Abstract:
A programmably configurable computer network, particularly applicable to small network applications such as home networks, includes a plurality of nodes which may be implemented through wall-box sized components. The nodes may be connected through telephone wires and may also offer telephone connectors at each node. The system may be powered by a high frequency power supply which is isolated from the external telephone system using a low pass filter. 
     In this way, the network can be automatically configured to achieve an efficient and specification compliant topology without requiring rewiring of the building.

Description:
This is a divisional of prior application Ser. No. 09/119,370 filed Jul. 20, 1998 now U.S. Pat. No. 6,216,160. 
    
    
     BACKGROUND 
     This invention relates generally to computer networks and particularly to networks with a relatively small number of nodes. 
     Computer networks connect computers and other devices together so that various computers on the network can share files, programs and resources. For example, it may be desirable to centralize files on one computer and allow access through the network from other computers. In addition, it may be desirable to share resources such as a printer with a number of computers. All of these functions can be achieved through computer networks. As a result of the advantages of computer networks, home computer networks are becoming more prevalent. Many homes have more than one computer and, for the reasons described above, many users would like to share resources and files among those computers. 
     Today, some builders provide houses which are pre-wired for such computer network connections. The homeowner merely plugs in the various components into pre-wired wall jacks. However, these pre-wired connections tend to be cost prohibitive for most homeowners. 
     Networks generally come in two basic types. The most common type uses twisted pair cables and includes what is known as a network hub. The hub includes a plurality of cable connectors so that each computer on the network may be connected to the hub. Some networks use coaxial cables where the cable goes directly from computer to computer without using a network hub. 
     The Ethernet is a standardized way of connecting computers into a network. The standards for the Ethernet are set forth in the Institute of Electrical and Electronics Engineers (New York, N.Y.) IEEE 802.3 standard. Most common Ethernet systems today transmit data at a rate of 10 million bits per second. A newer Ethernet version called Fast Ethernet has a bandwidth of 100 million bits per second and is sometimes referred to as 100BaseT. The 10 million bits per second networks are generally called 10BaseT when twisted pair cabling is utilized. 
     A popular network cable is unshielded twisted pair cable (UTP). Generally, UTP cable connects the Ethernet network by coupling the computers in a star arrangement. At the center of the star is the hub. UTP cable is generally connected to various devices such as computers through UTP connectors called RJ-45 connectors. The RJ-45 connectors are similar to the plug-in connectors used to connect telephones (which are called RJ-11 connectors). 
     There are a variety of rules for Ethernet connections compliant with the IEEE standard. One of the basic rules is that there may not be more than three hops. A hop is a connection from one device to another. In addition, there are rules with respect to the maximum length of cable. For 10BaseT cable, the maximum length is generally 100 meters. This normally means that about 90 meter runs may be used between nodes assuming 10 meter cables are used to connect a computer or other device to an RJ-45 connector. 
     While network technology has been applied widely to larger businesses, the cost has been prohibitive in many cases as applied to home and small business applications. A large component of the cost associated with home networks is the need to rewire existing homes to provide the Ethernet connections. Normally, this involves using UTP cabling and RJ-45 connectors to provide a plurality of connection points in different rooms of the house. These connection points are then wired together using the UTP cable to form the network. Usually, in a 10BaseT system, the network would also include a hub. 
     For existing homes, the wiring expense alone is prohibitive, and even for new homes, the expense is sufficiently great that new homes commonly do not include network wiring. 
     Thus, there is a continuing need for a network system that avoids the need for extensive rewiring or special network wiring. 
     SUMMARY 
     In accordance with one aspect, a computer network includes a plurality of nodes. A programmable switching network allows the nodes to be connected in a plurality of different ways. 
     In accordance with another aspect, a computer network includes a plurality of nodes connected to telephone lines. Telephone wires connect the various nodes to one another. A high frequency power supply for the nodes is connected to those telephone wires. However, a filter is arranged to isolate the network power supply from the external telephone service. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of one embodiment of a node in accordance with one embodiment of the present invention; 
     FIG. 2 is a flow diagram for the power-up sequence for the microcontroller shown in FIG. 1; 
     FIG. 3 is a flow diagram for implementing network configuration rules for the microcontroller shown in FIG. 1; 
     FIG. 4 shows an exemplary connection between a plurality of nodes in accordance with one aspect of the present invention; 
     FIG. 5 shows another exemplary connection between a plurality of nodes in accordance with one embodiment of the present intention; 
     FIG. 6 shows a perspective view of a cutaway building showing the connections to a plurality of devices connected by a network in accordance with one aspect of the present invention; 
     FIG. 7 is a perspective view of the rear of a connector plate implementing the node shown in FIG. 1; and 
     FIG. 8 is a front elevational view of the connector plate shown in FIG.  5 . 
