Abstract:
This invention provides an access-network device, a management device, a communication system, an information provision method, a management method, and a program that make it possible for the management device to acquire managed information being managed by the access-network device even if there is a node between the management device and the access-network device. The access-network device, which is incorporated into an access network, has a control unit and a communication unit. The control unit sets up a communication tunnel between the access-network device and the management device, which manages the access network, after the access-network device is incorporated into the access network. The communication unit uses the communication tunnel to transmit a layer 2 message containing information being managed by the access-network device.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an access-network device, a management device, a communication system, an information provision method, a management method, and a program and in particular, relates to an access-network device, a management device, a communication system, an information provision method, a management method, and a program which transmits its own managing information. 
       BACKGROUND ART 
       [0002]    In FIG. 12 of patent literature 1, a network monitoring system in which a monitoring system obtains information managed by each of a plurality of monitoring target devices by using Link Layer Discovery Protocol (LLDP) is described. 
         [0003]    The LLDP is a layer 2 protocol specified by IEEE (Institute of Electrical and Electronics Engineers) 802.1AB. In the LLDP, an LLDP frame which contains management information held by a node is transmitted and received between the nodes that are adjacent to each other (hereinafter, referred to as “adjacent node”). 
         [0004]    Each node notifies the adjacent node of the management information managed by the each node by transmitting the LLDP frame to the adjacent node. Further, the each node recognizes the management information managed by the adjacent node by using the LLDP frame received from the adjacent node. 
       CITATION LIST 
     Patent Literature 
       [0005]    [PTL 1] Japanese Patent Application Laid-Open No. 2012-134616 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    The monitoring system described in patent literature 1 obtains the management information managed by the monitoring target device by using the LLDP. 
         [0007]    For this reason, when the node exists between the monitoring system and the monitoring target device described in patent literature 1, a problem in which the monitoring system cannot obtain the management information from the monitoring target device by communication on layer 2 occurs. 
         [0008]    An object of the present invention is to provide an access-network device, a management device, a communication system, an information provision method, a management method, and a program which can solve the above-mentioned problem. 
       Solution to Problem 
       [0009]    An access-network device installed in an access network according to the present invention, includes: control means for setting a communication tunnel between a management device which manages the access network and the access-network device after the access-network device is installed in the access network; and communication means for transmitting a layer 2 message including information managed by the access-network device via the communication tunnel. 
         [0010]    A management device which manages an access network according to the present invention includes: communication means for receiving a layer 2 message including information managed by an access-network device from the access-network device installed in the access network via a communication tunnel set between the management device and the access-network device. 
         [0011]    A communication system which includes an access-network device installed in an access network and a management device which manages the access network according to the present invention, wherein the access-network device includes control means for setting a communication tunnel between the management device and the access-network device after the access-network device is installed in the access network and first communication means for transmitting a layer 2 message including information managed by the access-network device via the communication tunnel, and the management device includes second communication means for receiving the layer 2 message from the access-network device via the communication tunnel. 
         [0012]    An information provision method performed by an access-network device installed in an access network according to the present invention, includes: setting a communication tunnel between a management device which manages the access-network and the access-network device after the access-network device is installed in the access network; and transmitting a layer 2 message including information managed by the access-network device via the communication tunnel. 
         [0013]    A management method performed by a management device which manages an access network according to the present invention, includes: receiving a layer 2 message including information managed by an access-network device from the access-network device installed in the access network via a communication tunnel set between the management device and the access-network device. 
         [0014]    A program according to the present invention causes a computer to perform a control procedure in which a communication tunnel is set between a management device which manages an access network and the computer after the computer is installed in the access network and a transmission procedure in which a layer 2 message including information managed by the computer is transmitted via the communication tunnel. 
         [0015]    A program according to the present invention causes a computer to perform a reception procedure in which a layer 2 message including information managed by an access-network device is received from the access-network device installed in an access network via a communication tunnel set between the computer and the access-network device. 
       Advantageous Effect of Invention 
       [0016]    According to the present invention, even when the node exists between the management device and the access-network device, the management device can obtain the management information managed by the access-network device. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a block diagram showing a communication system  100  according to a first exemplary embodiment of the present invention. 
           [0018]      FIG. 2  is a block diagram showing a wireless base station eNB 1 . 
           [0019]      FIG. 3  is a figure showing a switch SW 1 . 
           [0020]      FIG. 4  is a figure showing a BRM  3 . 
           [0021]      FIG. 5  is a flowchart for explaining operation of a wireless base station eNB 1 . 
           [0022]      FIG. 6  is a flowchart for explaining operation of a switch SW 1 . 
