synchronous digital hierarchy. what is synchronous transmission synchronous transmission has been...

SYNCHRONOUSYNCHRONOUS DIGITAL S DIGITAL

HIERARCHYHIERARCHY

What is Synchronous What is Synchronous TransmissionTransmission

• Synchronous Transmission has been Synchronous Transmission has been developed to overcome the problems developed to overcome the problems associated with Plesichronous associated with Plesichronous Transmission, in particular the Transmission, in particular the inability of the PDH to extract inability of the PDH to extract individual circuits from high capacity individual circuits from high capacity systems without having to systems without having to demultiplex the whole system.demultiplex the whole system.

Main Feature of SDHMain Feature of SDH

• Network Management CapabilityNetwork Management Capability

• Channel ExtractionChannel Extraction

• Any existing PDH Transmission Rate Any existing PDH Transmission Rate to be packaged into an STM-1 frame.to be packaged into an STM-1 frame.

Principles of SDHPrinciples of SDH

• SDH DIAGRAMSDH DIAGRAM

SDH PriniciplesSDH Priniciples

• The SDH defines a number of containers, The SDH defines a number of containers, each corresponding to an existing PDH rate. each corresponding to an existing PDH rate.

• Information from PDH signal is mapped into Information from PDH signal is mapped into the relevant container. The way in which the relevant container. The way in which this is done is similar to bit stuffing this is done is similar to bit stuffing procedure carried out in PDH MUX.procedure carried out in PDH MUX.

• Each container then has some control Each container then has some control information known as the “path overhead” information known as the “path overhead” added to it.added to it.

Cont---------Cont---------

• PATH OVER HEADPATH OVER HEAD bytes allow the bytes allow the network operator to achieve end to end network operator to achieve end to end path monitoring of things such as error path monitoring of things such as error rates.rates.

• Together the container and the path Together the container and the path overhead form a “overhead form a “VIRTUAL CONTAINER”VIRTUAL CONTAINER”

FIGFIG

Cont-----------Cont-----------

• In a synchronous network, all equipment is In a synchronous network, all equipment is synchronized to an over all network clock.synchronized to an over all network clock.

• It is important to note that the delay It is important to note that the delay associated with a transmission link may associated with a transmission link may vary slightly with time. As a result the vary slightly with time. As a result the location of virtual containers within STM-1 location of virtual containers within STM-1 frame is may not be fixed.frame is may not be fixed.

• These variations are accommodated by These variations are accommodated by associating a pointer with each VC.associating a pointer with each VC.

Cont-----------Cont-----------

• The pointer indicates the position of The pointer indicates the position of the beginning of the VC in relation to the beginning of the VC in relation to the STM-1 frame. the STM-1 frame.

• It can be incremented as necessary It can be incremented as necessary to a accommodate movements of the to a accommodate movements of the position of the VC.position of the VC.

Cont--------Cont--------

• G.709 defines different combinations of G.709 defines different combinations of virtual containers which can be used to fill virtual containers which can be used to fill up the payload area of an STM-1 frame. The up the payload area of an STM-1 frame. The process of loading containers and attaching process of loading containers and attaching overhead is repeated at several levels in overhead is repeated at several levels in SDH, resulting the “nesting” of smaller VCs SDH, resulting the “nesting” of smaller VCs within larger ones. This process is repeated within larger ones. This process is repeated until the largest size of VC (VC-4 in Europe) until the largest size of VC (VC-4 in Europe) is filled, and this is loaded into the pay load is filled, and this is loaded into the pay load of the STM-1 of the STM-1

Cont-----------Cont-----------

• When the payload area of the STM- 1 When the payload area of the STM- 1 frame is full, some more information frame is full, some more information bytes are added to the frame to form bytes are added to the frame to form a “a “Section OverheadSection Overhead” ”

• The section overhead bytes are so-The section overhead bytes are so-called because they remain with the called because they remain with the payload for the fiber section between payload for the fiber section between to SDH MUX.to SDH MUX.

Purpose of Section Overhead Purpose of Section Overhead bytesbytes

• Their purpose is to provide Their purpose is to provide communication channels for communication channels for functions such as OA&M facilities.functions such as OA&M facilities.

• User channelUser channel• Protection switchingProtection switching• Section performanceSection performance• Frame alignment Frame alignment • Etc.Etc.

BYTE INTERLEAVING BYTE INTERLEAVING MULTIPLEXING SCHEMEMULTIPLEXING SCHEME

• When a higher transmission rate than When a higher transmission rate than the 155 Mbits/s of STM-1 is required in the 155 Mbits/s of STM-1 is required in a synchronous network, it is achieved a synchronous network, it is achieved by a relatively straight forward “by a relatively straight forward “Byte Byte interleaving Multiplexing scheme”interleaving Multiplexing scheme”

• In this way rates of 622 Mbits/s (STM-4) In this way rates of 622 Mbits/s (STM-4) - 10 Gbits/s (STM-64) can be achieved.- 10 Gbits/s (STM-64) can be achieved.

Benefits of Synchronous Benefits of Synchronous NetworkNetwork

• Network Simplification: A single SDH MUX Network Simplification: A single SDH MUX can perform the function of an entire PDH can perform the function of an entire PDH MUX mountain. MUX mountain.

• FigFig• Leading to significant reduction in the Leading to significant reduction in the

amount of equipment used. Lower amount of equipment used. Lower operating costs will also result through operating costs will also result through reduction in spares inventory required, reduction in spares inventory required, simplified maintenance, and also reduction simplified maintenance, and also reduction in floor space required by the equipment, in floor space required by the equipment, and lower power consumption.and lower power consumption.

Benefits of Network Benefits of Network simplification cont-------simplification cont-------

• The more efficient “drop and insert” of channels The more efficient “drop and insert” of channels offered by an SDH network, together with its offered by an SDH network, together with its powerful network management capabilities, will powerful network management capabilities, will lead to greater ease in provisioning of high lead to greater ease in provisioning of high bandwidth lines of news multimedia services as bandwidth lines of news multimedia services as well as ubiquitous access to those services. well as ubiquitous access to those services.

• Thus the simplification of the network, and Thus the simplification of the network, and flexibility this brings opens up the potential for flexibility this brings opens up the potential for network operator to generate new revenue.network operator to generate new revenue.

SurvivabilitySurvivability• The deployment of optical fiber throughout The deployment of optical fiber throughout

the network and adoption of the SDH the network and adoption of the SDH network element makes end to end network element makes end to end monitoring and maintenance of network monitoring and maintenance of network integrity a possibility. The network integrity a possibility. The network management capability of the synchronous management capability of the synchronous network will enable the failure of links or network will enable the failure of links or even nodes to be identified immediately. even nodes to be identified immediately. Using self healing ring architecture, the Using self healing ring architecture, the network will be automatically reconfigured network will be automatically reconfigured with traffic intensity rerouted until such a with traffic intensity rerouted until such a time as the faulty equipment has been time as the faulty equipment has been repaired.repaired.

Survivability cont-----Survivability cont-----

• Thus, failure in the network transport Thus, failure in the network transport mechanism will be invisible on an mechanism will be invisible on an end to end basis. Such failure will not end to end basis. Such failure will not disrupt services, allowing network disrupt services, allowing network operators to commit to extremely operators to commit to extremely high availability of service figures high availability of service figures and guarantee high levels of network and guarantee high levels of network performanceperformance

Software ControlSoftware Control• Provision of network management channels Provision of network management channels

within the SDH frame structure means that within the SDH frame structure means that a synchronous network will be fully a synchronous network will be fully software controllable. Network software controllable. Network management system will not only perform management system will not only perform traditional event management functions- traditional event management functions- dealing with alarms in the network, but will dealing with alarms in the network, but will also provide a host of other functions, such also provide a host of other functions, such as performance monitoring, configuration as performance monitoring, configuration management, resource management management, resource management Network Security, Inventory Management Network Security, Inventory Management and Network Planning and design.and Network Planning and design.

Software Control cont-------Software Control cont-------

• The possibility of remote provisioning The possibility of remote provisioning and centralized maintenance will and centralized maintenance will mean a great saving in time spent by mean a great saving in time spent by maintenance personnel in traveling maintenance personnel in traveling to remote sites, and this of course to remote sites, and this of course corresponds to expense saving.corresponds to expense saving.

