Introduction to Leased Introduction to Leased LineLine

Covering a detail study of Covering a detail study of types of Leased Lines and types of Leased Lines and

IPLCIPLC

Leased LineLeased Line Definition: Definition: A A leased lineleased line connects two locations connects two locations

for private voice and/or data telecommunication for private voice and/or data telecommunication service. Not a dedicated cable, a leased line is service. Not a dedicated cable, a leased line is actually a reserved circuit between two points. actually a reserved circuit between two points. Leased lines can span short or long distances. They Leased lines can span short or long distances. They maintain a single open circuit at all times, as maintain a single open circuit at all times, as opposed to traditional telephone services that reuse opposed to traditional telephone services that reuse the same lines for many different conversations the same lines for many different conversations through a process called "switching." through a process called "switching."

A A leased lineleased line is a telecommunication path between is a telecommunication path between two points that is available 24 hours a day for use two points that is available 24 hours a day for use by a designated user (Individual or Company). by a designated user (Individual or Company).

A A leased lineleased line can be a physical path owned by the can be a physical path owned by the user or rented from a telephone company user or rented from a telephone company

like BSNL/MTNL/VSNL. like BSNL/MTNL/VSNL.

Types of Leased LineTypes of Leased Line

Conventional Leased Line involving Conventional Leased Line involving the use of P-MUXthe use of P-MUX

Managed Leased Line involving the Managed Leased Line involving the use of V-MUX. (MLLN)use of V-MUX. (MLLN)

MPLS (Multi Protocol Label MPLS (Multi Protocol Label Switching)Switching)

Conventional Leased LineConventional Leased Line

In case of conventional leased circuit, In case of conventional leased circuit, we use P-MUX, a conventional we use P-MUX, a conventional multiplexer. The conventional multiplexer. The conventional multiplexer can give us bandwidth in multiplexer can give us bandwidth in multiple of 64 Kbps. Individually we multiple of 64 Kbps. Individually we can get 64Kbps and 2Mbps, In case a can get 64Kbps and 2Mbps, In case a client wants to go for 128 Kbps he client wants to go for 128 Kbps he has to go for two Modems of 64 Kbps has to go for two Modems of 64 Kbps each.each.

Conventional Leased Line Conventional Leased Line

MODEM MDF COXIAL COXIAL MDF MODEM

----------------LOCAL END A--------------------- ---------------FAR END B---------------

Conventional Leased LineConventional Leased Line A leased line structure is always divided into two segments A leased line structure is always divided into two segments

i.e. End A and End B , End A is our Local end an End B is the i.e. End A and End B , End A is our Local end an End B is the far end , End B can be in same geographical location or far end , End B can be in same geographical location or distant .distant .

Modems are placed at customer premises end A, and a Modems are placed at customer premises end A, and a cable pair is attached to the output of Modems, that cable cable pair is attached to the output of Modems, that cable pair is terminated at nearest pair is terminated at nearest DPDP (Distribution Pole)(Distribution Pole), and , and fromfrom DP DP it is routed to it is routed to MDF (Main Distribution Frame) MDF (Main Distribution Frame) if if the effective distance betweenthe effective distance between end A end A andand end B end B is less is less than 4.0 Km i.e. (Effective driving distance of Modems) the than 4.0 Km i.e. (Effective driving distance of Modems) the circuit is looped from MDF. In case the distance is more circuit is looped from MDF. In case the distance is more than 4.0 Km the circuit is routed to than 4.0 Km the circuit is routed to COXIAL, COXIAL, the end A the end A coaxial connects end B coaxial using an coaxial connects end B coaxial using an OFC (Optical OFC (Optical Fiber Cable). Fiber Cable). Same arrangement of Coaxial and MDF is Same arrangement of Coaxial and MDF is observed at End B. It can be observed from figure observed at End B. It can be observed from figure illustrated above.illustrated above.

Conventional Leased LineConventional Leased Line

Explanation of all terms usedExplanation of all terms used

MODEM:MODEM: It stand for Modulator and Demodulator , the basic It stand for Modulator and Demodulator , the basic concept is to make digital signal from Modem travel onto the concept is to make digital signal from Modem travel onto the cables in Analog format and at far end the analog signal is cables in Analog format and at far end the analog signal is again converted to digital format.again converted to digital format.

MDF:MDF: It stand for Main Distribution Frame, it has a array of It stand for Main Distribution Frame, it has a array of many pairs arranged in a pattern of “ AA-BB-CC” , where AA many pairs arranged in a pattern of “ AA-BB-CC” , where AA is Row , BB is Column and CC is pair identification number, for is Row , BB is Column and CC is pair identification number, for example 36-4-47 indicates 36 Row , 4 Column and 47 Pair.example 36-4-47 indicates 36 Row , 4 Column and 47 Pair.

Coaxial:Coaxial: It is the next hop to the MDF, a coaxial connects It is the next hop to the MDF, a coaxial connects another coaxial (may be at same geographical area or some another coaxial (may be at same geographical area or some distant location) through an OFC (distant location) through an OFC (Optical Fiber CableOptical Fiber Cable). An ). An OFC insures very low signal dissipation during transmission.OFC insures very low signal dissipation during transmission.

