Abstract:
An addressable outlet for use as part of local area network based on wiring installed in a building, such as telephone, electrical, cable television, dedicated wiring, and the like. The use of such wiring for data communications networks in addition to the wiring&#39;s primary usage creates a need for ways of determining the condition of the network and monitoring this information remotely. Network condition includes such factors as continuity of wiring, connector status, connected devices, topology, signal delays, latencies, and routing patterns. Providing basic processing and addressing capabilities within the outlet permits messaging to and from specific individual outlets, thereby allowing inquiries and reports of the condition of the immediate environment of each outlet. In addition, outlets can be configured with sensors to report on voltage, temperature, and other measurable quantities.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation of pending U.S. application Ser. No. 10/491,989, filed on Apr. 4, 2004, the disclosure of which is incorporated herein by reference 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to the field of wired Local Area Networks (LAN&#39;s) using outlets, and, more specifically, to an addressable outlet for use in such networks.  
       BACKGROUND OF THE INVENTION  
       [0000]     Outlets  
         [0003]     The term “outlet” herein denotes an electromechanical device, which facilitates easy, rapid connection and disconnection of external devices to and from wiring installed within a building. An outlet commonly has a fixed connection to the wiring, and permits the easy connection of external devices as desired, commonly by means of an integrated connector in a faceplate. The outlet is normally mechanically attached to, or mounted in, a wall. Non-limiting examples of common outlets include: telephone outlets for connecting telephones and related devices; CATV outlets for connecting television sets, VCR&#39;s, and the like; and electrical outlets for connecting power to electrical appliances. The term “wall” herein denotes any interior or exterior surface of a building, including, but not limited to, ceilings and floors, in addition to vertical walls.  
         [0000]     LAN Environment  
         [0004]      FIG. 1  shows a typical prior art LAN environment  10 . Such a network commonly uses 10BaseT or 100BaseTX Ethernet IEEE802.3 interfaces and topology, and features a hub  11  as a concentrating device, into which all devices are connected. Devices are connected to the hub  11  by data connectors  14   a,    14   b,  and  14   c,  which are housed within network outlets  15   a,    15   b,  and  15   c  respectively. Connections to the hub  11  are via cables  13   a,    13   b,  and  13   c  respectively. Data connectors  14   a,    14   b,  and  14   c  may be, for example, type RJ-45 connectors; and cables  13   a,    13   b,  and  13   c  may be, for example, Category 5 cabling. The data portion of network  10  uses data units (which may be computers)  7   a,    7   b,  and  7   c,  which connect to network connectors  14   a,    14   b,  and  14   c  via cables  16   a,    16   b,  and  16   c,  respectively. A server  12  may also be connected to the hub  11 , and can perform the external connection functionality, as well as other server functions as applied in the art.  
         [0005]     Although  FIG. 1  refers to the hub  11  as a concentrating device, it is to be understood that any type of device having multiple network interfaces and supporting a suitable connectivity can be used, non-limiting examples of which include shared hubs, switches (switched hubs), routers, and gateways. Hence, the term “hub” herein denotes any such device without limitation. Furthermore, network  10  can be any packet-based network, either in-building or distributed, such as a LAN or the Internet.  
         [0006]     The topology of network  10  as shown in  FIG. 1  incurs various maintenance difficulties. The wiring from the hub  11  to the data unit  7   a,  for example, includes wire  13   a,  connector  14   a  and wire  16   a.  Because these conductors are continuous, there is no easy way to distinguish a break or short-circuit in wire  13   a  from a break or short-circuit in wire  16   a,  nor from a break or short-circuit in connector  14   a.  Troubleshooting such failures requires disconnecting cables and inserting dedicated test equipment or making elaborate and thorough substitutions of components that are known to be functional. Such procedures are complicated, labor-intensive, time-consuming, and expensive. Furthermore, in the common case of an outlet to which no data unit is connected, there is no simple way to test the continuity of wiring from the hub to the outlet. In addition, in many cases it is necessary to test the LAN from a remote place (such as via the Internet) in cases where it is not possible to attach testing equipment to non-connected outlets.  
         [0007]     Discussion of network management and example of network management system are part of U.S. Pat. No. 5,812,750 to Dev et al.  
