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Redback Simplifies Delivery of IPTV, Business VPN, and Internet Services for Chunghwa Telecom

The SmartEdge Multi-Service Edge Router enables Chunghwa Telecom to effectively scale their residential and business service offerings to a nationwide customer base while simplifying overall network architecture and operations.

Chunghwa Telecom (CHT) is one of the primary telecommunications providers in the Asia Pacific region, with over four million broadband subscribers and a diverse portfolio of residential and business services. SmartEdge® Multi-Service Edge Routers (MSER) have been deployed nationwide to provide triple-play services along with innovative new multimedia applications such as karaoke on-demand and online gaming. With its advanced IP-services network, CHT also offers DSL wholesale services to third-party Internet Service Providers (ISPs) and MPLS-based Virtual Private Networks (VPNs) to business customers. With a substantial customer base and extensive service portfolio, CHT requires the highest levels of scalability, reliability, and flexibility to accommodate existing and emerging services. The SmartEdge MSER enables CHT to achieve these goals with a single converged broadband network, minimizing design complexity and reducing ongoing operational costs.

Situation
CHT’s customer base includes residential broadband users, wireless voice and data users, retail businesses, large enterprises, and third-party ISPs. Like many other large incumbents, CHT’s overall network has evolved over time to include several generations of infrastructure deployment and a diverse range of underlying network technologies. While organic growth of the network served to enhance service readiness by supplementing capacity, reach, or performance, the successive build-out of infrastructure over time inevitably created additional complexity throughout the network. Iterative stages of deployment created a multi-vendor environment consisting of disparate networks, making service provisioning and network troubleshooting increasingly difficult. Accommodating spares for equipment from multiple vendors increased operational costs. As network costs and complexity increased, so did the difficulty of introducing new services.

With an initiative to introduce next-generation services such as IPTV, VoIP, and multimedia on-demand, CHT needed an approach that would scale to meet the needs of millions of customers while maintaining operational simplicity. Increased bandwidth requirements along with minimized latency and jitter would be critical to deploying multimedia services successfully. At the same time, CHT needed an architecture that would allow for converged delivery of higher-margin business services such as MPLS VPNs.

CHT explored many options for a new architecture that would meet their needs. One aspect of the infrastructure upgrade involved moving from ATM-based DSLAMs with traffic carried over a legacy ATM network, to IP-DSLAMs and FTTx with traffic carried over an Ethernet network. A platform that could gracefully support this migration would ensure minimal disruption in service. Beyond this, CHT was concerned about how session management would be implemented. Multiple traffic flows per user could impose operational and scalability challenges. With millions of subscribers and dozens of services being offered, CHT’s new network would have to be reliable, scalable, and flexible.

Solution
As seen in the adjacent figure, CHT Broadband Services Network, the SmartEdge platform enabled CHT to deploy an efficient and flexible network, delivering its Multimedia On-Demand (MoD) services to consumers while also providing MPLS VPN to businesses. In addition, wholesale ISP traffic was carried to the appropriate upstream provider across the same converged infrastructure. Wireless data services can be easily integrated into CHT’s service portfolio for mobile business applications such as wireless VPNs. CHT was able to meet the demands of their entire customer base by using the advanced subscriber management and service creation capabilities of the SmartEdge MSER.

Multimedia Services
CHT’s Multimedia On-Demand (MoD) service launched in March 2004 and now has over 100,000 customers. The service consists of IPTV applications such as broadcast television and true Video On-Demand (VoD), as well as a range of innovative new multimedia services such as online gaming and karaoke on demand. MoD is opening up new revenue streams and helps to reduce customer churn by increasing service stickiness.

As a leader in the emerging IPTV market, CHT offers content such as live concerts, top-rated dramas, news feeds, movies, music, and learning channels to its subscribers. With over 200 channels of broadcast television and hundreds of titles available through Video on Demand (VoD) or Near-Video on Demand (NVOD), CHT needed a solution that could provide scalable IP multicast and dynamic bandwidth control.

The SmartEdge platform is used throughout CHT’s MoD service delivery network. Video content is passed through the core network to the distribution edge. SmartEdge routers at this location multicast the traffic downstream through the access network to end subscribers. With full hardware redundancy, in-service software upgrades, and hitless multicast subscriber switch-over, the SmartEdge MSER ensures continuous service delivery for MoD.

As CHT further expands it’s IPTV, VoIP, and multimedia services, sustaining a high quality of experience for subscribers will be critical. Advanced QoS with granular traffic control and service partitioning through virtual routers enable the SmartEdge MSER to efficiently allocate network resources to subscribers on a per-application basis, effectively addressing the real-time traffic requirements of these services.

Business VPN
In addition to offering consumer broadband services, CHT also provides data services to small and medium sized businesses as well as large enterprises. With increasing demand from business customers for higher bandwidth, greater flexibility, and easier connectivity, CHT was well-positioned with the SmartEdge MSER to offer MPLS VPN services to meet these customers’ needs. Services like Virtual Leased Line (VLL) for Layer 2 point-to-point transport, Virtual Private LAN Service (VPLS) for Layer 2 multipoint communications, and IP-VPN based on RFC2547 for Layer 3 connectivity are all offered on the same platform.