Managed Leased Line Managed Leased Line NetworkNetwork

The MLLN is an integrated, fully managed, The MLLN is an integrated, fully managed, multi-service digital network platform multi-service digital network platform through which service provider can offer a through which service provider can offer a wide range of services at an optimal cost to wide range of services at an optimal cost to Business Subscribers. Backed by a flexible Business Subscribers. Backed by a flexible Network Management System with powerful Network Management System with powerful diagnostics and maintenance tools, the diagnostics and maintenance tools, the MLLN can be used to provide high-speed MLLN can be used to provide high-speed leasedleased lines with improved QoS (Quality of lines with improved QoS (Quality of Service), high availability and reliability. The Service), high availability and reliability. The Network Management System also supports Network Management System also supports Service Provisioning, Network Optimization, Service Provisioning, Network Optimization, Planning and Service Monitoring. Planning and Service Monitoring.

Features of MLLNFeatures of MLLN The following are the few features, which are the The following are the few features, which are the

beneficial for the customers. beneficial for the customers. Customers need not to buy 2 pairs of Modems. Customers need not to buy 2 pairs of Modems. Modems will be supplied and maintained by Modems will be supplied and maintained by

Service Provider. Service Provider. 24 Hours performance monitoring of the circuit. 24 Hours performance monitoring of the circuit. Circuit fault reports generated proactively. Circuit fault reports generated proactively. On demand the bandwidth can be increased. On demand the bandwidth can be increased. Low lead-time for new circuit provisioning. Low lead-time for new circuit provisioning. Protection against the failure of the circuit. Protection against the failure of the circuit. Long drive on single pair copper. Long drive on single pair copper. Centrally managed from Network Management Centrally managed from Network Management

System. System.

Advantages of MLNN to Advantages of MLNN to SubscriberSubscriber

Lease Lease LineLine Network is unmanaged. The concept of manageability is Network is unmanaged. The concept of manageability is currently not a novelty, but rather a need. TRAI had currently advised the currently not a novelty, but rather a need. TRAI had currently advised the mandatory need of Service Level agreements (S LAs) for every service mandatory need of Service Level agreements (S LAs) for every service being provided. This SLA today exists only as a matter of dispute between being provided. This SLA today exists only as a matter of dispute between the service provider and the subscriber, which can be ensured only with the service provider and the subscriber, which can be ensured only with statistics on an end-to-end status, this is totally achieved with MLLN. statistics on an end-to-end status, this is totally achieved with MLLN.

Today a degradation / disruption in service is known to the service provider Today a degradation / disruption in service is known to the service provider on a subscriber notification. With the competition of service providers, the on a subscriber notification. With the competition of service providers, the subscriber would definitely choose a provider who could proactively detect subscriber would definitely choose a provider who could proactively detect a fault and take corrective measures. This is totally achievable using MLLN. a fault and take corrective measures. This is totally achievable using MLLN.

In such an above faulty status, MLLN feature of automatic re-routing of In such an above faulty status, MLLN feature of automatic re-routing of traffic ensures both customer satisfaction and also prevent a likely loss of traffic ensures both customer satisfaction and also prevent a likely loss of revenue of BSNL/MTNL. These could be the only measure for ensuring revenue of BSNL/MTNL. These could be the only measure for ensuring Carrier class operation and the uptimes cited in the S LAs. Carrier class operation and the uptimes cited in the S LAs.

With the tomorrow’s network the Customer would be demanding the With the tomorrow’s network the Customer would be demanding the service. Flexibility in the SLA i.e. the negotiable bandwidth during the service. Flexibility in the SLA i.e. the negotiable bandwidth during the different time of the day would be requirement this can only be provisioned different time of the day would be requirement this can only be provisioned through MLLN. Also today’s through MLLN. Also today’s leased lineleased line network being dedicated to fixed network being dedicated to fixed speeds has absolutely zero flexibility, which would be unheard of in the speeds has absolutely zero flexibility, which would be unheard of in the future. future.

TYPICAL STRUCTURE OF TYPICAL STRUCTURE OF MLLN SYSTEM.MLLN SYSTEM.

The MLLN is planned as three-tier structure of consisting of aggregation and connectivity at The MLLN is planned as three-tier structure of consisting of aggregation and connectivity at two different levels: two different levels: A. A. Central NodeCentral Node: It will provide following functionality: : It will provide following functionality: (i) (i) NMS Center. NMS Center. (ii) (ii) Connectivity to second stage nodes. Connectivity to second stage nodes. (iii)(iii)Leased lineLeased line aggregation. aggregation.

B. B. Second stage NodeSecond stage Node: It will be located at major cities of a Telecom Circle, where : It will be located at major cities of a Telecom Circle, where demand for demand for leased lineleased line is high. (Number of such nodes and their capacity is to be is high. (Number of such nodes and their capacity is to be planned by respective circles). planned by respective circles). It will provide following functionality: It will provide following functionality: (i) (i) Connectivity to third stage nodes. Connectivity to third stage nodes. (ii) (ii) Leased lineLeased line aggregation. aggregation.

