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:
Jul. 13, 2010
Filed:
Dec. 21, 2005
Karthikeyan Ramanan, Bangalore, IN;
Bhaskar Bhupalam, Sunnyvale, CA (US);
Venkatesh Gota, Bangalore, IN;
Karthikeyan Ramanan, Bangalore, IN;
Bhaskar Bhupalam, Sunnyvale, CA (US);
Venkatesh Gota, Bangalore, IN;
Cisco Technology, Inc., San Jose, CA (US);
Abstract
A method and apparatus are provided for preventing data-packet loss upon a switchover from an active to a standby PDSN, in a redundant PDSN environment. Data-packet loss is prevented by modifying the checking of the sequence number associated with the data-packets. The first sequence number received upon switchover is used to determine the order of the subsequent GRE frames. The standby PDSN sends keep-alive packets associated with an arbitrary sequence number to a packet control function (PCF). On receiving a response from the PCF, the arbitrary sequence number is used as a starting sequence number for sending the data-packets. Otherwise, keep-alive packets with modified numbers are sent to the PCF. In synchronized communication sessions between the PDSN and the PCF, data-packet loss can be prevented by disabling the checking of the sequence number upon a switchover. In another embodiment, data-packet loss is prevented by excluding the sequence number.