Abstract: A node in a packet network such as an ATM network receives a plurality of traffic classes and outputs them to an output link. The invention relates to a technique of scheduling the traffic classes in a time linked fashion at the node based on the bandwidth allocated to each traffic class. Traffic scheduling based strictly on priority may not satisfy delay and loss guarantees of traffic classes when there are many classes with many different priority levels. The rate based scheduling in a time-linked fashion solves these problems by limiting the bandwidth to which each class is accessible. According to one embodiment, the invention uses timeslot values and a linked list of the traffic classes.

Abstract: A random early detection (RED) methodology controls and avoids congestion in a packet network by anticipating congestion and periodically signaling congestion by marking or discarding packets. Sources respond to marked packets by slowing their transmission rates. Enhancements to the basic RED methodology improve performance and reduce buffer requirements in network switches. RED decisions are made as packets leave queues in switches, and RED marks can be accelerated from one packet to another. System response is linearized, and the RED process specifies a marking rate or period rather than a marking probability. A control algorithm permits a single queue operating point. Specific measures are provided for selecting which connection should be marked, and per-connection weight parameters allows customized treatment of connections.

Abstract: A method for scheduling low delay-jitter cell transmissions for multiple streams of Asynchronous Transfer Mode (ATM) traffic from a node is disclosed. Cells belonging to multiple streams of virtual circuits (VCs) and virtual paths (VPs) are stored in the node's memory. A link controller scans a time-space map to determine when a given stream will be sampled and its cells transmitted from the memory out over a link. The time-space map is comprised of time-slots whose spatial positions within the map correspond to times at which cells can be transmitted. A scattering technique, based on reverse-binary or other mapping schemes, ensures that each given stream occupies time-slots that are well-spaced within the time-space map. This ensures that cells belonging to a given stream are transmitted at well-spaced intervals of time.

Abstract: In an ATM network, the physical resources are shared by many connection and the bandwidth is allocated virtually to each connection. The connection admission control (CAC) algorithm uses traffic descriptors, desired quality of service (QOS) parameters etc., to compute a required bandwidth for a requested connection by which it makes a decision to admit or reject the connection. For admission control for a requested VBR connection, two required bandwidths are calculated in two different ways, both of which take into consideration impacts of CBR traffic which is being serviced. The admission decision is based on the lesser of the two bandwidths.

Abstract: The invention resides in a precise technique for determining the equivalent bit rate (EBR) of a variable bit rate (VBR) ATM connection. The technique extends a known single-source method developed by Gibbens and Hunt. The new technique applies to shared facilities and hence exploits the statistical-multiplexing gain. The calculation of the EBR is quite fast and is therefore suitable for real-time call-admission control in ATM switches. The admission criteria may be based on either the cell loss or cell delay.

Abstract: In an ATM network, the physical resources are shared by many connection and the bandwidth is allocated virtually to each connection. The connection admission control (CAC) algorithm uses traffic descriptors, desired quality of service (QOS) parameters etc., to compute a required bandwidth for a requested connection by which it makes a decision to admit or reject the connection. Unlike any prior CAC, the CAC of the invention for constant bit rate (CBR) service takes also into consideration the cells delay variation (CDV) for calculating the required bandwidth.

Abstract: A novel flexible scheduling mechanism which can be used in an ATM switch is disclosed. The new scheduling mechanism allows an ATM switch to handle ATM as well as STM traffic. Video, voice, and data traffic have different service requirements. It is desirable that an ATM switch also be able to handle STM traffic. The invention uses an STM scheduler and an ATM scheduler. A slot reservation technique is used in an STM scheduler in which certain slots can be reserved for STM traffic only. The STM scheduler has priority over the ATM scheduler so that STM traffic is handled with minimum delay to assure synchronous treatment of traffic with small cell delay variation.