Reliable IP Networks for Rail Operators en WhitePaper

S T R A T E G I C W H I T E P A P E R

Railway and metro operators rely heavily on their communications infrastructures to

operate safely and efficiently. These rail operators have traditionally deployed separate

networks supporting different applications using SONET/SDH-based TDM networking

technologies. Alcatel-Lucent delivers a converged IP/MPLS-based communications network

for rail operators using next-generation products and management tools. Alcatel-Lucent

IP/MPLS products support network resiliency, quality of service, virtualization, synchronous

Ethernet, convergence and a management platform that automates and simplifies opera-

tions management. Upgrading to a modern, reliable, and flexible Alcatel-Lucent IP/MPLS

communications network will enable a rail operator to migrate from a SONET/SDH-based

network to a multi-service IP/MPLS network that can support both new IP/Ethernet-based

applications and legacy TDM-based applications, thus reducing both CAPEX and OPEX

while maintaining reliability.

Reliable IP Networks for Rail OperatorsNetwork transformation to IP/MPLS for guaranteed mission-critical communications

Table of contents

1 Introduction

1 Railapplications

2 Data services

3 Voice communications services

3 Video surveillance

3 GSM-R

3 Intranet and Internet access

4 TheAlcatel-LucentIP/MPLSnetwork

5 The network architecture

8 CapitalizingonMPLScapabilities

8 High availability through MPLS

8 Virtualization

8 MPLS traffic engineering

9 Quality of Service

9 Effective management for easier day-to-day operations

10 Support for innovative applications

13 Conclusion

13 Acronyms

Reliable IP Networks for Rail Operators | Strategic White Paper 1

Introduction

Investments in rail infrastructure projects have been fueled by government grants that are dedicated to traffic reduction, public transit initiatives, stimulus, and carbon emissions reductions. Other business initiatives driving investments for the rail sector include increasing security, reducing costs, increasing safety, and managing obsolescence. Modern rail operators, including those operating railway and metro systems, are focusing on these initiatives while balancing the need to increase customer satisfaction. To ensure their ongoing success, many rail operators are making better use of information and com-munications technology (ICT) and capitalizing on technological innovations to reduce costs and increase passenger satisfaction. Another driver closely related to both safety and modernization issues is the requirement to deploy the Global System for Mobile Communications – Railway (GSM-R). All these initiatives are driving the growing demand for a more intelligent communications infra-structure that can support the various applications and greater bandwidth.

A key enabler is a modern, reliable, and flexible communications infrastructure that forms the core network in order to route the monitoring, control and status data effectively, efficiently and on time. Traditionally, rail operators have managed multiple networks supporting different applications. These networks often utilize TDM, ATM and/or frame relay technologies. Now, a growing number of applications are IP/Ethernet-based. Many of these IP applications are much more demanding in terms of bandwidth, availability and responsiveness. This requires many rail operators to consider an evolution of their communications infrastructures that would be very different from their tradi-tional TDM-centric networks.

Alcatel-Lucent has state-of-the-art, highly reliable, IP/MPLS-based communications equipment that can form a converged infrastructure for guaranteed delivery of the various mission-critical and corporate voice, data, and video services critical to a rail operation. This network can help rail operators meet their current requirements, enable the development of new services, and reduce costs. This approach provides rail operators with an effective solution for managing IP video, voice and data applications while continuing to support their legacy systems.

In addition, the Alcatel-Lucent network and service management platform allows rail operators to improve their efficiency by automating and simplifying operations management for communications services, thus reducing the barrier in introducing MPLS-based technologies and services.

Rail applications

A rail operator’s communications infrastructure supports a broad range of applications, including those related to the internal operations of the rail system, and those that support customer-oriented services (see Figure 1).

The rail operator’s applications include:

• Access control

• Alarms

• Cargo tracking

• Corporate LAN

• GSM-R

• Mobile radio

• Passenger information display

• Public address

• Public Internet access

• Signaling

Reliable IP Networks for Rail Operators | Strategic White Paper2

• Telephony

• Ticketing

• Video conference

• Video surveillance

• WLAN

Figure 1. Typical applications supported by a rail operator’s communications infrastructure

Each of these applications has a unique set of requirements in terms of bandwidth, quality of service (QoS), availability, latency, and so on. The ideal communications infrastructure will enable the rail operator to set parameters (for critical, priority and best-effort data, for example) for each service and traffic type (multiples of voice, data, and video) according to operational and business requirements. A communications network supporting low jitter and delay in a one-to-one or one-to-many topology is required to transport all traffic types effectively and reliably in real time.

