3Com Corporation

Sarit Shani

Haim Rochberger

David Margulis

Yoram Shamir

Sharon Barkai

Meir Morgenstern

Miki Kenneth

Gonen Ziv-Av

A method of providing redundancy and load sharing among multiple LECSs in an ATM network. The method creates and maintains a plurality of lists on each of the switches. Each list is an ordered set of LECSs that combine to create an active LECS list. The network is divided into a plurality of groups wherein each group is assigned one of the active LECS lists. The order of each active LECS list is unique in that no two groups have the same order of LECS. The first LECS on each list has the highest priority and is always the first choice when a request to join a VLAN is received from one of the connected LECs. If the primary lECS fails or cannot be reached for any reason, the switches utilize the second LECS on the list. Splitting up the network into multiple groups and assigning different lists serves to provide load sharing among the LECS. In the event the currently active LECS fails, the next on the list takes overt thus providing redundancy.

Method of providing redundancy and load sharing among multiple LECs in an asynchronous mode network

A method for creating and resolving split VLANs in ATM networks. The method utilizes a Network Management System (NMS) and a standard management protocol such as SNMP. The method monitors the network by continuously polling all the devices in the network. Status related information collected by the NMS is used to construct a physical and logical topology of the network. In response to the detection of one or more physical splits in the network, the NMS creates one or more corresponding logical splits in the network by splitting one or more VLANs. In the case of two split portions, the split VLAN can be created if a redundant LES and second LECS are located on the side of the split which does not include the primary LES. The second LECS is configured to use the address of the redundant LES in replying to requests to join an ELAN from the disconnected LECs. The repair of the physical split is detected by the NMS and, in response, the NMS modifies the databases of all the LECS in the ELAN so that the same primary LES address is returned to any LEC requesting to join an ELAN. LECs previously attached to the redundant LES are disconnected and subsequently attached to the primary LES.

Method of resolving split virtual LANs utilizing a network management system

A method of providing redundancy in a LAN Emulation network in the event an LES fails. The method is light in that it does not require complicated database synchronizations between LECSs and their associated complex message protocol exchanges. The method comprises defining a plurality of LESs per ELAN, but permitting only one of the LESs to be active at any one moment in time. All the LECSs are configured with the same Topology Database which include the all the potential LESs for each ELAN. The LECSs try to connect to each LES and the results are logged. The operative LESs having the highest priority is chosen as the active LES whereby all LECs get assigned to the active LES. When the active LES fails the LECs attempt a new connection to LECs. The LECs assigns the LECs to another operative LES in the database list. All the LECs previously connected to the failed LES, are attached to the new LES assigned by the LECs and communications are reestablished with the new LES. Splits are handles by having the LECs choose the LES with the highest priority to be the new active LES and sending a message to all the other LESs instructing them to disconnect their attached LECs. This causes the LECs to re-attach to the active LES.

Non-distributed LAN emulation server redundancy method

A method of determining an efficient route to a well known address that is particularly applicable to networks that do not have the capability of source routing for calculating routes to specific addresses such as ATM networks based on the IISP protocol. The well known address may represent any entity in the network that provides distributed services (e.g., network server applications) that are to be shared among many nodes and applications on the network, such as LECSs. The method of functions to automatically and dynamically register 'well known' addresses on the ports of each node that implements the invention. This permits applications on the network to route to the destination in the shortest possible path thus utilizing network resources in an efficient manner. If there is more than one location with the well known address, e.g., a redundant LECSs in the network, or more than one route to the location then the optimum location will be the one routed to. An optimum location can be determined using any suitable criteria to determine the optimum route to a LECS such as distance, hop count, cost function, link sum, link capacity, etc.

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Tel Aviv, Israel

Sarit Shani