Abstract:
Disclosed is a home network system using an IEEE 1394 protocol and a node configuration method thereof that can circumvent a bus reset of the IEEE 1394 protocol that are currently causing data loss. The home network system includes a root node operating as a home gateway of the home network and having a static node ID that performs a bus management function with respect to nodes of the home network system, and at least one node connected to the root node to form a tree structure. If a node addition/removal occurs in the home network system, a node ID of an added/removed node is allocated from the root node through a bus reset between the added/removed node and a node physically connected to the added/removed node.

Description:
CLAIM OF PRIORITY  
       [0001]     This application claims priority to an application entitled “Home Network System Using IEEE  1394  and Node Configuration Method Thereof,” filed in the Korean Intellectual Property Office on Sep. 16, 2004 and assigned Serial No. 2004-74153, the contents of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to a home network system using an IEEE 1394 protocol, and more particularly to an IEEE 1394 system designed to prevent undesirable effects of a bus reset of the current IEEE 1394 protocol.  
         [0004]     2. Description of the Related Art  
         [0005]     The conventional IEEE 1394 technology relating to a serial bus interface standard is first proposed by Apple Computer Inc. and Texas Instruments Incorporated. The IEEE 1394 technology has been developed under a code name “FireWire”, and in December 1995, it became standardized by the IEEE committee.  
         [0006]     The IEEE 1394 protocol may be a standard bus interface for a network PC (Personal Computer) and a portable computer. However, in these days of high-performance multimedia, the existing extended bus or interface cannot properly accommodate the speed of other new technologies, thus hindering the progress. The bottleneck phenomenon between peripheral devices and the main body of a computer system has become a serious obstacle in the new computer system requiring faster speed.  
         [0007]     In processing isochronous data (for example, AV stream data and so on) and asynchronous data (for example, control data, packet data, etc.), the IEEE 1394 protocol, which can connect  63  nodes at maximum as a serial bus interface, gives priority to the isochronous data, thus securing the QoS (Quality of Service) with respect to AV data used in a home network. Further, IEEE 1394a defines bitrates of S 100 , S 200  and S 400 , and IEEE 1394b defines optical media such as POF, GOF, MMF, etc., in a cable environment, so that a high rate of 3.2 Gbps is secured.  
         [0008]     Since the IEEE 1394 protocol as described above takes charge of a bus management that is a software stack, and a configuration among IEEE 1394 nodes and a root node for the bus management is not specified, a bus reset of the whole IEEE 1394 system is performed and a new node is constructed whenever a new IEEE 1394 appliance device is removed or added.  
         [0009]      FIGS. 1   a  and  1   b  are views illustrating an example of a node configuration according to a conventional IEEE 1394 protocol.  
         [0010]     In particular,  FIGS. 1   a  and  1   b  exemplify a system having a topology of a tree structure according to the IEEE 1394 protocol. In this case, the IEEE 1394 topology before a node configuration, as illustrated in  FIG. 1   a,  includes leaf nodes  102 ,  104  and  105  that are terminal nodes and branch nodes  101  and  103  that are nodes.  
         [0011]     The IEEE 1394 topology after the node configuration, as illustrated in  FIG. 1   b,  includes leaf nodes  102 ,  104  and  105  that are terminal nodes, a branch node  103  that is a node for connecting the nodes and a root node  101  selected from the branch nodes.  
         [0012]     The root node  101  requires performing the bus management. The determined root node  101  is not static as in other network systems, but is newly determined according to the addition/removal of a node.  
         [0013]      FIG. 2  is a flowchart illustrating the node configuration method according to the conventional IEEE 1394 system.  
         [0014]     First, if a bus reset event in that a new node  105  is added to or the existing node  104  is removed from the basic tree structure of  FIG. 1   a  occurs (step  21 ), the node  103  at which the event occurs generates a reset signal by re-determining the status bit of a physical (PHY) register that is connected to a port connected to the node  103  according to the change of the status of the port (step  22 ).  
