Achieving The Promise of Carrier-grade Ethernet
Services in the data network are typically classified into 2 major categories: Committed Information Rate (CIR) and Excess Information Rate (EIR). A CIR service guarantees its user a fixed amount of bandwidth, whereas an EIR service offers best-effort only transport. Both types of services share a single capacity-constrained infrastructure. Both are further defined by additional parameters.
A carrier's return on investment is directly related to its ability to transport more service instances over a fixed capacity-constrained infrastructure, keeping Quality of Service high. It is further associated with its ability to offer a broad range of added-value services, such as IPTV, Voice, and VPN, whose requirements can widely vary and pose technical difficulties when sharing the same infrastructure.
With the above in mind, the carrier's objective is to offer a maximum amount of best-effort EIR services over its network while reliably serving its committed CIR services. To achieve this PBB/PBT and T-MPLS approaches largely under-provision network resources, in order to avoid a situation where a burst in best-effort traffic would jeopardize the ability to serve committed traffic, leading to costly penalties. An additional issue with best-effort access on data networks is fair allocation among clients. With PBB/PBT and T-MPLS, the amount of bandwidth available to a particular client greatly depends on the client's location and the prevailing traffic conditions. This limits the value customers attach to EIR services and undercuts carriers' opportunities to offer differentiated access to its excess capacity.
Performing traffic engineering in real-time is thus key to next-generation Ethernet transport. Additional qualities are required to make Ethernet a carrier-grade technology:
- Rich OAM: capacity optimization, path calculation and configuration, iterative optimization.
- Path protection: sub-50ms failover.
- Support for next-generation services: efficient provisioning of point-to-multipoint and multipoint-to-multipoint services.
Multi-vendor support, the ability to support a variety of Ethernet switches in the core, is a desirable attribute as it allows carriers to use inexpensive switches to build their metro transport network. Vendors such as Tejas Networks, Ethos Networks, and Nortel offer solutions which meet the above requirements, yet preserve Ethernet's simplicity and flexibility.
Read more about this topic: Connection-oriented Ethernet
Famous quotes containing the words achieving the, achieving and/or promise:
“If mothers are to be successful in achieving their child-rearing goals, they must have the inner freedom to find their own value system and within that system to find what is acceptable to them and what is not. This means leaving behind the anxiety, but also the security, of simplistic good-bad formulations and deciding for themselves what they want to teach their children.”
—Elaine Heffner (20th century)
“If mothers are to be successful in achieving their child-rearing goals, they must have the inner freedom to find their own value system and within that system to find what is acceptable to them and what is not. This means leaving behind the anxiety, but also the security, of simplistic good-bad formulations and deciding for themselves what they want to teach their children.”
—Elaine Heffner (20th century)
“I anticipate with pleasing expectations that retreat in which I promise myself to realize, without alloy, the sweet enjoyment of partaking, in the midst of my fellow citizens, the benign influence of good laws under a free government, the ever favorite object of my heart, and the happy reward, as I trust, of our mutual cares, labors, and dangers.”
—George Washington (1732–1799)