David M Stauffer

US Patent:

53943902, Feb 28, 1995

Filed:

Oct 29, 1993

Appl. No.:

8/144989

Inventors:

David R. Stauffer - League City TX
Rebecca S. McMahon - Houston TX
Thomas J. Eckenrode - Endicott NY

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H04J 116

US Classification:

370 17

Abstract:

A History Store Circuit (HSC) is employed with a commercially available FDDI chipset to provide an interface between the PHY layer hardware and a memory system to record symbol stream segments received from the FDDI network. Memory system address and control signals are provided by the HSC. Multiplexor logic is included to support dual-ring network configurations. The HSC provides the electrical interconnection required to interface to the PHY layer hardware so as to allow reception of invalid frames, valid frames, and invalid/valid line state symbol streams from the fiber optic bus. In order to receive such invalid frames and state symbol streams from the fiber optic media, additional logic is provided to allow the user to focus on the segment of network traffic of interest. The HSC includes a Symbol Stream Comparator (SSC) and History Store Triggering Logic (HSTL) to facilitate control of the network traffic segment captured by the HSC. Using this logic, history store capture can be started or stopped based upon receipt of a specific network symbol stream.