International Business Machines Corporation

Fujitsu Corporation

Robert A Sultan

Fabrice Jean Verplanken

Jean Louis Calvignac

Daniel Orsatti

Sushil Pandhi

Ajay Sahai

Claude Basso

Richard Harold Boivie

Douglas H Dykeman

Jean-Yves Le Boudec

Antoni B Przygienda

Zubao Yang

A data communications network includes a ring configured for spatial reuse, such as a resilient packet ring. A first bridge is coupled to the ring and to an end station such as an interworking bridge or router. A second bridge coupled to the ring learns an association between the first bridge and the end station by monitoring packets originated in the network by the end station and sent on the ring by the first bridge. The second bridge learns the association by obtaining an identifier of the first bridge and an address of the end station from received packets. When the second bridge receives packets destined for the end station, the packets are forwarded as broadcast transmissions on the ring if the association between the first bridge and the end station has not yet been learned, and are forwarded as unicast transmissions to the first bridge on the ring if the association between the first bridge and the end station has been learned.

Spatial reuse and multi-point interconnection in bridge-interconnected ring networks

A ring network provides transparent local area network (LAN) service by allocating respective proportions of data transmission capacity of the ring to different closed user groups (CUGs), each including a plurality of LAN clients. At each node of the ring, the use of a connected segment of the ring is monitored for both pass-through and locally-generated traffic by the LAN clients on a per-CUG basis. When it is detected that use of the connected segment for a CUG is approaching the allocated proportion, an active LAN client of the CUG is selected and sent a throttle message indicating that the LAN client is to reduce its data transmission rate. Rate monitoring for is accomplished using a 'leaky bucket' mechanism. A 'rate cache' identifying the active senders and their transmission rates can also be used in selecting a LAN client for receiving the throttle message.

Aggregate rate transparent LAN service for closed user groups over optical rings

This invention relates to the merging of data cells arriving at an Asynchronous Transfer Mode (ATM) switching node from data frames originating with a number of senders. As is standard in ATM networks, each originating frame is segmented into a series of cells each having Virtual Path Identifier (VPI) and a Virtual Channel Identifier (VCI) in its header portion. On arrival at each switching node, the VCI of the first cell of a frame is overwritten by a new outgoing VCI value that is used for all other cells of the frame. Thus, the actual movement of each cell through the network is controlled only by the cell's VPI, whereas the VCI field is used only to distinguish frames from each other. A feature of the invention is that it can accommodate Early Packet Discard in a simple way by associated any discard indication determined for a frame with the outgoing VCI value which also applies to all cells of the entire frame.

Merging of data cells in an ATM network

The present invention is an apparatus that manages Packet-Discard at a switch in an ATM network. The apparatus includes a table having a number of table addresses (or indexes). Each table address stores a record for incoming data cells of a frame. The records indicate whether data cells of the frame are be discarded. The number of possible cell identifiers is greater than the number of table addresses. The apparatus also includes a processor unit which receives a data cell having a cell identifier. The processor unit determines a table key, based on the cell identifier such that the table key is within the range of the table addresses. The processor unit then searches a record in the table associated with the table key to determine whether the data cell is to be discarded.

Statistical packet discard

Routing bandwidth-reserved connections in information networks

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Katonah, NY, United States of America

Robert A Sultan