           [0023]      FIG. 7  is a flowchart for explaining operation of a BRM  3 . 
           [0024]      FIG. 8  is a figure showing an example of information stored in a storage unit  62 . 
           [0025]      FIG. 9  is a block diagram showing an example of a communication system  100 . 
           [0026]      FIG. 10A  is a figure showing a wireless base station composed of a communication tunnel control unit  44  and an LLDP processing unit  45 . 
           [0027]      FIG. 10B  is a figure showing a switch composed of a communication tunnel control unit  53  and an LLDP processing unit  54 . 
           [0028]      FIG. 11  is a figure showing a management device composed of a management unit  63 . 
           [0029]      FIG. 12  is a figure showing a wireless base station eNB used in a second exemplary embodiment. 
           [0030]      FIG. 13  is a figure showing a switch SW used in a second exemplary embodiment. 
           [0031]      FIG. 14  is a figure showing an example of a storage unit  62  storing a result of a determination using a first threshold value to a third threshold value. 
           [0032]      FIG. 15  is a figure showing an example of a format of an LLDP frame. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0033]    An exemplary embodiment of the present invention will be described below with reference to a drawing. 
       First Exemplary Embodiment 
       [0034]      FIG. 1  is a block diagram showing a communication system  100  according to a first exemplary embodiment of the present invention. 
         [0035]    The communication system  100  includes an access network  1 , an EPC (Evolved Packet Core) network  2 , and a management device  3 . Hereinafter, the management device is also called a BRM (Backhaul Resource Manager). 
         [0036]    The access network  1  includes wireless base stations eNB 1  and eNB 2  that are eNBs (evolved Node B) and networks  10 A,  10 B, and  10 C. 
         [0037]    Each of the networks  10 A,  10 B, and  10 C connects between the wireless base stations eNB 1  and eNB 2  and the EPC network  2 . 
         [0038]    Each of the networks  10 A,  10 B, and  10 C includes a plurality of switches and a plurality of routers. In  FIG. 1 , switches SW 1  to SW 4  are included in the network  10 A, switches SW 5  to SW 6  are included in the network  10 B, and switches SW 7  to SW 8  are included in the network  10 C. Each of the switches SW 1  to SW 8  is for example, an L2 (layer 2) switch or an L3 (layer 3) switch. 
         [0039]    The network  10 A is connected to the wireless base stations eNB 1  and eNB 2  when the wireless base stations eNB 1  and eNB 2  are in a normal state. 
         [0040]    The networks  10 B and  10 C are used as an alternative route when the network  10 A is in a congestion state or in a failure state. 
         [0041]    When the network  10 B or the network  10 C is a network for which security has to be taken into consideration, the network  10 B or the network  10 C may be used as the alternative route after a security tunnel is established to the network  10 B or the network  10 C. The Internet is one example of the network for which security has to be taken into consideration. However, the network for which security has to be taken into consideration is not limited to the Internet. An IPsec (Internet Protocol Security) tunnel is one example of the security tunnel. However, the security tunnel is not limited to the IPsec tunnel. 
         [0042]    Each of the wireless base stations eNB 1  and eNB 2  and the switches SW 1  to SW 8  is one example of an access-network device or a second access-network device. 
         [0043]      FIG. 2  is a block diagram showing the wireless base station eNB 1 . 
         [0044]    In  FIG. 2 , the wireless base station eNB 1  includes a wireless communication IF (interface)  41 , a network IF  42 , a communication processing unit  43 , a communication tunnel control unit  44 , and an LLDP processing unit  45 . 
         [0045]    The wireless communication IF  41  is connected to a terminal (not shown) such as a mobile phone, a smart phone, or the like by wireless. 
         [0046]    The network IF  42  is connected to the access-network device (in an example shown in  FIG. 1 , the switch SW 1 ) which directly communicates with the wireless base station eNB 1 . 
         [0047]    The communication processing unit  43  performs a function of the common wireless base station (eNB). For example, the communication processing unit  43  controls the communication between the terminal wirelessly connected to the wireless communication IF  41  and the EPC network  2 . 
         [0048]    The communication tunnel control unit  44  is an example of a control unit. 
         [0049]    The communication tunnel control unit  44  sets a communication tunnel (hereinafter, referred to as “a first communication tunnel”) between the BRM  3  and the wireless base station eNB 1  after the wireless base station eNB 1  is installed in the access network  1 . 
         [0050]    The communication tunnel control unit  44  sets the first communication tunnel by using for example, a VLAN (Virtual Local Area Network) or a VRF (Virtual Routing and Forwarding). 