Bandwidth on DemandBandwidth on Demand

• In a synchronous network it will be possible to In a synchronous network it will be possible to dynamically allocate network capability, or dynamically allocate network capability, or bandwidth, on demand. User any where within bandwidth, on demand. User any where within the network will be able to subscribe at very the network will be able to subscribe at very short notice to any service offered over the short notice to any service offered over the network, some of which may require large network, some of which may require large amount of bandwidth. An example of this is amount of bandwidth. An example of this is dialup video conferencing. User link just by dialup video conferencing. User link just by dialing the appropriate number, as opposed to dialing the appropriate number, as opposed to the current situation where videoconferencing the current situation where videoconferencing link must be booked days in advance.link must be booked days in advance.

Bandwidth on demand Bandwidth on demand Cont---Cont---

• Many other new services become Many other new services become possible in a synchronous network. possible in a synchronous network. These will represent new source of These will represent new source of revenue for network operators, and revenue for network operators, and increased convenience for users. increased convenience for users. Some examples are high speed Some examples are high speed packet services, LAN interconnection packet services, LAN interconnection and HDTVand HDTV

Future Proof Networking Future Proof Networking

• The synchronous Digital Hierarchy The synchronous Digital Hierarchy offers network operators a future offers network operators a future proof network solution, plus software proof network solution, plus software upgradeability and extensions to upgradeability and extensions to existing equipment. existing equipment.

ELEMENTS of SYNCHRONOUS ELEMENTS of SYNCHRONOUS TRANSMISSION SYSTEMTRANSMISSION SYSTEM

• Multiplexers: Synchronous Multiplexers, Multiplexers: Synchronous Multiplexers, as defined by ITU-T SDH as defined by ITU-T SDH recommendations, perform both recommendations, perform both multiplexing and line terminating multiplexing and line terminating functions, as shown in functions, as shown in

• FigFig

• Thus a synchronous MUX replaces a bank Thus a synchronous MUX replaces a bank of PDH and associated line terminating of PDH and associated line terminating equipment, while at the same time equipment, while at the same time bringing new functionality.bringing new functionality.

SDH MUX cont---------SDH MUX cont---------

• Synchronous Multiplexers can accept Synchronous Multiplexers can accept a wide range of tributaries, and offer a wide range of tributaries, and offer a number of possible output data a number of possible output data rate as shown in rate as shown in

• FigFig

• On the tributary side, all current PDH On the tributary side, all current PDH bit rates can be accommodated.bit rates can be accommodated.

SDH MUX cont----------------SDH MUX cont----------------

• The synchronous Optical Interface of the The synchronous Optical Interface of the synchronous multiplexer can be duplicated synchronous multiplexer can be duplicated for protection. This can be done in two ways, for protection. This can be done in two ways, either traditional 1+1 protection can be either traditional 1+1 protection can be provided, or the optical port can operate in provided, or the optical port can operate in an EAST/ WEST NODE to allow the an EAST/ WEST NODE to allow the implementation of ring topologies.implementation of ring topologies.

• Synchronous ring can improve resilience and Synchronous ring can improve resilience and reduce both fiber requirement and network reduce both fiber requirement and network cost.cost.

Point to Point ConfigurationsPoint to Point Configurations

• Synchronous Multiplexers can be Synchronous Multiplexers can be used effectively high capacity point used effectively high capacity point to point applications where they are to point applications where they are cost competitive with PDH solutions. cost competitive with PDH solutions. The equipment facilitates provision The equipment facilitates provision of new services and provide an of new services and provide an upgrade path as network evolves. upgrade path as network evolves.

• figfig

ADD DROP CONFIGURATIONADD DROP CONFIGURATION

• This configuration is similar to the This configuration is similar to the previous one but the fact that a previous one but the fact that a number of MUX are used to provide number of MUX are used to provide connectivity between nodes along a connectivity between nodes along a route. The MUX are configured to add route. The MUX are configured to add drop channel at these nodedrop channel at these node

RING CONFIGURATIONRING CONFIGURATION

• For areas of the network requiring high For areas of the network requiring high survivability, synchronous multiplexers survivability, synchronous multiplexers may be configured as a high capacity may be configured as a high capacity “self healing” fiber ring. The ring “self healing” fiber ring. The ring structure is able to reconfigure without structure is able to reconfigure without the intervention of external network the intervention of external network management should equipment or management should equipment or cable occur maintaining continuity of cable occur maintaining continuity of serviceservice

HUB CONFIGURATIONSHUB CONFIGURATIONS

• By using tributary interfaces, a terminal can By using tributary interfaces, a terminal can be configured as a fiber hub for use in multi-be configured as a fiber hub for use in multi-site network applications, This eliminates site network applications, This eliminates the need for back fiber terminals.the need for back fiber terminals.

• In addition to its operation capabilities, a In addition to its operation capabilities, a synchronous multiplexer offer a Network synchronous multiplexer offer a Network Management channel which may provide Management channel which may provide alarm and monitoring information for alarm and monitoring information for individual tributaries within an STM-1 signalindividual tributaries within an STM-1 signal

HUB CONFIGURATION HUB CONFIGURATION CONT---CONT---

• Not only does this provide enhanced Not only does this provide enhanced management abilities, but since management abilities, but since management within the SDH is to be management within the SDH is to be standardized, additional cost benefits standardized, additional cost benefits can be realized by network Operator can be realized by network Operator through more efficient Management through more efficient Management System.System.

CROSS CONNECT CROSS CONNECT FUNCTIONALITYFUNCTIONALITY

• Cross Connections in a synchronous Cross Connections in a synchronous network involves setting up semi-network involves setting up semi-permanent interconnections between permanent interconnections between different channels, enabling routing to be different channels, enabling routing to be performed down to a VC level.performed down to a VC level.

• This description seems to suggest that This description seems to suggest that cross connection is similar to switching, cross connection is similar to switching, but there are fundamental difference but there are fundamental difference between two .between two .

Cross Connect CONT------Cross Connect CONT------• The main difference is that a switch operates as The main difference is that a switch operates as

a temporary connection which is set up under a temporary connection which is set up under the control of the end user, while cross the control of the end user, while cross connection is a transmission technique use to connection is a transmission technique use to set up a semi permanent connection under the set up a semi permanent connection under the control of the network operator via a network control of the network operator via a network manager.manager.

• However, as network services evolves to However, as network services evolves to wideband and broadband, it is certainly wideband and broadband, it is certainly possible that the switch and cross connect possible that the switch and cross connect functions will begin to merge. This is functions will begin to merge. This is particularly true when ATM services begin particularly true when ATM services begin volume deploymentvolume deployment

Cross Connect Cont------Cross Connect Cont------

• There is also a distinction between the There is also a distinction between the plesiochronous cross connect unit which has plesiochronous cross connect unit which has established itself to some extent within established itself to some extent within current networks, and the synchronous current networks, and the synchronous cross connection function.cross connection function.

• The traditional PDH X-connect was The traditional PDH X-connect was developed to replace manual digital developed to replace manual digital distribution frames which were seen as distribution frames which were seen as reliable and labor intensive as shown in reliable and labor intensive as shown in

• FigFig• Slow to setup, prone to error and expensive.Slow to setup, prone to error and expensive.

X-CONNECT CONT-------X-CONNECT CONT-------• In deploying a plesiochronous automatic In deploying a plesiochronous automatic

Digital Distribution Frame, this allows Digital Distribution Frame, this allows traffic passing through the cross connect traffic passing through the cross connect to effectively share the physical to effectively share the physical connection at different instances in time. connection at different instances in time. However this requires that all traffic However this requires that all traffic through a PDH X-Connect is through a PDH X-Connect is synchronized, thus necessitating the synchronized, thus necessitating the expense of providing a justifications expense of providing a justifications mechanism at the interface between it mechanism at the interface between it and the network.and the network.

X-CONNET CONT-----X-CONNET CONT-----

• The traffic rates through plesiochronous The traffic rates through plesiochronous cross connect also need to be limited to a cross connect also need to be limited to a manageable size since these cross connect manageable size since these cross connect can only easily operate at a single rate. can only easily operate at a single rate. Most choose to switch at the 64 Kbits/s level Most choose to switch at the 64 Kbits/s level and interface at 2 Mbit/s. This means that and interface at 2 Mbit/s. This means that all traffic must be demultiplexed to 2 all traffic must be demultiplexed to 2 Mbits/s before it can be connected, thus Mbits/s before it can be connected, thus increasing equipment requirement, sized increasing equipment requirement, sized and cost.and cost.

X-Connect Cont---X-Connect Cont---• With the introduction of synchronous With the introduction of synchronous

transmission system the need for any transmission system the need for any justification of signals at the interface with the justification of signals at the interface with the cross connecting device is removed. Fig shows cross connecting device is removed. Fig shows the difference between PDH and SDH X-the difference between PDH and SDH X-Connect.Connect.

