Lisa Pierce: Much to weigh with metro Ethernet services

Keeping Pace

Businesses interested in becoming early adopters of metropolitan and long-haul Ethernet services should consider the following criteria when evaluating providers:

— Ownership of the fibre: ILECs and large CLECs own their networks. Most providers that only offer Ethernet services don’t.

— Resiliency of the infrastructure: some providers provision service on redundant rings with standby service. Others provision service on a single strand, with no failover protection. Some carriers’ network management capabilities prevent over-subscription while others are not as sophisticated and may experience congestion.

— Performance warranties: Preliminary service-level agreements and service-level objectives exist, but metrics vary sharply by provider.

Three distinct types of service have emerged:

— Services aimed at the companies, typically offered as managed Layer-3 VPN services and include tunnelling, encryption and firewalls.

— Services targeted at the service provider and carrier market provide true Layer-2 Ethernet capabilities, and like their enterprise services cousins, are proprietary services managed on an end-to-end basis.

— At the very high end, transport-centric wavelength services targeted at carriers, value-added service providers and ultra-large companies provide pure, point-to-point bandwidth (OC-12, OC-48 and OC-192).

Providers that focus on serving enterprise customers typically offer a variety of services. In contrast, many new providers only offer Ethernet and/or wavelength service.

Even though Ethernet is a worldwide standard for LANs, all existing metro Ethernet services are managed by providers on an end-to-end basis and include the routers or cards to interconnect the LAN and metropolitan-area network (MAN). Customers have no choice of vendor equipment, and multi-carrier connectivity is only achieved through provider business relationships.

One of the stated goals of the recently formed Metropolitan Ethernet Forum is to specify the necessary interfaces to support inter-provider Ethernet MAN transparency, but the forum has just begun, making it too soon to speculate on a timetable for the implementation of a future specification.

Pierce is a research fellow at Giga Information Group Inc.. She can be reached at