In order to win high-margin business customers with next-generation metro-Ethernet services, carriers must be able to offer Quality of Service (QoS) protection guarantees in the form of service level agreements (SLAs) that are at least as good as those offered today with T1/E1 access. Protection must be provided at every layer in the network—from the physical to the virtual—to successfully achieve this goal.

At the physical layer, the Metro Ethernet Copper Access solution offers resiliency in the form of a “Five-9’s” service guarantee. The MECA architecture is itself resilient, offering redundancy options on both the network and management planes. On the network plane, protocols such as 802.3ad link aggregation, spanning tree and rapid spanning tree can be used to provide protection against link and node failures in a metro-Ethernet network. Such methods not only provide protection, but they do so in a manner consistent with and interoperable across multiple vendors.

The multiple pairs in the bonded metro-Ethernet link provide additional resiliency against facility failures in the outside plant. For example, the loss of a copper pair, though affecting bandwidth, does not result in a service failure. Additionally, the MECA solution can offer further resiliency in multi-pair connections where aggregated pairs can be scattered across a large system, and the failure of a component in the system loses only the pairs associated with that component. By distributing the multi-pair group of an individual customer across a system, customers can even be protected against hardware failures in the central office. In addition to the increased resiliency, distributed bonding offers the benefit of no stranded pairs, which means that any copper pair anywhere in a system can be used for any bonded group.

In the virtual service layers, MECA employs the standard Ethernet Class of Service (CoS) framework to support tiered services. With CoS, individual services are assigned different priority values, which are then mapped to flows within the Ethernet switching infrastructure—from the edge through the core. Separate discard eligibility parameters are used to handle periods of congestion. SLAs can be configured using four flexible thresholds: Committed Information Rate (CIR), Excess Information Rate (EIR), Peak Information Rate (PIR) and Maximum Burst Size (MBS). The result is a solution that overcomes the limitations of DSL access multiplexers, and permits smooth migration to Multi-Protocol Label Switching (MPLS) technology.

Another advantage of the MECA QoS framework is its ability to help carriers deliver “stickier” services. Higher levels of customer satisfaction lead to “stickier” services, meaning business customers are less likely to seek alternative carriers for their data service requirements. Keeping customers satisfied, and loyal, is a key challenge for carriers today as they face and increased competitive threat from cable providers for lower speed data services, and wireless providers for traditional voice services. Metro-Ethernet can play a key role in keeping customers happy by enabling carriers to deploy a wider range of services, delivering them more quickly, and tailoring these services to more closely match specific customer needs.