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:
Dec. 02, 2008
Filed:
Jun. 12, 2006
Maurizio Portolani, Milpitas, CA (US);
Shyamasundar S. Kaluve, Santa Clara, CA (US);
Marco E. Foschiano, San Jose, CA (US);
Maurizio Portolani, Milpitas, CA (US);
Shyamasundar S. Kaluve, Santa Clara, CA (US);
Marco E. Foschiano, San Jose, CA (US);
Cisco Technology, Inc., San Jose, CA (US);
Abstract
A system and method are provided to prevent the formation of loops in a network. The network device includes a plurality of ports for receiving and forwarding network messages and a spanning tree protocol engine. The spanning tree protocol engine, in one embodiment, implements the Rapid Spanning Tree Protocol (RSTP) to transitions the ports among a plurality port states, including a discarding state, a learning state and a forwarding state. The network device further includes a loop guard engine that is in a communicating relationship with the spanning tree protocol engine and the ports. The loop guard engine monitors the receipt of bridge protocol data units (BPDUs) by the ports. If a given port stops receiving BPDUs, the loop guard engine prevents the spanning tree protocol engine from transitioning the given port to the forwarding state. Instead, the loop guard engine causes the port to transition to loop inconsistent state.