         [0000]     Home Networking  
         [0008]     Most existing offices and some of the newly built buildings facilitate the network structure of network  10 . However, implementing such a network in existing buildings typically requires installation of new wiring infrastructure. Such installation of new wiring may be impractical, expensive and hassle-oriented. As a result, many technologies (referred to as “no new wires” technologies) have been proposed in order to facilitate a LAN in a building without adding new wiring. Some of these techniques use existing wiring used also for other purposes such as telephone, electricity, cable television, and so forth. Doing so offers the advantage of being able to install such systems and networks without the additional and often substantial cost of installing separate wiring within the building. In order to facilitate multiple use of wiring within a building, specialized outlets are sometimes installed, which allow access to the wiring for multiple purposes. An example of home networking over coaxial cables using outlets is described in WO 02/065229 published 22 Aug. 2002 entitled: ‘Cableran Networking over Coaxial Cables’ to Cohen et al.  
         [0009]     The use of such wiring for additional purposes creates a need for ways of easily determining the condition of the wiring and obtaining this information remotely.  
         [0010]     Home networking using existing telephone lines will be described as an example.  
       DEFINITIONS AND BACKGROUND  
       [0011]     The term “telephony” herein denotes in general any kind of telephone service, including analog and digital service, such as Integrated Services Digital Network (ISDN).  
         [0012]     Analog telephony, popularly known as “Plain Old Telephone Service” (“POTS”) has been in existence for over 100 years, and is well-designed and well-engineered for the transmission and switching of voice signals in the 3-4 KHz portion (or “band”) of the audio spectrum. The familiar POTS network supports real-time, low-latency, high-reliability, moderate-fidelity voice telephony, and is capable of establishing a session between two end-points, each using an analog telephone set.  
         [0013]     The terms “telephone”, “telephone set”, and “telephone device” herein denote any apparatus, without limitation, which can connect to a Public Switch Telephone Network (“PSTN”), including apparatus for both analog and digital telephony, non-limiting examples of which are analog telephones, digital telephones, facsimile (“fax”) machines, automatic telephone answering machines, voice modems, and data modems.  
         [0014]     The terms “data unit”, “computer” and “personal computer” (“PC”) as used herein include workstations and other data terminal equipment (DTE) with interfaces for connection to a local area network  
         [0015]     In-home telephone service usually employs two or four wires, to which telephone sets are connected via telephone outlets.  
         [0000]     Home Networking Over Telephone Lines.  
         [0016]      FIG. 2  shows the wiring configuration of a prior-art telephone system including a network  20  for a residence or other building, wired with a telephone line  5 , which has a single wire pair that connects to a junction-box  34 , which in turn connects to a Public Switched Telephone Network (PSTN)  39  via a cable  33  (‘local loop’), terminating in a public switch  32 , which establishes and enables telephony from one telephone to another. The term “high-frequency” herein denotes any frequency substantially above such analog telephony audio frequencies, such as that used for data. ISDN typically uses frequencies not exceeding 100 KHz (typically the energy is concentrated around 40 KHz). The term “telephone line” herein denotes electrically-conducting lines which are intended primarily for the carrying and distribution of analog telephony signals, and includes, but is not limited to, such electrically-conducting lines which may be pre-existing within a building and which may currently provide analog telephony service.  
         [0017]     Junction box  34  separates the in-home circuitry from the PSTN and is used as a test facility for troubleshooting as well as for new wiring in the home. A plurality of telephones may connect to telephone lines  5  via a plurality of telephone outlets. Each outlet has a connector (often referred to as a “jack”), commonly being in the form of RJ-11 connectors in North-America. Each outlet may be connected to a telephone unit via a compatible “plug” connector that inserts into the jack.  
         [0018]     Wiring  5  is usually based on a serial or “daisy-chained” topology, wherein the wiring is connected from one outlet to the next in a linear manner; but other topologies such as star, tree, or any arbitrary topology may also be used. Regardless of the topology, however, the telephone wiring system within a residence always uses wired media: two or four copper wires terminating in one or more outlets which provide direct access to these wires for connecting to telephone sets.  
