3com Corporation

Leonard Schwartz

John A Flanders

William D Townsend

David C Ready

David Lipschutz

Thomas A Lemaire

Stephen L Van Seters

Paul J Giacobbe

Robert P Ryan

Ryan T Ross

Thomas V Radogna

Steven Van Seters

Quality of Service (&ldquo;QoS&rdquo;) variables for predetermined protocol Type data units are stored in a cache memory. For data units that are associated with a flow, thirteen bytes selected out of the Internet Protocol (&ldquo;IP&rdquo;) header are employed as at least a portion of a key to perform a cache lookup to obtain at least one Quality of Service variable from the cache. Both routing and QoS information may be stored in the cache for retrieval upon a single lookup operation.

Quality of service control mechanism and apparatus

A Receive Frame Processor (RFP) in a network bridge/router for receiving frame-characterizing information from other elements of the bridge/router and for generating plural code vectors which result in the selective processing of a received frame in software and/or hardware is provided. The received information is utilized in constructing code vectors representative of how a received frame is to be processed. Further data structures stored in conjunction with the RFP are indexed by the constructed code vectors and indicate whether the frame is to be processed in the RFP hardware, by software in an associated Frame Processor, or both. These data structures also indicate whether the port through which the frame was received is to be blocked to prevent misordering of received frames. If the frame is to be processed in software, the RFP generates a Receive Vector which is provided to the FP and which conveys the frame-characterizing code vectors to the FP. If the frame is to be processed in hardware by the RFP, a Transmit Vector is generated which contains information such as a mask of which transmit ports are to be utilized for forwarding the received frame, and information necessary for reconstructing a header for the received frame, including which encapsulation format is to be utilized for the frame.

Use of code vectors for frame forwarding in a bridge/router

At least a portion of the data units in a bridge/router device are analyzed for purposes of filtering by employing high speed logic circuits. A data unit is analyzed by such logic circuits by examining the header portion of the data unit, employing information obtained from the header portion to designate possible output ports for transmission of the data unit, examining a predefined per-port filter enable indicator to determine whether filtering is to be applied to the data unit, and applying filtering for each respective port for which the per-port filter enable indicator indicates that filtering is to be applied. Filtering is also implemented with logic circuits and executed at high speed. Filtering may be executed based on MAC address group, port group, combination MAC address and port group, protocol type, and non-unicast traffic frequency. Data units that cannot be analyzed by the logic circuits are analyzed by software.

Hardware filtering method and apparatus

A method and apparatus is disclosed for translating data link layer and network layer frame headers at speeds approximating the reception rate of frames on respective communication links. High-speed header translation is achieved via the use of a dedicated microsequencer which identifies the receive frame encapsulation type and the transmit frame encapsulation type and based on such identification, selects a processing routine which is then executed to translate the frame header. The microsequencer is employed to control the movement of control information and frame header and payload information from an input FIFO, through the dedicated header processor, and to an output FIFO. The headers of the respective frames are translated within the dedicated header processor to facilitate header translation at high speeds. Via use of the presently disclosed header translation apparatus, layer 2 and layer 3 header translations, as well as other header translation functions may be rapidly performed.

High speed header translation processing

Logic circuits are employed in a telecommunications bridge/router device to examine a received frame to determine which VLAN, if any, the frame is associated with. The protocol type, receive port identification, and receive VLAN tag are employed to determine the transmit port identification and transmit VLAN tag. A predefined table indicates which ports within the bridge/router are associated with the VLAN. The frame is excluded from transmission through the ports that are not associated with members of the respective the VLAN.

Growing community of inventors

Bedford, MA, United States of America

Leonard Schwartz