WO2008023382A1

WO2008023382A1 - Ethernet powered control/exchange/connector switch

Info

Publication number: WO2008023382A1
Application number: PCT/IN2006/000387
Authority: WO
Inventors: Mathew Santhosh
Original assignee: MRO-TEK Ltd
Current assignee: MRO-TEK Ltd
Priority date: 2006-08-21
Filing date: 2006-09-25
Publication date: 2008-02-28
Anticipated expiration: 2009-02-21

Abstract

This invention is an Ethernet Powered Control/Exchange/Connector Switch which functions without external power source, which is a 5-Port Ethernet Switch to control/exchange/connect data and to draw/manage power in network communication links used to couple multiple nodes in a data processing, LAN, MAN and the like systems together in a daisy chain arrangement.

Description

Ethernet Powered Control/Exchange/Connector Switch Field of invention:

The invention relates to a control/exchange/connector switch and in particular 5-port Ethernet access switch to control/exchange data and providing power in network communication links used to couple multiple nodes in a data processing, LAN₅ MAN etc systems together in a daisy chain arrangement. Prior Art:

Ethernet is the most widely used network topology. There are mainly two types of topologies in Ethernet bus and star, and coaxial, twisted-pair, or fiber optic cabling. Using proper connective equipment, multiple Ethernet- based LANs (local area networks) can be linked together with said any topology and/or cabling system.

Ethernet is a large and diverse family of frame-based computer networking technologies for local area networks (LANs) and it has been standardized as IEEE 802.3. Coaxial cable was used in networking, later replaced with point-to-point links connected together by hubs and/or devices in order to reduce installation costs, increase reliability, and enable point-to-point management and troubleshooting.

Computers were connected to an Attachment Unit Interface (AUI) transceiver, which in turn connected to the cable. While a simple passive wire was highly reliable for small Ethernets, it was not reliable for large extended networks, where damage to the wire in a single place, or a single bad connector could make the whole Ethernet segment unusable. Multipoint systems are also prone to very strange failure modes when an electrical discontinuity reflects the signal in such a manner that some nodes would work just fine while others would work slowly due to excessive retries or not at all; these could be much more painful to diagnose than a complete failure of the segment.

A greater length could be obtained by an Ethernet repeater, which took the signal from one Ethernet cable and repeated it onto another cable.

Ethernet on unshielded twisted-pair cables (UTP), beginning with Star LAN and continuing with 1 OBASE-T was designed for point-point links only and all termination was built into the device. These changed hubs from a specialist device used at the center of large networks to a device that every twisted pair-based network with more than two machines had to use. This structure made Ethernet networks more reliable by preventing faults with one peer or its associated cable from affecting other devices on the network. Also as twisted-pair Ethernet is point-to-point and terminated inside the hardware the total empty panel space required around a port is much reduced i.e., making it easier to design hubs with lots of ports and to integrate Ethernet onto computer motherboards.

While repeaters could isolate some aspects of Ethernet segments, such as cable breakages, they still forwarded all traffic to all Ethernet devices. This created significant limit on how many machines could communicate on an Ethernet network. To alleviate this, bridging was created to communicate at the data link layer while isolating the physical layer.

Fiber optic cables of Ethernet are commonly seen connecting buildings or network cabinets in different parts of a building, MAN, WAN etc., but are cost effective.

Power over Ethernet or PoE technology describes any system to transmit electrical power, along with data, to remote devices over standard twisted-pair cable in an Ethernet network. This technology is useful for powering EP telephones, wireless LAN access points, webcams, Ethernet hubs, computers, and other appliances where it would be inconvenient or infeasible to supply power separately.

IEEE 802.3af provides 48 volts DC over two out of four available pairs on a Cat.3/Cat.5 cable with the maximum current of 400 mA for the maximum load power of 19.20 watts wherein after counting losses, only about 12.95 watts are available. Most devised power supplies will lose another 10-20% of the available energy. A phantom technique is used so that the powered pairs may also carry data. This permits its use not only with 1 OBASE-T and 100BASE-TX, which use only two of the four pairs in the

cable, but also with IOOOB ASE-T (Gigabit Ethernet), which uses all four pairs for data transmission. This is possible because all versions of Ethernet over twisted pair cable specify differential data transmission over each pair with transformer coupling; the DC supply and load connections can be made to the transformer center-taps at each end. Each pair thus operates in common mode as one side of the DC supply, so two pairs are required to complete the circuit. The polarity of the DC supply is unspecified; the powered switch must operate with either polarity or pair 45+78 or 12+36 with the use of a bridge rectifier.