The following sections provide examples of some of the key service areas (for example, data services, voice communications services, video surveillance, GSM-R, and intranet and Internet access) followed by a clear explanation of how Alcatel-Lucent’s IP/MPLS communications network meets these requirements.

DataservicesSignaling is an important data service, one which needs to be treated as a mission-critical priority, as it is used to convey critical information about the state of the rail line, to control traffic flow, and to generate alarms.

Another data service is the provision of regular and ad-hoc announcements and passenger information at station terminals. The content may be generated at central operations or at a regional center, and may be specific to one station or broadcast to all stations.

Data Voice Telemetry Signaling AlarmsMobile radio/GSM-R

Ticketing Publicaddress

Videosurveillance

Management system Accesscontrol

Informationdisplay

Communicationsnetwork

Informationsystems

Communicationssystems

Securitysystems

Controlsystems


Other data services such as ticketing and access control require information from all stations to be aggregated back to central operations for processing.

VoicecommunicationsservicesMaintenance personnel rely heavily on the operations voice system to stay in contact with co-workers in order to perform routine duties. Voice communications can be within a station or span several stations, and can be wired or wireless. High-quality voice communications must be supported to provide an efficient work environment and to keep staff informed in the event of an emergency. The rail operator also operates a public address system to convey routine and urgent information to customers.

VideosurveillanceVideo surveillance has become paramount for rail operators to safeguard critical assets and ensure the safety of personnel and passengers. Often operated as a separate analog network, video surveillance is now one of the rail operator’s many IP applications. A typical rail operation has many stations, and at each station, high- quality closed-circuit television (CCTV) systems generate multicast IP video streams. These video streams can generate bandwidths up to 2.5 Mb/s, which are transported in real time to multiple operations centers. This application requires a cost-effective and reliable high-capacity communications network that can transport multicast streams in a many-to-few topology. Increasingly, CCTV cameras and CODECs have Ethernet and IP interfaces and support Internet group management protocol (IGMP) to register to a multicast group.

A rail infrastructure is often divided administratively into several regions. Each region is controlled by a network operations center, and the regions are supervised by a single central operation, which also serves as a backup for each regional center. The IP/MPLS communications network must be able to efficiently carry images of the CCTV to both the central operations and the regional centers.

GSM-RTo improve safety and overall communication, many rail operators are deploying GSM-R. GSM-R is a secure platform for voice and data communication among railway operational staff, including drivers, dispatchers, shunting team members, train engineers, and station controllers. GSM-R is part of a major initiative being undertaken by railways around the world to introduce a cost-effective digital replacement for existing incompatible in-track cable and analog radio networks. The GSM-R network will be utilized when introducing the emerging European Rail Traffic Management System (ERTMS) standard. The ERTMS project has been set up to create unique signaling standards through-out Europe. The deployment of GSM-R over a single, unified network significantly increases the network’s requirements for synchronization.

IntranetandInternetaccessRail company personnel working in the operations centers and administration buildings require access to the rail company’s intranet and the Internet. A wireless LAN would be particularly helpful for the rail operator’s mobile workforce, allowing them to easily access, for example, maintenance manuals and work orders while on the move. Passengers might also be provided with Internet access in the stations. This data traffic would be considered non-critical, so the communications network should have the option to transport these unicast streams in a best-effort mode.


The Alcatel-Lucent IP/MPLS network

There is a movement towards accepting and implementing an IP-based core network for a rail operator for all of its communications needs. Not all IP-based solutions are appropriate for rail operators. To simultaneously support all mission-critical and non mission-critical traffic of a rail operator, an IP/MPLS-based communications network is needed. IP networks have grown significantly in recent years, but they often lack the necessary scalability to support traffic that requires QoS levels beyond best-effort. Traditional IP and Ethernet networks also lack the ability to optimize the use of network resources and the capability to react to network events fast enough to guarantee end-to-end QoS per application. By using MPLS, the rail operator gets the best of both worlds — an IP network that has the robustness and predictability of a circuit-based network along with high capacity and support for bursty traffic. The IP/MPLS network enables the deployment of new IP/Ethernet applica-tions as well as support of existing TDM-based applications, allowing the rail operator to improve services for both internal and external rail company users on IP transformation. With an IP/MPLS network, the rail operator has a network with the following features:

• Highly scalable and reliable with redundancy and Fast Reroute (FRR) capabilities

• Addresses a range of QoS and service level agreement (SLA) requirements

• Optimizes bandwidth usage through traffic engineering

• Extensive OAM tools for troubleshooting and maintenance

Each application on the network has unique requirements in terms of bandwidth, QoS, and avail-ability. The IP/MPLS network enables the rail operator to set service parameters for each service and traffic type (voice, data and video) and multiple service levels within each traffic type according to operational requirements. This network is also capable of supporting low jitter and delay to handle all traffic types effectively and reliably in real time.

