Nortel Networks Corporation

Denny D Landaveri

Michel Khouderchah

Cheng Hsiang

David Ian Hopper

Du-Tuan Lam

Ranvir K Chitkara

Greg M Bernstein

Siamak Razzaghe-Ashrafi

George S Irwin

Gabriel Choi

Nader Tajbakshs

The present invention guarantees that voice data (and other information types) will switch within a predetermined time period. Systems and methods consistent with the present invention accomplish this guarantee by, among other things, establishing permanent virtual paths between each network element, guaranteeing each voice line a slot in a packet in each frame, employing both octet switching and packet switching, synchronizing the operation of the network elements to a reference clock, and providing several levels of network redundancy.

Private branch exchange built using an ATM Network

Multiple node network architecture

The present invention guarantees that voice data (and other information types) will switch within a predetermined time period. Systems and methods consistent with the present invention accomplish this guarantee by, among other things, establishing permanent virtual paths or circuits between each network element, guaranteeing each voice line a slot in a packet in each frame, employing both octet switching and packet switching, synchronizing the operation of the network elements to a reference clock, and providing several levels of network redundancy.

Virtual junctors

Using an ATM switch to grow the capacity of a switching stage

A method is provided for transitioning between redundant computer systems on a network. According to one aspect of the present invention, fault tolerance may be achieved in a network which includes one or more redundant computer systems by monitoring the status of a primary system and having a redundant system take over for the primary system upon determining the primary system has entered a predetermined state (e.g., lost power, CPU has gone down, etc.). Each host machine on the network includes an address translation table (e.g., an Address Resolution Protocol (ARP) cache) for purposes of dynamically mapping a logical address (e.g., an Internet Protocol (IP) address) to a physical address (e.g., a MAC address). Therefore, transitioning from the primary system to a redundant system that shares the same logical address may be accomplished by simply transmitting an ARP reply containing therein the shared logical address and the physical address of the redundant system or an ARP proxy server with which the redundant system is registered. In this manner, the host machines will update their address translation tables such that the shared logical address will be associated with the physical address provided in the ARP reply and further transmissions addressed to the shared logical address will in effect be redirected to the redundant system either directly or indirectly through the ARP proxy server.

Transitioning between redundant computer systems on a network

Growing community of inventors

Santa Clara, CA, United States of America

Denny D Landaveri