Abstract: A method and apparatus for determining a shortest path between a source node and a destination node in an optical network of nodes interconnected with optical transmission links is disclosed. A wavelength graph is used to represent an optical network as a set of electronic nodes and optical channel nodes corresponding to the network nodes with a set of internal links and optical channel links. The electronic node represents the electronic switching fabric that interconnects OEO equipment within a physical node. A single-source shortest path algorithm (e.g., Dijkstra's algorithm) is applied to the wavelength graph to determine a shortest path. The transformation of the network representation to include the electronic node greatly reduces the number of links in the wavelength graph and significantly increases the computational efficiency.

Abstract: A method and apparatus for determining a shortest path between a source node and a destination node in an optical network of nodes interconnected with optical transmission links is disclosed. A wavelength graph is used to represent an optical network as a set of electronic nodes and optical channel nodes corresponding to the network nodes with a set of internal links and optical channel links. The electronic node represents the electronic switching fabric that interconnects OEO equipment within a physical node. A single-source shortest path algorithm (e.g., Dijkstra's algorithm) is applied to the wavelength graph to determine a shortest path. The transformation of the network representation to include the electronic node greatly reduces the number of links in the wavelength graph and significantly increases the computational efficiency.

Abstract: A central controller, such as an RF distribution shelf (RFDS) of a hybrid fiber/coax (HFC) access system, keeps track of the different channels assigned to different remote units, such as the network interface units (NIUs) of the HFC system. Information about the different channel assignments (e.g., for upstream channels) is broadcast to the remote units as part of the overhead bits in each of the downstream channels. Each remote unit monitors the broadcast messages and, over time, updates its own version of the data structure containing the channel assignments, as appropriate. In one embodiment, the central controller also transmits a second type of broadcast message indicating when changes in the channel assignments occur.

Abstract: A data system, such as a computer network or a telecommunications system, has a base station and a number of nodes called network interface units (NIUs). Each NIU is assigned to one of a number of groups of NIUs. The base station transmits special data to the NIUs indicating which groups of NIUs are currently authorized to transmit upstream messages to the base station, where only the authorized NIUs are allowed to transmit upstream messages. When message collisions in the upstream direction becomes a problem, the base station can reduce the number of NIU groups that are authorized at any given time to transmit upstream messages, in order to attempt to reduce the rate of message collisions. In one possible embodiment, each NIU is assigned horizontal and vertical group words that identify to which group it is assigned. The special data contain additional horizontal and vertical code words that are monitored by the NIUs.