Third Stage NodeThird Stage Node: It will be located at smaller cities / towns of a Telecom Circle, : It will be located at smaller cities / towns of a Telecom Circle, where demand for where demand for leased lineleased line is lower (near 10). (Number of such nodes and their is lower (near 10). (Number of such nodes and their capacity is to be planned by respective circles). capacity is to be planned by respective circles). It will provide It will provide Leased LineLeased Line aggregation. aggregation.

MLNN RequirementsMLNN RequirementsFunctional RequirementsFunctional Requirements..

The MLLN system is able to provide the following functionality: The MLLN system is able to provide the following functionality: (i) (i) Speedy end-to-end service provisioning. Speedy end-to-end service provisioning. (ii) (ii) Round-the-clock end-to-end performance monitoring. Round-the-clock end-to-end performance monitoring. (iii)(iii)Automated alarm / fault management. Automated alarm / fault management. (iv) (iv) Easy re-routing and configuration. Easy re-routing and configuration. (v) (v) Accounting and Security management. Accounting and Security management. (vi) (vi) On-demand bandwidth availability up to 2 Mbps. On-demand bandwidth availability up to 2 Mbps.

Technical Requirements. Technical Requirements. The various components of the MLLN shall be: The various components of the MLLN shall be: a) a) Network Management System (NMS). Network Management System (NMS). b) b) Digital cross Connect (DXC). Digital cross Connect (DXC). c) c) Versatile Multiplexer (VMUX). Versatile Multiplexer (VMUX). d) d) Network Termination Unit (NTU). Network Termination Unit (NTU).

Features of MLLNFeatures of MLLNNetwork Management SystemNetwork Management System

NMS shall be able to be expanded to manage at least 1000 nodes (VMUX.DXC) and NMS shall be able to be expanded to manage at least 1000 nodes (VMUX.DXC) and 1,00,000 NTUs. 1,00,000 NTUs.

GUI Controlled ConsoleGUI Controlled Console SNMP Support V1 and V2SNMP Support V1 and V2 Configuration and Provision to manage and monitor all aspects and parameters of Configuration and Provision to manage and monitor all aspects and parameters of

the remote elements of the MLLN without the need of local intervention. the remote elements of the MLLN without the need of local intervention. It is possible to manage the entire networks’ faults from any single location. It is possible to manage the entire networks’ faults from any single location. NMS has the capability to configure the bandwidth on demand of any NMS has the capability to configure the bandwidth on demand of any leased lineleased line for for

specified time of the day. This bandwidth on demand is configurable to all possible specified time of the day. This bandwidth on demand is configurable to all possible programmable bandwidths of NTUs. programmable bandwidths of NTUs.

The NMS is capable of placing the Network elements In or Out of service The NMS is capable of placing the Network elements In or Out of service The fault events are logged in a fault log file and are accessible when required The fault events are logged in a fault log file and are accessible when required

through database style facilities for information retrieval. The fault information through database style facilities for information retrieval. The fault information provided contains type of network element, the time at which fault occurred, time provided contains type of network element, the time at which fault occurred, time when it corrected. when it corrected.

In addition to the fault information, it provides a brief explanation of the cause of the In addition to the fault information, it provides a brief explanation of the cause of the fault and fault and

proposed corrective action to be taken to rectify the fault. proposed corrective action to be taken to rectify the fault.

Features of MLLNFeatures of MLLN

Some more feature of MLLN are Some more feature of MLLN are described in white paper:described in white paper:

Fault ManagementFault Management Performance ManagementPerformance Management Route ManagementRoute Management

DIGITAL CROSS CONNECT DIGITAL CROSS CONNECT (DXC or DACC) in MLLN(DXC or DACC) in MLLN

DACC or DXC is a large capacity cross connect device and is DACC or DXC is a large capacity cross connect device and is installed at different main sites for providing VMUX installed at different main sites for providing VMUX connectivity. DACC is made up of Cluster Master control connectivity. DACC is made up of Cluster Master control subrack and slave subracks. Single Subrack (RXS-S) is used subrack and slave subracks. Single Subrack (RXS-S) is used as slave subrack and its units depend on the port capacity as slave subrack and its units depend on the port capacity ordered. ordered.

In addition to multiplexing and demultiplexing the signal, In addition to multiplexing and demultiplexing the signal, the node takes also care of cross-connecting the signal. the node takes also care of cross-connecting the signal. (The signal is first demultiplexed into a lower level after (The signal is first demultiplexed into a lower level after which it is cross-connected and then multiplexed again). A which it is cross-connected and then multiplexed again). A digital cross-connect (DXC) is a device used in transmission digital cross-connect (DXC) is a device used in transmission networks. It separates channels coming from other devices networks. It separates channels coming from other devices and rearranges them into new channels for output. A digital and rearranges them into new channels for output. A digital cross-connection means that the connection is set up and cross-connection means that the connection is set up and released by the network operator, but not through released by the network operator, but not through subscriber , which is the case in switching. subscriber , which is the case in switching.