    
    
     DETAILED DESCRIPTION 
     A programmably configurable node  10 , shown in FIG. 1, for a computer network includes network connectors  24   a  and  24   b  and a telephone connector  11 . The network connectors  24  may be conventional RJ-45 connectors used in a UTP system. The telephone connector  11  connects to the phone line  14  through a low pass filter  12 . 
     The low pass filter  12  prevents the high frequency signal that is developed by the power supply  16  from affecting telephone equipment. The power supply provides a DC signal for the microcontroller  18  and the analog switching matrix  22 . Only one node  10  needs to be connected to system power as illustrated in FIG.  1 . The other nodes may receive power through the node connected to system power. 
     The microcontroller  18  controls an analog switching matrix  22  which is connected to the network uplink pair  34  and the network downlink pair  36 . These pairs may also be referred to as the receive (R+, R−) and transmit (T+, T−) pairs. Switching matrix  22  also connects the network connectors  24   a  and  24   b  which, in the illustrated embodiment, are RJ-45 connectors. The microcontroller  18  drives a plurality of indicators  20  associated with each of the connectors  11  and  24  to indicate their status. Additional indicators can be provided as well. The switching network  22  may also connect to a plurality of transceivers  26  which in turn are coupled by a bus  30 . 
     The microcontroller  18  controls the configuration of the switching matrix  22  to provide a programmably configurable node. The node may be configured, for example, as a pass through node which simply passes any information it receives on to the next node in the network. In such case, the transceivers  26  are not utilized. 
     The switching matrix  22  may, however, configure the transceivers  26  to provide a plurality of programmable ports  10 . For example, through the transceivers  26 , the node  10  may act as a hub. A plurality of devices can be connected through the transceivers  26  as desired. 
     Referring to FIG. 2, upon power-on or after a reconfiguration order to the node  10 , the node  10  checks each transceiver  26  port, checks its status and creates a network map, as indicated in block  64 . Next, a check is made to determine whether there is more than one connection to the node, as indicated in diamond  66 . If so, the networks maps from all downstream nodes are collected and consolidated into one map, as indicated in block  68 . The flow waits until all other nodes have reported. The node only sends its local network map upstream, as indicated at block  66 . Otherwise the node receives maps from downstream nodes and only then sends its map to upstream nodes. 
     In block  72 , the node receives upstream network maps, which the node consolidates. The consolidated map is then sent downstream (block  74 ). The appropriate network configuration rules are then applied to the network map as shown in block  76 . The rules could implement, for example, the IEEE 802.3 standard. 
     Generally, all of the nodes apply the same rules and should deduce the same configuration for the network. However, in some cases, it may be desirable to denominate one microcontroller in one hub as the master and other microcontrollers in other hubs as slaves to that master. 
     The simple network management protocol (SNMP) may enable various hubs to be interrogated as to their current condition and the condition of any resources connected to those hubs. The SNMP describes how information is exchanged those hubs. The SNMP describes how information is exchanged between various network devices. Thus, not only may devices connected to a given hub have their status evaluated, but hub-to-hub status evaluations may be accomplished as well. 
     The network configuration rules may be implemented using the flow shown in FIG.  3 . All nodes except the one with system power may initially be enumerated as #0, while the node with system power is enumerated as #1, as indicated in block  78 . In the consolidated maps (FIG. 2, block  72 ), the nodes are numbered successively extending away from the system hub, as indicated in block  80 . Priority is given to the nodes on the lowest numbered local port. Next a check is made (diamond  82 ) to determine if there are more than three hops. If not, the configuration is complete. 
     If there are more than three hops, the number of hops must be reduced to three. A first attempt to resolve the excessive number of hops is to let nodes with one or less devices configure themselves as a pass through to a single connector (block  84 ). A check is made at diamond  86  to see if the number of hops still exceeds three. If not the configuration is complete. 
