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:
Apr. 29, 2003
Filed:
Dec. 22, 1999
Sycamore Networks, Inc., Chelmsford, MA (US);
Abstract
A network device includes latches disposed between control outputs of control logic such as a field-programmable gate array (FPGA) and control inputs of functional elements through which network traffic flows. The control logic generates a latch enable signal that controls the operation of the latches. The latch enable signal is in a latching state to maintain the latches open during normal operation. During an upgrade, the control outputs may take on incorrect or indeterminate values, due to entering a high-impedance state. Therefore, during the upgrade the latches are closed, maintaining the pre-upgrade values on the inputs of the functional elements and preventing the control logic outputs from affecting operation of the device. After re-programming is complete and the control outputs are in a determinate state, the latches are re-opened. A pullup/pulldown circuit is used to maintain the latch enable signal in a latching state during the upgrade.