         [0051]    The communication tunnel control unit  44  communicates with the BRM  3  and performs a setting process for setting the first communication tunnel. Further, because a method for setting the communication tunnel is a publicly known technique, the detailed description will be omitted. 
         [0052]    The LLDP processing unit  45  is an example of a communication unit and a first communication unit. 
         [0053]    The LLDP processing unit  45  generates the LLDP frame which contains information (hereinafter, referred to as “first management information”) managed by the wireless base station eNB 1 . In this exemplary embodiment, the LLDP processing unit  45  manages the first management information. Hereinafter, the LLDP frame which contains the first management information is referred to as “a first LLDP frame”. 
         [0054]    The first management information is an example of the management information. The first management information includes identification information of the wireless base station eNB 1  and information indicating a communication state of the wireless base station eNB 1 . The information indicating the communication state of the wireless base station eNB 1  includes information indicating a current state of the wireless base station eNB 1  among three states: a normal state, a congestion state, and a failure state and information of a band usage amount of a line between a node existing in the next hop of the wireless base station eNB 1  and the wireless base station eNB 1  in the access network  1 . 
         [0055]    The first LLDP frame is an example of a layer 2 message. 
         [0056]    The LLDP processing unit  45  transmits the first LLDP frame via the first communication tunnel. 
         [0057]    For example, the LLDP processing unit  45  performs the encapsulation of the first LLDP frame for the first communication tunnel and generates a packet for notification (hereinafter, referred to as “a packet for first notification”). 
         [0058]    The LLDP processing unit  45  transmits the packet for first notification via the first communication tunnel. 
         [0059]    The wireless base station eNB 2  has a function that is the same as that of the wireless base station eNB 1 . Therefore, the wireless base station eNB 2  can be understood by replacing the word “wireless base station eNB 1 ” with the word “wireless base station eNB 2 ” in the above-mentioned description about the wireless base station eNB 1 . 
         [0060]    Further, the network IF  42  in the wireless base station eNB 2  is connected to the access-network devices (in an example shown in  FIG. 1 , the switches SW 1  and SW 5 ) which directly communicate with the wireless base station eNB 2 . 
         [0061]      FIG. 3  is a figure showing the switch SW 1 . 
         [0062]    In  FIG. 3 , the switch SW 1  includes a network IF  51 , a communication processing unit  52 , a communication tunnel control unit  53 , and an LLDP processing unit  54 . 
         [0063]    The network IF  51  is connected to the access-network devices (in an example shown in  FIG. 1 , the wireless base stations eNB 1  and eNB 2  and the switches SW 2 , SW 4 , SW 5 , and SW 7 ) which directly communicate with the switch SW 1 . 
         [0064]    The communication processing unit  52  has a switch function. For example, when the switch SW 1  is the L2 switch, the communication processing unit  52  performs a function of the common L2 switch. Further, when the switch SW 1  is an L3 switch, the communication processing unit  52  performs a function of the common L3 switch. 
         [0065]    The communication tunnel control unit  53  is an example of the control unit. 
         [0066]    The communication tunnel control unit  53  sets the communication tunnel (hereinafter, referred to as “a second communication tunnel”) between the BRM  3  and the switch SW 1  after the switch SW 1  is installed in the access network  1 . The communication tunnel control unit  53  sets the second communication tunnel by using for example, the VLAN or the VRF. As described above, because the method for setting the communication tunnel is a publicly known technique, the detailed description will be omitted. 
         [0067]    The LLDP processing unit  45  is an example of the communication unit and the first communication unit. 
         [0068]    The LLDP processing unit  54  generates the LLDP frame which contains information managed by the switch SW 1  (hereinafter, referred to as “second management information”). In this exemplary embodiment, the LLDP processing unit  54  manages the second management information. Hereinafter, the LLDP frame which contains the second management information is referred to as “a second LLDP frame”. 
         [0069]    The second management information is an example of the management information. The second management information includes identification information of the switch SW 1  and information indicating the communication state of the switch SW 1 . The information indicating the communication state of the switch SW 1  includes information indicating a current state of the switch  1  among three states: a normal state, a congestion state, and a failure state and information of the band usage amount of the line between the node existing in the next hop of the switch SW 1  and the switch SW 1  in the access network  1 . 
         [0070]    The second LLDP frame is an example of the layer 2 message. 
         [0071]    The LLDP processing unit  54  transmits the second LLDP frame via the second communication tunnel. 