         [0015]     Then, the generated reset signal is broadcast to all nodes in the IEEE 1394 system, so that it deletes topology information stored in PHY registers of the respective nodes and performs the bus configuration.  
         [0016]      FIG. 3  is a detailed flowchart illustrating the bus configuration process of the node configuration method according to the conventional IEEE 1394 system.  
         [0017]     Referring to  FIG. 3 , the respective node in the IEEE 1394 system, from which the topology information stored in the PHY register is deleted by the transferred reset signal, confirms the topology information that indicates whether or not the corresponding node is a terminal node (i.e., lead node or branch node), and stores the topology information in the PHY register of the respective node (step  231 ).  
         [0018]     Then, a node, which is not the terminal node (i.e., which is the branch node) but can perform a bus management function, is determined as the root node (step  232 ). That is, a node that can perform the bus management function among branch nodes is voluntarily determined as the root node. For example, the branch node  101  of FIG la becomes the root node  106  of  FIG. 1   b.    
         [0019]     After a node tree is formed around the root node, a leaf node of a leaf node group having the smallest number of leaf nodes among existing leaf node groups (for example, the node  103  in  FIG. 1   b ) that is connected to the root node is first allocated with a node ID # 0 , and then other remaining leaf nodes of the group are allocated with node IDs in order according to paths from the corresponding nodes to the root node. Additionally, a leaf node of another leaf node group having the next smallest number of leaf nodes among the existing leaf node groups (for example, the node  104  or  105  in  FIG. 1   b ) that is connected to the root node is allocated with the next node ID, and then other remaining leaf nodes of the group are allocated with node IDs in order according to paths from the corresponding nodes to the root node, respectively. Through the above-described process of giving the node IDs, all the nodes in the system are provided with the node IDs, and the root node is finally provided with a node ID having the largest number among the node IDs (step  233 ).  
         [0020]     As described above, in the case in which a node is added to or removed from the IEEE 1394 system, a bus reset of the whole system occurs, and a new node configuration is performed. This may be advantageous in providing the variableness in operation in such a manner so that no static root node exists as in USB or other networks, but the root node is changed according to the situation.  
         [0021]     However, in the case in which the IEEE 1394 system is operated in association with home network appliances, the bus reset occurring in the whole system whenever the IEEE 1394 appliance is added to or removed from the system may cause a data loss at the nodes in which data transmission is performed.  
         [0022]     Meanwhile, in order to solve the problem caused by the bus reset, there is a related technology where a root node and branch nodes are connected by the IEEE 1394 protocol and installed at home, and the connection of the corresponding nodes is performed using upper application layer of an LLC of IEEE  1394 . However, this technology has limitations in that the system cannot be constructed by the IEEE 1394 protocol as a whole.  
       SUMMARY OF THE INVENTION  
       [0023]     Accordingly, the present invention has been designed to solve the above and other problems occurring in the prior art and provides additional advantages, by providing a stable IEEE 1394 system and a node configuration method thereof that can prevent a bus reset of the whole system by providing a static root node in the IEEE 1394 system, intercepting a bus reset event by software, and performing a node ID allocation according to a node change as an operation between the root node and a specified node at which the node change occurs.  
         [0024]     In one embodiment, there is provided a home network system using an IEEE 1394 protocol, comprising a root node operating as a home gateway of the home network and having a static node ID that performs a bus management function with respect to the nodes of the home network system, and at least one node connected to the root node to form a tree structure, wherein if a node addition/removal occurs in the home network system, a node ID of an added/removed node is allocated from the root node through a bus reset between the added/removed node and a node physically connected to the added/removed node.  
