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Moving beyond yesterday’s network

Fri, 11/30/2007 - 7:40pm
Peter Chahal, Director of Solution Marketing in the IP Division at Alcatel-Lucent

Service-aware routers handle quality, reliability issues

For cable multiple system operators (MSOs), the network status quo is not an option. Tomorrow’s MSO networks must be more service-oriented and user-centric. They must continue to deliver residential services and allow those offerings to evolve with triple play and quad play services that meet customer demand and address increasing threats from telcos. At the same time, these networks must allow MSOs to drive for new opportunities in commercial markets.

These combined needs are driving operators to converge consumer and commercial retail and wholesale business services over a common Internet protocol/multiprotocol label switching (IP/MPLS) network. And this transformation is playing a big role in the deployment of Carrier Ethernet and the upgrade of the existing hybrid fiber/coax (HFC) access network to DOCSIS 3.0, universal edge quadrature amplitude modulation (QAM) and modular cable modem termination systems (M-CMTS) that provide more flexibility to scale upstream and downstream capabilities.

By taking a more holistic approach to network transformation, MSOs are gradually making inroads with both retail and wholesale commercial customers, with the goal of delivering a bigger return on investment.

On the retail front, MSOs are introducing business services to small-medium enterprises (SMEs) and large enterprises to support a new wave of multimedia and “on-demand” IP-based applications on which SMEs and large enterprises are becoming increasingly reliant. This includes global teleconferencing, VoIP and digital media. These applications are as demanding as they are sensitive to shortfalls in bandwidth, latency, jitter and overall predictability. While less than voice quality might have been acceptable for older applications, SMEs and large enterprises need and will only accept superior delivery standards for these new services.

Figure 1
Figure 1: SME Business Telecom Services & Plans (% of Respondents). Source:
Heavy Reading “Multi-Client Study on Prospects for Cable Operators in
Business Services” June 2007

On the wholesale front, MSOs are introducing wireless backhaul services to address the wireless industry’s need for high capacity solutions. The wireless industry is undergoing a transition as networks that were built 10 years ago are being upgraded to support new multimedia service offerings. This opens the door for MSOs to offer competitive solutions to meet the wireless operators’ bandwidth capacity demand and stringent quality of service (QoS) requirements.

But to deliver the new wave of applications and services, meet residential and commercial customer expectations for quality, and maximize profits, MSOs must look beneath the underlying network infrastructure to the routers that route and aggregate services. Those routers must be advanced, service routing platforms that enable delivery of today’s and tomorrow’s high-performance video, high-speed data and voice/mobility services with the highest possible level of quality and service reliability.

Embracing commercial business services
Attacking the commercial services market has deep significance on three levels for MSOs.

First, MSOs can capture a bigger share of the retail business services market. According to Heavy Reading, the U.S alone generates tens of billions of dollars annually for business services with less than 1 percent going to MSOs. The MSOs’ approach to address the retail business services market is driven by the belief that SME customers are poorly served by the telcos. VoIP is seen as the inflection point that MSOs will lead with as part of their bundled service offering, including business video and business VPNs at an attractive price point (Figure 1).

But in the business services market, MSOs face a different set of challenges that are not inherent in the residential market. Attributes such as tiered service differentiation and high availability are key to delivering uninterrupted business-critical services, or even life-line services with stringent service level agreements (SLAs).

Second, MSOs can leverage their converged network to address the wholesale aspect of commercial business. The need for higher capacity is reshaping today’s wireless backhaul and backbone networks, and addressing backhaul capacity requirements represents much of the cost of operating a mobile network. That’s because today’s base stations must scale from their current average capacity of 2-3 Mbps to 50-70 Mbps in the future – and up to 100 Mbps for the most intensive 4G applications. A converged, service-aware IP/MPLS network that is designed to deliver stringent QoS and high availability puts the MSOs in an ideal position to compete for this business.

Figure 2
Figure 2: Converged, service-aware IP/MPLS network.

Third, MSOs can optimize costs by consolidating residential and commercial business services on a common network. A converged, service-aware IP/MPLS network (Figure 2) enables the integration of services from the existing HFC plant with new services deployed over home-run fiber for enterprise and wholesale customers. It supports the delivery of video and voice, and enriches the service mix with support for Layer 2 and Layer 3 virtual private networks (VPNs). Since IP/MPLS enables the carrier attributes of Ethernet, MSOs can differentiate their Carrier Ethernet service to address a wider range of business customers – all on a common network.

Driving network transformation
To enable MSOs to capture a bigger share of the commercial market and address the challenges facing them with the new wave of business services, they need service routing platforms that can transform their IP/MPLS networks into advanced service delivery infrastructures with service reliability, service QoS, service management and performance.

Service reliability: Making network outages a thing of the past
To meet customer expectations for uninterrupted service, MSOs need comprehensive high availability features that cover the node, the network and the service, including the applications riding on the service.

But the lack of hardware and software self-healing capabilities and hitless upgrade processes in legacy routers prevent MSOs from delivering always-on IP/MPLS services. To properly address these concerns, MSOs need service routers designed to mitigate the issues that cause network outages (Figure 3).