         [0072]    For example, the LLDP processing unit  54  performs the encapsulation of the second LLDP frame for the second communication tunnel and generates the packet for notification (hereinafter, referred to as “a packet for second notification”). The LLDP processing unit  54  transmits the packet for second notification via the second communication tunnel. 
         [0073]    The description about each of the switches SW 2  to SW 8  can be obtained by replacing the word “switch SW 1 ” with the word “switch SW 2 ”, “switch SW 3 ”, . . . , or “switch SW 8 ” in the above-mentioned description about the switch SW 1 . 
         [0074]    Further, the network IF  51  in the switch SW 2  is connected to the access-network device (in an example shown in  FIG. 1 , the switches SW 1  and SW 3 ) which directly communicates with the switch SW 2 . 
         [0075]    Further, the network IF  51  in each of the switches SW 3  to SW 8  is connected to the access-network device which directly communicates with the each of the switches SW 3  to SW 8 . 
         [0076]      FIG. 4  is a figure showing the BRM  3 . 
         [0077]    In  FIG. 4 , the BRM  3  includes a network IF  61 , a storage unit  62 , and a management unit  63 . 
         [0078]    The network IF  61  is connected to the access-network device which directly communicates with the BRM  3 . 
         [0079]    The storage unit  62  stores the communication state of each of the devices (in an example shown in  FIG. 1 , the wireless base stations eNB 1  and eNB 2  and the switches SW 1  to SW 8 ) in the access network  1 . 
         [0080]    The management unit  63  is an example of the communication unit and a second communication unit. 
         [0081]    The management unit  63  receives a packet for notification from each of the wireless base stations eNB 1  and eNB 2  and the switches SW 1  to SW 8  via each communication tunnel. The management unit  63  performs the decapsulation of each of the packets for notification and obtains each LLDP frame. The management unit  63  stores information indicating the communication state that is contained in the LLDP frame in the storage unit  62 . 
         [0082]    The management unit  63  controls the communication state of the access network  1  by using the communication state of each of the devices (the wireless base stations eNB 1  and eNB 2  and the switches SW 1  to SW 8 ) stored in the storage unit  62 . 
         [0083]    Next, operation will be described. 
         [0084]    First, the operation of the wireless base station eNB 1  will be described. Further, because the operation of the wireless base station eNB 2  conforms to the operation of the wireless base station eNB 1 , the description will be omitted. 
         [0085]      FIG. 5  is a flowchart for explaining the operation of the wireless base station eNB 1 . 
         [0086]    After the wireless base station eNB 1  is installed in the access network  1 , the communication tunnel control unit  44  sets the first communication tunnel between the BRM  3  and the wireless base station eNB 1  (step S 101 ). 
         [0087]    For example, when the power-supply voltage is supplied to the wireless base station eNB 1  after the wireless base station eNB 1  is installed in the access network  1 , the communication tunnel control unit  44  sets the first communication tunnel between the BRM  3  and the wireless base station eNB 1 . 
         [0088]    Next, the communication tunnel control unit  44  notifies the LLDP processing unit  45  of first communication tunnel information indicating an IP (Internet Protocol) addresses of the wireless base station eNB 1  and the BRM  3  that are the end-point devices of the first communication tunnel. When the LLDP processing unit  45  receives the first communication tunnel information, the LLDP processing unit  45  holds the first communication tunnel information. 
         [0089]    On the other hand, when the power-supply voltage is supplied to the wireless base station eNB 1 , the communication processing unit  43  performs the function of the common wireless base station (eNB) and specifies the communication state of the wireless base station eNB 1  (step S 102 ). 
         [0090]    In this exemplary embodiment, the communication processing unit  43  specifies the band usage amount of the line between the node existing in the next hop of the wireless base station eNB 1  and the wireless base station eNB 1  by using an amount of the data transmitted and received between the communication processing unit  43  and the network IF  42  as the communication state of the wireless base station eNB 1 . Further, the data is the packet or the frame. 
         [0091]    Further, the communication processing unit  43  specifies the current state of the wireless base station eNB 1  among three states: the normal state, the congestion state, and the failure state by using the amount of the data transmitted and received between the communication processing unit  43  and the network IF  42  as the communication state of the wireless base station eNB 1 . 
         [0092]    Next, the communication processing unit  43  outputs the communication state of the wireless base station eNB 1  to the LLDP processing unit  45 . 
         [0093]    When the LLDP processing unit  45  receives the communication state of the wireless base station eNB 1 , the LLDP processing unit  45  holds and manages the communication state of the wireless base station eNB 1  (step S 103 ). 
         [0094]    Next, the LLDP processing unit  45  generates the first LLDP frame that contains the information indicating the communication state of the wireless base station eNB 1  and the identification information of the wireless base station eNB 1  (step S 104 ). 