         [0025]     In another embodiment, there is provided a node configuration method in an IEEE 1394 home network system provided with a root node that has a static node ID and performs a bus management of the whole system. The method includes a first step of, if a specified bus reset event occurs in the home network system, performing a bus reset between a node in which the bus reset event occurs and an upper node directly connected to the node, a second step of, after performing the bus reset, updating configuration information stored at the upper node according to status information of the node at which the bus reset event occurs and transmitting corresponding information to the root node, a third step of the root node processing a node ID of the node at which the bus reset event occurs according to the transmitted information, and a fourth step of updating whole system node information according to the node ID processed at the third step and transmitting the updated node information to the whole nodes of the home network system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]     The above features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0027]      FIGS. 1   a  and  1   b  are views illustrating an example of a node configuration according to a conventional IEEE 1394 protocol;  
         [0028]      FIG. 2  is a flowchart illustrating a node configuration method of a conventional IEEE 1394 system;  
         [0029]      FIG. 3  is a detailed flowchart illustrating a bus configuration process of the node configuration method in the conventional IEEE 1394 system;  
         [0030]      FIG. 4  is a view illustrating the construction of an IEEE 1394 system to which a node configuration method is applied according to the present invention;  
         [0031]      FIG. 5  is a flowchart illustrating a node configuration method in an IEEE 1394 system according to the present invention; and  
         [0032]      FIG. 6  is a flowchart illustrating a node ID determining process in the node configuration method according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0033]     Embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings. For the purposes of clarity and simplicity, a detailed description of known functions and configurations incorporated herein will be omitted as it may obscure the subject matter of the present invention.  
         [0034]      FIG. 4  is a view illustrating the construction of an IEEE 1394 system to which a node configuration method is applied in accordance with the present invention.  
         [0035]     Referring to  FIG. 4  which exemplifies a home network, a root node  41  serves as a home gateway in the home network system, and specified branch nodes  42 ,  43  and  44  have static node IDs and operate always using constant node IDs. Accordingly, it is not required to search for the root node through a bus reset and to reconfigure node IDs of the whole system as in the prior art. The network shown in  FIG. 4  is small for purpose of illustration. In practice most networks would include a much larger number of branches and leaf devices.  
         [0036]     The root node  41  and the branch nodes  42 ,  43  and  44  having the static node IDs generally serve as a backbone network of the home network system. Further, the branch nodes  42 ,  43  and  44  having the static node IDs are connected to leaf nodes  45  and  46 , and a branch node  47  that is connected to another leaf node  48 , respectively.  
         [0037]     In the embodiment of the present invention, if the addition/removal of the IEEE 1394 device occurs at a lower node such as the leaf node  45 ,  46  or the branch node  47 , a bus reset is not performed with respect to the whole system. However, the IEEE 1394 compliance system configures the node information according to the addition/removal of the device. Specifically, a bus reset is performed between the corresponding device and its upper node, the addition/removal information is recognized through the information exchange between the corresponding devices, the recognized information is transferred to the root node  41  having the static node ID to reconfigure the node information of the whole system, and the reconfigured node information is transferred to the nodes of the whole system to update the node information.  
         [0038]      FIG. 5  is a flowchart illustrating the node configuration method in an IEEE 1394 system according to the present invention.  
         [0039]     If a bus reset event that a new node is added to the leaf node  45 ,  46  or the existing leaf  48  is removed from the branch node  47  occurs (step  51 ), a control operation is performed so that the bus reset of the whole IEEE 1394 system, which may occur by hardware between the node at which the bus reset event occurs (i.e., the newly added node or the removed node), and its upper node directly connected to the newly added node or the removed node) does not occur. Instead, the configuration information of the newly added node or the removed node is grasped through the signal process on a physical (PHY) layer through a reset operation that is performed only between the newly added node or the removed node and its upper node, and the corresponding configuration information is updated by the upper node (step  52 ).  
         [0040]     The signal process on the PHY layer for grasping the configuration information of the newly added node is performed in a manner that the PHY device of the upper node senses the change of the state of the new node (i.e., lower node) and receives self-ID information of the corresponding node from the new node. Also, the PHY device transfers the node configuration information of the whole system from the upper node to the newly added node.  
         [0041]     Then, the configuration information updated by the upper node is transmitted to the root node (step  53 ).  