Service routers provide rapid network protection capabilities through MPLS fast reroute (FRR) that compare with SONET/SDH for link and node outages. The MPLS FRR feature provides sub-50 ms restoration, overcoming native Ethernet’s limitations in the areas of resiliency and re-convergence. The inherent scalability of FRR enables support for tens of thousands of connections and services, over carrier Ethernet.

Figure 3
Figure 3: Service routers reduce causes of network failures.

Network protection can be further streamlined by pairing FRR with non-stop routing, a technique that provides control plane parallelization in the service router. With non-stop routing, up-to-date routing state information is constantly maintained on the standby control plane module, and topology information and adjacencies are retained during a control plane failure. Non-stop routing provides true stateful resiliency of interior gateway, exterior gateway and multicast routing protocols, as well as MPLS signaling protocols.

With non-stop routing maintaining the routing protocols, non-stop service keeps enterprise VPN services (VLL, VPLS, and IP-VPN) and applications running during a control plane failure. Traditionally, the service and applications riding on the service would have timed out. Since the secondary control module is fully aware of the services and sessions, there is zero downtime during a control plane switchover. This ensures service level guarantees are maintained at all times, and that Carrier Ethernet services can offer rapid and better than SONET-like restoration.

A service router solution designed from the ground up with these resiliency mechanisms enables highly available services and guarantees service outages do not take place during upgrades. This enables MSOs to offer stringent SLAs during planned and unplanned network events.

Service QoS: The cornerstone of service velocity 
Service quality is required to guarantee deterministic bandwidth. For an SME or large enterprise to trust its operations to a business VPN, over Ethernet or over the DOCSIS network, it must provide quality controls that are comparable to those available in connection-oriented frame relay or ATM networks.

A service router designed for a converged MSO network will meet individual service quality requirements for business or residential services traversing the converged IP/MPLS network. The service router employs Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for reserving network resources along the path and service-aware hierarchical QoS (H-QoS) to facilitate network and service capacity planning. Together, these mechanisms ensure that traffic flows of all types can be prioritized and controlled across the network.

Figure 4 provides an example of tailored Layer 2 VPN (VPLS) and Layer 3 IP VPN services delivered over the DOCSIS network and direct-run fiber to a multi-tenant unit. In this example, the MSO can implement hierarchical QoS to tailor the service to the enterprise application’s unique requirements. Advanced hierarchical scheduling is implemented through a tiered SLA, in which different application QoS levels are provided through the VPN service.

For example, specific committed information rates (CIR) and peak information rates (PIR) can be applied to each application riding the business VPN. In addition, an overall QoS level can be assigned to the collection of services used by the enterprise. This combined capability enables the MSO to cater to the dynamic traffic patterns of multimedia and on-demand applications to meet the most demanding SLAs.

The combination of traffic engineering mechanisms of MPLS with hierarchical QoS (H-QoS), on the service router, ensures applications such as business video and VoIP have predictable delivery, even over Ethernet. MSOs can tailor the business VPN service to suit the end customer’s requirement for the different traffic types, using the right SLA arrangements.

Service management: Improving operational efficiency
To ensure the long-term profitability of commercial business, MSOs must also be able to introduce and maintain new services cost-effectively. To do this they must improve overall operational efficiencies by:

  • Improving activation time for new services from days to hours or minutes.
  • Having a common view of the network to apply end-to-end policies and reduce the time to identify and fix a service issue – all from a central network operations center (NOC).
  • Providing commercial business customers with a better window to track or request changes to their service, anytime.

Ensuring that both the MSO’s and the business customer’s requirements are met requires service-aware management systems. A service-aware manager presents the network as a single virtual node to enable enhanced service provisioning and assurance capabilities that maximize the operations, administration, maintenance and provisioning (OAM&P) functions available in the service router. With these tools, MSOs can provide comprehensive fault management and assurance on a per-service basis. They can monitor performance metrics for latency, jitter and packet loss to provide proactive management of delay-sensitive applications.

Figure 4
Figure 4: Service differentiation with compelling H-QoS service attributes.

These tools also allow MSOs to test application flows in both directions for video, VoIP and business critical data, and thereby enable fast, accurate, efficient resolution of a customer’s service problems, from a central NOC.

For example, the customer located equipment environment may use IEEE ping tests, while the VPLS environment will use MAC or service pings. With service-aware management, an MSO can apply service verification policies to a richly modeled Carrier Ethernet service, and the service-aware policy will apply the right OAM test to the right technology on an end-to-end basis.

With detailed performance metrics, MSOs can move further up the value chain by offering enterprise customers Web portals. These Web portals can be used to provide customers with reports that demonstrate how their SLAs were met over time and what level of performance their traffic actually experienced over the network. They can also enable enterprises to change QoS levels on one of their services or increase bandwidth when necessary. All of these help MSOs build customer loyalty and increase revenue.

Service routing is the key
Consolidating services over a common IP/MPLS infrastructure only addresses the delivery challenges MSOs face as they work to address residential and commercial service requirements.

To address service quality and reliability issues, MSOs must look beyond the underlying infrastructure to the routers that route and aggregate services through their networks. Those routers must be advanced, service-aware platforms designed from the ground up to guarantee the highest levels of service availability and service quality from hardware and software architectures. In addition, service management must be tightly integrated with these service routers to ensure ongoing service reliability and minimize operational costs.

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