         [0095]    Next, the LLDP processing unit  45  refers to the first communication tunnel information, performs the encapsulation of the first LLDP frame for the first communication tunnel, and generates the packet for first notification (step S 105 ). 
         [0096]    Here, the encapsulation for the first communication tunnel is a process of adding a header which indicates the IP address of the wireless base station eNB 1  that is a transmission source and the IP address of the BRM  3  that is a transmission destination to the first LLDP frame. 
         [0097]    Next, the LLDP processing unit  45  transmits the packet for first notification from the network IF  42  (step S 106 ). 
         [0098]    Because the packet for first notification is obtained by performing the encapsulation for the first communication tunnel, the packet for first notification can pass through the first communication tunnel and can be received by the BRM  3 . 
         [0099]    Next, the LLDP processing unit  45  waits until a first time set in advance elapses after transmitting the packet for first notification (step S 107 ). 
         [0100]    When the first time elapses after transmitting the packet for first notification, the LLDP processing unit  45  outputs an output instruction to the communication processing unit  43 . 
         [0101]    When the communication processing unit  43  receives the output instruction, the communication processing unit  43  performs a process of step S 102 . 
         [0102]    Next, the operation of the switch SW 1  will be described. Further, because the operation of the switches SW 2  to SW 8  conforms to the operation of the switch SW 1 , the description will be omitted. 
         [0103]      FIG. 6  is a flowchart for explaining the operation of the switch SW 1 . 
         [0104]    When the power-supply voltage is supplied to the switch SW 1  after the switch SW 1  is installed in the access network  1 , the communication tunnel control unit  53  sets the second communication tunnel between the BRM  3  and the switch SW 1  (step S 201 ). 
         [0105]    Next, the communication tunnel control unit  53  notifies the LLDP processing unit  54  of second communication tunnel information indicating the IP addresses of the wireless base station eNB 1  and the switch SW 1  that are the end-point devices of the second communication tunnel. When the LLDP processing unit  54  receives the second communication tunnel information, the LLDP processing unit  54  holds the second communication tunnel information. 
         [0106]    On the other hand, when the power-supply voltage is supplied to the switch SW 1 , the communication processing unit  52  performs the function of a common switch and further, specifies the communication state of the switch SW 1  (step S 202 ). 
         [0107]    In this exemplary embodiment, the communication processing unit  52  specifies the band usage amount of the line between the node existing in the next hop of the switch SW 1  and the switch SW 1  by using an amount of the data transmitted and received between the communication processing unit  52  and the network IF  51  as the communication state of the switch SW 1 . 
         [0108]    Further, the communication processing unit  52  specifies the current state of the switch SW 1  among three states: the normal state, the congestion state, and the failure state by using the amount of the data transmitted and received between the communication processing unit  52  and the network IF  51  as the communication state of the switch SW 1 . 
         [0109]    Next, the communication processing unit  52  outputs the communication state of the switch SW 1  to the LLDP processing unit  54 . 
         [0110]    When the LLDP processing unit  54  receives the communication state of the switch SW 1 , the LLDP processing unit  54  holds and manages the communication state of the switch SW 1  (step S 203 ). 
         [0111]    Next, the LLDP processing unit  54  generates the second LLDP frame that contains the information indicating the communication state of the switch SW 1  and the identification information of the switch SW 1  (step S 204 ). 
         [0112]    Next, the LLDP processing unit  54  refers to the second communication tunnel information, performs the encapsulation of the second LLDP frame for the second communication tunnel, and generates the packet for second notification (step S 205 ). 
         [0113]    Here, the encapsulation for the second communication tunnel is a process of adding a header which indicates the IP address of the switch SW 1  that is the transmission source and the IP address of the BRM  3  that is the transmission destination to the second LLDP frame. 
         [0114]    Next, the LLDP processing unit  54  transmits the packet for second notification from the network IF  51  (step S 206 ). 
         [0115]    Because the packet for second notification is obtained by performing the encapsulation for the second communication tunnel, the packet for second notification can pass through the second communication tunnel and can be received by the BRM  3 . 
         [0116]    Next, the LLDP processing unit  54  waits until a second time set in advance elapses after transmitting the packet for second notification (step S 207 ). The second time may be equal to or different from the first time. 
         [0117]    When the second time elapses after transmitting the packet for second notification, the LLDP processing unit  54  outputs an output instruction to the communication processing unit  52 . 
         [0118]    When the communication processing unit  52  receives the output instruction, the communication processing unit  52  performs a process of step S 202 . 