V-MUXV-MUX

VERSATILE MULTIPLEXER (VMUX) VERSATILE MULTIPLEXER (VMUX) Versatile Multiplexer (VMUS) is a small capacity Versatile Multiplexer (VMUS) is a small capacity

cross connect device and is installed at different cross connect device and is installed at different sites for providing user connectivity. VMUX is made sites for providing user connectivity. VMUX is made up of Basic Node, which is the building block of the up of Basic Node, which is the building block of the MLLN system. The VMUX is provided with two types MLLN system. The VMUX is provided with two types of interfaces to connect STU-160 ( SDSL product of interfaces to connect STU-160 ( SDSL product family used for point- to- point connections) and family used for point- to- point connections) and CTU-S ( HDSL product family modem , with line CTU-S ( HDSL product family modem , with line connection rate up to 4640 Kbit/s ) modems. connection rate up to 4640 Kbit/s ) modems.

There are Four types of VMUXs supplied Viz. VMUX-There are Four types of VMUXs supplied Viz. VMUX-Type I, VMUX-Type-II, VMUX-Type-III/DC operation, Type I, VMUX-Type-II, VMUX-Type-III/DC operation, VMUX-Type-III AC operation. VMUX-Type-III AC operation.

NTU used with MLLNNTU used with MLLN Base band modems (Network Terminating Units = NTUs) are usually customer Base band modems (Network Terminating Units = NTUs) are usually customer

premises equipment (CPE). They are typical “last mile equipment.” premises equipment (CPE). They are typical “last mile equipment.” NTUs can also be used for standalone point-to-point connections without the NMS. NTUs can also be used for standalone point-to-point connections without the NMS. NTUs allow use of the existing telecom copper cables (twisted pair) for digital traffic NTUs allow use of the existing telecom copper cables (twisted pair) for digital traffic

with medium distances (5 km) and high speeds. with medium distances (5 km) and high speeds. NTUs must be capable of being managed from the centralized NMS for the following NTUs must be capable of being managed from the centralized NMS for the following

essential parameters: essential parameters: (i) (i)

Speed Speed (ii) (ii)

LineLine loop testing loop testing (iii)(iii)

Diagnostic Diagnostic

NTU on the DTE side must support the V.35/V.24/V.28/V.36/ V.11/G.703 data NTU on the DTE side must support the V.35/V.24/V.28/V.36/ V.11/G.703 data interfaces. interfaces.

NTU must be functionally compatible for all features with the integrated NTU must be functionally compatible for all features with the integrated LineLine drivers drivers of the VMUX ports. of the VMUX ports.

NTU must perform internal self-tests on power-up and provide a visual indication if an NTU must perform internal self-tests on power-up and provide a visual indication if an internal failure is detected. internal failure is detected.

After power-up, the NTU configurations shall be automatically downloaded from the After power-up, the NTU configurations shall be automatically downloaded from the connected node. connected node.

What is MPLS?What is MPLS?

Stands for Multi Protocol Label SwitchingStands for Multi Protocol Label Switching Multiprotocol Label Switching (MPLS) is a high-performance Multiprotocol Label Switching (MPLS) is a high-performance

method for forwarding packets (frames) through a network. method for forwarding packets (frames) through a network. It enables routers at the edge of a network to apply simple It enables routers at the edge of a network to apply simple labels to packets (frames). ATM switches or existing routers labels to packets (frames). ATM switches or existing routers in the network core can switch packets according to the in the network core can switch packets according to the labels with minimal lookup overhead. labels with minimal lookup overhead.

MPLS integrates the performance and traffic management MPLS integrates the performance and traffic management capabilities of Data Link Layer 2 with the scalability and capabilities of Data Link Layer 2 with the scalability and flexibility of Network Layer 3 routing. It is applicable to flexibility of Network Layer 3 routing. It is applicable to networks using any Layer 2 switching, but has particular networks using any Layer 2 switching, but has particular advantages when applied to ATM networks. It integrates IP advantages when applied to ATM networks. It integrates IP routing with ATM switching to offer scalable IP-over-ATM routing with ATM switching to offer scalable IP-over-ATM networks.networks.

The main conceptThe main concept of MPLS is to include a of MPLS is to include a labellabel on each on each packet.packet.

Data in MPLS LabelData in MPLS Label

Destination Destination Precedence Precedence Virtual Private Network membership Virtual Private Network membership Quality of Service (QoS) information Quality of Service (QoS) information The route for the packet, as chosen The route for the packet, as chosen

by traffic engineering (TE) by traffic engineering (TE)

Process InvolvedProcess Involved With Label Switching the complete analysis of the Layer 3 header With Label Switching the complete analysis of the Layer 3 header

is performed only once: at the edge label switch router (LSR), is performed only once: at the edge label switch router (LSR), which is located at each edge of the network. At this location, the which is located at each edge of the network. At this location, the Layer 3 header is mapped into a fixed-length label, called a label.Layer 3 header is mapped into a fixed-length label, called a label.

