Ethernet as a service (EaaS) is the use of high-bandwidth, fiber optic media such as Packet over SONET (PoS) to deliver 10 Mbps, 100 Mbps or even 1000 Mbps Ethernet service to one or more customers across a common bidirectional broadband infrastructure. Ethernet, a networking technology defined in IEEE 802.3 and related specifications, is best understood as a carrier sense multiple access/collision detect (CSMA/CD) form of baseband networking. The service arrives to the recipient via a broadbandchannel that it must accommodate, manage, and service within its overall infrastructure.
Key concerns for implementation include careful provision and management of bandwidth so that one user's consumption of best-effort Internet services and high-bandwidth realtime services (such as voice, video on demand, or streaming media) does not lead to resource contention or performance or stability problems. Most carriers address these issues by designing their infrastructure to support multiple Ethernet overlays across a shared optical layer that uses wavelength division multiplexing (WDM) or dense wavelength division multiplexing (DWDM) to accommodate the load and to achieve appropriate economies of scale and cost per bit of communications.
At the service provider level, Ethernet services to consumers are usually separated from those to businesses, where consumer Internet access delivery may also be separated from IPTV and video on demand services. This separation requires construction of multi-service Ethernet-based metro services.(See Tom Nolle's carrier backbone transport tip cited for related information).