         [0119]    Next, the operation of the BRM  3  will be described. 
         [0120]      FIG. 7  is a flowchart for explaining the operation of the BRM  3 . 
         [0121]    When the management unit  63  receives the packet for first notification or the packet for second notification (hereinafter, referred to as “packet for notification”) via the network IF  61  (step S 301 ), the management unit  63  performs the decapsulation of the packet for notification and detects the LLDP frame (step S 302 ). 
         [0122]    Next, the management unit  63  associates the information indicating the communication state of the transmission source of the LLDP frame that is contained in the LLDP frame with the identification information of the transmission source and stores them in the storage unit  62  (step S 303 ). 
         [0123]      FIG. 8  is a figure showing an example of the information stored in the storage unit  62 . In  FIG. 8 , “eNB 1  to eNB 2 ” and “SW 1  to SW 8 ” are shown as the identification information of each device. 
         [0124]    The management unit  63  monitors the occurrence of congestion and the occurrence of the failure in the access network  1  by using the information stored in the storage unit  62 . 
         [0125]    Further, the management unit  63  instructs each of the devices (the wireless base stations and the switches) in the access network  1  to change routing information according to a congestion status or a failure status in the access network  1 . 
         [0126]    For example, as shown in  FIGS. 8 and 9 , when the switch SW 1  is in the congestion state and the switch SW 4  is in the failure state, service quality is degraded by a packet loss or a delay in the access network  1 . Therefore, in order to avoid the degradation of service quality due to the packet loss and the delay in the access network  1 , the management unit  63  operates as follows. 
         [0127]    The management unit  63  refers to the storage unit  62  and transmits an instruction to update the routing information by which the traffic of the wireless base station eNB 2  is changed to the traffic of a switch SW# 5  whose maximum band usage amount is not exceeded to the wireless base station eNB 2 . 
         [0128]    In the wireless base station eNB 2 , the communication processing unit  43  changes the traffic of the wireless base station eNB 2  to the traffic of the switch SW# 5  according to the instruction to update the routing information received from the management unit  63 . 
         [0129]    Further, the management unit  63  may refer to the storage unit  62  and control the band of the wireless base station eNB 1  connecting to only the switch SW 1  (for example, a change of the transmission/reception band or a change of the band of a line for low-priority service). 
         [0130]    Next, the effect of this exemplary embodiment will be described. 
         [0131]    After the wireless base station eNB 1  is installed in the access network  1 , the communication tunnel control unit  44  sets the first communication tunnel between the BRM  3  and the wireless base station eNB 1 . The LLDP processing unit  45  transmits the first LLDP frame via the first communication tunnel. 
         [0132]    For this reason, even when the node exists between the wireless base station eNB 1  and the BRM  3 , the first LLDP frame reaches the BRM  3 . 
         [0133]    Further, after the switch SW 1  is installed in the access network  1 , the communication tunnel control unit  53  sets the second communication tunnel between the BRM  3  and the switch SW 1 . The LLDP processing unit  54  transmits the second LLDP frame via the second communication tunnel. 
         [0134]    For this reason, even when the node exists between the switch SW 1  and the BRM  3 , the second LLDP frame reaches the BRM  3 . 
         [0135]    The management unit  63  of the BRM  3  receives the first LLDP frame or the second LLDP frame via each communication tunnel. 
         [0136]    Accordingly, even when the node exists between the BRM  3  and the access-network device (for example, the wireless base station eNB 1  or the switch SW 1 ), the BRM  3  can obtain the information managed by the access-network device from the LLDP frame. 
         [0137]    The wireless base station composed of the communication tunnel control unit  44  and the LLDP processing unit  45 , the switch composed of the communication tunnel control unit  53  and the LLDP processing unit  54 , or the BRM composed of the management unit  63  also has the above-mentioned effect. 
         [0138]      FIG. 10A  is a figure showing the wireless base station composed of the communication tunnel control unit  44  and the LLDP processing unit  45 .  FIG. 10B  is a figure showing the switch composed of the communication tunnel control unit  53  and the LLDP processing unit  54 .  FIG. 11  is a figure showing the BRM composed of the management unit  63 . 
         [0139]    In this exemplary embodiment, the first LLDP frame contains information indicating the communication state of the wireless base station eNB 1 . 
         [0140]    Further, the second LLDP frame contains information indicating the communication state of the switch SW 1 . 
         [0141]    For this reason, even when the node exists between the BRM  3  and the access-network device, the BRM  3  can obtain information indicating the communication state of the access-network device. Further, the BRM  3  can centrally manage the state management (the monitoring of the band usage amount and the monitoring of the failure) in an L2 network. 
