ver fiber rings. Resilient Packet Ring also employs the SDH/ SONET concept of dual-counter-rotating rings, but in the case of Resilient Packet Ring, they are called ringlets. Ringlets connect Resilient Packet Ring stations at nodes where ingress and egress data traffic is dropped. MAC messages are used to direct the traffic in both directions around the ringlet. Bandwidth negotiation between the nodes is done by using a fairness algorithm. Furthermore, all the traffic on a given ringlet is assigned a class of service, with the standard specifying three classes: Class A (high) traffic exists to support low-latency and low-jitter applications, such as voice and video, requiring a pure committed information rate (CIR); Class B (medium) traffic combines CIR and excess information rate (EIR) metrics, introduc- ing queuing based on fairness; and Class C (low) traffic, used for basic Internet access, covers best-effort traffic, providing whatever bandwidth may be available. An important feature of Resilient Packet Ring is spatial reuse: Resilient Packet Ring removes the signal off the ringlet when it reaches the destination, allowing the freed space to carry additional traffic. (SHD/SONET, by comparison, uses the bandwidth around the entire ring.) The Overlay and Peer-to-Peer Models Compared The OTN represents a new generation of physical framework, and it will therefore undoubtedly replace the existing PDH and SDH/SONET infrastructures, support- ing WDM, greater bandwidth, and instant provisioning. GigE and 10GigE, offering the benefits of both low cost and familiar protocol solutions, will be favored by those seeking economical and rapid deployments. Both models have the support of strong communities, and we are therefore likely to see evidence of both going for- ward. We need to be able to control these networks, and that's the realm of the IP+optical control plane, which is the subject of the following section. The IP+Optical Control Plane The optical network is becoming an ideal IP transport infrastructure in both 