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:
Jan. 30, 1996
Filed:
Mar. 21, 1994
Satoshi Kakuma, Kanagawa, JP;
Shuji Yoshimura, Kanagawa, JP;
Kazuo Hajikano, Kanagawa, JP;
Masami Murayama, Kanagawa, JP;
Yuzo Okuyama, Kanagawa, JP;
Fujitsu Limited, Kanagawa, JP;
Abstract
An ATM (asynchronous transfer mode) exchange has a buffer for system #0 and a buffer for system #1 providing P-MEM's for storing data including an A bit and for a VCI/VPI currently in use is set to '1'. Upon detecting a switchover between the systems, every B bit is reset to '0'. When the exchange while changing from a master to a slave receives a cell having a slave indication and while changing from a slave to a master it receives a cell having a master indication, respective systems rewrite B bits for VCI/VPI's of respective cells to '1'. In the meantime, each of the P-MEM's calculates exclusive 'OR' operations between the A bit and the B bit for every VCI/VPI, and further obtains a disjunction among all the exclusive 'OR' operations thus obtained. Then, when both P-MEM's obtain '0' for their respective disjunctions, cells are read out from one of the buffers in the system changing from a slave to a master. This enables the ATM exchange having a switch duplexed by mutually asynchronous active and backup systems to switchover the systems without causing a cell to be duplicated or lost.