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:
Oct. 06, 2009
Filed:
May. 16, 2005
Marco Di Benedetto, Santa Clara, CA (US);
Ramana Mellacheruvu, San Jose, CA (US);
Umesh Mahajan, Cupertino, CA (US);
Marco Di Benedetto, Santa Clara, CA (US);
Ramana Mellacheruvu, San Jose, CA (US);
Umesh Mahajan, Cupertino, CA (US);
Cisco Technology, Inc., San Jose, CA (US);
Abstract
A method and apparatus for continuing the operation of a spanning tree protocol at a network device despite crashes or failures at that device is disclosed. The network device includes a plurality of line cards having ports for receiving and forwarding messages and a plurality of supervisor cards for processing at least some of those messages. Upon start-up, one of the supervisor cards is designated the active supervisor, while all other supervisor cards are designated standby supervisors. The active supervisor runs the spanning tree protocol (STP). The active supervisor informs the standby supervisors of the states of ports set by the STP. When a crash or failure occurs at the active supervisor, one of the standby supervisors is immediately designated to be the new active supervisor, and the new active supervisor uses the states of ports set by the original STP.