Passive network tap device

• US 20040120259A1
• Filed: 12/20/2002
• Published: 06/24/2004
• Est. Priority Date: 12/20/2002
• Status: Abandoned Application

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Carson, Douglas, Copley, Mark H., Scott, Alistair, Jones, Stewart
• Application Number:
  US10/327,552
• Publication Number:
  US 20040120259A1
• Time in Patent Office: Days
• US Class Current: 370/250
• CPC Class Codes: H04L 43/12 Network monitoring probes

Abstract

A tap device comprises a network entry connection, a network exit connection, and a network interconnection path there between. A high impedance tap circuit is electrically connected to the network connection path, and comprises an isolation transformer and active buffer element. Advantageously, a power interruption to said tap circuit does not affect network communications.

Claims

1. A tap device comprising:

a network entry connection,

a network exit connection,

a network interconnection path between said network entry connection and said network exit connection,

a tap circuit electrically connected to said network interconnection path, said tap circuit comprising an isolation transformer and active buffer element.

2. A tap device as recited in claim 1 said network entry and exit connections comprising differential signal connections and said tap circuit converts said differential signal connections to a single-ended signal connection.

3. A tap device as recited in claim 1 and further comprising a plurality of said network entry and exit connections having a respective said network connection path there between, a plurality of said tap circuits wherein an output of said buffer elements are aggregated.

4. A tap device as recited in claim 1 wherein said isolation transformer is a one to one transformer.

5. A tap device as recited in claim 1 wherein said buffer element has an amplifying factor of two.

6. A tap device as recited in claim 1 having a powered up state and a powered down state wherein an input impedance to said tap circuit is high relative to said network interconnection path in both said powered up and a powered down states.

7. A tap device comprising:

a first tap electrically connected to a first network interconnection path,

a second tap electrically connected to a second network interconnection path,

a buffer amplifier having an input end and an output end, and

an isolation transformer having an input side and an output side, said input side connected to said first and second taps and said output side connected to said input end of said buffer amplifier.

8. A tap device as recited in claim 7 wherein said output end of said buffer is connected to a monitoring path.

9. A tap device as recited in claim 8 wherein said monitoring path is connected to a processor and display device that collects and analyzes data present on said monitoring path.

10. A tap device as recited in claim 8 wherein said output end of said buffer is connected to a voltage divider circuit that is matched to an impedance of said monitoring path.

11. A tap device as recited in claim 7 and further comprising a plurality of first and second taps, and a respective plurality of buffer amplifiers and isolation transformers, wherein each one of said output ends of said buffer amplifier are aggregated onto a single monitoring path.

12. A tap device as recited in claim 7 wherein said isolation transformer is a one to one transformer.

13. A tap device as recited in claim 7 wherein said buffer amplifier has an amplifying factor of two.

14. A tap device as recited in claim 7 wherein said isolation transformer converts a differential signal present on said first and second interconnection paths to a single ended signal for presentation to said buffer amplifier.

15. A tap device as recited in claim 7 having a powered up state and a powered down state wherein an input impedance to said tap circuit is high relative to said network interconnection path in both said powered up and said powered down states.

16. An apparatus for eavesdropping onto a data network comprising:

an input port having at least first and second input interconnection points,

an output port having at least first and second output interconnection points,

first and second interconnection paths between said first input interconnection point and said first output interconnection point, and said second input interconnection point and said second output interconnection point, respectively,

a first tap electrically connected to said first interconnection path,

a second tap electrically connected to said second interconnection path,

an isolation transformer having first and second primary winding ends and first and second secondary winding ends, said first tap connected to said first primary winding end and said second tap connected to said second primary winding end,

a buffer having positive and negative input connections and an output end, said first secondary winding end connected to said positive input connection and said second secondary winding end connected to said negative input connection.

17. An apparatus for eavesdropping as recited in claim 16 wherein said output end of said buffer is connected to a monitoring path.

18. An apparatus for eavesdropping as recited in claim 17 wherein said monitoring path is connected to a processor and display device that collects an analyzes data present on said monitoring path.

19. An apparatus for eavesdropping as recited in claim 17 wherein said output end of said buffer is connected to a voltage divider circuit that is matched to an impedance of said monitoring path.

20. An apparatus for eavesdropping as recited in claim 16 and further comprising a plurality of first and second taps, and a respective plurality of buffers and isolation transformers, wherein each one of said output ends of said buffer amplifier are aggregated onto a single monitoring path.

21. An apparatus for eavesdropping as recited in claim 16 wherein said isolation transformer is a one to one transformer.

22. An apparatus for eavesdropping as recited in claim 16 wherein said buffer amplifier has an amplifying factor of two.

23. An apparatus for eavesdropping as recited in claim 16 wherein said isolation transformer converts a differential signal present on said first and second interconnection paths to a single ended signal for presentation to said buffer amplifier.

24. A method for insuring uninterrupted operation of a monitored network comprising the steps of:

connecting a first tap device to the monitored network, the first tap device comprising a chassis, a power supply, a rear transition module and an aggregator,

monitoring said network through said first tap device,

removing power from said first tap device,

removing said rear transition module from said first tap device,

installing said rear transition module into a second tap device, said second tap device comprising a chassis, a power supply and an aggregator,

powering said second tap device, and

monitoring said network through said second tap device.

25. A method as recited in claim 24 wherein said rear transition module comprises a tap interface having a sufficiently high impedance relative to a network interconnection path in both a powered-up and powered-down state so that data communication on said monitored network is unaffected transitioned between said powered-up and said powered-down states.

26. A method for programming a network switch to perform an aggregation function comprising the steps of:

disabling a spanning bridge tree protocol, a generic attribute registration protocol VLAN registration protocol, and a generic attribute registration protocol multicast registration protocol,

defining virtual local area networks as one or more switch ports with a high speed port, and

turning a switch learning mode off.

27. A method for programming a network switch as recited in claim 26 wherein said switch ports are 100BaseT ports and said high speed port is a Gigabit port.