Digital Equipment Corporation

Cabletron Systems, Inc.

Enterasys Networks, Inc.

Digital Equipment Corp., Patent Law Group

Ciena Luxembourg S.a.r.l.

Harvey, George A.

Hawe, William

Koning, Gerard

Miles, Kevin

Lauck, Anthony

Harper, John

Oran, David

William R Hawe

Henry S Yang

Radia Joy Perlman

Anthony G Lauck

Barry A Spinney

Amar Gupta

Butler W Lampson

G Paul Koning

Charles W Kaufman

Kadangode K Ramakrishnan

John A Harper

Jerry D Hutchison

Mark F Kempf

Floyd J Backes

Joseph J Tardo

David J Mitton

Jerry Hutchison

Richard W Graham

Morrie Gasser

Gregory M Waters

Siman-Tov Ben-Michael

Philip P Lozowick

B J Herbison

George A Harvey

Luc A Pariseau

David R Oran

Michael W Carrafiello

Kevin Miles

Ching S Lee

Shirish S Sathaye

Gerard Koning

Robert E Thomas

Brendan Hannigan

Paul D Callahan

Bruce A Schofield

Stephen Suryaputra

Andre N Fredette

Indermohan S Monga

David Oran

John Harper

A technique for logically connecting local communications networks (CNs) that may be separated by wide area networks containing routers and other network components. A logical link is formed between two devices called tunnelers, such that, once a tunnel has been established between two CNs, other devices on the CNs can communicate. The tunneling mechanism of the invention requires that each CN have only one active tunneler at any particular time, referred to as the designated tunneler, and each of the tunnelers is configured to have knowledge of the identities of the other tunnelers. A tunnel is established after a successful exchange of messages between two tunnelers, and then traffic may be forwarded through the tunnel in a transparent manner. The tunneling mechanism permits messages to be forwarded between CNs separated by a wide area network containing routers. Moreover, the mechanism permits filtering of traffic, such that only selected types of traffic, or messages for selected destinations or from selected sources, are forwarded through tunnels. The tunneling mechanism inherently precludes the formation of closed communication loops. An alternate embodiment of the invention optimizes the configuration process for particular network topologies.

Method and apparatus for transparently bridging traffic across wide area networks

A method for connecting a first communication system with a third communications system, by passing through a second communications system, is disclosed. A first frame is received from the first communications system, where the first frame has a multicast address as a destination address. The multicast address requires the frame to be transmitted onto the second multicast address is translated into a functional address. The functional address is written into a second frame, and the second frame is transmitted onto the second communications system. A station receiving the second frame translates the functional address into a multicast address and writes the multicast address into the destination address field of a third frame, and transmits the third frame onto the third communications system.

Many to few group address translation through a network bridge

A technique for logically connecting local area networks (LANs) that may be separated by wide area networks containing routers and other network components. A logical link is formed between two bridge-like devices called tunnelers, such that, once a tunnel has been established between two LANs, other devices on the LANs can communicate as if the tunnel were a bridge. The tunneling mechanism of the invention requires that each LAN or extended LAN have only one active tunneler at any particular time, referred to as the designated tunneler, and each of the tunnelers is configured to have knowledge of the identities of the other tunnelers. A tunnel is established after a successful exchange of messages between two tunnelers, and then traffic may be forwarded through the tunnel in a transparent manner. The tunneling mechanism permits messages to be forwarded between LANs separated by a wide area network containing routers. Moreover, the mechanism permits filtering of traffic, such that only selected types of traffic, or messages for selected destinations or from selected sources, are forwarded through tunnels. The tunneling mechanism inherently precludes the formation of closed communication loops. An alternate embodiment of the invention optimizes the configuration process for particular network topologies.

Method and apparatus for transparently bridging traffic across wide area

A technique for modifying the IEEE 802.3 standard for selecting backoff times in a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) network, in the event that a collision is sensed by a node that has captured the network communication channel. If there is a small number of active nodes on the network, one node may capture the channel and the standard backoff algorithm makes it increasingly unlikely for another node to transmit. The new technique provides for less aggressive, i.e. longer, backoff times before at least the first retransmission attempt made by a node that has captured the channel. Three specific examples of the technique are disclosed. Even though the invention represents a departure from the standard CSMA/CD backoff algorithm, the overall average backoff times provided by the invention can be selected to be consistent with the average times provided by the standard. Moreover, nodes using the invention interoperate successfully with nodes that do not.

Method and apparatus for use in a network of the ethernet type, to

A technique to facilitate decryption processing of information packets transmitted over a communication network after encryption in accordance with a specific network protocol, the details of which may be subject to later change as standards are developed or modified. Programmable registers are used in the decryption process to hold information for identifying an incoming information packet as being subject to the specific protocol and requiring decryption, and identifying a starting location of a data field to be decrypted. Specifically one programmable register contains a first offset locating an identifier field in the packet, in which a cryptographic identifier will be found if the packet is one conforming to the protocol; another programmable register contains a cryptographic identifier value that will be found in the identifier field if decryption is to be performed, and a third programmable register contains a second offset to locate the beginning of a data field to be decrypted.

Method and apparatus for end-to-end encryption of a data packet in a

A technique for modifying the IEEE 802.3 standard for selecting transmit-to-transmit interpacket gap (IPG) intervals in a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) network, to provide fairness and good channel utilization in the event that a node has captured the network communication channel. If there is a small number of active nodes on the network, one node may capture the channel and the standard backoff algorithm makes it increasingly unlikely for another node to transmit. The new technique provides for use of a longer interpacket gap (IPG) interval to be used by a node that has been initially unsuccessful in contention for the channel, thereby ensuring that the other node may continue to transmit back-to-back data packets without interruption or collision. After a preselected time interval, the nodes reverse their roles by selecting the opposite IPG intervals. The initial receiver now selects the shorter IPG interval and captures the channel for the preselected time interval.

