Ethernet network implementing redundancy using a single category 5 cable

• US 20060250947A1
• Filed: 05/04/2005
• Published: 11/09/2006
• Est. Priority Date: 05/04/2005
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Micrel Incorporated (Microchip Technology Incorporated)
• Inventors: Allen, Robert J.
• Granted Patent: US 7,433,302 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• CPC Class Codes: H04L 12/40182 by using a plurality of communication lines
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085
• CPC Class Codes: Y10S 370/908 Local area network
• CPC Class Codes: Y10S 370/91 Carrier sense multiple access, e.g. ethernet, 10base-t

Abstract

A method for providing redundancy in a daisy chain local area network employing Category 5 cabling for connecting network devices uses the normally unused twisted wire pairs in the single Cat 5 cable connecting adjacent network devices. The method includes forming in each network device a passive signal path connecting pins of an upstream port associated with the normally unused twisted wire pairs of the Cat 5 cable to pins of a downstream port associated with the normally unused twisted wire pairs of the Cat 5 cable, forming loop back connections at the terminal network devices where the loop back connections connect the normally used twisted wire pairs to the normally unused twisted wire pairs of the Cat 5 cable connected to the terminal network devices, and implementing a Spanning Tree Protocol in each of the network devices for defining an active signal path through the local area network.

Claims

1. A daisy chain local area network employing Category 5 (Cat 5) cabling for connecting network devices, the local area network providing communications over two twisted wire pairs (the “

normally used”

twisted wire pairs) of the Cat 5 cabling connecting the network devices, leaving two twisted wire pairs of the Cat 5 cabling unused (the “

normally unused”

twisted wire pairs), the daisy chain local area network comprising;

a plurality of network devices connected in a daisy chain configuration between first and second terminal network devices, the first and second terminal network devices being network devices at the two ends of the daisy chain of network devices, each adjacent pair of network devices and terminal network devices being connected by a single Cat 5 cable, each of the plurality of network devices comprising;

an upstream port and a downstream port, each of the ports being coupled to a Cat 5 cable, each of the ports having pins associated with the normally used twisted wire pairs and the normally unused twisted wire pairs of the Cat 5 cable; and

a passive signal path connecting the pins of the upstream port associated with the normally unused twisted wire pairs of the Cat 5 cable to the pins of the downstream port associated with the normally unused twisted wire pairs of the Cat 5 cable; and

a loop back connection coupled to each of the first and second terminal network devices, the loop back connection being operative to electrically connect the normally used twisted wire pairs to the normally unused twisted wire pairs of the Cat 5 cable connected to the respective first and second terminal network devices,

wherein the passive signal paths through the plurality of network devices and the loop back connections of the first and second terminal network devices form a redundancy loop in the local area network and a Spanning Tree Protocol is implemented in each of the plurality of network devices and the first and second terminal network devices for defining an active signal path through the local area network.

2. The daisy chain local area network of claim 1, wherein at least one of the first and second terminal network devices comprises:

an upstream port and a downstream port, at least one of the ports being coupled to a Cat 5 cable, each of the ports having pins associated with the normally used twisted wire pairs and the normally unused twisted wire pairs of the Cat 5 cable;

a passive signal path connecting the pins of the first upstream port associated with the normally unused twisted wire pair of the Cat 5 cable to the pins of the downstream port associated with the normally unused twisted wire pair of the Cat 5 cable; and

a loop back connector coupled a first port being the port of the terminal network device not coupled to the Cat 5 cable, the loop back connector connecting the pins of the first port associated with the normally used twisted pairs of a Cat 5 cable to the pins of the first port associated with the normally unused twisted pairs of a Cat 5 cable.

3. The daisy chain local area network of claim 1, wherein at least one of the first and second terminal network devices comprises a multi-port switching device having a plurality of data ports coupled to a switching fabric, the at least one of the first and second terminal network devices comprising:

a first port being coupled to a Cat 5 cable, the first port having pins associated with the normally used twisted wire pairs and the normally unused twisted wire pairs of the Cat 5 cable;

a first signal path connecting the pins of the first port associated with the normally unused twisted wire pairs of the Cat 5 cable to a first data port of the multi-port switching device; and

a second signal path connecting the pins of the first port associated with the normally used twisted wire pairs of the Cat 5 cable to a second data port of the multi-port switching device,

wherein the normally unused twisted wire pairs of the Cat 5 cable is electrically connected to the normally used twisted wire pairs through the switching fabric of the multi-port switching device to implement the loop back connection at the at least one of the first and second terminal network devices.

4. The daisy chain local area network of claim 1, wherein the plurality of network devices and the first and second terminal network devices comprise switches having three or more ports.

