Nortel Networks Corporation

Siamak Razzaghe-Ashrafi

Denny D Landaveri

A method and system for verifying and updating a software subsystem stored on a network system (NS) device is provided. A technique is provided, which verifies and corrects an altered or corrupt software subsystem in flash memory. The verification technique checks to verify that the software subsystem has not been altered since the software subsystem was originally stored on the network system (NS) device. If it has been altered, a software system generator regenerates the software system. Another technique is provided which ensures that the software subsystem in the NS device is updated properly. The latest versions of the software subsystem and corresponding software system generator are stored on a server coupled to the NS device over a network. The updated software system generator stored on the server is downloaded onto the NS device. The software subsystem is updated by invoking the updated software system generator. The software system generator generates an updated software subsystem, which replaces the software subsystem on the NS device.

Method and apparatus for managing software in a network system

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.

Growing community of inventors

Santa Clara, CA, United States of America

Siamak Razzaghe-Ashrafi