The apparatus stores a manual flag having a stored manual flag logic value, and the manual flag is stored in a first non-volatile memory. The apparatus stores a trusted flag having a stored trusted flag logic value, and the trusted flag is stored in a second non-volatile memory. The apparatus is connected to a computer network for performing a first boot-up operation. The apparatus learns an address of a neighbor apparatus connected through the communications network. The apparatus is responsive: to the manual flag, and to the trusted flag, and to the first boot-up operation, and to learning a neighbor address of the neighbor apparatus, for configuring an address of the apparatus from an identifier stored in a third non-volatile memory, and from the neighbor address, and for changing the stored trusted flag logic value to a second logic value. Also the apparatus chooses, responsive to the manual flag, between using a manually loaded address or performing the configuring an address. Additionally, the apparatus decides, responsive to a neighbor trusted flag learned by communicating with the neighbor apparatus through the communications network, to use the neighbor address of the neighbor apparatus in configuring an address of the apparatus.

Automatic assignment of addresses in a computer communications network

A multicast connection arrangement is provided by which a source node may establish multicast virtual circuits to a group of destination nodes of an arbitrary-topology network using a single procedure, and may subsequently modify those circuits, i.e., add or delete destination nodes, with a single, related procedure. The arrangement includes a multicast setup packet for opening the multicast virtual circuits, the packet containing a multicast identifier field, a virtual circuit field and a destination field identifying a list of desired destination node addresses. The multicast setup packet may be also used to add destination nodes to the circuits while a multicast delete packet is used to delete nodes from the circuits. When adding nodes to the multicast virtual circuits, a topology analysis process is provided to prevent the formation of an unstable network topology.

Virtual circuit manager for multicast messaging

A frame having a desired destination address written into the destination address field of the frame is transmitted onto a first communications system, the frame is received by the apparatus, the frame is transmitted by the apparatus onto a second communications system with a second destination address written into the destination address field of the second frame, and also the desired destination address is written into a predetermined field of the second frame along with an indicator. The indicator is capable if being interpreted by a receiving station to mean that the desired destination address is written into the predetermined field of the second frame.

Encapsulation of an address within a forwarded frame in a computer

A method for connecting a first communications system with a second communications system is disclosed. A first frame is received at a first station. The first station is connected to both the first communication system and the second communication system. The first frame has a destination address field, and the destination address field contains a desired destination address. The first station forwards, in response to the desired destination address, the first frame onto the second communications system as a second frame, and the first station writes a second destination address into a destination address field of the second frame. The first station writes the desired destination address into a predetermined field of the second frame. The first station writes, an indicator into the second frame, the indicator is capable of being interpreted by a receiving station to mean that the desired destination address is written into the predetermined field of the second frame. The receiving station receives the second frame. The receiving station is also connected to a third communications system. The receiving station reads, in response to the indicator, the desired destination address from the predetermined field of the second frame, and writes the desired destination address into a destination address field of a third frame. The receiving station forwards the second frame onto the third communications system as a third frame.

A novel mechanism prevents interleaving of packet cells from different source nodes on the same multicast port group at switches of a multicast virtual circuit in a cell-switched network: however, different cells bound for different multicast port groups may be interleaved. The mechanism comprises specific routing information that is stored in each multicast group port entry of a forwarding table located within each switch of the multicast virtual circuit. The forwarding table also stores information relating to each multicast port group including a virtual circuit value for each port of the multicast group. The specific routing information is provided for each multicast port group entry to notify the switch when data traffic for a particular packet is pending through a port of the multicast group and when that data traffic ceases, i.e., when the 'end-of-packet' is reached. This ensures that the packets may be correctly reassembled at the destination nodes.

Method and apparatus for selective interleaving in a cell-switched

A connection apparatus for connecting a first communication system with a second communication system and a third communication system. A first frame is received from the first communication system, where the first frame has a multicast address as a destination address, and where the destination address requires the first frame to be transmitted onto the second communication system. The multicast address is translated into a functional address, and the functional address is written into a second frame transmitted onto the second communication system. The second frame is received and is transmitted onto a third communication system, and the functional address is translated into a multicast address for the third communication system, and the multicast address is written into a destination field of the frame as it is transmitted onto the third communication system. The second communication system may be a token ring system based upon an IEEE 802.5 standard, and the functional address may be written into a DSAP field and into a PROTOCOL TYPE field of an 802.5 Standard frame.

A technique for modifying the IEEE 802.3 standard for selecting transmit-to-transmit interpacket gap (IPG) intervals in a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) network, in the event that a node has captured the network communication channel. If there is a small number of active nodes on the network, one node may capture the channel and the standard backoff algorithm makes it increasingly unlikely for another node to transmit. The new technique provides for less aggressive, i.e. longer, interpacket gap (IPG) intervals to be used by a node that has captured the channel, thereby increasing the likelihood that another node will gain access.

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 plurality of physical addresses are derived from address information stored in an address memory of a bridge or other multi-port communication device, wherein the stored address information does not directly specify all the addresses. In a first embodiment, the stored addressing information specifies a single address value from a first block of preferably consecutive address values. A processor uses the first address value to derive a second address value from a second, different block of preferably consecutive address values, and then assigns both as, e.g., port addresses. In a second embodiment of the invention, the address memory stores address information which specifies a range of preferably consecutive address values, for instance, the first and last address values of the range. A processor fetches these address values from the address memory, identifies all address values within the range, and assigns them as, e.g., port addresses.

Method and apparatus for deriving addresses from stored address

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Pepperell, MA, United States of America

William R Hawe