         [0019]     It is often desirable to use existing telephone wiring simultaneously for both telephony and data networking. In this way, establishing a new local area network in a home or other building is simplified, because there is no need to install additional wiring.  
         [0020]     The concept of frequency domain/division multiplexing (FDM) is well-known in the art, and provides means of splitting the bandwidth carried by a wire into a low-frequency band capable of carrying an analog telephony signal and a high-frequency band capable of carrying data communication or other signals. Such a mechanism is described, for example, in U.S. Pat. No. 4,785,448 to Reichert et al. (hereinafter referred to as “Reichert”). Also widely used are xDSL systems, primarily Asymmetric Digital Subscriber Loop (ADSL) systems.  
         [0021]     Examples of relevant prior-art in this field are the technology commonly known as HomePNA (Home Phoneline Networking Alliance), WO 99/12330 to Foley and as disclosed in U.S. Pat. No. 5,896,443 to Dichter (hereinafter referred to as “Dichter”). Dichter and others suggest a method and apparatus for applying a frequency domain/division multiplexing (FDM) technique for residential telephone wiring, enabling the simultaneous carrying of telephony and data communication signals. The available bandwidth over the wiring is split into a low-frequency band capable of carrying an analog telephony signal, and a high-frequency band capable of carrying data communication signals. In such a mechanism, telephony is not affected, while a data communication capability is provided over existing telephone wiring within a home.  
         [0022]     In addition to illustrating a residential telephone system,  FIG. 2  also shows the arrangement of a Dichter network. Network  20  serves both analog telephones and provides a local area network of data units. Data Terminal Equipment (DTE) units  7   a,    7   b,    7   c  and  7   d  are connected to the local area network via Data Communication Equipment (DCE) units  25   a,    25   b,    25   c  and  25   d,  respectively. Examples of Data Communication Equipment include, but are not limited to, modems, line drivers, line receivers, and transceivers (the term “transceiver” herein denotes a combined transmitter and receiver), which enables data communication over the high spectrum of telephone line  5 . DCE units (‘phoneline modems’)  25   a,    25   b,    25   c  and  25   d  are respectively connected to high pass filters (HPF)  24   a,    24   b,    24   c  and  24   d,  which allow access to the high-frequency band carried by telephone line  5 . In order to avoid interference to the data network caused by the telephones, low pass filters (LPF&#39;s)  23   a,    23   b,    23   c  and  23   d  are added to isolate the POTS carrying band, so that telephones  26   a,    26   b,    26   c  and  26   d  connects to telephone line  5  for providing PSTN. Furthermore, a low pass filter may also be connected to Junction Box  34  (not shown in the figure), in order to filter noise induced from or input to PSTN wiring  33 .  
         [0023]     WO 01/71980 published Sep. 27, 2001 entitled “Telephone Outlet and System for a Local Area Network Over Telephone Lines” in the name of the present inventor and assigned to the present assignee, describes the integration of DCE  25 , HPF  24 , and LPF  23  components into outlets  21  in order to reduce complexity, as shown in  FIG. 2 . This allows direct connection of telephone sets  6   a,    6   b,    6   c,  and  6   d  to outlets  21   a,    21   b,    21   c,  and  21   d,  respectively, via dedicated connectors (as is done in prior-art common telephone outlets), as well as direct and easy connection of data units  7   a,    7   b,    7   c,  and  7   d  to the respective outlets via dedicated jacks, as is usually done in LAN systems (as shown in  FIG. 1 ).  
         [0024]     The topology of network  20  as shown in  FIG. 2  exhibits the maintenance difficulties previously discussed. The data flow from data unit  7   a  to data unit  7   b,  for example, is via wiring  16   a,  wiring  5   b  and wiring  16   b,  as well as connectors such as  22   a  and  22   b.  Having continuous data flow, there is no easy way to distinguish a short-circuit in wiring  16   a  from a short-circuit in wiring  16   b,  or from a short-circuit in wiring  5   b,  or from a short-circuit in any of the interim connectors. Similarly, a break in the wiring cannot be easily or remotely isolated to wiring  16   a  or wiring  16   b.  Troubleshooting any of the above failures can only be accomplished by trial and error and requires disconnecting cables  16   a,    16   b,    16   c,  and  16   d,  and inserting other data units to the outlets. If the failure, however, is in wiring  5   c,  more troubleshooting will be necessary, and can ultimately involve disconnecting the entire network. As noted above, this is a complicated, expensive, labor-intensive, and time-consuming effort. Furthermore, in the common case of an outlet into which no data units are connected, there is no simple way to test wiring continuity to the outlet. In addition, as explained in WO 99/03255 to Bell, in many cases it is required to test the LAN from a remote place (e.g. via the Internet), and no local presence is available to approach the disconnected outlets for attaching testers.  