• Probably the most important difference Probably the most important difference between the plesiochronous network digital between the plesiochronous network digital cross-connect (referred the plesiochronous cross-connect (referred the plesiochronous network digital cross connect (refered as DXC) network digital cross connect (refered as DXC) and the synchronous cross connect function is and the synchronous cross connect function is the actual deployment planning. the actual deployment planning.

Cont---Cont---

• A DXC is required wherever a large add-drop A DXC is required wherever a large add-drop function is performed or where a lot of function is performed or where a lot of manual reconfiguration takes place in the manual reconfiguration takes place in the network to provide new service or groom network to provide new service or groom existing service for efficient facility existing service for efficient facility utilization.utilization.

• Any of these application required the use of Any of these application required the use of a distinct piece of plesiochronous equipment a distinct piece of plesiochronous equipment called a DXC to perform the function.called a DXC to perform the function.

DXX Cont---DXX Cont---

• The synchronous X-Connect function, The synchronous X-Connect function, when required does not necessarily when required does not necessarily mean the need for a separate piece mean the need for a separate piece of equipment. The flexibility of SDH of equipment. The flexibility of SDH allows the cross connect functionality allows the cross connect functionality to reside in almost any network to reside in almost any network element, the most obvious being an element, the most obvious being an add-drop MUX. add-drop MUX.

SDXC (Synchronous Digital X-SDXC (Synchronous Digital X-Connet)Connet)• There are two types of dedicated SDXC There are two types of dedicated SDXC

commonly referred to, the commonly referred to, the • SDXC 4/4.SDXC 4/4.• SDXC 4/1SDXC 4/1• These are used in special applications to These are used in special applications to

supplement the distributed cross-connect supplement the distributed cross-connect functionality of a synchronous network. The functionality of a synchronous network. The numbering scheme describe the VC level at numbering scheme describe the VC level at which they can accept inputs and cross-which they can accept inputs and cross-connect respectively. It can be seen that connect respectively. It can be seen that the difference between the two is the the difference between the two is the multiplex level at which they can cross multiplex level at which they can cross connect traffic.connect traffic.

SDXC 4/4SDXC 4/4

• The SDXC 4/4 is usually designed to The SDXC 4/4 is usually designed to accept input s at 140, 155 or 622 accept input s at 140, 155 or 622 Mbits/s or higher. It can cross-Mbits/s or higher. It can cross-connect at 155 or 140 Mbits/s. It may connect at 155 or 140 Mbits/s. It may be used in the core of the be used in the core of the transmission network for network transmission network for network protection as an alternative to STM-protection as an alternative to STM-16 base protection ring architecture.16 base protection ring architecture.

SDXC 4/1SDXC 4/1

• The SDXC 4/1 can usually accept The SDXC 4/1 can usually accept combinations of 2,155 and 622 Mbits/s combinations of 2,155 and 622 Mbits/s input. It can cross connect VC-1 containers, input. It can cross connect VC-1 containers, i.e 2Mb/s channels, though in many cases i.e 2Mb/s channels, though in many cases 4/1 cross connects will also be able to cross 4/1 cross connects will also be able to cross connect VC-2s, concatenated VC-2s, VC-3, connect VC-2s, concatenated VC-2s, VC-3, and VC-4. These pieces of equipment may and VC-4. These pieces of equipment may be used where special circumstances lead be used where special circumstances lead to the requirement for a point of additional to the requirement for a point of additional flexibility in the outer core transmission flexibility in the outer core transmission network. network.

SYNCHRONOUS DEPLOYMENTSYNCHRONOUS DEPLOYMENT• Multi-vendor ConnectivityMulti-vendor Connectivity

• Technological Discontinuity.Technological Discontinuity.

• Reduction in equipment.Reduction in equipment.

• Improved Network Resilience.Improved Network Resilience.

• Network Management.Network Management.

• Single Stage Multiplexing.Single Stage Multiplexing.

• Single Stage Multiplexing.Single Stage Multiplexing.

• Distributed Bandwidth Management.Distributed Bandwidth Management.

• Software Down loadSoftware Down load

• Ring Deployment.Ring Deployment.

SDH DeploymentSDH Deployment

• Implementation of New Services.Implementation of New Services.

• Improved Earning.Improved Earning.

• Deployment TriggersDeployment Triggers

• ModernisationModernisation

• The SDH SolutionThe SDH Solution

• Network EvolutionNetwork Evolution

• Management Services NetworkManagement Services Network

• International Services NetworkInternational Services Network

Multi vendor Connectivity Multi vendor Connectivity

The standardisation of synchronous interfaces The standardisation of synchronous interfaces means that a planner can mix and match means that a planner can mix and match products from different vendors in the products from different vendors in the network, without having to concerned about network, without having to concerned about their ability to work together. However there their ability to work together. However there is still the possibility of implementing the is still the possibility of implementing the standards in different ways. Thus the standards in different ways. Thus the network planner must understand the network planner must understand the impact of choosing between such options impact of choosing between such options as, Floating,or Fixed mode mapping, or as, Floating,or Fixed mode mapping, or choosing between asynchronous, bit choosing between asynchronous, bit synchronous or Byte synchronous mapping. synchronous or Byte synchronous mapping.

Technological DiscontinuityTechnological Discontinuity

• Because synchronous can carry Because synchronous can carry plesiochronous payload it can be deployed plesiochronous payload it can be deployed in an evolutionary manner. However, in an evolutionary manner. However, because of the changes associated with because of the changes associated with synchronous systems it does represent synchronous systems it does represent something of a technological discontinuity. something of a technological discontinuity. Thus, in order to effectively overcome the Thus, in order to effectively overcome the limitations of the PDH, network operators limitations of the PDH, network operators must plan the introduction of the must plan the introduction of the synchronous into their network with care.synchronous into their network with care.

Reduction in EquipmentReduction in Equipment

• SDH will lead to simplification of the SDH will lead to simplification of the network. The multiplexing structure network. The multiplexing structure allows for greater integration of allows for greater integration of products, along with greater control of products, along with greater control of equipment. The network planner faces equipment. The network planner faces the exciting challenge of using the exciting challenge of using synchronous equipment in such a way synchronous equipment in such a way as to unleash the full power inherent in as to unleash the full power inherent in it.it.

Improved Network Improved Network ResilienceResilience

• A synchronous network will be more reliable A synchronous network will be more reliable due to both the increased reliability of due to both the increased reliability of individual elements, and the more resilient individual elements, and the more resilient structure of the whole network. Synchronous structure of the whole network. Synchronous will allow development of network topologies will allow development of network topologies which will be able to achieve which will be able to achieve “network “network protection”protection” , that is survive failures in the , that is survive failures in the network by reconfiguring and maintaining network by reconfiguring and maintaining service by alternate means. Network service by alternate means. Network Protection can be achieved the use of cross Protection can be achieved the use of cross connect functionality to achieve restoration connect functionality to achieve restoration or through the use of self-healing ring or through the use of self-healing ring architectures. architectures.

NETWORK MANAGEMENTNETWORK MANAGEMENT• SDH gives the network operator the opportunity SDH gives the network operator the opportunity

to manage network performance effectively and to manage network performance effectively and make change flexibility as required. make change flexibility as required. Synchronous equipment will have a significant Synchronous equipment will have a significant proportion of its design embedded in software proportion of its design embedded in software instead of hardware. Therefore, the network instead of hardware. Therefore, the network manager will be able to control equipment manager will be able to control equipment configuration changes through software configuration changes through software management. What is ultimately required is the management. What is ultimately required is the ability for the network manager to implement ability for the network manager to implement what is called “ IN SERVICE PROVISIONING”. what is called “ IN SERVICE PROVISIONING”.

NETWORK MANAGEMENT NETWORK MANAGEMENT --------

• This is where a request for service is This is where a request for service is entered into the network manager via a entered into the network manager via a terminal or other electronic mean and is terminal or other electronic mean and is then broken down into a series of then broken down into a series of instructions to each network element instructions to each network element involved in that service. Each network involved in that service. Each network element is then configured and provisioned element is then configured and provisioned in software to support the service request in software to support the service request without having to be taken out of service. without having to be taken out of service. It is important that the network operator It is important that the network operator plans his network in such a way as to take plans his network in such a way as to take advantage of benefits resulting from “advantage of benefits resulting from “in in service provisioning”.service provisioning”.

