and bit rate (PDH’s) to be fit in STM- N frame.
Multiplexing of 140Mbps Signal•Synchronous multiplexing of 140 Mbps signal Involves,• Forming Container C-4• Forming Virtual Container VC-4• Forming Administrative Unit AU-4• Formation of Administrative Unit Group (AUG)• Adding SOH to form STM-1
Multiplexing of 34Mbps SignalSynchronous multiplexing of 34 Mbps signal Involves,• Forming Container C-3• Forming Virtual Container VC-3• Forming Tributary Unit TU-3• Formation of Tributary Unit Group (TUG-3)• Multiplexing TUG-3 into VC-4• Next Procedure same as 140Mbps
Multiplexing of 2Mbps SignalSynchronous Multiplexing of 2 Mbps signal Involves,• Forming Container C-1• Forming Virtual container (VC-12)• Forming Tributary Unit (TU-12)• Multiplexing of TU-12 to form TUG-3• Next procedure same as 34Mbps
Contents• Introduction• SDH Network in Layers• Elements of SDH Network• Terminal multiplexer• ADD/DROP multiplexer• Regenerators• Digital cross connect(DXC)• Network management system(NMS)
Introduction• Devices that implement SDH transmission referred as SDH NE’s.• NE’s include regenerator section, multiplex section and path terminating section equipments.• SDH NE’s integrate to form the Digital loop carrier(DLC) to support SDH architecture and topologies.• SDH NE are subdivided into various layers.
Terminal Multiplexer• TM is a path terminating element that concentrate or aggregate DS1,E1s ,STM-Ns.• Various PDH signals are mapped with their associated SDH electrical payload in TM. For eg.
Terminal Multiplexer• Application of TM: 1. Transmission system (STM-1, STM-4,STM-16) 2. Multiplexing of Signals 3. For higher bit rates signals 4. Point-to-point (Chain network)
ADD/DROP Multiplexer(ADM)• PTE that can multiplex & demultiplex various signals to or from STM-N signals. At add/drop side, only those signals that need to be accessed are dropped or inserted. Remaining traffic continues through NE without signal processing.• Single stage ADM can multiplex or demultiplex one or more tributary signals to or from STM-N. Used in Terminal side(low speed side) where lower bit rate signals can add or drop into high speed SDH signals.
ADM• Automatic back-up path switching is possible using elements in ring in fault.• Next generation multiservice platform have their roots in ADM which carry data services over SDH.
REGENERATORS• It regenerates attenuated signals which causes due to long distance between multiplexer.(Signals becomes too low to drive receiver)• Also called as repeater. As it retransmit regenerated high power signal. They derive their clock signal from incoming data stream.• Since 1990, REG have been replaced by optical amplifier.
REGENERATORS• Functions of REG.: 1. Regeneration of signals 2. Amplification 3. Retransmission of high power signals toward receiver.• Applications: 1. In point-to-point and in ring network 2. For long haul distance communication
DIGITAL CROSS-CONNECT(DXC)• Used for setting up semi-permanent interconnection between different channels. Regroup & switch data streams between interfaces of cross connect system. For eg. UMUX- multiservice access system( equipped for cross connect system with STM-4 system).• 2 types- 1.Broadband DXC & 2.Wideband DXC
DIGITAL CROSS-CONNECT(DXC)• Core function is cross connection• Used at hub stations.• Used for grooming telecommunication traffic, switching traffic from one to other in network failure condition
NETWORK MANAGEMENT SYSTEM• NMS is combination of software & hardware used to monitor and administer a network.• Network elements(NE’s ) in a network are managed by this NMS system.• NMS manages NE such as fault, accounting, configuration and performance managements.• NMS employs various protocols to perform these tasks such as SNMP protocol can be used to gather information from devices in network.
CONTENTSa) Introduction.b) Topology types i)point to point. ii)point to multipoint. iii)Ring topology. iv)Mesh topology. v) star topology.c)Extended star topology.d)Deployment of SDH.
Introduction1)How the nodes in the system are connected.2)Topology can be considered at many different levels: physical, logical, connection, or organizational.3)Topology is considered in terms of the information flow. – Nodes in the graph are individual computers or programs, – links between nodes indicate that those nodes are sharing information regularly in the system.
Topology typesa) Point to point topologyb) Point to multipoint topologyc)Ring topologyd)Mesh topologye)Star topology
Ring topology• A single centralized server cannot handle high client load, so a common solution is to use a cluster of machines arranged in a ring to act as a distributed server.• Communication between the nodes coordinates state- sharing, producing a group of nodes that provide identical function but have failover and load- balancing capabilities.• Unlike the other topologies here, ring systems are generally built assuming the machines are all nearby on the network and owned by a single organization.
Mesh Topology advantages &disadvantages Advantage. 1.Improves Fault Tolerance Disadvantages.1.Expensive2.Difficult to install3.Difficult to manage4.Difficult to troubleshoot
Star topologyAll computers connect to a centralized point.The central point is called the hub.
Star topology advantages• Advantages• Easy to add devices as the network expands• One cable failure does not bring down the entire network (resilience)• Hub provides centralised management• Easy to find device and cable problems• Can be upgraded to faster speeds• Lots of support as it is the most used
Star topology disadvantages DisadvantagesA star network requires more cable than a ringor bus networkFailure of the central hub can bring down theentire networkCosts are higher (installation and equipment)than for most bus networks