In addition to those MPLS advantages, the Alcatel-Lucent IP/MPLS network supports advanced capabilities, including non-stop routing, non-stop services and FRR, to provision VPNs based on Virtual Leased Line (VLL), Virtual Private LAN Service (VPLS), and IP VPNs as well. This support allows for virtualization of a single network infrastructure to support different services and traffic types. One service is carried across one VPN while the traffic of different services is securely separated in their own virtual private networks. The Alcatel-Lucent multiservice MPLS network can also support existing TDM traffic with pseudowire services, so a rail operator can choose when to migrate existing services to IP.

The Alcatel-Lucent IP/MPLS implementation provides a service-oriented approach that focuses on service scalability and quality, as well as per-service operations, administration and maintenance (OAM). With a service-aware infrastructure, the rail operator has the ability to tailor services such as mission-critical applications so that it has the guaranteed bandwidth to meet peak requirements. The Alcatel-Lucent service router supports IP routing and switching, which enables the rail operator to support real-time Layer 2 and Layer 3 applications.

The Alcatel-Lucent IP/MPLS network, which extends MPLS capabilities from the core to access, includes the following main components:

• Alcatel-Lucent 7750 Service Router (SR)

• Alcatel-Lucent 7705 Service Aggregation Router (SAR)

• Alcatel-Lucent 7450 Ethernet Service Switch (ESS)

• Alcatel-Lucent 7210 Service Access Switch (SAS)


• Alcatel-Lucent OmniSwitch™ 6855 Hardened LAN Switch (HLS)

• Alcatel-Lucent 5620 Service Aware Manager (SAM)

• Alcatel-Lucent 5650 Control Plane Assurance Manager (CPAM)

The network and service administration of the Alcatel-Lucent IP/MPLS communications infra-structure is handled by the industry-leading Alcatel-Lucent 5620 SAM, an integrated application that covers all aspects of element, network and service management on one platform. It simplifies the programming and management of the network, including automating routine tasks, correlating alarms to problems, managing the assignment of end-to-end connections, and facilitating the intro-duction and administration of new services, all through a user-friendly point-and-click interface. The Alcatel-Lucent 5620 SAM can also manage many of the other Alcatel-Lucent and third-party elements within the network.

Microwave transmission systems can be used to provide connectivity coverage to one or several sections of the network where no other means of transmission is available. An optical transport layer, Coarse Wavelength Division Multiplexing (CWDM) and Dense Wavelength Division Multi-plexing (DWDM) can also be used for increasing backbone network capacity to transfer video, voice and data.

Figure 2 shows the concept of the Alcatel-Lucent IP/MPLS communications network for rail operations.

Figure 2. Alcatel-Lucent IP/MPLS communications network for rail operations

ThenetworkarchitectureFigure 3 illustrates how the sub-systems and devices, rail station LANs, and a wide area network are tied together along with the key capabilities utilized in each layer of the network to support the mix of video, data and voice traffic.

Regional center

IP/MPLSnetwork

Depot

Station

Station

Operations center

5620 SAM SCADA, signaling,video management

7750 SR

SCADA, videomanagement

OmniPCX

7750 SR

7750 SR 7750 SR

PSTN

7705 SAR

7210 SAS

7705 SAR

Interlockingequipment

7705 SAR

7210 SAS

OS 6855

WLANInformationdisplay

Informationdisplay

Ticketingsystem

Ticketingsystem

7705 SAR

RTU


Figure 3. Network architecture

The Alcatel-Lucent 7705 SAR, 7210 SAS, and OmniSwitch products aggregate traffic from equipment and users in a station and support the station LAN segment. The LAN network layer aggregates all Ethernet traffic from the station LAN segments, which are typically interconnected using optical fibers alongside the tracks. Alternatively, microwave wireless is used at the physical layer to connect remote sites or where deploying fiber optics is impractical. Several LAN segments belonging to one line of a rail system typically make up one ring of the network. This ring is interconnected at its east and west points to the Ethernet aggregation network layer of the communications network.

