Reliability Evaluation of SBC's "Fiber To The Node" NetworkSBC is in the process of creating a new network by deploying fiber deeper into neighborhoods and using IP technology to deliver video, voice, data and other advanced services and applications over a single network connection. The services could be accessed and shared via any number of IP-enabled household devices, such as TVs, set-top boxes, PCs, PDAs or phones. An IP network can provide a highly flexible infrastructure for fast delivery of advanced services, while also reducing maintenance and upgrade costs when comparedThe strategy is to drive fiber much deeper into local neighborhoods. Two complementary networks is being build. First for new network builds, such as developing subdivisions, we would build and deploy Fiber to the Premises (FTTP). In existing neighborhoods, Fiber to the Node (FTTN) technology will be used to run fiber much deeper in the network to nodes that serve 300 to 500 homes. From the nodes to each home or small business, existing network connections will continue to be used.The FTTN/FTTP strategy would deliver an optimal balance of network capability, cost, speed of deployment, reliability, and convenience for customers. Reliability is one of the key aspects of this new architecture, especially since it will deliver delay sensitive voice and video services in addition to data services.This paper will provide the results of most recent FTTN network reliability studies in SBC. These will include availability/downtime analysis of various segments of the network from the Residential gateway, to the fiber nodes in the neighborhood as well as the network equipment in the Central Offices and Video Headend offices. Attached figure shows a high level view of the various segments of the network. We will show the results of our analysis for the following sub-networks:1. FTTP and its connection to FTTN,2. FTTN Access VDSL3. FTTN Metro Transport network4. FTTN Video Super Headend office network5. FTTN Video Headend Office network6. FTTN Data backbone networkThe paper will also address layer 1 and layer 2/3 restoration and protection mechanisms as they apply to the FTTN network, and compare applicable protocols (1+1 & M:N redundancies, MPLS, VRRP, etc.) in light of the services they are protecting, and the customer impact they will have.We will present the Availability numbers (# of 9's) for various segments relative to each other, showing how the access network has a major impact on the reliability (since it has more single points of failure), while showing the stringent requirement for the backbone video network.

© 2006 Optical Society of America

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