Digital Equipment Corporation

Top Layer Networks, Inc.

Cabletron Systems, Inc.

Enterasys Networks, Inc.

Digital Equipment Corp., Patent Law Group

Barry A Spinney

Henry S Yang

William R Hawe

K K Ramakrishnan

Rajendra K Jain

Robert E Thomas

Robert J Simcoe

George Varghese

Nigel T Poole

Krishna Narayanaswamy

Amar Gupta

Peter L Higginson

Theodore L Ross

Richard L Szmauz

Graham Cobb

John Bassett

Charles W Kaufman

Butler W Lampson

Gregory M Waters

Cary B Robins

Joseph J Tardo

Luc A Pariseau

Joseph H Brown, Iv

Scott William Nolan

A process and system for flexibly switching connections of data packet flows between nodes of data processing system networks by dividing data packets into cells and logically linking these cells on multiple queues of linked pointer lists.

System and process for flexible queuing of data packets in network switching

A network device for interconnecting computer networks, the device including a bridge having a plurality of ports through which network communications pass to and from the bridge, the bridge also including a first interface enabling a user to partition the plurality of bridge ports into a plurality of groups, wherein each group represents a different virtual network, wherein the bridge treats all ports within a given group as part of the virtual network corresponding to that group and the bridge isolates the virtual networks from each other, whereby any communications received at a first port of the bridge are directly sent by the bridge to another bridge port only if the other bridge port and the first bridge port are part of the same group.

Virtual LANs

A process and system for switching connections of data packet flows between nodes of data processing system networks operating on diverse protocols according to the application layer information on the data packets. The process retrieves and hashes the header information to from an index into memory where a flow tag pointer is stored. The flow tag points to flow switching information that directs the forwarding of the packet. The switching information is sent along with the packet data to direct the forwarding state information about the flow is updated in the flow switching information. The hash function includes a multiplication and division by polynomials forming a hash result and a signature result. Both hash and signature are used to ensure that the information retrieved is valid. If invalid, The pre hashed header information is parsed to determine the forwarding information. This forwarding information is stored for later use and the appropriate flow tag pointer is stored in the hash result index.

System and process for GHIH-speed pattern matching for application-level switching of data packets

In a data communication switch, process and apparatus for tracking the number of data bytes associated with data flow that is part of a session and automatically lowering the priority given to the transmission of the remainder of a flow once a certain threshold has been reached that indicates that the flow is part of a bulk e-mail or other bulk file transfer.

Application-level data communication switching system and process for automatic detection of and quality of service adjustment for bulk data transfers

A process and system for switching connections of data packet flows between nodes of data processing system networks operating on diverse protocols according to the application layer information on the data packets.

System and process for application-level flow connection of data processing networks

A network device for interconnecting computer networks, the device including a bridge having a plurality of ports through which network communications pass to and from the bridge, the bridge also including a first interface enabling a user to partition the plurality of bridge ports into a plurality of groups, wherein each group represents a different virtual network, wherein the bridge treats all ports within a given group as part of the virtual network corresponding to that group and the bridge isolates said virtual networks from each other, whereby any communications received at a first port of the bridge are directly sent by the bridge to another bridge port only if the other bridge port and the first bridge port are part of the same group.

Device for partitioning ports of a bridge into groups of different

A translation is performed by using a programmable hashing technique on an input number to generate a hashed number. A subset of the hashed number bits are used to index a first hash table. In first hash table locations where a hash collision does not occur, the first hash table entry contains an index into an output table which contains the desired translated output number. In first hash table locations where a hash collision occurs, the first hash table entry contains a pointer to a first resolution table area in a second hash table. The first resolution table area contains entries which are indexed by additional bits selected from the hashed number in accordance with a mask field in the first hash table location. If collisions occur in the resolution table a new resolution table is created and the process is repeated. The resolution process thus proceeds in stages until all input numbers have been translated.

Hash-based translation method and apparatus with multiple level

In accordance with principles of the invention, a frame removal mechanism for token ring networks is disclosed. The disclosed system uses strip delimiter frames. The system transmits one or more information frames onto a computer network. The system further transmits one or more strip delimiter frames onto the computer network after the information frame transmission. The system detects strip delimiter frames on the computer network, and strips information frames received from the computer network after the information frame transmission is begun and until one of the strip delimiter frames is detected.

