3com Corporation

Stephen L Van Seters

Christopher P Lawler

John A Flanders

David C Ready

Stephen A Hauser

Edward A Heiner, Jr

Mark A Sankey

G Stodel Friedman

James Scott Hiscock

David J Husak

David Lipschutz

Joris Johannes Maria Wils

William D Townsend

Robert P Ryan

Leonard Schwartz

Shannon Q Hill

Ryan T Ross

Robert Millard France

John Joseph Harrison, Jr

Thomas A Radogna

A Logical Switch Set (LSS) is provided comprising two or more switches that act as a single packet forwarding device with specific connection rules. The single packet forwarding device is a single logical unit. The LSS may be used as either a redundant switch set (RSS) or as a Load Sharing Switch Set (LSSS). The maximum throughput of the LSSS increases with each additional switch. A LSSS can only interconnect with the other devices via trunked links that contain at least one physical connection to each switch. The RSS may include a trunk link connection and a resilient link connection

Logical switch set

A method and apparatus for receiving and transmitting network frames via an internetworking device, in which a first portion of a total number of buffers is allocated among port-dedicated buffer pools, and a second portion is placed in a common pool accessible by any of the network ports. A frame is received at a first port, and a list of buffers accessible only by that port is referenced to identify buffers not already in use. A second list of buffers in the common pool is referenced to identify unused buffers for use if insufficient unused buffer space is available in the port-dedicated buffer pool. Frame data is then stored in the identified buffer(s). Upon retransmission, the buffer(s) used to store the. transmitted frame is released to the port-dedicated and/or common buffer pool(s).

Method and apparatus for internetworking buffer management

A method and cache management for a bridge or bridge/router providing high-speed, flexible address cache management. The unit maintains a network address cache and an age table, searches the cache for layer 2 and layer 3 addresses from received frame headers, and returns address search results. The unit includes an interface permitting processor manipulation of the cache and age table, and supports a 4-way set associative cache to store the network addresses. A plurality of functions implemented in hardware enables software manipulation of the associated cache. Four cache operating modes are selectable. The unit can identify and select destination ports within a Load Balanced Port Group for frame forwarding. The unit utilizes Virtual LAN identification in conjunction with a MAC address for lookup in the cache. A cyclic redundancy code for each address to be looked up in the cache is used as an index into the cache. If a cache thrash rate exceeds a predetermined threshold, CRC table values can be rewritten. Four time-sliced cache lookup units are provided, each consisting of a cache lookup controller for comparing a received network address to an address retrieved from an identified cache set.

High speed cache management unit for use in a bridge/router

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 are disclosed which permit multipoint trunking among a plurality of network devices connected by a trunk comprising at least two physical links. A trunk control message protocol (TCMP) is described which assures that message traffic may be delivered to the respective devices over the individual links of the trunk prior to inclusion of the respective links as active links in the trunk. The trunk acts as a single network port for each of the devices utilizing the trunk and is layered over a plurality of media access control (MAC) ports which interface to the respective links. The disclosed trunking technique and apparatus permit the bandwidth of the trunk to be increased in increments through the addition of links to the trunk.

Method and apparatus for multipoint trunking

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 receiving and transmitting network frames via an internetworking device, in which a first portion of a total number of buffers is allocated among port-dedicated buffer pools, and a second portion is placed in a common pool accessible by any of the network ports. A frame is received at a first port, and a list of buffers accessible only by that port is referenced to identify buffers not already in use. A second list of buffers in the common pool is referenced to identify unused buffers for use if insufficient unused buffer space is available in the port-dedicated buffer pool. Frame data is then stored in the identified buffer(s). Upon retransmission, the buffer(s) used to store the transmitted frame is released to the port-dedicated and/or common buffer pool(s).

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

Stow, MA, United States of America

Stephen L Van Seters