At each router across the network, only the label need be At each router across the network, only the label need be examined in the incoming cell or packet in order to send the cell examined in the incoming cell or packet in order to send the cell or packet on its way across the network. At the other end of the or packet on its way across the network. At the other end of the network, an Edge LSR swaps the label out for the appropriate network, an Edge LSR swaps the label out for the appropriate header data linked to that label.header data linked to that label.

A key result of this arrangement is that forwarding decisions A key result of this arrangement is that forwarding decisions based on some or all of these different sources of information can based on some or all of these different sources of information can be achieved by means of a single table lookup from a fixed-length be achieved by means of a single table lookup from a fixed-length label. For this reason, label switching makes it feasible for routers label. For this reason, label switching makes it feasible for routers and switches to make forwarding decisions based upon multiple and switches to make forwarding decisions based upon multiple destination addresses. destination addresses.

Label switching integrates switching and routing functions, Label switching integrates switching and routing functions, combining the reachability information provided by the router combining the reachability information provided by the router function, plus the traffic engineering benefits achieved by the function, plus the traffic engineering benefits achieved by the optimizing capabilities of switches. These benefits are described in optimizing capabilities of switches. These benefits are described in more detail in the next section.more detail in the next section.

Benefits of MPLSBenefits of MPLS Reduces Control Load on Network Cores; More RobustReduces Control Load on Network Cores; More Robust With MPLS, transit traffic entering at the edge of the provider's autonomous With MPLS, transit traffic entering at the edge of the provider's autonomous

system can be given labels that are associated with specific exit points. As a system can be given labels that are associated with specific exit points. As a result, internal transit routers and switches need only process the connectivity result, internal transit routers and switches need only process the connectivity with the provider's edge routers, shielding the core devices from the with the provider's edge routers, shielding the core devices from the overwhelming route signaling volume exchanged in the Internet. This overwhelming route signaling volume exchanged in the Internet. This separation of interior routes from full Internet routes also provides better fault separation of interior routes from full Internet routes also provides better fault isolation and improved stability. isolation and improved stability.

Traffic Engineering CapabilitiesTraffic Engineering Capabilities IntegrationIntegrationTraffic engineering enables us to shift the traffic load from over utilized portions Traffic engineering enables us to shift the traffic load from over utilized portions to underutilized portions of the network, according to traffic destination, traffic to underutilized portions of the network, according to traffic destination, traffic type, traffic load and time of day. type, traffic load and time of day.

Higher ReliabilityHigher Reliability Traditional IP over ATM involves setting up a mesh of Permanent Traditional IP over ATM involves setting up a mesh of Permanent

Virtual Circuits (PVCs) between routers around an ATM cloud, and the Virtual Circuits (PVCs) between routers around an ATM cloud, and the Next Hop Resolution Protocol (NHRP) achieves a similar result with Next Hop Resolution Protocol (NHRP) achieves a similar result with switched virtual circuits (SVCs). But there are a number of problems switched virtual circuits (SVCs). But there are a number of problems with this approach, all arising from the method that the PVC links with this approach, all arising from the method that the PVC links between routers are overlaid on the ATM network. This makes the ATM between routers are overlaid on the ATM network. This makes the ATM network structure invisible to the routers. A single ATM link failure network structure invisible to the routers. A single ATM link failure could make several router-to-router links fail, creating problems with could make several router-to-router links fail, creating problems with large amounts of routing update traffic and subsequent processing. large amounts of routing update traffic and subsequent processing.

Benefits of MPLSBenefits of MPLS Better EfficiencyBetter Efficiency

Without extensive tuning of routing weights, all PVCs are seen by Without extensive tuning of routing weights, all PVCs are seen by IP routing as single-hop paths with the same cost. This might lead IP routing as single-hop paths with the same cost. This might lead to inefficient routing in the ATM network. to inefficient routing in the ATM network.

VPN Scalability and ManageabilityVPN Scalability and ManageabilityMPLS can make IP Virtual Private Network services highly scalable MPLS can make IP Virtual Private Network services highly scalable and very easy to manage. Virtual Private Network services are an and very easy to manage. Virtual Private Network services are an important service for providing enterprises with private IP important service for providing enterprises with private IP networks within their infrastructures. When an ISP offers a VPN networks within their infrastructures. When an ISP offers a VPN service, the carrier supports many individual VPNs on a single service, the carrier supports many individual VPNs on a single infrastructure. With an MPLS backbone, VPN information can be infrastructure. With an MPLS backbone, VPN information can be processed only at the ingress and exit points, with MPLS labels processed only at the ingress and exit points, with MPLS labels carrying packets across a shared backbone to their correct exit carrying packets across a shared backbone to their correct exit point. In addition to MPLS, the Multiprotocol Border Gateway point. In addition to MPLS, the Multiprotocol Border Gateway Protocol (BGP) is used to deal with information about the VPNs. Protocol (BGP) is used to deal with information about the VPNs. The combination of MPLS and Multiprotocol BGP makes MPLS-The combination of MPLS and Multiprotocol BGP makes MPLS-based VPN services easier to manage, with straightforward based VPN services easier to manage, with straightforward operations to manage VPN sites and VPN membership. It also operations to manage VPN sites and VPN membership. It also makes MPLS-based VPN services extremely scalable, with one makes MPLS-based VPN services extremely scalable, with one network able to support hundreds of thousands of VPNs. network able to support hundreds of thousands of VPNs.