The station LAN segments use virtual LANs (VLANs) to create network virtualization. Unique VLAN IDs are assigned to identify separate virtual networks for voice, video aggregation and broadcast, and data. These virtual networks are securely separated as though they were individual LANs.

The WAN consists of Ethernet aggregation and core layers based on the Alcatel-Lucent 7705 SAR, 7450 ESS, and 7750 SR. VPLS and IP-VPN are used to provide network virtualization. The Alcatel-Lucent IP/MPLS network has proven very successful in helping rail operators to deploy a converged network for all applications while maintaining QoS for each type of application.

This carrier-grade design is ideal for the rail environment because it is capable of coping with thousands of video streams, voice traffic, and various data services simultaneously.

Much as Ethernet has emerged as the de-facto standard for LANs, it has also become the standard with the CCTV camera. Each camera has an IP/Ethernet-based interface and is recognized by means of an IP address and a MAC address. Ethernet has also become a standard offering in metropolitan area applications. Ethernet provides scalable bandwidth in flexible increments. It is a cost-effective technology and is well understood as it has been in LANs for years. Like campus networks, rail WANs benefit from cost savings in terms of equipment, facilities, provisioning and maintenance. This translates to CAPEX and OPEX reductions.

7210 SAS

Railway end users at station 1 Railway end users at station n

LAN

Ethernet aggregation

WAN

OS 6855 7705 SARVLAN assignment

Security policyTDM services

Sync E

Ethernet aggregationFast restoration

Access control list

Core

Efficient multicast replicationFast restoration

Access control list7750 SR7750 SR

7450 ESS 7450 ESS


Convergence of data, voice and video traffic on a single network creates a need for high-capacity networks that support high bandwidth and flexible multipoint communications. An IP/MPLS network is capable of connecting several thousand CCTV cameras. The WAN core must be able to handle traffic of several Mb/s per camera and thousands of multicast streams. These multicast streams are switched to the regional centers that are distributed across the rail network, one per region, and the central operations site. The regional centers are connected to the aggregation network layer, while the central operations site has a direct connection to the core (see Figure 4). The inter-connectivity in the core is typically 10 Gb/s but can be scaled according to growth using link aggre-gation groups (LAGs). The connectivity between the core and the aggregation network layers can be 1 Gb/s, a multiple of 1 Gb/s using LAGs, or 10 Gb/s. In the physical layer, these connections can be implemented using fiber optics or microwave wireless where appropriate depending on the terrain.

Data flows between several administrative regions are controlled and prevented where appropriate using access control lists (ACLs). The IP addresses of the end-user terminals within each adminis-trative region are assigned and grouped according to the respective region. This assignment method allows for dedicated per-region control lists to be created. These lists do not have to be changed when new end-user terminals are connected to the network.

In the aggregation network layer, a VPLS service aggregates the traffic from the different LAN segments towards the core network layer. For each administrative domain, separate VPLS service instances are provisioned for the various voice, data and video traffic.

Figure 4. Physical network topology

7705 SAR

StationA-n

StationB-n

StationB-1

StationA-2

StationA-1

Central operations

7705 SAR7705 SAR

7750 SR

7750 SR 7750 SR

7750 SRRegionalcenter A

Regionalcenter B

CoreNetwork

aggregation

Administration region “A”

Administration region “B”

Stationaggregation

7450 ESS7450 ESS

7450 ESS7450 ESS

7705 SAR7705 SAR


Each aggregation segment has dual connections to the core. The virtual router redundancy protocol (VRRP), running between the core and aggregation networks, determines which of the two connections is currently the active one.

In the core network layer, separate IP-VPNs are provisioned for voice, video and data. The video traffic is routed towards the central operations site.

Capitalizing on MPLS capabilities

An increasing number of rail operators are deploying their own MPLS-based networks. MPLS brings the advantages of a circuit-based network to an IP network, and enables network convergence, virtualization and resiliency.

MPLS is used to transport different types of traffic using pseudowire, VLL, VPLS and IP VPNs. In an MPLS network, Open Shortest Path First (OSPF) is commonly used as the Interior Gateway Protocol (IGP) and supports the setup of MPLS paths.