         [0025]     U.S. Pat. No. 4,787,082 entitled Data flow control arrangement for local area network (Delaney et al.) published Nov. 22, 1988 discloses a local data distribution network wherein a plurality of bidirectional data distribution busses are each connected to a bus master control circuit at a terminal end of the bus. Connected to each of the data distribution busses are a plurality of passive outlets to which intelligent connectors or stations may be connected. Each station has a unique address and is utilized for individually coupling data processing devices to the bus. A bus termination hub switching facility cooperates with the included group of bus master control circuits to interconnect data processing stations on the various busses. The bus termination hub facility includes bus monitoring, status polling and maintenance facilities. A faulty bus is disconnected if a fault is discovered during monitoring intervals. It remains disconnected until the fault is corrected.  
         [0026]     JP 55132197A2 published Oct. 14, 1980 in the name of Sharp Corporation and entitled “Unit Controlling Electric Equipment Making Use of House Wiring” relates to the control of electrical equipment connected to house wiring. An address information signal is sent through a coupling unit from a transmission controller to house wiring. On the reception side, reception controllers receive the address information signal through coupling units inserted into sockets provided at respective positions of the house wiring. From one of controllers whose incorporated address information agrees with the received address information, answer information is sent back to the transmission side. On the transmission side, an operation command code is sent out upon receiving the answer information from the reception side so as to control electric equipment.  
         [0027]     In both above prior art patents, passive outlets are used, hence there is no way to distinguish between a failure in the wiring into which the outlets are connected, and a failure in the wiring/equipment connected to the outlet.  
         [0028]     There is thus a widely recognized need for, and it would be highly advantageous to have, a method and system for allowing remote diagnosis of LAN environment outlets without requiring local access to the network and without dismantling the network. This goal is met by the present invention.  
       SUMMARY OF THE INVENTION  
       [0029]     It is an object of the present invention to allow convenient determination of the status of installed wiring within a building, and the outlets and connectors thereto.  
         [0030]     It is a further object of the present invention to allow convenient determination of the condition of devices and apparatus connected to the various outlets of an installed wiring system. It is moreover an object of the present invention to permit such determination remotely.  
         [0031]     In order to attain these objectives, the present invention provides an outlet having an address which uniquely identifies the outlet within an information network that is established, at least in part, over wiring to which the outlet is connected. Associated with this unique network address is processing circuitry and an addressing unit capable of storing and utilizing the unique network address, to allow the outlet to receive and send messages associated with the address. The processing circuitry interfaces with the network to support such messaging, and may generate content for messages to be sent to other devices on the network, and may likewise receive and process messages sent to the outlet from other devices. The unique network address is associated with both the sending and receiving of messages over the network. In the case of receiving messages, the unique address allows the circuitry in the outlet to discriminate between messages intended for that outlet and messages intended for other devices. In the case of sending messages, the unique address serves to identify the source of the message. Because addresses are associated both with senders and receivers, the processing circuitry may respond to messages sent to the outlet from other devices by sending messages from the outlet to other devices.  
         [0032]     Outlets according to the present invention include, but are not limited to, electrical power outlets, telephone outlets, and cable television outlets.  
         [0033]     The term “information network” herein denotes any system that allows multiple devices to send and receive information of any kind, wherein each device may be uniquely identified for purposes of sending and receiving information. Information networks include, but are not limited to, data networks, control networks, cable networks, and telephone networks. A data network utilizing outlets according to the present invention can be a local area network (LAN) or part of a wide-area network, including the Internet.  