MPLS Network StructureMPLS Network Structure The basic elements in a label switching network are:The basic elements in a label switching network are:

Edge Label Switch RoutersEdge Label Switch RoutersEdge Label Switch Routers are located at the boundaries of a Edge Label Switch Routers are located at the boundaries of a network, performing value-added network layer services and network, performing value-added network layer services and applying labels to packets. These devices can be either routers, applying labels to packets. These devices can be either routers, such as the Cisco  7500, or multilayer LAN switches, such as the such as the Cisco  7500, or multilayer LAN switches, such as the Cisco Catalyst 5000. Cisco Catalyst 5000.

ATM Label Switch RoutersATM Label Switch RoutersThese devices switch labeled packets or cells based on the labels. These devices switch labeled packets or cells based on the labels. ATM Label Switch Routers may also support full Layer 3 routing or ATM Label Switch Routers may also support full Layer 3 routing or Layer 2 switching in addition to label switching. Examples of ATM Layer 2 switching in addition to label switching. Examples of ATM LSRs include the Cisco 6400, the Cisco 8540 Multiservice Switch LSRs include the Cisco 6400, the Cisco 8540 Multiservice Switch Router, Cisco BPX 8650, and Cisco 7500. Router, Cisco BPX 8650, and Cisco 7500.

Label Distribution ProtocolLabel Distribution ProtocolThe Label Distribution Protocol (LDP) is used in conjunction with The Label Distribution Protocol (LDP) is used in conjunction with standard network layer routing protocols to distribute label standard network layer routing protocols to distribute label information between devices in a label switched network. information between devices in a label switched network.

MPLS StructureMPLS Structure

MPLS VPN FeatureMPLS VPN Feature Centralized ServiceCentralized Service ScalabilityScalability SecuritySecurity MPLS Switching VPNs offer the same level of security MPLS Switching VPNs offer the same level of security

as connection-oriented VPNs. Packets from one VPN as connection-oriented VPNs. Packets from one VPN will not inadvertently go to another VPN. Security is will not inadvertently go to another VPN. Security is provided at the edge and core of a provider provided at the edge and core of a provider network: at the edge, security ensures that packets network: at the edge, security ensures that packets received from a customer are placed on the correct received from a customer are placed on the correct VPN at the backbone, VPN traffic is kept separate VPN at the backbone, VPN traffic is kept separate Malicious spoofing of a provider edge (PE) router is Malicious spoofing of a provider edge (PE) router is nearly impossible because the packets received nearly impossible because the packets received from customers are IP packets. These IP packets from customers are IP packets. These IP packets must be received on a particular interface or sub must be received on a particular interface or sub interface to be uniquely identified with a VPN label.interface to be uniquely identified with a VPN label.

Introduction to IPLCIntroduction to IPLC

An IPLC (international private leased An IPLC (international private leased circuit) is a point-to-point private line circuit) is a point-to-point private line used by an organization to used by an organization to communicate between offices that communicate between offices that are geographically dispersed are geographically dispersed throughout the world. throughout the world.

An IPLC can be used for Internet An IPLC can be used for Internet access, business data exchange, access, business data exchange, video conferencing, and any other video conferencing, and any other form of telecommunication. form of telecommunication.

What is OSS in IPLC?What is OSS in IPLC? OSS stands for One Stop Shopping, a concept developed to OSS stands for One Stop Shopping, a concept developed to

facilitate the provision of IPLCs at the most convenient and facilitate the provision of IPLCs at the most convenient and efficient way desired by the Industrial, Commercial and efficient way desired by the Industrial, Commercial and Governmental organizations throughout the world.Governmental organizations throughout the world.

To simplify IPLC ordering and billing, a concept called One To simplify IPLC ordering and billing, a concept called One Stop Shopping (OSS) was developed. OSS allows an Stop Shopping (OSS) was developed. OSS allows an organization to place a single order with a single carrier for organization to place a single order with a single carrier for two private leased circuits for two offices in two different two private leased circuits for two offices in two different countries. In the past, an organization had to contact each countries. In the past, an organization had to contact each carrier in each country to order the two circuits, which carrier in each country to order the two circuits, which included two separate invoices. OSS consolidates the billing included two separate invoices. OSS consolidates the billing for both circuits into a single invoice, handles all currency for both circuits into a single invoice, handles all currency issues, and allows the organization to report all problems issues, and allows the organization to report all problems from either circuit to one carrier. from either circuit to one carrier.

Benefits of OSSBenefits of OSS

Single-End OrderingSingle-End Ordering: allows the : allows the customer to order both halves of a circuit customer to order both halves of a circuit through a single carrier. through a single carrier.

Single-End BillingSingle-End Billing: consolidates the : consolidates the billing for both half circuits into a single billing for both half circuits into a single invoice. invoice.