Cat.5 cable uses 24 AWG should be able to handle 800 mA and 48V. The cable has 8 wires and therefore the absolute max power is 48 * 0.8 * 4 = 153.6 W. The additional heat generated in the wires by PoE or resistance in the RJ-45 connectors will reduce the amount of net power available, particularly in crowded cable closets with a lack of proper ventilation.

Therefore the object of the present invention is to provide Broadband Ethernet connectivity to the Customer using the switch Daisy- 105. It is a 5 Port network switch that transports Traffic from the Access Ports and transmits it out to various users. The Customer traffic is propagated via point to multipoint Topology using Daisy Chain architecture.

It is surprisingly found that Daisy- 105 switch doesn't need an external Power Source, which extracts the power, needed for its operation from the Ethernet data cable.

Some of the existing 5 port switches in the industry are known to be working with either an external DC Input voltage or with an AC Input power in which case the unit will have an in built power supply.

Some of the existing switches or similar network switches in the industry are known to deliver power in the Ethernet port are capable of delivering lesser than 12 watts of power on a CAT-5 cable.

The 10/100 B - T Ethernet traffic can be transmitted on CAT-5 cable only up to 100 meters distance. Hence when there is a need for the data to travel more than 100 meters either a Hub or Layer 2 switches has to be used to extend the data further after 100 meters. Since the hub or a switch needs external power, it cannot be used in a remote location where there is no power source. So, it is a need to find out a switch, which can provide power without using external power.

It is found that a switch is capable of providing power on Ethernet cable, has a very limited power sourcing capability, which can be used to power one user. The daisy chain topology of this system is meant for point-to-multipoint application where there will be one master (Power source) and other connected switch is a slave (Powered switch). With this concept, the Ethernet driving distance again will get limited to 200 meters.

Therefore the object of the invention is to develop a switch (control/exchange/connector switch), which can function without the need of an external Power source. The switch has 5 numbers of 10/100-Base TX Ethernet port complying IEEE 802.3 specification and has one input Ethernet port from which power is derived, one output port on which power is fed to next switch and three user ports for data connectivity.

The switch has one DC Input jack on whom power can be fed externally if there is no power available from the predecessor and it can extend the LAN by more than 100 meters by connecting multiple switches in series.

The switch allows the user ports to communicate only with the input port, thereby denying the user ports from accessing the other user and sense if the switch connected to output port is another Daisy- 105 or a standard Ethernet port and switch OFF the power on this port accordingly.

The switch senses a short on the power line and shut OFF the power for safety reason and indicates whether it is feeding the power to the next switch and indicates whether it is receiving power from its previous switch.

The switch can source 3.5 watts of power on each user ports.

SUMMARY OF THE INVENTION

The foregoing and other problems are overcome and the objects of the invention are realized with a switch used for providing Broadband Ethernet connectivity to the Customer is capable of providing power on Ethernet cable, has a very limited power sourcing capability, used to power one user and function without the need of an external Power source and extend the

LAN by more than 100 meters by connecting multiple switches in series having means to sense the connectivity of the switch to ensure the output port is linked to another Daisy- 105 or a standard Ethernet port, shut OFF the power when a short on the power line and indicate whether it is feeding the power to the next switch and indicate whether it is receiving power from its previous switch. It is a 5 Port network switch that transports Traffic from the Access Ports and transmits it out to various users. The Customer traffic is propagated via point to multipoint Topology using Daisy Chain architecture.

BRIEF DESCRIPTION OF THE DRAWINGS

The above set forth and other features of the invention are made more apparent in the ensuing Detailed Description of the Invention when read in conjunction with the attached Drawings, wherein:

FIG. 1 is a Block Diagram of the Ethernet Powered switch Daisy- 105 in accordance with an embodiment of the invention;

FIG. 2 illustrates the DC voltage in the range 48 to 55 volt is fed in the unused pairs of CAT-5 cable with another embodiment of the invention.

FIG. 3 illustrates in greater detail to separate the power and data from a single cable, send the data to the user and use the remaining power to the next box in the chain with another embodiment of the invention.

Fig. 4 depicts the Power Sense and control Module block according to another embodiment of the invention.

FIG. 5 illustrates the switches in the network Daisy Chain topology which are sequentially powered in accordance with another embodiment of the invention;

Detailed description of the invention

Daisy- 105 is a 5-port Ethernet access switch compliant to IEEE 802.3 standards. Five pairs in the CAT-5 cable, 10/100 Ethernet ports, three are for users, one is the input port and the other one is the output port used to connect the next switch. The power and Ethernet data are multiplexed onto the CAT-5 cable by a device called Daisy Feeder. The first box connected to the feeder is the source of power for the next box. The block diagram of the module is shown in Fig-1

An object of the present invention is to provide a method to transport data and power on the same cable. According to present invention DC voltage in the range 48 to 55 volt is fed in the unused pairs of CAT-5 cable as shown in Fig-2.

