When Ethernet switches first were employed in the telco central office, existing Layer 2/Layer 3 switches for the LAN were simply scaled up to offer more ports and faster speeds per port, and in many cases that worked just fine. But the development of new standards for packet prioritization and fault resilience, the product of such organizations as IEEE, Internet Engineering Task Force, and Metro Ethernet Forum, has tasked the network-interface OEM with new requirements for service-aware support at the network demarcation point.

By relying on Ethernet as the underlying common Layer 2 protocol, service providers not only flatten their own networks, but also allow their customers to enable unified services across multiple operators. One access device thus can link with many operators.

New generations of switch, MAC, and physical-layer chips for Ethernet, such as Vitesse Semiconductor Corp.’s Serval switch, address the new QoS and timing demands. Serval integrates a MIPS processor to support advanced features such as multiple packet queuing policies, and has an on-board ternary CAM memory to aid in Layer 3 classification. As a result the switch can support any combination of MPLS, MPLS-TP, and traditional bridging.

Network timing is critically important at the edge of the network, for insuring consistent and accurate SLAs. Serval supports 1588v2