5. The daisy chain local area network of claim 1, wherein the plurality of network devices and the first and second terminal network devices comprise switches, hubs, gateways, bridges or routers.

6. The daisy chain local area network of claim 1, wherein the local area network comprises a 10BaseT or 100BaseTX Ethernet network.

7. The daisy chain local area network of claim 6, wherein the plurality of network devices and the first and second terminal network devices comprise layer 2 devices.

8. The daisy chain local area network of claim 6, wherein the plurality of network devices and the first and second terminal network devices comprise layer 2 switches having three or more ports.

9. The daisy chain local area network of claim 1, wherein the passive signal path in each of the plurality of network devices connects the respective pins of the upstream port to the respective pins of the downstream port without going through the magnetic components in the network device.

10. The daisy chain local area network of claim 1, wherein the Spanning Tree Protocol comprises the IEEE 802.1d Spanning Tree Protocol.

11. A method for providing redundancy in a daisy chain local area network employing Category 5 (Cat 5) cabling for connecting network devices, the local area network providing communications over two twisted wire pairs (the “

normally used”

twisted wire pairs) of the Cat 5 cabling connecting the network devices, leaving two twisted wire pairs of the Cat 5 cabling unused (the “

normally unused”

twisted wire pairs), the method comprising;

providing a plurality of network devices connected in a daisy chain configuration between first and second terminal network devices, the first and second terminal network devices being network devices at the two ends of the daisy chain of network devices, each adjacent pair of network devices and terminal network devices being connected by a single Cat 5 cable;

forming in each of the plurality of network devices a passive signal path connecting pins of an upstream port of the respective network device associated with the normally unused twisted wire pairs of the Cat 5 cable to pins of a downstream port of the respective network device associated with the normally unused twisted wire pairs of the Cat 5 cable;

forming a loop back connection at each of the first and second terminal network devices, the loop back connection being operative to electrically connect the normally used twisted wire pairs to the normally unused twisted wire pairs of the Cat 5 cable connected to the respective first and second terminal network devices; and

implementing a Spanning Tree Protocol in each of the plurality of network devices and the first and second terminal network devices for defining an active signal path through the local area network.

12. The method of claim 11, wherein forming a loop back connection at each of the first and second terminal network devices comprises:

forming in at least one of the first and second terminal network devices a passive signal path connecting pins of an upstream port of the respective terminal network device associated with the normally unused twisted wire pairs of the Cat 5 cable to pins of a downstream port of the respective terminal network device associated with the normally unused twisted wire pairs of the Cat 5 cable; and

at a first port being the port of the terminal network device not coupled to the Cat 5 cable, connecting the pins of the first port associated with the normally used twisted pairs of the Cat 5 cable to the pins of the first port associated with the normally unused twisted pairs of the Cat 5 cable.

13. The method of claim 11, wherein forming a loop back connection at each of the first and second terminal network devices comprises:

implementing in at least one of the first and second terminal network devices a multi-port switching device having a plurality of data ports coupled to a switching fabric;

coupling a first port of the at least one of the first and second terminal network devices to a Cat 5 cable, the first port having pins associated with the normally used twisted wire pairs and the normally unused twisted wire pairs of the Cat 5 cable;

forming a first signal path connecting the pins of the first port associated with the normally unused twisted wire pairs of the Cat 5 cable to a first data port of the multi-port switching device;

forming a second signal path connecting the pins of the first port associated with the normally used twisted wire pairs of the Cat 5 cable to a second data port of the multi-port switching device; and

connecting the normally unused twisted wire pairs of the Cat 5 cable to the normally used twisted wire pairs through the switching fabric of the multi-port switching device to implement the loop back connection at the at least one of the first and second terminal network devices.

14. The method of claim 11, wherein the plurality of network devices and the first and second terminal network devices comprise switches having three or more ports.

15. The method of claim 11, wherein the plurality of network devices and the first and second terminal network devices comprise switches, hubs, gateways, bridges or routers.

16. The method of claim 11, wherein the local area network comprises a 10BaseT or 100BaseTX Ethernet network.

17. The method of claim 16, wherein the plurality of network devices and the first and second terminal network devices comprise layer 2 devices.

18. The method of claim 16, wherein the plurality of network devices and the first and second terminal network devices comprise layer 2 switches having three or more ports.

19. The method of claim 11, wherein forming in each of the plurality of network devices a passive signal path comprises:

connecting pins of an upstream port of the respective network device associated with the normally unused twisted wire pairs of the Cat 5 cable to pins of a downstream port of the respective network device associated with the normally unused twisted wire pairs of the Cat 5 cable without going through the magnetic components in the network device.

20. The method of claim 11, wherein the Spanning Tree Protocol comprises the IEEE 802.1d Spanning Tree Protocol.