The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 27, 2002
Filed:
Jun. 29, 1999
Arun Girdharilal Khanna, Cupertino, CA (US);
Arunkumar Bhushappagala Thippeswamy, Cupertino, CA (US);
Frank Gerard Bordonaro, Los Gatos, CA (US);
Scott Allan Bales, Durham, NC (US);
Uwe Sellentin, San Jose, CA (US);
Cisco Technology, Inc., San Jose, CA (US);
Abstract
A transparently-bridged wide area network connecting Ethernet/IEEE 802.3-based local area networks uses redundant proxy devices one each LAN for internetwork communications. The proxy devices on a given LAN, implemented as data link switching (DLSw) devices, mediate for proxy services by generation and maintenance of a token between the proxy devices capable of providing the corresponding proxy services. In the case of transfer of a data frame, a proxy device having received a frame from an end station determines whether any other proxy device possess a token authorizing the establishment of a circuit connection via a wide area network for transfer of the frame to another local area network. If the proxy devices determines that another proxy device possess the token, the proxy device lacking the token drops the frame. If the proxy device possesses the token, then the frame can be transferred via the wide area network. Multiple tokens may be used for distributing distinct proxy services between multiple proxy devices. In addition, each proxy device lacking a token monitors for the periodic presence of a “heart-beat” indicating the continued presence of tokens, enabling generation of new tokens if existing tokens are lost. Hence, redundant DLSw-type proxy devices may be implemented on a local area network while maintaining a stable and a robust communications system.