Single Stage MultiplexingSingle Stage Multiplexing

• The SDH multiplexing structure allows The SDH multiplexing structure allows many different tributaries to be many different tributaries to be multiplexed together into an STM-n multiplexed together into an STM-n signal in a single stage of multiplexing. signal in a single stage of multiplexing. Thus the network planner is not bound Thus the network planner is not bound by a rigidly hierarchical network by a rigidly hierarchical network structure, as he was with the PDH. The structure, as he was with the PDH. The planner now has at his disposal the planner now has at his disposal the bandwidth flexibility essential for the bandwidth flexibility essential for the introduction of new services.introduction of new services.

Distributed Bandwidth Distributed Bandwidth ManagementManagement

• The plesiochronous cross connect The plesiochronous cross connect was originally conceived as a devie was originally conceived as a devie to sumplify routing and gromming at to sumplify routing and gromming at srtrategic poinit s in the network, srtrategic poinit s in the network, However, the necessity to transport However, the necessity to transport traffic to cross connet site often traffic to cross connet site often outwidhed the benefirs gained.outwidhed the benefirs gained.

•

Distributed Bandwidth Distributed Bandwidth Management-- Management--

• In a sunchronoos network, the abitlity of In a sunchronoos network, the abitlity of multiplexers to perform routing and multiplexers to perform routing and frooning down to the VC level means that frooning down to the VC level means that cross connect functionality can be cross connect functionality can be distributed througout the network. This distributed througout the network. This “distributed bandwidth management’ “distributed bandwidth management’ capability means that standalone cross capability means that standalone cross connects are only required to be deployed connects are only required to be deployed at points in the network where exceptional at points in the network where exceptional felxibility is required. felxibility is required.

Distributed Bandwidth Distributed Bandwidth Management --Management --

• The distribution of cross conect funactinality, The distribution of cross conect funactinality, togerhter with the connectivity procide aby togerhter with the connectivity procide aby rsilient ring structures means that in a rsilient ring structures means that in a sycronos network it becones possible to sycronos network it becones possible to mange the distrubution of banwith down to mange the distrubution of banwith down to th VC level. This distributed badwidth th VC level. This distributed badwidth manamenent capabilty is essntial to manamenent capabilty is essntial to techniques such as “in service provisioning” , techniques such as “in service provisioning” , and flexible badwidth allocation as well as to and flexible badwidth allocation as well as to berfwork managemet techniques tha berfwork managemet techniques tha bneawork operators will be able to talke full bneawork operators will be able to talke full adavantage of the power of SDHadavantage of the power of SDH

Software Down LoadSoftware Down Load

• In a sychchronous network it wll become In a sychchronous network it wll become posible to down load software an posible to down load software an configuration ifomaton to Netowrk Elemant configuration ifomaton to Netowrk Elemant via the Embedded Commmunication via the Embedded Commmunication channe. (ECC). Using this facility it will channe. (ECC). Using this facility it will become possible to amange sofware become possible to amange sofware relaeases and updatred remotely, with relaeases and updatred remotely, with download as done either aurmaically or download as done either aurmaically or amanually. This abitly waill further amanually. This abitly waill further contribute to the redcution of operating contribute to the redcution of operating cost is a sychronous network.cost is a sychronous network.

RING DEPLOYMENTRING DEPLOYMENT

• Telecommunication users, particularly Telecommunication users, particularly business isers are becoming increasing business isers are becoming increasing dependent on the efficient transfer of dependent on the efficient transfer of information. Use of telecommunication information. Use of telecommunication for vital transactions, such as for vital transactions, such as elecrtroing funds trasfers, order elecrtroing funds trasfers, order processing ., customer service and processing ., customer service and inverntory control makes service makes inverntory control makes service makes sercie surviability moer important than sercie surviability moer important than ever before.ever before.

RING DEPLOYMENT ----RING DEPLOYMENT ----

• In many cases, loss of service can hace In many cases, loss of service can hace disastrous results, Conseqently many disastrous results, Conseqently many users are now looking for a gurantee as users are now looking for a gurantee as to conitinuity of service and willing to to conitinuity of service and willing to pay a premium to get it. By using pay a premium to get it. By using synchronous equpment to implement a synchronous equpment to implement a survivable network architecture, network survivable network architecture, network operators can thus repsond to this operators can thus repsond to this demand, in the process generating demand, in the process generating additonal revenus.additonal revenus.

RING DEPLOYMENT---RING DEPLOYMENT---

• The synchronous ring structure, with its The synchronous ring structure, with its inherent resilience, is a powreful building inherent resilience, is a powreful building block form which surviable neworks cab be block form which surviable neworks cab be bult. Within ETSI TM3 a recommendation bult. Within ETSI TM3 a recommendation (G.sna1) is currently being drafted which (G.sna1) is currently being drafted which describes sychronous network applicatons, describes sychronous network applicatons, including both point to point and ring including both point to point and ring toplogies. It will describe the way in which toplogies. It will describe the way in which SDH rings can be used to provie end to end SDH rings can be used to provie end to end path protection and multiplex section (MS ) path protection and multiplex section (MS ) pretection at the tranmission media level pretection at the tranmission media level against link and node failures.against link and node failures.

Ring Deployment ---Ring Deployment ---

• Two main types of sychronous ring Two main types of sychronous ring architecture are being defined.architecture are being defined.

• 1- The (unidirectional) dedicated path 1- The (unidirectional) dedicated path switched ring sends traffic both ways switched ring sends traffic both ways around the ring, and uses a protection around the ring, and uses a protection switch mechanism to select the alternate switch mechanism to select the alternate signal at the receiver end upon failure signal at the receiver end upon failure detection. This is a “Dedicated protection detection. This is a “Dedicated protection Ring”.Ring”.

RING DEPLOYMENT --- RING DEPLOYMENT ---

• The (bidirectional) sharen ed MS The (bidirectional) sharen ed MS switched ring is able to share switched ring is able to share protection capabililty which is reseced protection capabililty which is reseced all the way around the ring. In the all the way around the ring. In the event of a failure to route traffic event of a failure to route traffic through the spare capacity. To protect through the spare capacity. To protect all traffic on the ring it is only all traffic on the ring it is only necessary to reserve enough necessary to reserve enough protection capacity to protect the protection capacity to protect the largest working span. This is Shared largest working span. This is Shared Protection Ring (SPRing)Protection Ring (SPRing)

RING DEPLOYMENT ----RING DEPLOYMENT ----

• The ability to share protecton The ability to share protecton capacityh in bidirectional SPRings capacityh in bidirectional SPRings can in many instances offer a can in many instances offer a significant capacity advage over significant capacity advage over unidirectional DPRings. This means, unidirectional DPRings. This means, in economic terms less equipment, in economic terms less equipment, lower cost, and less operations effort lower cost, and less operations effort for the network opeators.for the network opeators.

RING DEPLOYMENT--RING DEPLOYMENT--

• Two types of ring achitecture are best Two types of ring achitecture are best suited to different applications.suited to different applications.

• 1- Unidirectional DPRing are best suited 1- Unidirectional DPRing are best suited to hub taffic applications, whre the to hub taffic applications, whre the simplicity of the implementation and the simplicity of the implementation and the high availabiity offered by DPRings for high availabiity offered by DPRings for the end to end path is important. This the end to end path is important. This would typically occur in the access would typically occur in the access network.network.

Ring DEPLOYMENT--Ring DEPLOYMENT--

• Bidirectional SPRings are best suited Bidirectional SPRings are best suited to site /adjacent site and uniform to site /adjacent site and uniform traffic applications, where the traffic applications, where the capacity advantage of SPRing is capacity advantage of SPRing is significant. This would occur in significant. This would occur in metropolitan, junction, and trunk metropolitan, junction, and trunk network applications.network applications.

Ring Deployment --Ring Deployment --

• Another important characteristics of the Another important characteristics of the survivable ring architecture is the survivable ring architecture is the aotomous operation at the transmission aotomous operation at the transmission level for fast recovery form tlink and level for fast recovery form tlink and node failures. This reduces node failures. This reduces management complexity associated management complexity associated with TMN. This fast switching time at with TMN. This fast switching time at which rings recover from failure means which rings recover from failure means negligible impact on service negligible impact on service interruptions.interruptions.

RING DEPLOYMENT---RING DEPLOYMENT---

• The autonomous network surviability offered The autonomous network surviability offered by rings is further enhanced by the inherent by rings is further enhanced by the inherent “Distributed Bandwidth Management’ “Distributed Bandwidth Management’ capability, where each ADM node on the ring capability, where each ADM node on the ring is capable of routing and grooming at the VC is capable of routing and grooming at the VC level to provide a efficiency of control and level to provide a efficiency of control and management over the transmission network, management over the transmission network, as well as reduces the required number of as well as reduces the required number of stand – alone cross connects such as SDXC stand – alone cross connects such as SDXC 4/1 for hubbing of traffic and SDXC 4/4 for 4/1 for hubbing of traffic and SDXC 4/4 for network protection.network protection.

