Cisco Technology, Inc.

Patricia Ann Webster

Arun G Khanna

Frank Gerard Bordonaro

Uwe Sellentin

Arunkumar Bhushappagala Thippeswamy

Scott Allen Bales

A transparently-bridged wide area network connecting Ethernet/IEEE 802.3-based local area networks uses redundant proxy devices on each LAN for internetwork communications. The proxy devices, implemented as data link switching (DLSw) devices, prevent looping of traffic such as explorer frames by sharing their MAC addresses to enable the proxy devices to recognize data packets from another proxy device. Incoming explorer frames from the wide area network are modified by performing an address substitution, where the source address in a received explorer frame is replaced with the address of the local proxy device. The proxy device then outputs the modified explorer frame onto the local area network. Any other proxy device on that same local network will then be able to detect the modified explorer frame as a frame forwarded by another proxy device, as opposed to a data frame from an end station on that local area network. Hence, redundant DLSw-type proxy devices may be implemented on a local area network while maintaining a stable and a robust communications system.

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Los Gatos, CA, United States of America

Patricia Ann Webster