         [0142]    In the BRM  3 , the storage unit  62  stores the information indicating the communication state of each access-network device. For this reason, the management unit  63  refers to the information stored in the storage unit  62  and thereby, can set traffic routing which is taking into consideration the whole access-network  1  and instruct each access network device to control the band. 
         [0143]    Further, the management unit  63  performs centralized monitoring of the traffic status and the failure status in the access network at an L2 level using the LLDP function and thereby, can realize the effective utilization of the resource of the access network  1  and provide a stable service to an end user. 
       Second Exemplary Embodiment 
       [0144]    In the first exemplary embodiment, each access-network device transmits the information managed by the each access-network device to the BRM  3  via the communication tunnel. In contrast, in a second exemplary embodiment, the access-network device transmits the information managed by the each access-network device and the information managed by another access-network device that is adjacent to the each access-network device to the BRM  3  via the communication tunnel by using the LLDP frame. 
         [0145]    The difference between the first exemplary embodiment and the second exemplary embodiment will be described below. The configuration of the entire communication system according to the second exemplary embodiment is the same as that of the first exemplary embodiment shown in  FIG. 1 . 
         [0146]    In the second exemplary embodiment, the each access-network device (the wireless base station and the switch) transmits/receives the LLDP frame to/from the another access-network device that is adjacent to the each access-network device and acquires information indicating the communication state of the another access-network device. 
         [0147]    Hereinafter, the another access-network device that is adjacent to the each access-network device is referred to as “adjacent device”. 
         [0148]    The LLDP frame transmitted/received between the access-network device and the adjacent device contains the information indicating the current state of the transmission source of the LLDP frame among three states: the normal state, the congestion state, and the failure state and the information of the band usage amount of the line between the node existing in the next hop of the transmission source and the transmission source as the communication state of the transmission source. 
         [0149]      FIG. 12  is a figure showing a wireless base station eNB used in the second exemplary embodiment. In  FIG. 12 , the same reference numbers are used for the elements having the same function as the elements shown in  FIG. 2 . 
         [0150]    In  FIG. 12 , the wireless base station eNB includes the wireless communication IF (interface)  41 , the network IF  42 , the communication processing unit  43 , the communication tunnel control unit  44 , and an LLDP processing unit  45   a.    
         [0151]    The LLDP processing unit  45   a  is an example of the communication unit. 
         [0152]    The LLDP processing unit  45   a  transmits/receives the LLDP frame to/from the adjacent device. As described above, this LLDP frame contains the information indicating the current state of the transmission source of the LLDP frame among three states: the normal state, the congestion state, and the failure state and the information of the band usage amount of the line between the node existing in the next hop of the transmission source and the transmission source as the communication state of the transmission source. 
         [0153]    The LLDP processing unit  45   a  manages the information indicating the communication state of the wireless base station eNB 1  of which the communication processing unit  43  notifies the LLDP processing unit  45   a  and the information indicating the communication state of the adjacent device of which the adjacent device notifies the LLDP processing unit  45   a.    
         [0154]    The LLDP processing unit  45   a  generates a third LLDP frame that contains the information indicating the communication state and the identification information of the wireless base station eNB 1  and the information indicating the communication state and the identification information of the adjacent device. The LLDP processing unit  45   a  refers to the first communication tunnel information, performs the encapsulation of the third LLDP frame for the first communication tunnel, and generates a packet for third notification. The LLDP processing unit  45   a  transmits the packet for third notification from the network IF  42 . 
         [0155]      FIG. 13  is a figure showing a switch SW used in the second exemplary embodiment. In  FIG. 13 , the same reference numbers are used for the elements having the same function as the elements shown in  FIG. 3 . 
         [0156]    In  FIG. 13 , the switch SW includes the network IF  51 , the communication processing unit  52 , the communication tunnel control unit  53 , and an LLDP processing unit  54   a.    
         [0157]    The LLDP processing unit  54   a  is an example of the communication unit. 
         [0158]    The LLDP processing unit  54   a  transmits/receives the LLDP frame to/from the adjacent device. As described above, this LLDP frame contains the information indicating the current state of the transmission source of the LLDP frame among three states: the normal state, the congestion state, and the failure state and the information of the band usage amount of the line between the node existing in the next hop of the transmission source and the transmission source as the communication state of the transmission source. 
         [0159]    The LLDP processing unit  54   a  manages the information indicating the communication state of the switch SW of which the communication processing unit  52  notifies the LLDP processing unit  54   a  and the information indicating the communication state of the adjacent device of which the adjacent device notifies the LLDP processing unit  54   a.    
