Abstract

Ring based optical Metropolitan Area Networks (MANs) are used to interconnect “network nodes” of service providers as well as “network nodes” of enterprises to those of service providers. For Internet traffic, these “network nodes” are primarily IP routers. A metro ring that interconnects IP routers consists of ring nodes interconnected by optical fiber. These ring nodes can be (i) Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Add/Drop Multiplexers (ADMs), (ii) packet switches that implement ring based MAC protocols, such as the Spatial Reuse Protocol (SRP),¹ which is one of the options proposed to the IEEE 802.17 group as a Reliable Packet Ring (RPR) solution, and (iii) Wavelength Division Multiplexed (WDM) Optical Add/Drop Multiplexers (OADMs). Owing to the importance of providing highly reliable service, all three types of ring nodes support fast restoration following fiber cuts or other failures. In this paper, after briefly describing the three rings in Section 2, we analyze the network throughput of the rings before and after a failure/restoration in Section 3.

© 2002 Optical Society of America