         [0034]     Therefore, according to the present invention there is provided an outlet for use with wiring installed in a building, and having at least one address that uniquely identifies the outlet within an information network. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]     The invention is herein described, by way of non-limiting example only, with reference to the accompanying drawings, wherein:  
         [0036]      FIG. 1  shows a prior art local area network.  
         [0037]      FIG. 2  shows a prior art local area network over telephone lines.  
         [0038]      FIG. 3  shows a local area network outlet according to the present invention.  
         [0039]      FIG. 4  shows a local area network according to the present invention.  
         [0040]      FIG. 5  shows a local area network over telephone lines outlet according to the present invention.  
         [0041]      FIG. 6  illustrates the front panel of a telephone outlet according to the present invention.  
         [0042]      FIG. 7  shows a local area network over telephone lines according to the present invention.  
         [0043]      FIG. 8  illustrates a general form of an outlet according to the present invention, which can serve in various wired network environments, such as CATV and electrical power networks.  
         [0044]      FIG. 9  shows a remote-managed local area network according to the present invention. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0045]     The principles and operation of a network according to the present invention may be understood with reference to the drawings and the accompanying description. The drawings and descriptions are conceptual only. In actual practice, a single component can implement one or more functions; alternatively, each function can be implemented by a plurality of components and circuits. In the drawings and descriptions, identical reference numerals indicate those components that are common to different embodiments or configurations.  
         [0046]      FIG. 3  schematically shows an outlet  30  according to a first embodiment of the invention. As shown in  FIG. 3 , outlet  30  includes a three-port hub  11 . One port goes to a connector  31 , which connects the outlet  30  to network wiring as previously described, and as is known in the art (such as to wiring  13   a  in  FIG. 1 ). Another hub port goes to a connector  38 , enabling connection of a data unit as described previously and as is known in the art (such as to data unit  7   a  via wiring  16   a  in  FIG. 1 ). The third port goes to a processing unit  36 , integrated within outlet  30 . Processing unit  36  provides the basic functionality of a data unit (such as data unit  7   a  of  FIG. 1 ), and principally includes an address unit  37 , with a stored address  39 , that is unique within the network. For example, in an Ethernet network using interfaces 10BaseT or 100BaseTX according to IEEE802.3, the processing unit  36  may include a MAC (Media Access Control) address or an IP (Internet Protocol) address, as the address  39 . In this manner, outlet  30  becomes an addressable entity within the network, and is able to respond to messages carrying address  39 , or to transmit messages containing address  39  as a source. Because the outlet  30  is an addressable entity in the network, it is possible to execute remote diagnostics to determine the status and health of the outlet  30 . For example, a message calling for a reply can be sent to the outlet  30 . Receiving an answer from such an outlet confirms the existence of the outlet in the network, as well as the basic functionality of the outlet and any connections to the outlet via which the answer is received. Furthermore, one or more status devices may be integrated in the outlet and addressed either individually or as a group, to providing meaningful data about the outlet status and the condition of the network in general. Typical status devices are voltage sensors, continuity detectors, hub activity indicators, transducers etc. Network condition includes, but is not limited to, such factors as continuity of wiring, connector status, connected devices, topology, signal delays, latencies, and routing patterns. Although the outlet  30  has been described above as having a single data networking interface  38 , multiple interfaces can be supported, each connected to a different port of hub  11 . Processing unit  36  may also be capable of analyzing received messages, in order to perform actions in response thereto, as well as composing messages for sending, in order to respond to received messages, or to initiate messages to other devices on the network. For example, processing unit  36  may detect an abnormal condition or emergency situation, and may therefore notify other devices on the network via messages.  
         [0047]     Managed devices such as managed hub, managed switch and router are known in the art. Outlet  30  may be viewed as a managed device housed within an outlet.  