HighavailabilitythroughMPLSThe IP/MPLS network assures high availability through fast path restoration and network reconver-gence within 50 ms. Network resiliency is achieved by means of the end-to-end restoration capa-bilities of the MPLS FRR feature. High availability is essential to a rail operator’s communications network, which carries mission-critical voice, video and data information. With MPLS FRR, video, voice and data service interruptions are greatly minimized during network failures. To protect the network against node or interconnection failures, end-to-end standby MPLS paths are provisioned. MPLS offers the flexibility to provision hot or cold-standby paths to protect an active path.

The Alcatel-Lucent IP/MPLS implementation includes the unique additional high availability features of non-stop routing and non-stop services supported on the Alcatel-Lucent service router portfolio. The benefits are unparalleled availability and reliability:

• Non-stop routing ensures that a control card failure has no service impact. Label Distribution Protocol (LDP) adjacencies, sessions and the database remain intact if there is a switchover.

• Non-stop service ensures that VPLS and IP VPN services are not affected when there is a Control Fabric Module switchover.

VirtualizationThe Alcatel-Lucent IP/MPLS communications network provides for the virtual isolation of various traffic types on a single infrastructure. This allows the full separation of traffic from different applications or operations within the rail operator, allowing for a secure environment and effective bandwidth allocation. Advanced MPLS VPNs — such as virtual private LAN service (VPLS) and IP virtual private networks (IP VPNs) — are supported, and can be used to provide different appli-cations or user groups an environment that is private and unaffected by other traffic. One service is carried across one VPN while the traffic of different services is securely separated in their own VPN, effectively providing separate private networks.

MPLStrafficengineeringMPLS supports traffic engineering, which allows for the selection of the best path across the network, taking the physical paths of the links and interfaces into account. This mechanism is used in rail communications networks to ensure that the active and standby MPLS paths do not use fibers in the same cable bundle alongside the rail tracks.

Damage to a cable bundle can occur during rail construction or maintenance, or as a result of animals or acts of nature, and it can affect several or all fibers within a cable bundle. Therefore, it is important to implement a standby path that is physically isolated from the primary path.


MPLS’s RSVP-traffic engineering feature allows for the coloring of paths according to the physical topology of the cables (see Figure 5). Fibers in the same cable duct or cable bundle have the same color. The colors are assigned to the cables during the initial configuration of the network. When the rail operator configures MPLS paths, the RSVP protocol, which is used to set up the paths, is able to search for paths including or excluding certain colors. This mechanism eliminates the pos-sibility of the active and standby paths using the same fibers or fiber bundle.

Figure 5. MPLS path configurations

QualityofServiceIn a rail communications environment where multiple services converge over a common infrastructure, QoS is essential. The Alcatel-Lucent IP/MPLS communications infrastructure enables the network to discriminate among various types of traffic, based on a rich set of classification attributes (including MAC address, IEEE 802.1p, and IP addresses) and prioritize transmission of higher priority traffic over lower priority. The Alcatel-Lucent hierarchical quality of service (H-QoS) implementation also allows lower priority traffic to burst in order to fill available bandwidth when higher priority appli-cations go idle. H-QoS uses an advanced scheduling mechanism to implement service hierarchies. These hierarchies provide maximum isolation and fairness across different traffic while optimizing link utilization. With multiple levels and instances of shaping, queuing and priority scheduling, the Alcatel-Lucent IP/MPLS network can manage traffic flows to ensure that performance parameters (such as bandwidth, delay and jitter) for each application are met.

Effectivemanagementforeasierday-to-dayoperationsA key element of reliable and flexible MPLS-based networks is a set of effective, simplified management tools that provide easy configuration and control of the network, effective problem isolation and resolution, and support of new management applications. The Alcatel-Lucent IP/MPLS network supports OAM tools that simplify the deployment and day-to-day operation of a rail communications network. For example, service tests, interface tests and tunnel tests allow for rapid troubleshooting and enable proactive awareness of the state of traffic flows to help minimize service downtime.

Core

Blue

CyanGreen

Red


The Alcatel-Lucent IP/MPLS network is fully managed by the industry-leading Alcatel-Lucent 5620 Service Aware Manager. The Alcatel-Lucent 5620 SAM is an integrated application that covers all aspects of element, network and service management on one platform. It automates and simplifies operations management on a converged MPLS network, driving network operations to a new level of efficiency. The Alcatel-Lucent 5620 SAM product suite supports element management, network commissioning, service provisioning and service assurance.