The same DSL access infrastructure used to reach residential broadband customers is used to provide business customers in high-rise office buildings or retail locations with MPLS VPN service. Larger customers requiring higher bandwidth or alternative connectivity may attach to a VPN with a dedicated Ethernet link, ATM connection, or any of the other interface types available on the SmartEdge MSER.

Virtual context technology enables the SmartEdge MSER to create thousands of logically separate domains within a single platform, each functioning as an independent virtual router. VPN traffic is isolated in this manner with each virtual router having its own route tables, IP address space, and routing protocol instances. Traditional issues regarding overlapping IP address space or routing instability caused by one customer impacting another customer are eliminated with this functionality. Each customer can also monitor and manage their individual virtual router instance as if it were a private physical router.

CHT chose the SmartEdge MSER for their MPLS VPN service due to its proven scalability, carrier-class reliability, and well-established deployment throughout the world. In particular, the ability to offer both Layer 2 and Layer 3 VPN services on a single integrated platform enabled CHT to overcome previous challenges of managing separate Layer 2 and Layer 3 VPN implementations on multiple different platforms. From the same SmartEdge MSER, CHT could easily offer managed IP service using IP-VPN, transparent Layer 2 connectivity using VLL or VPLS, or a combination of Layer 2 and Layer 3 VPN services, all based on end customer’s requirements rather than on limitations of previous deployed network elements.

With a need to support intricate MPLS VPN architectures for larger customers, CHT used the advanced features on the SmartEdge MSER to deploy hierarchical VPLS and IP-VPNs in hub-and-spoke configuration. This was an important factor in order to effectively scale VPN customers with thousands of locations throughout the country.

Broadband Aggregation
With 95% ownership of copper access lines throughout Taiwan and a subscriber base of over 4 million broadband customers, CHT reaches a considerable population of broadband users in the country. While the majority of its broadband subscribers directly access its HiNet Internet service, CHT also provides wholesale DSL service to third-party ISPs. The SmartEdge MSER aggregates traffic from both types of Internet users and determines the appropriate VLAN mapping to distinguish customers transiting to upstream providers versus those that are native HiNet customers. The SmartEdge MSER provides granular subscriber control and VLAN scalability beyond traditional limits, essential capabilities to differentiate traffic types and support a massive number of users.

The SmartEdge MSER aggregates DSL traffic in various methods depending on available access technology and customer connectivity needs. Newer IP-DSLAMs are directly connected to the SmartEdge MSER via Gigabit Ethernet, without a need for an intermediate Ethernet aggregation network, while traffic from older ATM-based DSLAMs traverses a legacy ATM network. New users or existing users that need to be upgraded are added to the IP/Ethernet- based infrastructure with the legacy ATM infrastructure gradually being retired. With the ability to connect both ATM and Ethernet DSLAMs the SmartEdge MSER ensures graceful migration of users by facilitating the coexistence of legacy and new infrastructure.

CHT determined that while VLAN scalability of the SmartEdge MSER is beyond the traditional 4,096 VLAN limit, intermediate devices would be restricted by this constraint and would impact the preferred method of service delivery. To avoid this limitation, DSLAMs were directly connected to the SmartEdge MSER without using an intermediate transport network. Beyond the scalability consideration, multiple users sharing a single VLAN also created security concerns as malicious traffic from a single user could impact many other users. A dedicated VLAN per user achieved traffic isolation and enabled a more manageable instance of traffic flow for applying user policies or enforcing specific QoS treatment. With support of up to 96,000 VLANs per chassis, the SmartEdge MSER ensures the scalability of user services.

In cases where CHT offers broadband access through a combination of Fiber-to-the-Building (FTTB) and VDSL, gigabit Ethernet over fiber is extended from the SmartEdge MSER to a Layer 3 Ethernet switch in a multi-tenant building. This switch aggregates low-density VDSL DSLAMs, serving users on each floor over traditional twisted-pair wiring. The terminating VTU-R modem at the user provides Ethernet connectivity via a 100 Mbps Ethernet port. End users of this service may be CHT’s own HiNet Internet or MoD subscribers, wholesale DSL users, or business customers accessing MPLS VPN services.

Benefits
As one of the top ten broadband providers in the world, CHT plays a major role in substantiating new services in the Asian telecommunications market. With a complete range of services including IPTV and multimedia applications, Layer 2 and Layer 3 MPLS VPNs, Internet access, and DSL wholesale, CHT needed a broadband platform that would ensure high reliability, scalable service delivery, and the flexibility to accommodate current and future applications.

The SmartEdge platform enabled CHT to effectively scale their residential and business service offerings to a nationwide customer base while simplifying overall network architecture and operations. With a single converged broadband network, CHT can easily leverage a large existing base of wireless subscribers and the widespread adoption of wireless data applications to integrate new 3G wireless mobility into their business VPN offering.

In the overall network design, CHT was able to use the SmartEdge MSER to overcome traditional scalability limitations and create a more manageable service delivery architecture. The robust service creation capabilities of the SmartEdge MSER provide CHT with centralized control and the ability to further expand their service portfolio with innovative new applications.