According to the present invention, The "Power Filter" block monitors the current drawn by the switches connected to its output. The filter block is designed to shut off the power if the current drawn from the source exceeds 2 amps.

Another object of the present invention is to separate the power and data from a single cable, send the data to the user and use the remaining power to the next box in the chain in Fig - 3.

According to the present invention, the Ethernet data (Transmit and Receive) is transported in 2 pairs of cable whereas the power is transmitted in the remaining pair. In order to reduce the path resistance, one pair of cable is used for each Positive and Negative terminal of Power supply. According to the present invention, the power extracted from the "ESf Port" is used for 2 purposes. a) To power the digital section of the board which operates on a very low voltage - 3.3V DC. b) To power rest of the switches connected in the chain, which is achieved by simply bypassing the IN power to OUT port.

Another object of the present invention is to ensure that power is shut down for the next switch in the daisy chain if there is a short circuit in the cable. According to the present invention, the sensing circuitry of the power sense and control module will momentarily power the next switch and verify if the power drawn exceeds the preset limit. If it senses a healthy condition, it triggers the control module enables the MOSFET and the IN power will be transmitted to the OUT power. The condition of the power is indicated through the LEDs. Fig -4 depicts the Power Sense and control Module block.

Another object of the present invention is to ensure that power is shutdown if the connected switch is not a Daisy- 105 but some other Ethernet

port. According to the present invention the power sense module has a mechanism to detect if the switch connected to the "OUT" Port is Diasy-105 or ) not. It is any other standard Ethernet switch, which is not Daisy- 105, pin no. 7 and 8 of the out port will see a 75 ohms termination at the far end. If this condition is detected, the DC power on Pin no.s 7 and 8 is shut down thereby avoiding any damage to the third party switch.

Another object of the present invention is to ensure that the switch in the Daisy Chain is sequentially powered. This methodology prevents heavy in rush current on the power source. According to present invention as shown in Fig-5, the first switch powers up only if a valid link is present at the input port. Subsequently all other switch checks whether a valid link is present on the out port. Since it takes a finite time for the Ethernet link to come up, the switches will power one after the other.

Another object of the present invention is to ensure that the user port can also be modified as a powered port. According to the present invention a preset DC voltage that has a preset current driving capacity is coupled to pin no. 7 and pin no. 8 of the user RJ-45 connector. However if the user tries to sink excessive current from this port, the power will be shutdown on the dedicated pins of RJ-45 connector.

The Powered Ethernet switch Daisy- 105 as per the invention does not require a separate external power source like AC Input or DC Adapter and it

can be used to extend 10/100-Base T networks up to 1000 meters thereby- eliminating the need for using expensive Fiber cables and media conversion technology. The proposed switch extracts power from the data cable and provides power to the next switch in the daisy chain.

The Powered Ethernet switch Daisy- 105 can be used to power the switches on the user ports which has a wattage of even lesser than 3.5 watts according to the present invention.

The Powered Ethernet switch Daisy- 105 is provided with DC input jack assists in creating more segments of Daisy chain where the power from main source is completely consumed. Ethernet traffic can be spread out in a wide area by having multiple segments.

Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.

Accordingly a control/exchange/connector switch which extracts power from the Ethernet data cable and providing power in network

communication links used to couple multiple nodes in a data processing, LAN, MAN and the like systems in a daisy chain arrangement comprises a housing with rubber gaskets with a lock for preventing unauthorized access to Ethernet ports having five port cable for receiving data and power; a feeder to feed power and data through IN Port to power the digital section of the board and to power rest of the switches connected in the chain; a power filter to control the power fed into the system; DC Input jack to provide power when required; a selector switch to choose power from adapter or from the Input Ethernet port; power sense and control Module block; LED indications on the front panel indicate the status of power at the Input and output ports; OUT Port is to connect similar switch in a Daisy chain. Advantage of the Invention

Since the switch does not need any external power source, it can be placed anywhere at the reach of data cable. So the present invention is highly economical.

If there is a need to extend the reach of Ethernet traffic beyond 100 meters switches can be simply daisy chained without looking at the availability of a power point.

Each box consumes certain amount of power and also there is a drop in voltage because of cable resistance in the RJ-45 connectors particularly in

crowded cable closets with a lack of proper ventilation, the additional heat generated in the wires by PoE or resistance.