Implementation of New Implementation of New ServicesServices

• Synchronous technology allows planners to look Synchronous technology allows planners to look at their network in terms of service demands at their network in terms of service demands rather than just the provisioning of point to point rather than just the provisioning of point to point facilities. In order to succeed in an increasingly facilities. In order to succeed in an increasingly competitive telecommunication world, service competitive telecommunication world, service providers must take an integrated approach in providers must take an integrated approach in network planning in order to achieve a network network planning in order to achieve a network the power of which is greater than the power of the power of which is greater than the power of its constituents parts. Only by doing this will the its constituents parts. Only by doing this will the operator be able to build a network operator be able to build a network infrastructure strong enough to ensure support infrastructure strong enough to ensure support of any service to anyone, anywhere. of any service to anyone, anywhere.

Improved EarningImproved Earning• By taking careful of all the issues discussed By taking careful of all the issues discussed

above, the network operator will be able to above, the network operator will be able to acieve a significant incrase in earinings. acieve a significant incrase in earinings. Synchronous will help him to reduce Synchronous will help him to reduce network costs (e.g through reduction in network costs (e.g through reduction in equipment), improved network equipment), improved network survivability (e.g through reduction in survivability (e.g through reduction in equipment), improve network survivability equipment), improve network survivability e.g( through the deployment of rings) e.g( through the deployment of rings) reduce operating costs (e.g through the reduce operating costs (e.g through the deployment of more reliable equipment deployment of more reliable equipment and the use of network management ) and and the use of network management ) and increas revenues by offering new services.increas revenues by offering new services.

DEPLOYMENT TRIGGERSDEPLOYMENT TRIGGERS

• Changes to the network are generally made Changes to the network are generally made either to grow its capacity of to mederanise either to grow its capacity of to mederanise it. This secton sets out to examine why it. This secton sets out to examine why such changes to the network might arise, such changes to the network might arise, and how they can be achieved. and how they can be achieved.

• Fig Fig Show a common method of terminating Show a common method of terminating

fiber in an exchange, demultiplexing the fiber in an exchange, demultiplexing the traffic and managing the routing and traffic and managing the routing and grooming function at the DDF.grooming function at the DDF.

GROWTHGROWTH• The need for network growth occurs in response The need for network growth occurs in response

to either geographic movement of end users, to either geographic movement of end users, increase in number of end – users or increased increase in number of end – users or increased banwdth rquirements, particularly form business banwdth rquirements, particularly form business users. Such a requirement can currently lead to a users. Such a requirement can currently lead to a number of problems, such as exhaustion of optical number of problems, such as exhaustion of optical channels on the PDH optical line system, and the channels on the PDH optical line system, and the need to expand the digital distibution frame.need to expand the digital distibution frame.

• Optical fiber channel exhaustion is currently Optical fiber channel exhaustion is currently overcome by deploying a new PDH system in overcome by deploying a new PDH system in parallel to eh old one, and using it to transport parallel to eh old one, and using it to transport new traffic as necessary.new traffic as necessary.

• Expansion of DDF is an unpleasent task involving Expansion of DDF is an unpleasent task involving much manual reconnection activity with its much manual reconnection activity with its possible human error.possible human error.

Modernization Modernization

• The network may need to modernized for The network may need to modernized for a number of reasons. Some of the most a number of reasons. Some of the most common reason in response to demand for common reason in response to demand for increased quality of service, in order to cut increased quality of service, in order to cut operating costs or in order to offer new operating costs or in order to offer new services and hence generate new revenus. services and hence generate new revenus.

• The DDF is likely to be limiting factor in The DDF is likely to be limiting factor in any network modernisation programme. any network modernisation programme. Any changes made in the current network Any changes made in the current network are likely to have limited effects as a result are likely to have limited effects as a result of the inefficiency of the DDF.of the inefficiency of the DDF.

SDH SOLUTION--SDH SOLUTION--

• SDH equipment can be used to overcome the SDH equipment can be used to overcome the limitations outlined above, as shown in fig. limitations outlined above, as shown in fig.

• An SDH multiplexer, with its increased An SDH multiplexer, with its increased capacity, can be deployed in place of its PDH capacity, can be deployed in place of its PDH counterpart. There is no need initially for full counterpart. There is no need initially for full scale repalcement of DDF. By utilizing the scale repalcement of DDF. By utilizing the cross connection functionality embeded in the cross connection functionality embeded in the SDH MUX it is possible to automate the SDH MUX it is possible to automate the mangement of chage in the private curcuits mangement of chage in the private curcuits and leave the fairly stable PSTN circuits on and leave the fairly stable PSTN circuits on the DDF. the DDF.

SDH SOLUTION---SDH SOLUTION---

• The cross connect capability of the SDH The cross connect capability of the SDH MUX has the added benefit of manageing MUX has the added benefit of manageing the routing of thorough traffic, thus further the routing of thorough traffic, thus further offloading the DDF. Over time, as the use of offloading the DDF. Over time, as the use of SDH in this exchange grows, it amy become SDH in this exchange grows, it amy become appropriate to repalce the DDF with a stand appropriate to repalce the DDF with a stand alone SDXC. This economic decision will alone SDXC. This economic decision will occur as more and more traffic moves off occur as more and more traffic moves off the copper cables and on the fiber. the copper cables and on the fiber.

SDH SOLUTION--SDH SOLUTION--

• Thus SDH has provided a number of Thus SDH has provided a number of benefits in this example. These are:benefits in this example. These are:

• 1- Provision for capacity growth.1- Provision for capacity growth.• 2- Automation of the DDF function2- Automation of the DDF function• a- Faster Implementation of changesa- Faster Implementation of changes• b- Improved reliability b- Improved reliability • c- Reduced whole –life cost of ownershipc- Reduced whole –life cost of ownership• 3- Integration of product functions3- Integration of product functions• 4- Ability to support enhanced services.4- Ability to support enhanced services.

SDH SOLUTIONSDH SOLUTION

• It is important to note, however, that It is important to note, however, that no deployment of SDH equpment no deployment of SDH equpment should take place in isolation from a should take place in isolation from a total network plan. Such a plan will total network plan. Such a plan will ensure that any piece of equipment ensure that any piece of equipment deployed will improve monitoring, deployed will improve monitoring, survivability, provisioning, and survivability, provisioning, and control of the complete network.control of the complete network.

Network EvolutionNetwork Evolution• There are several possible deployment methods There are several possible deployment methods

for synchronous equipment whithin hteth inter for synchronous equipment whithin hteth inter office area of a neawork, one of which is the office area of a neawork, one of which is the use of the ring topology. Delployement of use of the ring topology. Delployement of synchronous rings will bring immence synchronous rings will bring immence felexibility and resiliene to the nertwork.felexibility and resiliene to the nertwork.

• The junction ara includes a number parucular The junction ara includes a number parucular applications which can utilize rings of applications which can utilize rings of synchronous mulitplexers. One example is in synchronous mulitplexers. One example is in the area of restructing local exchanges, to the area of restructing local exchanges, to improve fiber utilisation and reduce operating improve fiber utilisation and reduce operating and equipment costs and equipment costs

Network Evolution---Network Evolution---• Most European networks are Most European networks are

characterised by highly interconnected characterised by highly interconnected mocal exchanges, which are in turn mocal exchanges, which are in turn connected to main local area exchanges connected to main local area exchanges for access to higher levels of the for access to higher levels of the transmission hierarchy as shown in fig.transmission hierarchy as shown in fig.

• Although maintaining a high availablitiy, Although maintaining a high availablitiy, this method of traffic collection is high in this method of traffic collection is high in equipment caost and somewhat watesful equipment caost and somewhat watesful of fiber.of fiber.

Network Evolution ----Network Evolution ----• In an attempt to reduof thece costs, some In an attempt to reduof thece costs, some

operators have proposed the use of small operators have proposed the use of small remote units to concentrate PSTN traffic. These remote units to concentrate PSTN traffic. These are connected to higher levels of the are connected to higher levels of the transmission hierarchy via main local exchange. transmission hierarchy via main local exchange. The transport of the traffic from these remotes The transport of the traffic from these remotes to themain local exchange provides an ideal to themain local exchange provides an ideal opportunity for the deployment of sychrnous opportunity for the deployment of sychrnous systems to reduce operating costs. systems to reduce operating costs.