     Otherwise, the flow lets the nodes with no devices and only two node connections configure themselves as a pass through, as shown in block  88 . Again a check is made, this time a diamond  90 , to see if the three hop rule is still violated. If not the configuration is complete. 
     Otherwise, the user is signaled to move a device. Nodes which have one device more than the other nodes indicate by flashing an indicator associated with their device ports (block  92 ). 
     All of the nodes have the same rules and the same network map. Thus all the nodes know what changes must be made to all the other nodes. 
     Referring now to FIG. 5, a plurality of nodes  38  are connected together in the exemplary fashion shown in FIG.  2 . The nodes  38  are connected to one another using conventional telephone cabling. Conventional telephone cable used in homes includes four wire pairs. These wire pairs may be utilized to provide two telephone lines and two lines for providing network interconnections in an in-home system. The illustrated embodiment uses the Ethernet 10BaseT system. 
     In the configuration shown in FIG. 4, a node  38   c  has configured itself with one upload port and four standard ports. The node  38   d  has configured itself with one upload port and three standard ports through the appropriate programming of the transceivers  26 . The nodes  38   a ,  38   b  and  38   e  are all configured as one upload and two standard ports. Thus, the wiring connections may be dynamically configurable based on the needs of the system and the rules of the appropriate network such as the IEEE 802.3 standard. These rules may be stored in the memory  19  of the microcontroller  18 . 
     Referring next to FIG. 5, a network consisting of nodes  38   f  through  38   j  are connected in a generally linear fashion. The network is wired with five outlets in series. Since the node  38   g  does not have computers attached to it, it has configured itself as a pass through node in order not to exceed the 10BaseT hop limits. As indicated by the indicators  20   a  and  20   c , the network connections of the node  38   g  have been deactivated. 
     A house  40  may be provided with a network shown in FIG. 6, using a plurality of nodes  38   k  through  38   n . Each of these nodes may be formed by the circuitry shown in FIG. 1 within a standard wall electrical box. In the illustrated embodiment, a telephone  41  is connected to the node  38   k  together with a printer  42 . Computers  44   a  and  44   b  are connected to the nodes  38   l  and  38   m  respectively. 
     A box unit  52 , illustrated in FIG. 7, for housing a node  38 , includes a cover plate  54  and a housing  56 . The housing  56  contains the circuitry shown in FIG.  1  and provides a plurality of connections  60  to the telephone pairs. The cover plate  54  also includes an opening  58  for securing the box  52  to the wall. 
     After the appropriate connections have been made to the telephone pairs, the box  52  is secured to the wall using standard fasteners in the opening  58  so that the cover plate  54  faces outwardly, as illustrated in FIG.  8 . The cover plate  54  then provides two network connection plugs,  24   a  and  24   b , and a telephone connection plug  11 . These connection plugs may be labeled as indicated to prevent confusion. Indicators  2   a ,  20   b , and  20   c , which may be conventional light emitting diodes (LED), may be provided to give status information with respect to each of the connectors  24  or  11 . 
     Each node  10  may also include packet regeneration, automatic polarity detection/correction and the IEEE defined link integrity test function which continually monitors the receive pair to assure link continuity. In addition, each node may include segment partitioning and jabber lock-up protection. 
     Using as few as three phone line pairs, two to four local area network (LAN) devices may be connected using standard connectors. The nodes do not require any local power supply. Instead, they are supplied with operating power from a high frequency signal applied to the primary phone line either at the phone junction box, at one of the nodes, or within the wall. The power supply may be isolated from the telephone company lines at the utility box via a low-pass filter. 
     Through the use of the microcontrollers  18 , the network can be automatically configured to achieve the most desirable topology consistent with the applicable standards. When power is supplied, each node communicates with each adjacent node to develop a connection topology. Then, the nodes plan a topology which meets the restrictions of any applicable standards. Each node can configure itself as a pass through, repeater or hub. Further, each port on each node can be configured as a standard uplink or pass through port as well as reconfiguring its polarity. 
     Although the present invention has been described with respect to a 10BaseT system, the concepts set forth herein are also applicable to other network connections and to higher throughput Ethernet connections as well. 
     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of the present invention.