Frame removal mechanism for token ring networks

Frame processing apparatus, and a related method for its operation, for use in a station connected to a token ring network, to ensure rapid stripping of frames from the network without reference to source addresses in the frames, and in spite of the possible presence of extraneous no-owner frames on the network. The adverse effects of extraneous no-owner frames are avoided by any of three techniques. First, transmitted information frames are preceded by a start strip delimiter frame and followed by an end strip delimiter frame. The process strips all incoming frames (except tokens and ring initialization frames, which are specially handled), but does not count the stripped frames until the start strip delimiter frame is detected. Therefore, extraneous frames preceding the transmitted information frames will be stripped but not counted, and all of the transmitted frames will be stripped. In another approach, an estimated stripping time is used to terminate stripping. Frame counters are not then needed and extraneous frames will be stripped prior to the desired information frames. A third approach is to preset the transmitted frame count to some selected value, so that more frames will be stripped than were transmitted. Thus, preceding extraneous frames will be stripped, but the end strip delimiter will still terminate stripping and preclude overstripping.

Frame removal mechanism for token ring networks using one or more start

A system for stripping frames transmitted by a station on a token ring network is disclosed. During operation of the system, the station receives a grant of permission to transmit onto the network. In an example embodiment, the grant of permission is a token. After receipt of the grant of permission to transmit, the station transmits one or more information frames onto the network. Upon transmission of the information frames, the station stops forwarding frames received from the network, thus removing received frames from the network. Removing received frames from the network is referred to as `stripping`. Following transmission of the information frames, the station transmits an end strip delimiter frame onto the network. Upon receipt of the end strip delimiter frame, the station terminates stripping. In an example embodiment, the system is used in a bridge station, the bridge station connecting a first network with a second network.

Frame removal mechanism using end delimiter frames for token ring

A way of doing source address and destination address lookups is described, as may be used in a packet data communication system. A way of searching a relatively large database is described, using a combination of programmable hash algorithms, binary search algorithms, and a small content-addressable memory (CAM). The technique is efficient in space, time and cost, compared to prior methods. For example, prior methods using conventional binary reads may have used thirteen reads, whereas this technique requires on average two reads, with a worst case of four reads.

Address lookup in packet data communications link, using hashing and

A technique for establishing and maintaining full duplex communication between two stations connected to a token ring network, without physically reconfiguring the station connections or otherwise disturbing the network. Each station continually performs a two node test to ascertain whether there are only two active stations on the network, and updates a two node flag that indicates whether or only two active stations are present. The two node test uses both upstream neighbor and downstream neighbor addresses to update the two node flag, and requires validation of either one of these addresses if the other one of them appears to have changed since the previous observation. A concurrently running full duplex control process uses the two node flag and other conditions to decide whether to initiate or continue transition to full duplex mode. The control process uses an exchange of full duplex request and acknowledgment frames and completes the transition to full duplex mode when each station has transmitted and received a Restricted Token.

Negotiation protocol for establishment of full duplex communication on a

A packet data communication network employs a local switch, router or bridge device functioning to transfer packets between segments of a larger network. When packets enter this device, an address translation is performed to generate local source and destination addresses which are much shorter than the globally-unique addresses contained in the packet as dictated by the protocol. These local addresses are inserted in a header that is added to the packet, in addition to any header already contained in the packet. This added header travels with the packet through the local switch, router or bridge device, but then is stripped off before the packet is sent out onto another network segment. The added header may also contain other information, such as a local name for the source and destination segment (link), as well as status information that is locally useful, but not part of the packet protocol and not necessary for transmission with the packet throughout the network. Local congestion information, results of address translations, and end-of-message information, are examples of such status information.

Packet format in hub for packet data communications system

A system for stripping frames transmitted by a station on a token ring network is disclosed. During operation of the system, the station receives a grant of permission to transmit onto the network. In an example embodiment, the grant of permission is a token. After receipt of the grant of permission to transmit, the station transmits one or more frames onto the network. The station counts the number of frames transmitted onto the network. The count of frames transmitted onto the network is the `frame count`. Upon transmission of the frames, the station stops forwarding frames received from the network, thus removing received frames from the network. Removing received frames from the network is referred to as `stripping`. Following transmission of the information frames, the station counts the number of frames stripped from the network. The count of frames stripped from the network is the `strip count`. When the strip count equals the frame count, the station terminates stripping. In an example embodiment, the system is used in a bridge station, the bridge station connecting a first network with a second network.

Frame removal mechanism using frame count for token ring networks

A station transmits a sequence of one or more frames on a token ring, keeping count of the frames transmitted. At the end of the transmitted frame the station originates onto the ring one or more coded marker frames and finally transmits a token. After the station transmission is begun, the station strips from the ring all the frames it receives, decrementing its count for each properly stripped frame, until either its count is reduced to zero or one of its marker frames is detected.

Growing community of inventors

Wayland, MA, United States of America

Barry A Spinney