One power source can drive only up to 8 boxes. A DC Input jack is provided to every box, so that at the desired location where the power from main source is completely consumed, an auxiliary power source can be used. With this feature, number of boxes connected in the chain can go even more than 25, depending on the Ethernet bandwidth availability.

The ports in the 5 port Ethernet switch are grouped in such a way that the users can not communicate with each other, but can communicate only with the Uplink port (i.e IN Port). This ensures Security of user ports.

The sensing circuit in the OUT Port shuts OFF the power if the port is connected to a standard user port (Non - Daisy). This ensures the safety of a third party switch, even if it is accidentally connected.

If the cable carrying the power gets shorted accidentally, then the power is shutdown in Daisy switch, thereby protecting the source delivering the power.

The LED indications on the front panel indicate the status of power at the Input and output ports, thereby if there is any fault in the cable can be easily identified.

Claims

1. A control/exchange/connector switch which extracts power from the Ethernet data cable and providing power in network communication links used to couple multiple nodes in a data processing, LAN, MAN and the like systems in a daisy chain arrangement comprises a housing with rubber gaskets with a lock for preventing unauthorized access to Ethernet ports having five port cable for receiving data and power; a feeder to feed power and data through IN Port to power the digital section of the board and to power rest of the switches connected in the chain; a power filter to control the power fed into the system; DC Input jack to provide power when required; a selector to choose power from adapter or from the Input Ethernet port; power sense and control Module block; LED indications on the front panel indicate the status of power at the Input and output ports; OUT Port is to connect similar switch in a Daisy chain.

2. A control/exchange/connector switch as claimed in claim 1, five port cable is CAT-5 cable having five pairs, 10/100 Ethernet ports, 3 are for users, one is the input port and the other one is the output port used to connect the next switch.

3. A control/exchange/connector switch as claimed in claim 1, the power and Ethernet data are multiplexed onto the CAT-5 cable using feeder

and the first box in the daisy chain is connected to the feeder is the source of power for the next box in the Daisy chain.

4. A control/exchange/connector switch as claimed in claim 1, the Power Filter block monitor the current drawn by the switch connected to its output and shut off the power if the current .drawn from the source exceeds 2 amps.

5. A control/exchange/connector switch as claimed in claim 1, Ethernet data (Transmit and Receive) is transported in 2 pairs of cable whereas the power is transmitted in the remaining pair.

6. A control/exchange/connector switch as claimed in claim 1, the power extracted from the IN Port is used to power the digital section of the board, which operates on a very low voltage — 3.3V DC.

7. A control/exchange/connector switch as claimed in claim 1, the power extracted from the ESI Port is used to power rest of the switches connected in the chain, which is achieved by simply bypassing the IN power to OUT port.

8. A control/exchange/connector switch as claimed in claim 1, the power sensing circuit of the power sense and control module will momentarily power the next switch and verify the power drawn exceeds the preset limit and the OUT Port shuts OFF the power if the port is connected to a standard user port (Non - Daisy) which ensures the safety of a third party switch, even if it is accidentally connected.

9. A control/exchange/connector switch as claimed in claim 1, the OUT port that transmits power and data to the succeeding similar switch in the Daisy chain.

10. A control/exchange/connector switch as claimed in claim 1, selector mounted inside the enclosure is used to select DC power source either from the DC Jack or from the 'IN' Ethernet port.

11. A control/exchange/connector switch as claimed in claim 1, LED indications are mounted in the front side of the housing to indicate the condition of power at both Input and Output ports and to indicate the link and activity status of the respective Ethernet ports and any fault in the cable can be easily identified.

12. A control/exchange/connector switch as claimed in claim 1, DC input jack is housed inside the enclosure and has a cable entry provision at the bottom of the housing and assists in creating more segments of Daisy chain where the power from main source is completely consumed.

13. A control/exchange/connector switch as claimed in claim 1, Ethernet traffic can be spread out in a wide area by having multiple segments of the switch claimed in the daisy chain.

14. A control/exchange/connector switch as claimed in claim 1, power is shutdown when the connected switch is some other Ethernet port, which is other than the switch claimed in claim 1 to 17.

15. A control/exchange/coπnector switch as claimed in claim 1, the daisy chain topology of this system is meant for point-to-multipoint application where there will be one master (Power source) and other connected switch is a slave (Powered switch).

16. A control/exchange/connector switch as claimed in claim 1, the first switch powers up only if a valid link is present at the input port wherein all other switches checks whether a valid link is present on the out port and takes a finite time for the Ethernet link tα come up, the switches wilt power one after the other and are sequentially powered which prevents heavy inrush current on the power source.

17. A εontrol/exchange/connector switch such as herein described and exemplified.