The Reality of Multiservice Edge Routing

In the last few years, the telecommunications industry has focused on reducing CAPEX and streamlining OPEX. Carrier networks are complex, and include many platforms and devices. As new services are introduced, service providers look for solutions from vendors that have longevity and do not require network overlays.

High operational expenses are directly proportional to the number of platforms carriers support. Each platform has its own operating system with associated syntax and commands. Network operation specialists need in-depth knowledge of the operating systems, often leading to lengthy and expensive training. If a platform is coupled with an element or network management system, integrating operations support systems (OSS) incurs additional costs.

One way to optimize CAPEX and OPEX is to simplify the network by consolidating multiple types of services over a single, integrated, cohesive infrastructure. IP and multiprotocol label switching (MPLS) are seen as the enabling technologies of choice for this network, but the real challenge lies at the provider edge (PE), where service-aware intelligence is needed. The routers deployed at the PE - known as multiservice edge routers - must satisfy service providers’ stringent requirements for availability, reliability and manageability. In the past, finding a platform with these attributes was difficult.

Today, there are service routers with purpose-built service awareness that address service providers’ requirements. Service routers offer carriers the next phase of routing because they are built from inception to guarantee the highest levels of availability, resiliency and redundancy from the hardware and software architectures, and offer breadth and depth of multiservice feature support.

Additionally, the service awareness embedded within service routers enables service level agreement- (SLA) based IP offerings with highly granular quality of service (QoS), comprehensive operation, administration and management (OAM) tools for easy troubleshooting and service based billing/accounting models. In addition, service routers have tightly integrated service-aware management to ensure ongoing reliability. A multiservice edge router built upon the foundation of service routing paves the way toward service and network consolidation.

High Availability
One of the key concerns that service providers have with multiservice routers is in the area of availability and reliability. With the consolidation of multiple different services such as data, voice and video services on a single platform, service providers need the most stringent levels of service availability in their network.

During the day-to-day operation of the network, a service provider must minimize the number of outages in the network, particularly unplanned ones. A hardware failure is an example of an unplanned outage and can cause disruptions to the network and to the services transported over the network. Hardware redundancy of power supplies, fans, switch fabric and control planes mitigates the risk of component failures. However, resiliency must be implemented network-wide, not just at the node level.

In the case of a control plane failure, for example, the failure can have a devastating impact on the network. Routes carrying customer traffic may be lost, or even worse, traffic will continue to be forwarded by the router even though it may have outdated route information. This results in traffic being “black-holed” and the loss of customer data. Recovery or reconvergence with conventional routers can be lengthy and time-consuming.

Service routers with Non-Stop Routing (NSR) and Non-Stop Services (NSS) offer the highest level of insurance against a control plane failure. There are no lengthy reconvergence times because the switchover from an active to standby control plane is done instantly. With a service router, routing updates from other peer routers continue to be processed, therefore no traffic is lost. A service router does not need information from a neighboring router to recover seamlessly from a hardware failure. This minimizes disruption and eliminates route flooding in the network. In a network based on service routers, customer data is forwarded using the correct route all the time, thereby guaranteeing maximum service uptime.

Multiservice Support
Service provider networks have a large installed base of existing services. Much time and effort is spent configuring and maintaining the legacy networks that support these services.

A multiservice edge router must be able to support legacy services as well as new services that a carrier introduces, all on the same platform. Service routers include comprehensive support for a variety of legacy protocols such as ATM, frame relay and Ethernet. In addition, service routers support newer and emerging protocols like IP, MPLS and VPLS. And because of the embedded service awareness of the service router, full service isolation between existing and emerging services is achieved.

Quality of Service
One of the defining attributes of a service router is its ability to meet individual service-quality requirements for all services traversing the IP/MPLS network. Service-aware hierarchical-QoS (H-QoS) facilitates network and service capacity planning. This mechanism ensures traffic flows of all types can be prioritized and controlled across the network and that each service has the reliability and resources to meet customer performance expectations.

Service-aware QoS provides service-based queuing, policing and shaping, with per-service bandwidth guarantees to meet the most demanding SLAs – without the extra cost of special modules for advanced features.

OAM
Other capabilities, such as timely fault detection and ease of troubleshooting in the network, allow service providers the means to proactively maintain high network reliability at all times.

Service routers have been purpose-built with comprehensive toolkits to isolate problems at three levels: nodal, network and service. Most routers support basic tests to identify any nodal malfunctions or failures that are on board and to test connectivity to adjacent routers in the network.

Service routers differentiate themselves by offering service-specific tests. These tests enable an operator to verify that a service is configured accurately and to provide end-to- end service-aware connectivity testing. The service-level tests can be performed on a VPLS media access control (MAC) address or a virtual private routed network (VPRN) identifier. The key with a service router is that the OAM packets follow the exact same path that the customer’s data does and so the service provider has highly accurate information returning from the OAM test. This enables service providers to isolate issues associated with a customer’s service quickly and clearly, before any SLA violations occur.

Other attributes of a service router include support for service mirroring – the ability to mirror packets to an analyzer. The packets can be sent in a tunnel without the need for an analyzer to be connected directly to every router. This alone provides a huge CAPEX savings for the service provider. Service routers provide even more flexibility with the ability to offer more granular packet information, right down to a particular service or customer.

Service-Aware Accounting and Billing
Service routers extend the same flexibility used in service mirroring to service-aware accounting and billing. Service routers collect a wide variety of statistics that can be specified by the network operator. Most importantly these statistics are associated with a customer ID or address such that customer-specific accounting and billing reports can be generated without having to do lengthy parsing of raw statistical data.

Service-Aware Management
Service routers include service-aware network management systems that allow a network operator to commission and configure the router quickly. Network operators use the network management system to correlate customers with their services and can monitor the health of a customer’s service easily, with the simple click of a mouse.

As service providers strive to be more efficient and cost effective, the consolidation of multiple services (voice, video and data) over a common IP/MPLS network infrastructure is inevitable. The success of a converged IP/MPLS network is closely linked to the ability of the multiservice edge router to support all traffic types traversing the network and to meet service reliability metrics to support new and existing SLA-based services. The reality is that with service routing, multiservice edge routers are able to satisfy all of these stringent requirements and pave a smooth path toward profitable, simplified networks.

Hema Ganapathy is director of product marketing for Alcatel’s IP division.

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