For IP routing management control, the Alcatel-Lucent 5650 CPAM offers real-time control plane visualization, proactive control plane surveillance, configuration, validation and diagnosis. It enables rail operators to overlay Layer 2 and Layer 3 services, MPLS tunnels and various OAM traces on the control plane map. This simplifies problem resolution, reduces control plane configuration errors, and reduces troubleshooting time.

SupportforinnovativeapplicationsThe Alcatel-Lucent IP/MPLS network has proven to be highly successful at supporting innovative applications. For example, Alcatel-Lucent developed a fully IP/MPLS-based solution to support train dispatch by the driver via CCTV. Video cameras on the platform transfer images directly to a monitor in the driver’s cab and to the control center. The system not only speeds up operations, but also enhances safety. Also, economic benefits are realized with a reduction in the personnel required for dispatching the trains, especially when the volume of trains is high.

Circuit Emulation Service over MPLS

Rail operators need to consider how to leverage new IP/MPLS network technologies when migrating legacy TDM systems and services. Rail operators can take advantage of the IP/MPLS Circuit Emulation Service (CES) functionality and transition their legacy applications gradually. CES delivers the same quality of experience as the existing TDM network infrastructure, with the same level of predictability. The Alcatel-Lucent IP/MPLS network has a circuit emulation interworking function that ensures all information required by a TDM circuit is maintained across the packet network. This allows a full transition to a packet network over time while providing TDM service continuity.

Two principal types of circuit emulation can be used: Circuit Emulation Service over Packet (CESoPSN) and Structured Agnostic TDM over Packet (SAToP). CESoPSN allows NxDS0 service, including full T1/E1 capability. SAToP provides the ability to carry unstructured T1/E1 circuits across the IP/MPLS network.

In an IP/MPLS network, the MPLS tunnel is used as the transport layer (Figure 4). A pseudowire (PWE3) is created to identify the specific TDM circuit within the MPLS tunnel. Circuit emulation interworking function ensures that all information required by the T1/E1 circuit is maintained across the packet network. This provides a transparent service to the end devices.

Figure 6. Circuit Emulation Service functionality overview

CES IWF

The CES interworking function(IWF) applies to the properencapsulation to the nxDS0

or T1/E1 traffic

Flexible configuration tobuffers within the CESIWF allows control ofpacketization, latencyand jitter (to meet the

requirements forTDM services)

Pseudowiresidentify the specific

CES connection

MPLS tunnelstransport traffic

from point A to B

TDM

MPLS tunnel

CES IWF

TDM


Synchronous Ethernet

In most TDM networks, synchronization is distributed within the network using the SONET/SDH mechanisms built into the physical layer definition. To deliver the TDM service via a packet network, the same or better synchronization must be achieved through other means. Some TDM applications require Stratum-level clocking and distribution of information with very stringent accuracy. Rail operators are looking to migrate their synchronization infrastructures to a familiar and manageable model. To enable rapid migration of these networks, Synchronous Ethernet may be the easiest and quickest way to achieve (frequency) synchronization and to allow the benefits of an Ethernet network infrastructure to be realized without any change to the existing TDM network applications. The concept behind synchronous Ethernet is similar to SONET/SDH system timing capabilities.

With Synchronous Ethernet, the network elements derive the physical layer transmitter clock from a high-quality frequency reference via the physical Ethernet interfaces. This does not affect the operation of any of the Ethernet layers and is transparent to them. The receiver at the far end of the link locks onto the physical layer clock of the received signal, and thus itself gains access to a highly accurate and stable frequency reference. Then, in a way similar to conventional hierarchical master-slave network synchronization, this receiver locks the transmission clock of its other ports to the frequency reference and a fully synchronous network is established. The implementation of Synchronous Ethernet will allow a rail operator to gracefully integrate its existing systems and future deployments into a conventional industry-standard synchronization hierarchy. The Alcatel-Lucent IP/MPLS products support Synchronous Ethernet, which has proven to out-perform the standards requirements used by SONET/SDH, allowing migration from SONET/SDH to a full IP/MPLS network as desired.

One application where Synchronous Ethernet has proven effective in allowing rail operators to migrate their network to IP/MPLS and save costs is in the deployment of GSM-R over a single, unified network. Traditionally supported on SDH network, GSM-R is a secure platform for voice and data communication between railway operational staff. GSM-R base stations need to be fed with synchronization of E1 circuits. The Alcatel-Lucent IP/MPLS network is able to comply with stringent ITU-T specifications including G.8261/8262 and G.823/824/825. Synchronous Ethernet is used to distribute synchronization to GSM-R base stations, as depicted in Figure 7.