• Fig show how the remotes would be connected Fig show how the remotes would be connected to the main local exchange using sycnronous to the main local exchange using sycnronous systems to reduce opertating cost. systems to reduce opertating cost.

Network Evolution ---Network Evolution ---• Fig shows how the remotes would be connected Fig shows how the remotes would be connected

to the main local exchange via using to the main local exchange via using synchronous transmission equipment. The synchronous transmission equipment. The equipment may be deployed either in a equipment may be deployed either in a flattened ring or in a true physical ring. Such an flattened ring or in a true physical ring. Such an STM-1 Ring may have several remote STM-1 Ring may have several remote connected onto it, with each terminating a connected onto it, with each terminating a mixture of private circuit (PC) traffic and PSTN mixture of private circuit (PC) traffic and PSTN traffic, as shown in fig.traffic, as shown in fig.

• Protection would be provided by routing the Protection would be provided by routing the high availability private circuit traffic may either high availability private circuit traffic may either be treated similarly, or could be split in some be treated similarly, or could be split in some ratio for diverse routing to maintain traffic in ratio for diverse routing to maintain traffic in the event of a fiber break.the event of a fiber break.

Network Evolution---Network Evolution---• Consider the particular example shown in Consider the particular example shown in

fig with an STM-1 ring connecting five fig with an STM-1 ring connecting five remote to a main local exchange.remote to a main local exchange.

• A typical route may be capable of A typical route may be capable of supporting up to 16x2 Mbits/s of traffic, supporting up to 16x2 Mbits/s of traffic, although in practice it may only terminate although in practice it may only terminate around half of this. For the purpose of around half of this. For the purpose of discussion consider a network in which discussion consider a network in which traffic will comprise both PSTN and traffic will comprise both PSTN and private circuit (PC) traffic, with around 80-private circuit (PC) traffic, with around 80-90% of this being PSTN.90% of this being PSTN.

Network Evolution---Network Evolution---

• Assuming that two of the remotes Assuming that two of the remotes connect eight channels of PSTN with connect eight channels of PSTN with two 2Mbps PCs connected directly two 2Mbps PCs connected directly onto SDH MUX, and the remaining onto SDH MUX, and the remaining three remote carry sixteen channels three remote carry sixteen channels of PSTN and four PCs the traffic on of PSTN and four PCs the traffic on the ring is: the ring is:

Network Evolution---Network Evolution---

• 2 remotes with 8x2Mbits/s PSTN +2X2Mbits/s 2 remotes with 8x2Mbits/s PSTN +2X2Mbits/s PCs=PCs=

• = 8 channels (half routed clockwise and half = 8 channels (half routed clockwise and half routed anti-clockwise) + 2 channels (routed routed anti-clockwise) + 2 channels (routed both ways)both ways)

• = 8 + (2x2)= 8 + (2x2)

• = 12 channels (from each of the 2 remotes)= 12 channels (from each of the 2 remotes)

• = 24 channels on ring---------------------------------A= 24 channels on ring---------------------------------A

Network Evolution ----Network Evolution ----

• 3 remote with 16x2Mbit/s PSTN + 4X2Mbits/s PCs 3 remote with 16x2Mbit/s PSTN + 4X2Mbits/s PCs = =

• = 16 channels (half routed clockwise, half anti = 16 channels (half routed clockwise, half anti clockwise + 4 channels (routed both ways)clockwise + 4 channels (routed both ways)

• = 16 + (4x2)= 16 + (4x2)

• = 24 channels (from each of the 3 remotes)= 24 channels (from each of the 3 remotes)

• = 72 channels on ring---------------------------------B= 72 channels on ring---------------------------------B

• A+B = 96 (TOTAL NUMBER OF CHANNELS ON A+B = 96 (TOTAL NUMBER OF CHANNELS ON RING)RING)

Network EvolutionNetwork Evolution

• Since the taotal ring capacitynis 126 channels Since the taotal ring capacitynis 126 channels this givces a fill factor on the ring of 96/ 126 this givces a fill factor on the ring of 96/ 126 = 75%. This figure follows aroung 25% of the = 75%. This figure follows aroung 25% of the ring capacity for expansion, before the ring ring capacity for expansion, before the ring would bneed upgardation in its capacity i.e to would bneed upgardation in its capacity i.e to STM-4. It must be remembered that provision STM-4. It must be remembered that provision must be mad4e at the tring head for all must be mad4e at the tring head for all channls requireing access to the main local channls requireing access to the main local exchange. In many instances this will involves exchange. In many instances this will involves use of multiple muxs at the ring head.use of multiple muxs at the ring head.

Network EvolutionNetwork Evolution• Bt taking advantage of the embedded cross Bt taking advantage of the embedded cross

connect functinality in the ring head mux, it connect functinality in the ring head mux, it is possible to goon the 2 M bits/s channels, is possible to goon the 2 M bits/s channels, separating PSTN traffic from other separating PSTN traffic from other transmission based sevices ans in figure transmission based sevices ans in figure 5.6 A furhter consequence of this is that 5.6 A furhter consequence of this is that the number of main local exchange sites the number of main local exchange sites may be reudces and they may be relocated may be reudces and they may be relocated at certral sites to simplify adminitration. at certral sites to simplify adminitration. This can be achieved with syschronous This can be achieved with syschronous links form the ring head to the exchange at links form the ring head to the exchange at either the STM -1 or STM-4 level.either the STM -1 or STM-4 level.

Network EvolutionNetwork Evolution• Further links from the ring head would provide Further links from the ring head would provide

access to the higher level of the transmission access to the higher level of the transmission network.network.

• At this stage, the network comprises a number of At this stage, the network comprises a number of isolated areas of synchronous transmission isolated areas of synchronous transmission equipment, which may be considered as islands. equipment, which may be considered as islands. The next stage of development will take one of the The next stage of development will take one of the two paths. The network operators may choose to two paths. The network operators may choose to ocntinue this staratefgy u ntill islands grow to the ocntinue this staratefgy u ntill islands grow to the extent a which they begin tjo merge. extent a which they begin tjo merge.

• The alternative is to provide links between the The alternative is to provide links between the islands using higher rate synchronous systems, islands using higher rate synchronous systems, hence allowing the befefits of the complete hence allowing the befefits of the complete sysnchronous network to be realised at an earlier sysnchronous network to be realised at an earlier stage.stage.

Managed Services NetworkManaged Services Network

• Analysis of the continued growth in Analysis of the continued growth in communications traffic througout communications traffic througout Europe shows that the largest areas of Europe shows that the largest areas of expansion are due to non PSTN traffic. expansion are due to non PSTN traffic. In order to maintain the migration to a In order to maintain the migration to a Managed Transmission Network, Managed Transmission Network, supporting new services efficiently, supporting new services efficiently, there is a need for greater control over there is a need for greater control over the transmission network.the transmission network.


• To achive this control requires a level of To achive this control requires a level of fexibility within both trunk and junction fexibility within both trunk and junction network. This flexibility can be provided by network. This flexibility can be provided by the use of distributed bandwidth the use of distributed bandwidth management techniques, to allow for management techniques, to allow for effective conrol of the network capacity. By effective conrol of the network capacity. By distributing cross connect functionality distributing cross connect functionality througout the network, and using flexible througout the network, and using flexible synchronous ring architectures, new services synchronous ring architectures, new services can be made available at a relatively low can be made available at a relatively low incremental cost to the network operator. incremental cost to the network operator.


• An intergrated synchronus network An intergrated synchronus network allows the end user a range of allows the end user a range of interfaces, which can accommodate the interfaces, which can accommodate the types of traffic mentioned above within types of traffic mentioned above within the SDH signal. Thus a synchronous the SDH signal. Thus a synchronous network could act as transpoer network could act as transpoer tnetwork for a wide ranfg eof secices as tnetwork for a wide ranfg eof secices as shown in figure 5.7 Thses may include shown in figure 5.7 Thses may include any of the follwingany of the follwing

Managed Services NetworkManaged Services Network• ISDN, PSTN,Private Circuits, PSS Telex, Fax , ISDN, PSTN,Private Circuits, PSS Telex, Fax ,

X-400, Cable Tv, Video Phone, computer X-400, Cable Tv, Video Phone, computer links LANs, VPN, Cellular and ATM and links LANs, VPN, Cellular and ATM and BISDNBISDN

• The requirement of such sercice and in The requirement of such sercice and in parutcular MANs, LANs, and other computer parutcular MANs, LANs, and other computer oriented services, raise an issue which oriented services, raise an issue which relates to the sychronous signal structure relates to the sychronous signal structure itself.itself.