         [0048]      FIG. 4  shows a Local Area Network (LAN)  40  according to the present invention. Basically, the infrastructure of network  40  is the same as that of prior art network  10  ( FIG. 1 ), in which hub  11  is connected in a ‘star’topology to various end units via network wiring  13   a  and  13   b,  which are connected respectively to outlets  15   a  and  15   b  (in  FIG. 1 ). However, according to the present invention, outlets  15   a  and  15   b  of prior-art network  10  are replaced by outlets  30   a  and  30   b,  respectively, which contain addressable processing units  36   a  and  36   b,  as previously described with reference to  FIG. 3 . For example, outlet  30   a  has built-in processing unit  36   a,  addressing unit  37   a,  and address  39   a.  Outlet  30   a  allows for connection of data unit  7   a  via a connector  38   a  using wiring  16   a.  Similarly, outlet  30   b  allows data unit  7   b  to be connected to the network via wiring  16   b  to a connector  38   b.  Addressing units  37   a  and  37   b  integrated within outlets  30   a  and  30   b,  respectively, allow for unique identification of outlets  30   a  and  30   b  by addresses  39   a  and  39   b,  respectively.  
         [0049]     Network  40  offers the advantages of being able to individually address each outlet, hence allowing remote diagnostics. The outlets  30   a  and  30   b  of network  40  can now facilitate fault localization. For example, the server  12  will transmit a message to outlet  30   a,  using outlet  30   a  address, followed by a message to data unit  7   a.  In the case wherein outlet  30   a  responds to the server  12  and data unit  7   a  does not respond, the most probable scenario is that the connection between the data unit and outlet  30   a  is faulty or no data unit is connected to outlet  30   a.  Hence, assuming data unit  7   a  is connected, the fault is easily limited only to connector  38   a,  wiring  16   a  or data unit  7   a.  Similarly, in the case wherein no reply is received from outlet  30   a,  the fault is localized to cable  13   a,  connector  31   a  or outlet  30   a.    
         [0050]     Powering the outlet  30  can be implemented either locally, by connecting a power supply to each outlet, or, preferably, via the network itself. In the latter case, commonly known as “Power over LAN”, the power can be carried to the outlet from a central location either by an additional wire pair, using the well-known phantom configuration, or by the FDM (Frequency Division/Domain Multiplexing) method. The latter commonly employs DC feeding, which is frequency-isolated from the data carried in the higher part of the spectrum.  
         [0051]     In another embodiment, the present invention is used in a data network over in-building telephone lines, where analog telephony signals are carried in the low-frequency portion of the spectrum, and data communication signals are carried in the high-frequency portion.  FIG. 5  shows an outlet  50  according the present invention, which is able to separate and combine signals in different portions of the spectrum. Outlet  50  connects to the telephone wiring via a connector  22 , preferably located at the rear part of outlet  50 , where outlet  50  mechanically mounts to an interior wall of the building. A Low Pass Filter (LPF)  23  isolates the analog telephony part of the spectrum for connection to an analog telephone via a jack  56 . Jack  56  is preferably a standard telephone jack, such as RJ-11 in North-America. Data communication signals are isolated by a High Pass Filter (HPF)  24 , which connects to a Data Communications Equipment (DCE) unit  25 , which serves as a modem for data communications over the telephone line media. An integrated hub  11  allows sharing data between processing unit  36 , including address unit  37  with address  39 , and a data jack  38 , for connecting external devices to the network via DCE unit  25 . Processing unit  36  with integrated address unit  37  allows messages directed to or from the outlet to be uniquely routed. Outlet  50  supports both standard analog telephony (via jack  56 ) as well as data communications via jack  38 .  
         [0052]      FIG. 6  pictorially illustrates the front panel of a telephone outlet  50  according to the present invention, having both telephony connector  56  and data connector  38 .  
         [0053]      FIG. 7  illustrates a network  70  that operates over telephone lines  5   a,    5   b,  and  5   c,  and employs outlets  50   a  and  50   b  according to the present invention. Network  70  supports regular PSTN telephony service via analog telephone sets  26   a  and  26   b,  connected to the telephone connectors of outlets  50   a  and  50   b  respectively. Simultaneously, data networking can be accomplished by data units  7   a  and  7   b.  Outlets  50   a  and  50   b  can each be addressed by any other outlet or data unit in the network using dedicated addresses  39   a  and  39   b,  conveyed by address units  37   a  and  37   b,  respectively. Similarly, outlets  50   a  and  50   b  can address any other entity in the network, and as such both the outlets and the various network segments can be fault isolated as described above.  