         [0042]     The root node receives the configuration information updated by the bus reset event, determines the node ID of the node newly added according to the bus reset event or deletes the node ID of the removed node (step  54 ). The node ID determining process for the added node will be explained in more detail later with reference to  FIG. 6 .  
         [0043]     As described above, the root node manages the node IDs of the whole IEEE 1394 system by storing the node ID configuration information about the nodes in the whole IEEE 1394 system, and adding/changing the node ID configuration information.  
         [0044]     Additionally, the root node sends the node ID configuration information newly configured to the whole nodes through the 63 rd  ID (i.e., a broadcast ID) of the IEEE 1394 system (step  55 ), so that all the nodes in the system update the newly configured node information (step  56 ).  
         [0045]      FIG. 6  is a flowchart illustrating the node ID determining process in the node configuration method according to the present invention.  
         [0046]     The root node receives the configuration information updated by the bus reset event and determines the node ID of the node added according to the bus reset event. For this, the root node set the present node ID as an initial value (step  61 ). In the embodiment of the present invention, it is set to “0”.  
         [0047]     Then, the root node confirms whether the present node ID is the node ID that is in use (step  62 ). That is, the root node confirms whether the present node ID is the node ID that has already been allocated to another node in the IEEE 1394 system.  
         [0048]     If the present node ID is in use as a result of confirmation, the root node changes the present node ID value in a specified manner (step  63 ) and confirms whether the corresponding node ID value is in use (step  62 ). In the embodiment of the present invention, it is exemplified that the present node ID value is increased by “1”.  
         [0049]     Meanwhile, if the present node ID is not in use as a result of confirmation, the root node allocates the corresponding node ID value to the newly added node, and adds this node ID value to an ID list (i.e., a list of all node IDs of the whole system) of a bus manager in order to update the node ID configuration information of the nodes in the whole IEEE 1394 system that is stored in the root node (step  64 ).  
         [0050]     More specifically, the root node which has received the news that a new node is added allocates a node ID to the newly added node to manage the newly added node. In this case, the allocated node ID must not overlap the node IDs already allocated to the existing nodes. Accordingly, in the embodiment of the present invention as illustrated in  FIG. 6 , the root node initially sets the present node ID to “0”, confirms whether there is a node that uses the node ID of “0”, and if a node that uses the corresponding node ID exists, increases the node ID value by “1” to confirm whether the node ID of “1” is in use. If a node that uses the corresponding node ID exist, it increases again the node ID value by “1”, and confirms whether the node ID of “2” is in use, so that it can allocate the node ID that has not yet been used to the new node.  
         [0051]     In the embodiment of the present invention, the root node of the IEEE 1394 system serves as a gateway at home and is implemented in the form of a wallplate at home, and the static branches are also implemented in the form of a wallplate at home. Accordingly, the system reset operation does not affect the respective static node IDs, and the only node IDs of the leaf or branch nodes connected to the static nodes are newly updated to operate the whole IEEE 1394 system accordingly. That is, in order to achieve a home network, the IEEE 1394 interface connected to the IEEE 1394 devices that include a user&#39;s AV system and so on is built in the form of a wallplate, and serves as a leaf node of the whole home network system.  
         [0052]     As described above, according to the present invention, the bus reset of the whole IEEE 1394 system is prevented, and thus the IEEE 1394 that is favorable to multimedia can stably be used in implementing the home network system. Specifically, in comparison to the existing IEEE 1394 system that cannot avoid the bus reset occurrence when a new node is added or the existing node is removed and thus suffers from a data interruption when the isochronous data such as audio/video data is transmitted, the present invention performs a control operation so that the bus reset occurs locally without affecting the whole IEEE 1394 system, resulting in that a stable home network can be constructed. Furthermore, since the node IDs of other nodes are not changed even if a new node is added or the existing node is removed, the stability can be secured in processing the asynchronous data.  
         [0053]     It should be noted that the method according to the present invention can be implemented by a program and stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk, optomagnetic disk, etc.) in a computer-readable form.  
         [0054]     While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.