Clock skew estimation and removal

US006661810B1

(12) United States Patent

Skelly et al.

(io) Patent No.: (45) Date of Patent:

US 6,661,810 Bl Dec. 9,2003

(58) Field of Search 370/516, 503,

370/509, 507, 517, 518, 519, 252; 375/371;

348/497; 709/248

(56) References Cited

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(List continued on next page.)

Primary Examiner—Chi Pham

Assistant Examiner—Alexander O. Boakye

(74) Attorney, Agent, or Firm—Leonard Charles Suchyta;

James K. Weixel

OBTAIN DELAY MEASUREMENTS

IDENTIFY MINIMUM DELAY POINTS

DEFINE FEASIBLE REGION

FIT LINE TO POINTS

DETERMINE SKEW

OTHER PUBLICATIONS

Sue B. Moon, Paul Skelly, and Don Towsley, "Estimation and Removal of Clock Skew from Network Delay Measurements", Technical Report 98-43, Department of Computer Science, University of Massachusetts at Amherst. Paul Skelly and Man Li, EIPMon: An EIP Monitoring Tool.

David L. Mills, Network time protocol NTP (version 3): Specification, implementation and analysis, RFC 1305, Network Information Center, SRI International, Menlo Park, CA May 1992.

Henning Schulzrinne, RTP profile for audio and video conferences with minimal control, RFC 1890, Internet Engineering Task Force, Jan. 1996.

Henning Schulzrinne, Steve Casner, R. Frederick, and Van Jacobson, RTP: A transport protocol for real-time applications, RFC 1889, Internet Engineering Task Force, Jan. 1996.

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