Single-End Fault ReportingSingle-End Fault Reporting: allows the : allows the customer to report faults resulting from customer to report faults resulting from either half circuit to the Co-ordinating either half circuit to the Co-ordinating Carrier Carrier

Benefits of IPLC Benefits of IPLC

Secure, Dedicated NetworkSecure, Dedicated Network Widest Range of ApplicationsWidest Range of Applications

(Video, Voice, Graphics etc.)(Video, Voice, Graphics etc.)Reliability Reliability

Introduction to ISDNIntroduction to ISDN How Plain Old Telephone System OperatesHow Plain Old Telephone System OperatesBefore getting into what ISDN is, let’s take a look at how our traditionalBefore getting into what ISDN is, let’s take a look at how our traditionaltelephone service, known as Plain Old Telephone Service (POTS), operates.telephone service, known as Plain Old Telephone Service (POTS), operates.Typically you pick up the telephone receiver, enter the number, and the partyTypically you pick up the telephone receiver, enter the number, and the partyanswers at the other end. Your voice—which is an analog wave—is convertedanswers at the other end. Your voice—which is an analog wave—is convertedinto a digital signal through a process called Pulse Code Modulationinto a digital signal through a process called Pulse Code Modulation(PCM). PCM samples your voice 8000 times a second and converts the audio(PCM). PCM samples your voice 8000 times a second and converts the audiolevel into an 8-bit value. This 64Kbps channel, or DSO (Data Source Object),level into an 8-bit value. This 64Kbps channel, or DSO (Data Source Object),is multiplexed with 23 other channels to form a T1. If we do the calculations,is multiplexed with 23 other channels to form a T1. If we do the calculations,we’ll notice that a T1 is 1.544MB, and 24 * 64KB is only 1.536MB. Wherewe’ll notice that a T1 is 1.544MB, and 24 * 64KB is only 1.536MB. Whereare the other 8KB? They are used by a single framing bit that is added toare the other 8KB? They are used by a single framing bit that is added toevery 24-channel block. Now we have 1.544MB. However, bit-robbedevery 24-channel block. Now we have 1.544MB. However, bit-robbedsignaling uses the lowest significant bit for signaling, or for indicating thatsignaling uses the lowest significant bit for signaling, or for indicating thatthe line is on or off the hook, leaving a practical channel bandwidth ofthe line is on or off the hook, leaving a practical channel bandwidth of56Kbps. Bit-robbed signaling is also known as inband signaling.56Kbps. Bit-robbed signaling is also known as inband signaling.

Introduction to ISDNIntroduction to ISDN

ISDN Stand for Integrated Services Digital Network.ISDN Stand for Integrated Services Digital Network. The "Integrated" part of ISDN's name refers to the The "Integrated" part of ISDN's name refers to the

combining of voice and data services over the same wires combining of voice and data services over the same wires (so computers can connect directly to the telephone (so computers can connect directly to the telephone network without first converting their signals to an analog network without first converting their signals to an analog audio signal, as modems do). This integration brings with it audio signal, as modems do). This integration brings with it a host of new capabilities combining voice, data, fax, and a host of new capabilities combining voice, data, fax, and sophisticated switching .sophisticated switching .

ISDN provides a raw data rate of 144 Kbps on a single ISDN provides a raw data rate of 144 Kbps on a single telephone company twisted pair. To better suit voice telephone company twisted pair. To better suit voice applications, this 144 Kbps channel is partitioned into sub applications, this 144 Kbps channel is partitioned into sub channels: two 64 Kbps B (for channels: two 64 Kbps B (for bearerbearer) channels and one 16 ) channels and one 16 Kbps D (for Kbps D (for datadata) channel. Each B channel can carry a ) channel. Each B channel can carry a separate telephone call and usually has its own telephone separate telephone call and usually has its own telephone number, called a number, called a Directory Number (DN). Directory Number (DN). You can combine You can combine the two B channels together to form a single 128 Kbps data the two B channels together to form a single 128 Kbps data channel through a process called channel through a process called bondingbonding. The incoming . The incoming twisted pair enters a Telco-provided box called the twisted pair enters a Telco-provided box called the network network terminator terminator (NT1), which breaks the 144 Kbps channel into (NT1), which breaks the 144 Kbps channel into the two B and single D sub channels. the two B and single D sub channels.

ISDN Bandwidth = 2 B +1 D = 144 KbpsISDN Bandwidth = 2 B +1 D = 144 Kbps Where B is Bearer Channel i.e. 64 Kbps and D is Data Where B is Bearer Channel i.e. 64 Kbps and D is Data

Channel i.e. 16 KbpsChannel i.e. 16 Kbps

Typical Setup of ISDNTypical Setup of ISDN

ISDN Reference PointsISDN Reference Points

ISDN TerminologyISDN Terminology Network Termination Type 1 (NT1) is used to convert a four-wire ISDN Network Termination Type 1 (NT1) is used to convert a four-wire ISDN

connection to the two-wire ISDN used by the local loop facility.connection to the two-wire ISDN used by the local loop facility. Terminal Adapter (TA) allows a TE2 (Specialized ISDN terminals are referred Terminal Adapter (TA) allows a TE2 (Specialized ISDN terminals are referred

to as terminal equipment type 1 (TE1). Non-ISDN terminals, such as DTE, that to as terminal equipment type 1 (TE1). Non-ISDN terminals, such as DTE, that predate the ISDN standards are referred to as terminal equipment type 2 predate the ISDN standards are referred to as terminal equipment type 2 (TE2). device to communicate with the Telco's network by providing any (TE2). device to communicate with the Telco's network by providing any necessary protocol and interface conversion. In essence, a TA adapts the necessary protocol and interface conversion. In essence, a TA adapts the unipolar signal coming from non-ISDN device into a bipolar signal to be used unipolar signal coming from non-ISDN device into a bipolar signal to be used by the ISDN network.by the ISDN network.

