3com Corporation

David C Ready

John A Flanders

William D Townsend

Leonard Schwartz

Stephen L Van Seters

Christopher P Lawler

David Lipschutz

Thomas A Lemaire

Paul J Giacobbe

Robert P Ryan

Ryan T Ross

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

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.

Method and apparatus for VLAN support

A method and apparatus for increasing the throughput of a communications internetworking device. The method involves the generating, by internetworking device hardware, of a predetermined code vector in response to the current state of the communications internetworking device and information contained in a data packet received by the internetworking device. In response to the hardware generated predetermined code vector, a predetermined software routine is executed by a microprocessor in the internetworking device which controls how the data packet is to be transmitted to its destination. By using hardware to generate the code vector, time is saved over having software determine how the internetworking device is to handle the data packet.

Packet characterization using code vectors

A method and apparatus for increasing the throughput of a communications internetworking device using concurrent reception and transmission of data packets. The method involves the beginning of a retransmission by the communications internetworking device, to a destination network, of a frame undergoing reception by the communications internetworking device, from a source network, prior to the completion the reception of the frame from the source network by the communications internetworking device.

Method and apparatus for the concurrent reception and transmission of

An internetworking device providing enhanced packet header translation for translating the format of a header associated with a source network into a header format associated with a destination network of a different type than the source network. The device includes a memory for storing an address portion of a received packet header in a first block of buffer locations and the remainder of the received packet in a second block of buffer locations, spaced from the first block of buffer locations by a gap. The gap permits supplemental header information to be written into the buffer when necessary for translation. The device further includes a split memory, having an SRAM portion and a DRAM portion allocated to each buffer, with at least the address portion of a received packet and the gap located in the SRAM portion, so as to optimize the translation performance of the device.

Growing community of inventors

Westwood, MA, United States of America

David C Ready