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:
May. 20, 1997
Filed:
Jul. 17, 1995
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Abstract
A hitless path switching method without a bit loss. The same digital line signals on a working path and a protection path are continuously monitored independently for bit errors. If a bit error occurs in the working path and no bit error occurs in the protection path, a switching trigger is produced and a switching operation from the working path to the protection path is performed on a data block basis. Only correct data are transferred to downstream apparatuses. Reliable hitless switching is achieved not only in response to a failure in a path, but also in response to a bit error. Using data blocks of one frame length with an indicator for bit error checking placed at its beginning or top makes effective switching possible.