• In order to serve the requirements of these In order to serve the requirements of these services it is necessary that the SDH services it is necessary that the SDH improves upon the granularity of secices improves upon the granularity of secices rates availble inder the existing PDH.rates availble inder the existing PDH.


• A typical example would be customer A typical example would be customer requriement for a 10Mbps data pipe. requriement for a 10Mbps data pipe. The only way inwhainc hisn cluld be The only way inwhainc hisn cluld be supported by existing transmission supported by existing transmission equimpemnt would be cia the use of a equimpemnt would be cia the use of a 34 Mbps pont to point systems with 34 Mbps pont to point systems with terminal equimpmnent providing a bit terminal equimpmnent providing a bit stuffing operation to pack out the spare stuffing operation to pack out the spare 24 Mbps of capacity. This would of 24 Mbps of capacity. This would of course be very efficient.course be very efficient.

Managed Services NetworkManaged Services Network• The way in which the SDH provides a higher granulariy The way in which the SDH provides a higher granulariy

to transmission rates is cia the use of contatenated” to transmission rates is cia the use of contatenated” TUs. Concatenated involves the association of a TUs. Concatenated involves the association of a numbner of TU s within ones STM-1 singals in order to numbner of TU s within ones STM-1 singals in order to offer a rate that is a muulple of the TU signal. The way offer a rate that is a muulple of the TU signal. The way in which this is done will not be descirberd in deatail. in which this is done will not be descirberd in deatail. However deraisn of the first level of contenation of can However deraisn of the first level of contenation of can be found in G709. This describe the method for be found in G709. This describe the method for conruguous contatenation of TU-2 s, which allow conruguous contatenation of TU-2 s, which allow transmission rates given by transmission rates given by

• MXTU-2 capacity = MX6312kbits/s ( M= 1 to 21)MXTU-2 capacity = MX6312kbits/s ( M= 1 to 21)• Thus the 10 Mbps interconnect requiremetn above Thus the 10 Mbps interconnect requiremetn above

could be satisfied by the use of two TU-2 concatenated. could be satisfied by the use of two TU-2 concatenated. This would be reffeered to as a TU-2 mc (with a This would be reffeered to as a TU-2 mc (with a capacity of 13696 kbps)capacity of 13696 kbps)

International Services International Services NetworkNetwork

• An evolving Managed Transmission Network An evolving Managed Transmission Network (MTN) must be based upoi identifiable cost (MTN) must be based upoi identifiable cost befifits to the network operator, and/or the befifits to the network operator, and/or the possibility of increased revenues. The drive possibility of increased revenues. The drive for the introduction of an international for the introduction of an international service network is generated by the need to service network is generated by the need to provide business users with increasing provide business users with increasing amounts of capacity over leased digital amounts of capacity over leased digital circuits, across international boundaries.circuits, across international boundaries.

International Services International Services Network Network • In the UK, both the areas of leased In the UK, both the areas of leased

narrowbnand (Kilostream) and 2 Mbits/s narrowbnand (Kilostream) and 2 Mbits/s (Mega stream) services have seen a rapid (Mega stream) services have seen a rapid take up (The forecasts for growth in take up (The forecasts for growth in Megastream traffic are now estimated at Megastream traffic are now estimated at 50% per annum. With the introduction of 50% per annum. With the introduction of digital PBXs and the networking of digital PBXs and the networking of compituers throughout Euporpe, a need can compituers throughout Euporpe, a need can be identified for Nx2 Mbits/s services can be identified for Nx2 Mbits/s services can not be supported at all on existing not be supported at all on existing plesiochronous equipment.plesiochronous equipment.

International Services International Services Network Network

• As demand increases for these services to be As demand increases for these services to be provided on a PAN European for these services provided on a PAN European for these services to be provided on PAN European basis, work in to be provided on PAN European basis, work in taking place on the concept of a Pan European taking place on the concept of a Pan European Wideband Leased Line Network (WBLLN). It is Wideband Leased Line Network (WBLLN). It is likely that such a network will utilize the likely that such a network will utilize the integration of managed national networks integration of managed national networks based upon The SDH. Only the SDH offers based upon The SDH. Only the SDH offers within realistic timescales. More importantly it within realistic timescales. More importantly it is only via the provision of NX2 Mbps on an is only via the provision of NX2 Mbps on an international basis that moves can be made international basis that moves can be made towards an International Broadband towards an International Broadband Communication Network, IBCN.Communication Network, IBCN.

International Services International Services NetworkNetwork• In physical term the network will appear in In physical term the network will appear in

the form shown in figure 5.8. The Services the form shown in figure 5.8. The Services Access Point (SAP) will be located near or Access Point (SAP) will be located near or possibly on the customer’s premises, whilst possibly on the customer’s premises, whilst the services Access Node will provide the 1.5 the services Access Node will provide the 1.5 Mbits/s , 2 Mbps and Nx 2 Mbps cross connect Mbits/s , 2 Mbps and Nx 2 Mbps cross connect facilities for grooming to the MN layer. An facilities for grooming to the MN layer. An overlay of high capacity synchronous links overlay of high capacity synchronous links would effectively be formed, to interconnect would effectively be formed, to interconnect the international nodes.the international nodes.

International Services International Services NetworkNetwork

• With regards to management, the network With regards to management, the network Level Control function shown in figure 5.8 Level Control function shown in figure 5.8 may be centralised or distributed. It would may be centralised or distributed. It would control the elements of the transmission control the elements of the transmission network to set up paths. The service network to set up paths. The service management function engages the management function engages the resources of this MTN to provide, reallocate resources of this MTN to provide, reallocate and charge for services to the customer. The and charge for services to the customer. The setting up of the paths across international setting up of the paths across international boundaries will involve peer to peer boundaries will involve peer to peer negotiation between Services Managers negotiation between Services Managers according to agreed interworking standards.according to agreed interworking standards.

Network ManagementNetwork Management

• The topic of network management is The topic of network management is a complex one and frequently means a complex one and frequently means different things to different people. It different things to different people. It is not the ain of this presentation to is not the ain of this presentation to delve into Network Management to delve into Network Management to any great depth. However with the any great depth. However with the introduction of the SDH, the introduction of the SDH, the management of tranmsision network management of tranmsision network may be viewed In different context. may be viewed In different context.

NMNM

• With the emergence of the ISO OSI With the emergence of the ISO OSI seven layer reference model, as a basis seven layer reference model, as a basis for open standards, the opportunity for open standards, the opportunity was seen to bring about was seen to bring about interoperability in the management of interoperability in the management of transmission networks. This transmission networks. This opportunity was not missed in the opportunity was not missed in the definition of the SDH.definition of the SDH.

• The SDH provide a method and format The SDH provide a method and format of transmission designed for Network of transmission designed for Network Management.Management.

NMNM

• This section will begin by describing This section will begin by describing the provions for Transmission the provions for Transmission Management, made within the SDH Management, made within the SDH Signal Structure. This will be followed Signal Structure. This will be followed by a number of general concept by a number of general concept refardng the Mangement Hierarchy and refardng the Mangement Hierarchy and Management functionality. Finally the Management functionality. Finally the topic of open Network Management topic of open Network Management Platform will be briefly be covered.Platform will be briefly be covered.

The Physical Management The Physical Management Path.Path.

• With reference to OSI 7-Layer reference model, With reference to OSI 7-Layer reference model, layer 1 of this model requires the difinition of layer 1 of this model requires the difinition of Physical path for commnications.Physical path for commnications.

• Within existing plesiochronous networks, no Within existing plesiochronous networks, no provisions was made for a standard provisions was made for a standard management path within ITU-T management path within ITU-T recommendations. To overcome the lack of a recommendations. To overcome the lack of a management channle, many manufacturers management channle, many manufacturers developed propreitary systems, based on either developed propreitary systems, based on either the use of spare bits within the signal frmae or the use of spare bits within the signal frmae or vial line coding methods similar to those used vial line coding methods similar to those used in submarine systems.in submarine systems.