         [0054]     Although the invention has been so far demonstrated as relating to telephone wiring and telephone outlets, the invention can be similarly applied to any type of wired networking within a building, such as CATV or electrical power wiring.  FIG. 8  illustrates an outlet  80 , which is a general embodiment of the present invention. Outlet  80  is similar in overall layout to the outlet  50  shown in  FIG. 5 . Outlet  80  connects to the relevant wiring via a connector  81  and contains an integrated data/service splitter/combiner unit  82 , which isolates the data carried over the wiring from the main service signal. In the case of telephony, unit  82  contains a low-pass filter (such as LPF  23   a  as shown in  FIG. 7 ) and a high-pass filter (such as HPF  24   a  as shown in  FIG. 7 ). In the case of electrical power wiring, the AC power is split by unit  82  and fed to a socket  84 , for supplying electrical power as is normal for such an outlet. In this case, a modem  83  being a power-line carrier (PLC) modem interfaces the hub  11  to the integrated data/service splitter/combiner unit  82  to allow data communication over the power line. Similarly, in the case of a CATV application, where the CATV wiring is used for the network infrastructure, modem  83  is a coaxial cable modem, and unit  82  isolates the CATV signal from the data signal.  
         [0055]     Although the invention has been so far described as relating to Ethernet/IP-based data networks, the invention can be similarly applied to any type of data network. Furthermore, although packet networks are the most common for local area networks, the invention is not restricted to packet networks only, and can be applied to any digital data network, where network entities are identified uniquely by addresses.  
         [0056]     Furthermore, although the invention has been described as relating to networks based on continuous electrical conducting media (telephone, CATV, or electrical power), and the relevant modem and associated circuitry are connected in parallel to the wiring infrastructure, the invention can be applied equally to the case wherein the wiring is not continuous, but is in discrete segments. Such an arrangement is disclosed in WO 0007322 published Feb. 10, 2000 and entitled “Local Area Network of Serial Intelligent Cells” in the name of the present inventor and assigned to the present assignee.  
         [0057]     Although outlets  30 ,  50  and  80  are each described above as having a single data connection, it is to be understood that multiple data network interfaces can be included within an outlet, each connected to different port of the respective hub (such as hub  11   a,  as shown in  FIG. 7 ).  
         [0058]     In addition, although the present invention has been described with respect to a single address associated with each outlet, it will be appreciated that multiple addresses can also be assigned to an outlet. Different addresses can be associated with different data ports and/or with different functionalities of the outlet thus improving fault isolation by separately addressing the addressable data ports or functionalities until an absence of a response signal to a diagnostic message indicates that the addressed port and/or functionality of the outlet is faulty or that there is a break in the connection path thereto.  
         [0059]     While the invention has been described with regard to local area networks, wherein the fault is localized locally, it will be appreciated that assigning addresses to outlets facilitates also remote diagnostics and fault localization. Such a network  90  is described in  FIG. 9 . Network  90  comprises local area network part similar to network  40  above (Phoneline, CATV or powerline based networks can equally be used). However, an external connection is added to an external network  92 . The connection makes use of a gateway  93 , bridging between the external WAN and the internal LAN, commonly known as Integrated Access Device (IAD), Home or Residential Gateway (RG). For example, the external network can be a Wide Area Network (WAN), either wired or non-wired. For example, the external network  92  can be the Internet. The connection can be via different access technologies such as xDSL (using xDSL modem), CATV based (using Cable Modem or Set Top Box) or wireless (satellite or terrestrial). A remote server  91  is a data unit connected remotely to the WAN  92 , and hence can communicate with the local area network and its components, data units  7   a,    7   b  and outlets  30   a  and  30   b.  In such an arrangement, fault isolation can be performed remotely, managed by the server  91 . By communicating with the outlets  30   a  and  30   b  and the data units  7   a  and  7   b,  the server  91  can determine the fault localization to a segment level as described above. Furthermore, the remote server  91  may check the system integrity up to the outlets level, even if no data units are connected or operative. In such a case, a Telco (through xDSL connection) or CATV provider (through Cable modem or set-top-box) can remotely test and verify the status of the network within a home.