and without common points of failure. This means that Paths can be engineered. Capacity mismatches between physical network build and offered load can be compensated for. First-line resiliency in the form of protection can be delegated to the data plane. This is discussed further in the subsection on protection. When considering a network that uses both learning/bridging and configured behavior, the traffic associated with either forwarding behavior must be distinguishable such that best-effort traffic does not degrade engineered traffic, particularly as the traffic matrix can change dynamically in response to failures and/or maintenance activities. This can be achieved either by instantiating connection state into the switches or via use of class-based queueing and edge policing of class markings. The latter approach can be implemented via the 802.1p class-of-service feature, which has been extended in 802.1ad to include discard eligibility. This is similar to layer-3 QoS mechanisms that are designed around a LAN-style environment where a small amount of QoS-sensitive traffic requires priority over a large bulk of best-effort traffic. The combination of traffic-engineering-class queueing, CAC, and ESPs results in an environment where there is a correspondence between offered load and committed resources, thereby fostering the ability to offer real and measurable guarantees of performance. Put simply, traffic that is engineered and associated with CAC is given a higher priority than bridged traffic. In particular, the introduction of CAC connections now permits paths to be securely dimensioned SO that there is no congestive frame loss. This then provides Ethernet, rather than relying on another technology, with a mechanism to offer EPLs. In addition, it can be envisaged that schemes that allow for some overbooking of capacity can be implemented. We should of course note that many of the capabilities previously described can also be provided in other technologies that can provide engineered paths, but there are al