Abstract: The virtually unused switching fabric of an OC-192 SONET transport node is used to greater effect when used as a switching node. Several of the nodes are used in the central office (CO) of a communication network. Each node terminates an optical network link and each node hosts a number of transport cards that also terminate different optical network links. The nodes provide space-switching between the cards. Additionally an intra-CO optical link is provided that interconnects the nodes to allow traffic flow between any of the optical network links in the CO that are terminated by transport cards or the nodes.

Abstract: The virtually unused switching fabric of an OC-192 SONET transport node is used to greater effect when used as a switching node. Several of the nodes are used in the central office (CO) of a communication network. Each node terminates an optical network link and each node hosts a number of transport cards that also terminate different optical network links. The nodes provide space-switching between the cards. Additionally an intra-CO optical link is provided that interconnects the nodes to allow traffic flow between any of the optical network links in the CO that are terminated by transport cards or the nodes.

Abstract: A new architectural arrangement for network elements deployed in a central office (CO) is disclosed. The architectural arrangement involves dividing the network elements into an optical layer comprised of elements that have optical signal interfaces and switch optical signals, an opto-electrical layer comprised of elements that have optical signal interfaces and switch electrical signals, and an electrical layer comprised of elements that have electrical signal interfaces and switch electrical signals. The opto-electrical layer connects the optical and the electrical layer, and also connects lower-rate optical links into the CO. This layered architectural arrangement allows for more efficient use to be made of the small number of high-rate ports supported in the optical layer, and for the off loading of switching responsibility from both the optical and the electrical layers. This, in turn, improves the overall performance and capacity of the CO.

Abstract: A method for distributing synchronization in an optical communications network is disclosed. In order to keep costs to a minimum, the method consists of deploying requisite primary reference source (PRS) clocks only at those sites having access to more or less than two independent synchronization distribution paths (SDPs). PRS clocks are also preferably installed at sites located substantially far from a site already equipped with a PRS clock. As a result, a small number of PRS clocks end up being installed, leading to substantial cost savings for the telecommunications service provider. Subsequently, a building integrated timing supply (BITS) system is deployed at all sites comprising more than one network element. The BITS has two timing inputs, a primary and a secondary timing reference, selected from two of the accessible SDPs.