Figure 7. Synchronous Ethernet for GSM-R base stations

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referenceclock

GigEGigE

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Video surveillance

The railway communications network must be able to efficiently handle the massive amounts of video traffic generated by the CCTVs at each station. Maintaining the flow of this video traffic from each station towards its regional center and central operations is key to the safe and efficient operation of the rail system.

Modern video surveillance systems are IP-based and are integrated with the IP backbone using a network-based architecture. Managing video traffic can be a challenge for rail operators that are still using traditional networks. Adding CCTV traffic onto an IP network unprepared for video traffic can adversely impact all services on the network. The Alcatel-Lucent IP/MPLS network can address the video surveillance requirements for guaranteed delivery of mission-critical CCTV video traffic and concurrent support of other critical data and voice traffic on a single converged network. The network is capable of handling current video traffic levels and future growth, including significant increases in bandwidth.

Distributed video surveillance offers many advantages, including support for real-time video streaming to many locations and the flexibility to deploy video analytics software remotely. Because access and distribution of CCTV streams can be very dynamic and mission-critical in nature, the highly scalable and reliable Alcatel-Lucent IP/MPLS network is ideal for handling thousands of video streams now required in modern CCTV applications.

A modern video surveillance operation can have many high-quality CCTV cameras generating multicast IP video streams. These video streams are transported in real time to multiple locations. CCTV cameras and CODECs have Ethernet and IP interfaces and support Internet Group Manage-ment Protocol (IGMP) to register these devices to a multicast group. Each CCTV channel belongs to a different multicast group; therefore, each has a different multicast IP address assigned to the packets carrying footage for the channel. IGMP is used by the video management workstation to communicate to the edge routers for the channel that the operator is requesting.

Using the multicast capabilities of VPLS technology in the aggregation network provides a powerful and cost-effective solution for the delivery of CCTV traffic to the local monitoring stations and for central video management (see Figure 8).

Figure 8. Video surveillance over an IP/MPLS network

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Storage Videoanalytics Storage Local

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Conclusion

Rail operators should ensure that their IP network transformation is enabled with an IP/MPLS network, as only MPLS can provide the reliability that is needed for mission-critical services. A service-aware IP/MPLS network provides the additional benefit of supporting consolidated voice, data and video applications that can be managed through configurable QoS levels. The Alcatel-Lucent IP/MPLS product portfolio leads the industry in reliability and OAM tools, key enablers for meeting the “always-on” requirement for mission-critical rail operations. The Alcatel-Lucent IP/MPLS network can help address rail communications challenges with:

• High network availability

• Network virtualization with QoS guaranteed for priority traffic

• Sophisticated synchronization options

• Reduced operating and maintenance costs

• Integration of video surveillance into the communications network

• Access to critical information in real time

• Guaranteed communications amongst vehicles, stations, regional centers, central operations, emergency personnel and passengers, with non-stop routing and non-stop services

• Improved passenger safety through effective, always-on communications

AcronymsACL Access control list

ATM Asynchronous transfer mode

CAPEX Capital expenditure

CCTV Closed circuit television

CES Circuit Emulation Service

CPAM Control Plane Assurance Manager

CWDM Coarse Wavelength Division Multiplexing

DWDM Dense Wavelength Division Multiplexing

FRR Fast Reroute

GSM-R Global System for Mobile Communications – Railway

ICT Information communications technology

IGMP Internet group management protocol

IGP Interior gateway protocol

IP/MPLS Internet protocol/multiprotocol label switching

IP VPN Internet protocol virtual private network

IT Information technology

LAG Link aggregation group

LAN Local area network

OAM Operations, administration and maintenance

OPEX Operational expenditure

OSPF Open shortest path first

PIM Protocol independent multicast

PIM-SM Protocol independent multicast – sparse mode

QoS Quality of service

SDH Synchronous Digital Hierarchy

SLA Service Level Agreement

SONET Synchronous Optical Network

TDM Time division multiplexing

VLAN Virtual local area network

VPLS Virtual private LAN service

VPN Virtual private network

VRRP Virtual router redundancy protocol

WAN Wide area network

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Reliable IP Networks for Rail Operators en WhitePaper

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