Abstract: A method and apparatus for scheduling the transmission of a number of data streams over a common communications link, where each of the data streams conforms to a corresponding set of flow control parameters. Each of the data streams to be transmitted on the communications link is stored in a corresponding queue. The status of each queue is maintained, and a target transmission time is calculated for each queue. Signals are then generated for each queue at a time at least after the target transmission time, and these signals are used to indicate to a corresponding queue that is can transmit a cell on the link. Upon reception of a corresponding signal, a queue then transmits at least one cell onto the communications link.

Abstract: A rights controlling concentrator (RCC) is an apparatus for separating and controlling "rights of receiving" and "rights of transmitting" of a group of stations or groups of stations on a ring-of-trees local area network. RCC elements perform collectively to separately control, limit and/or make available the "rights of receiving" and the "rights of transmitting" of a group of stations or groups of stations. Control of the "rights of receiving" ensures that its membership is only forwarded frames transmitted by an external station which has a destination within the membership, and that the external stations only be forwarded frames transmitted by the membership which have a destination within the external stations. Frames that are transmitted to a destination in one group traverse only stations within that group. Frames that are deemed by the RCC not to be of interest to any group of stations are withheld from that group by the RCC controlling both frame receiving and transmitting rights.

Abstract: In standard token-based LANs (e.g., FDDI, Token Ring) an equal share of the ring bandwidth is made available to each node. Certain nodes (e.g., bridges, routers, servers) require a larger representation (bandwidth) than other nodes. A surrogate (bridge/router) node is presented which achieves this in a standard compliant manner. The bridge/router may serve as a surrogate on each ring representing multiple stations from the other ring. The multiplicity of stations is adjusted either statically or dynamically to provide sufficient added bandwidth to the surrogate to reduce delay and packet loss characteristic of the conventional single station bridge or router. The increased bandwidth utilization and FDDI ring performance resulting from the implementation of this invention is transparent to the individual stations and the ring in a way that is advantageous to both single media and multimedia usages within defined network local and non-local areas.

Abstract: A method and apparatus allow the interoperability of a token ring packet data network managed by the timed-token protocol (FDDI-I) and a TDM network (FDDI-II) with a given bandwidth allocation assigned to the packet data timed-token protocol. Only a single token is used, and the delay and loss of packets which cannot be transmitted on account of limited bandwidth is reduced. The flow of packets into the slots of the communications ring following the TDM protocol is controlled by varying the amount of time in which the token is held by the interface between the two communication rings. That is, the time in which the token is held by the interface is a function of the number TDM slots allocated to the transmission of packet data.