Enhanced real-time topology analysis system or high speed networks

• US 5,778,172 A
• Filed: 04/22/1996
• Issued: 07/07/1998
• Est. Priority Date: 04/22/1996
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Riedle, Christopher G., Hershey, Paul C.
• Primary Examiner(s): Coleman, Eric
• Application Number:
  US08/635,811
• Time in Patent Office: 806 Days
• Field of Search: 395/200.66, 395/187.01, 395/200.54, 395/200.55, 395/186
• US Class Current: 726/9
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 41/32 Specific management aspects for broadband networks

Abstract

The disclosed system allows determination of topological aspects of a high speed data communications network in real time without interfering with the operation of the network. The topographical information determined by the present invention includes the cable length of the network, the cable length between stations on the network, and the station addresses and relative order of stations on the network. The system determines the cable length of the network by dividing the amount of time that a token spends on the cables of the network as it travels completely around the network by the propagation speed per unit length of the cables of the network. The system determines the length of cable between any two adjacent stations on the network by determining the length of time between frames transmitted by the adjacent stations, and dividing this time by the propagation speed per unit length of the cable of the network. Lastly, the system determines the number of stations and the addresses of these stations on the network by extracting source addresses from the pertinent network frames.

Claims

1. A method for determining the total length of cable on a token ring network, said token ring network periodically transmitting a token which, on an as needed basis, is captured by a station on said network in order for said station to transmit data on said network, comprising the steps of:

determining the length of time that said token spends on the cables of said token ring network as said token makes a complete rotation around said token ring network;

calculating said length of time that said token spends on the cables of said token ring network as a function of the propagation speed per unit length of cable of said token ring network; and

determining the presence of a security breach on said network by comparing said cable length with the authorized length of cable on said network.

2. A method for determining the length of cable between any two adjacent stations on a token ring network, said token ring network having at least one station with an event driven interface, comprising the steps of:

configuring said event driven interface to identify active monitor present frames and standby monitor present frames by loading bit patterns into said event driven interface which correspond to said active monitor present frames and said standby monitor present frames;

using said event driven interface to identify an active monitor present frame or a first standby monitor present frame transmitted from a first station;

recording a first clock reading of said station having said event driven interface after said station identifies said active monitor present frame or said first standby monitor present frame;

using said event driven interface to identify a next standby monitor present frame transmitted from a second station, said second station located adjacent to said first station;

recording a second clock reading of said station having said event driven interface after said station identifies said next standby monitor present frame;

determining the length of time between said active monitor present frame or said first standby monitor present frame and said next standby monitor present frame by multiplying the difference in said first and second clock readings by the time per clock pulse of said network giving a first result;

subtracting from said first result the length of time required to generate a notification response giving a second result;

dividing said second result by the propagation speed per unit length of cable of said token ring network giving the cable length between said first station, and said second station; and

determining the presence of a security breach on said network by comparing said cable length between said two adjacent stations with the authorized length of cable between said two adjacent stations.