RR Defines the reference point between non-ISDN equipment and a TA .The R Defines the reference point between non-ISDN equipment and a TA .The R reference point allows a non-ISDN device to appear on the network as an reference point allows a non-ISDN device to appear on the network as an ISDN device.ISDN device.

SS The point between the user terminals and NT2, or in other words, between The point between the user terminals and NT2, or in other words, between a TE1 or a TA and the Network Termination (which is either an NT1 or an a TE1 or a TA and the Network Termination (which is either an NT1 or an NT2).NT2).

TT Defines the reference point between NT1 and NT2 devices. Defines the reference point between NT1 and NT2 devices. S/TS/T interface as the name implies, this combines both the S and the T interface as the name implies, this combines both the S and the T

interfaces. This interface is governed by the ITU (International interfaces. This interface is governed by the ITU (International Telecommunication Union) I.430 standard, which defines the connection as a Telecommunication Union) I.430 standard, which defines the connection as a four-wire connection. The S/T interface is typically an RJ 45, 8-pin cable using four-wire connection. The S/T interface is typically an RJ 45, 8-pin cable using pins 3 and 6 to receive data, and pins 4 and 5 to transmit data.pins 3 and 6 to receive data, and pins 4 and 5 to transmit data.

UU This reference point is also known as a U interface. This is a two-wire This reference point is also known as a U interface. This is a two-wire connection between the NT1 and the telephone company (LE).connection between the NT1 and the telephone company (LE).

Understanding the workingUnderstanding the working The B channels carry customer voice or data signals. The D channel The B channels carry customer voice or data signals. The D channel

carries signals between your ISDN equipment and the phone company's carries signals between your ISDN equipment and the phone company's central office. The two bearer plus one data channel is called the central office. The two bearer plus one data channel is called the Basic Basic Rate Interface Rate Interface (BRI) in Telco lingo, or sometimes just (BRI) in Telco lingo, or sometimes just 2B+D 2B+D for short. for short. We can buy ISDN in bulk: 23 B channels with a single 64 Kbps D We can buy ISDN in bulk: 23 B channels with a single 64 Kbps D channel. This service, called the channel. This service, called the Primary Rate Interface Primary Rate Interface (PRI),(PRI), inherits inherits most of the capabilities and limitations of BRI, so what you learn about most of the capabilities and limitations of BRI, so what you learn about 2B+D applies to PRI's 23B+D service, as well. 2B+D applies to PRI's 23B+D service, as well.

A Single four-wire cable carries the 2B+D channels to another box A Single four-wire cable carries the 2B+D channels to another box called the called the Terminal Adapter Terminal Adapter (TA). Unlike the NT1, which provides only a (TA). Unlike the NT1, which provides only a single function (creating the 2B+D channels), the TA can do many single function (creating the 2B+D channels), the TA can do many things. Its job is to connect any and all of your things. Its job is to connect any and all of your Terminal Equipment Terminal Equipment (TE) (TE) -- computers, fax machines, LANs, or telephone sets -- to one or both of -- computers, fax machines, LANs, or telephone sets -- to one or both of the B channels. In this example, the TA is shown as a separate unit, but the B channels. In this example, the TA is shown as a separate unit, but it could easily be contained within the computer (as an add-in card or it could easily be contained within the computer (as an add-in card or integrated feature) or integrated with the NT1 into a single box as a integrated feature) or integrated with the NT1 into a single box as a modem replacement or stand-alone TCP/IP router. modem replacement or stand-alone TCP/IP router.

The external The external ISDN reference points, ISDN reference points, labeled R, S/T, and U. (Don't strain labeled R, S/T, and U. (Don't strain yourself trying to deduce what R, S, T, and U stand for -- they are yourself trying to deduce what R, S, T, and U stand for -- they are simply consecutive letters of the alphabet, chosen by the ITU -- The simply consecutive letters of the alphabet, chosen by the ITU -- The International Telegraphic Union, a standards-setting body --International Telegraphic Union, a standards-setting body -- as the next as the next available designations from the entire set of ITU standards.) Each available designations from the entire set of ITU standards.) Each interface point requires an electrically different device connection and interface point requires an electrically different device connection and cabling. The U reference point is the incoming unshielded twisted pair cabling. The U reference point is the incoming unshielded twisted pair (UTP); the S/T reference point is a four-wire UTP cable. (UTP); the S/T reference point is a four-wire UTP cable.