Methods for providing a reliable server architecture using a multicast topology in a communications network

摘要

Multicast techniques are employed to provide host computer elements access to multiple redundant servers of a communication network in such a way that the hosts need not know which of the servers is active. In one embodiment, the servers provide a gateway function between an Ethernet LAN and an external network. The Ethernet LAN comprises one or more hosts connected to one or more switches, the switches connected to corresponding servers defining an active/standby pair. The servers are connected to an external network by corresponding active/standby links. The hosts send messages directed to a multicast address to at least one of the switches. The switches forward the messages on ports according to a multicast routing topology having been determined by performing IGMP "snooping" of messages issued from the servers. Both the active and standby servers receive the messages; and the active server sends the messages to the external network. In case the active server fails or is removed from service, the standby server is promoted to active server and assumes the role of the formerly active server without necessitating any communication to the hosts to inform them of the change in status of the active server.