• Despite the restrictions on transmission rates, Despite the restrictions on transmission rates, some of the methods employed are capable of some of the methods employed are capable of superviosion and monitoring of equipment and to superviosion and monitoring of equipment and to a limited extent even remote configuration. The a limited extent even remote configuration. The major drawbacks with these systems revovle major drawbacks with these systems revovle around the fact that management is restrictred to around the fact that management is restrictred to a channle which can only be accessed at a a channle which can only be accessed at a specifir transmission rate e.g. 2 Mbits/s , 8 Mbits/s specifir transmission rate e.g. 2 Mbits/s , 8 Mbits/s , 34 Mbtis/s, hence requireing mutiplexing to , 34 Mbtis/s, hence requireing mutiplexing to access it. This restiction linits management to a access it. This restiction linits management to a section by section facility. More importantly, it is section by section facility. More importantly, it is possible for inteworking to exist between diffent possible for inteworking to exist between diffent systems. It is quire probable that one systems. It is quire probable that one manufacturer’s equipment will not even support a manufacturer’s equipment will not even support a management channle between two pieces of management channle between two pieces of equipment for a third party.equipment for a third party.


• With the introduction of a new method of With the introduction of a new method of transmission, the SDH, the opportunity was taken transmission, the SDH, the opportunity was taken to implement tohe ideals embodied in the OSI 7 to implement tohe ideals embodied in the OSI 7 layer referenc emodel to difine a management layer referenc emodel to difine a management channel. This began with the definition of ovehead channel. This began with the definition of ovehead capacity in the STM-1 frame, thus offering a capacity in the STM-1 frame, thus offering a difined management channle of section by section difined management channle of section by section communication. This was extended further to communication. This was extended further to define overheads at the AU level and the TU level define overheads at the AU level and the TU level thus providing management capacity over the thus providing management capacity over the core of the transmission network and slaos a path core of the transmission network and slaos a path management channel associtated with a path management channel associtated with a path extending from end to end across an entire extending from end to end across an entire network. This is bes t shown by studying Fig 6.1network. This is bes t shown by studying Fig 6.1


• It is this ability to provide path amangement to the It is this ability to provide path amangement to the VC-1 (2 Mbits/s) level which highlights a significant VC-1 (2 Mbits/s) level which highlights a significant advance in telecommunication management with advance in telecommunication management with the infroduction of the SDH. However, the move the infroduction of the SDH. However, the move towards management standards did not stop at towards management standards did not stop at this point. ITU-T recommendations G.783 and this point. ITU-T recommendations G.783 and G.784 go on to propose how the management G.784 go on to propose how the management channels should be used; referred to as the Data channels should be used; referred to as the Data Communication Channel (DCC) of sometimes the Communication Channel (DCC) of sometimes the Embedded Communication Channel (ECC) and Embedded Communication Channel (ECC) and further propose the protocols which should be further propose the protocols which should be employed for the remaining 6 layers of the OSI employed for the remaining 6 layers of the OSI model.model.


• In these clear definitions and in the In these clear definitions and in the continuing work of the SDH study groups, continuing work of the SDH study groups, the first major steps have been taken the first major steps have been taken towards the implementation of Open towards the implementation of Open Network Management System in the Network Management System in the Telecommunication Industry.Telecommunication Industry.

Management Hierarchy Management Hierarchy

• Fig 6.2 shows a simplified model of the Fig 6.2 shows a simplified model of the Network Management Hierarchy. The Network Management Hierarchy. The definition of distinct levels may vary due to definition of distinct levels may vary due to system size and the management strategy, system size and the management strategy, however the principal structure remains the however the principal structure remains the same. The following section describe the same. The following section describe the Network Control Layer , the element Network Control Layer , the element managemetn level of network managemetn level of network management , e.g the Service Management management , e.g the Service Management Layer, are not described.Layer, are not described.

Network Control LayerNetwork Control Layer• At the network Control level the management system is At the network Control level the management system is

required to provide monitoring and control of a required to provide monitoring and control of a complete management domain (e.g a subnetwork or complete management domain (e.g a subnetwork or possibly a complete network.possibly a complete network.

• The management system may also be required to The management system may also be required to perform more analytical processing, such as perform more analytical processing, such as performance monitoring and cost analysis described in performance monitoring and cost analysis described in section 6.3.section 6.3.

• In the early stages of deployment the NCL will be In the early stages of deployment the NCL will be required to communicate with a number of element required to communicate with a number of element manages from a range of manufacturers. These element manages from a range of manufacturers. These element managers may include systems providing supervision of managers may include systems providing supervision of existing plesiochronus equipment via mediation devices. existing plesiochronus equipment via mediation devices. With regards to the degree of funcitonality within the With regards to the degree of funcitonality within the NCL as with the other level of management, this vary. A NCL as with the other level of management, this vary. A comparison is shown in Table 6.1comparison is shown in Table 6.1

ELEMENT MANAGER LAYERELEMENT MANAGER LAYER

• The element manger would provide The element manger would provide many of the facilities descibed within many of the facilities descibed within section 6.3. It would also be section 6.3. It would also be expected to support addditonal expected to support addditonal management packafges to provide management packafges to provide the funcitons of financial, resource the funcitons of financial, resource and maintenance analysis on the and maintenance analysis on the information it collect.information it collect.

ELEMENT MANAGER LAYERELEMENT MANAGER LAYER

• Although the element management may Although the element management may reside within a network element, it is more reside within a network element, it is more likely that it will be a software package likely that it will be a software package implemented on some operating implemented on some operating system/hardware platform. The size of the system/hardware platform. The size of the platform and its capabilities may vary due to platform and its capabilities may vary due to the need for element manager to monitor the need for element manager to monitor and control various sized domains. The and control various sized domains. The management systems must however offer management systems must however offer the capability of migration form smaller to the capability of migration form smaller to larfer systems as a network expands.larfer systems as a network expands.

NETWORK ELEMENTSNETWORK ELEMENTS

• There is a degree of management There is a degree of management which resides within the elements which resides within the elements themselves, and it is feasible that the themselves, and it is feasible that the element manager for a particular element manager for a particular management domin may physically management domin may physically reside within a network element.reside within a network element.

NETWORK ELEMENTNETWORK ELEMENT

• Basic fucntionality witin the element should Basic fucntionality witin the element should include the facilities listed in the subsequent include the facilities listed in the subsequent section 6.3) applied to the single element. In section 6.3) applied to the single element. In some circumstances the decision may be some circumstances the decision may be taken to implement a distributed taken to implement a distributed management system whereby individual management system whereby individual element s perform a high degree of the element s perform a high degree of the functionality described. Such an functionality described. Such an implementation has a number of advantage implementation has a number of advantage with regards to the speed at which the with regards to the speed at which the network as a whole can react to various network as a whole can react to various events, in particular the case of path events, in particular the case of path restoration for protection purposes.restoration for protection purposes.

NETWORK ELEMENTSNETWORK ELEMENTS

• The alternative is an element with a The alternative is an element with a minimum functionality, allowing minimum functionality, allowing management fucntins to be management fucntins to be performed at the Element performed at the Element Mangement Layer. A comparison of Mangement Layer. A comparison of the benefits of each strategy is the benefits of each strategy is shown in table. 6.1shown in table. 6.1

Functionality of Network Functionality of Network Management SystemManagement System

• The classification of network The classification of network management functions is described management functions is described in ISO as below. The functionality of in ISO as below. The functionality of the a management system should the a management system should include these features via the initial include these features via the initial systems with a provision for systems with a provision for additional feature packages or additional feature packages or modules.modules.


• Configuration Management Configuration Management

• Fault ManagementFault Management

• Performance managementPerformance management

• Accounting Management.Accounting Management.


The resource manager is not restricted in its The resource manager is not restricted in its capabilities to the management of SDH capabilities to the management of SDH equipment only. Managed objects defined equipment only. Managed objects defined in line with Open Network Standards could in line with Open Network Standards could extend to include the following items extend to include the following items within its management domain.within its management domain.

1- Network Element1- Network Element2- Test Equipment2- Test Equipment3- Manpower3- Manpower4- Other Management Systems 4- Other Management Systems


Such a management system would be expected not Such a management system would be expected not only to manage synchronous network elements, only to manage synchronous network elements, but also posses the ability to manage additional but also posses the ability to manage additional equipment in the network via direct equipment in the network via direct communication or another management system. communication or another management system. Since many existing management systems are Since many existing management systems are propriety in nature, this infer the use of some propriety in nature, this infer the use of some type of mediation device between the two type of mediation device between the two systems. In addition to the required functionality systems. In addition to the required functionality described above , a management system would described above , a management system would be expexted to offer the ability to operate be expexted to offer the ability to operate enhanced packeages offering features for Traffic enhanced packeages offering features for Traffic Analysis, Maintenance costing,, Failure analysis Analysis, Maintenance costing,, Failure analysis etc. etc.

synchronous digital hierarchy. what is synchronous transmission synchronous transmission has been...

Documents