         [0160]    The LLDP processing unit  54   a  generates a fourth LLDP frame that contains the information indicating the communication state and the identification information of the switch SW and the information indicating the communication state and the identification information of the adjacent device. The LLDP processing unit  54   a  refers to the second communication tunnel information, performs the encapsulation of the fourth LLDP frame for the second communication tunnel, and generates a packet for fourth notification. The LLDP processing unit  54   a  transmits the packet for fourth notification from the network IF  51 . 
         [0161]    In the BRM  3 , when the management unit  63  receives the packet for third notification or the packet for fourth notification (hereinafter, referred to as “notification packet”) via the network IF  61 , the management unit  63  performs the decapsulation of the notification packet and detects the LLDP frame. 
         [0162]    The management unit  63  stores the information indicating the communication state of the transmission source of the LLDP frame, the identification information of the transmission source, the information indicating the communication state of the adjacent device, and the identification information of the adjacent device that are contained in the LLDP frame to the storage unit  62 . 
         [0163]    Next, the effect of this exemplary embodiment will be described. 
         [0164]    The LLDP processing unit  45   a  generates the third LLDP frame that contains the information indicating the communication state of the wireless base station eNB and the information indicating the communication state of the adjacent device. The LLDP processing unit  45   a  transmits the third LLDP frame via the first communication tunnel. 
         [0165]    For this reason, even when another node exists between the wireless base station eNB and the BRM  3 , the third LLDP frame reaches the BRM  3 . 
         [0166]    Further, the LLDP processing unit  54   a  generates the fourth LLDP frame that contains the information indicating the communication state of the switch SW and the information indicating the communication state of the adjacent device. The LLDP processing unit  54   a  transmits the fourth LLDP frame via the second communication tunnel. 
         [0167]    For this reason, even when another node exists between the switch SW and the BRM  3 , the fourth LLDP frame reaches the BRM  3 . 
         [0168]    Accordingly, the BRM  3  can obtain the information managed by the access-network device of which another node exists between the BRM  3  and the access-network device from the LLDP frame. 
         [0169]    Further, in each sub network in the access network  1 , when at least one device among the access-network devices belonging to the sub network transmits the third or fourth LLDP frame, the BRM  3  can manage the communication state of the access network  1 . 
         [0170]    The following modification can be made to the above-mentioned each exemplary embodiment. 
         [0171]    The access-network device does not calculate the band information (the band usage amount) and the BRM  3  calculates the band information. For example, information (IflnOctets and IfOutOctets) of a standard MIB (Management information base) of the access-network device is transmitted to the BRM  3  from the access-network device via the communication tunnel by the LLDP frame. The BRM  3  calculates the band information (the band usage amount) by using the information of the standard MIB. The standard MIB is specified in RFC (Request For Comment) 1213. 
         [0172]    As another modification example, in a case in which the criteria required for the monitoring of the access network  1  is not high, the access-network device may not notify the BRM  3  of the band information (band usage amount) and the BRM  3  may not monitor the band information. 
         [0173]    Further, the access-network device may manage the band usage amount of the data transmitted and received by a physical line or a logical line unit (a unit of VLAN or a unit of a virtual IP address) and transmit the LLDP frame containing the information of the band usage amount to the BRM  3  via the communication tunnel. In this case, the BRM  3  can monitor the band usage amount per the logical line. Therefore, the band usage amount can be precisely managed per VLAN, per service, or the like and the BRM  3  can precisely perform the control. 
         [0174]    The management unit  63  holds a first threshold value for determining the congestion state and when the band usage amount of a certain line exceeds the first threshold value, the management unit  63  may determine that the line is in the congestion state. 
         [0175]    Further, the management unit  63  holds a second threshold value for determining the release of the congestion state and when the band usage amount of the line to which it is determined that the line is in the congestion state decreases to the second threshold value, the management unit  63  may determine that the congestion state of the line is over. Further, the second threshold value is smaller than the first threshold value. 
         [0176]    The management unit  63  holds a third threshold value for determining a quasi-congestion state in which the state of the line is approaching the congestion state and when the band usage amount of a certain line is greater than the third threshold value and smaller than the first threshold value, the management unit  63  may determine that the line is in the quasi-congestion state. Further, the third threshold value is smaller than the first threshold value and greater than the second threshold value. 
         [0177]      FIG. 14  is a figure showing an example of the storage unit  62  storing a result of the determination using the first to third threshold values. Here, the data speeds of 680 Mbps, 650 Mbps, and 480 Mbps are used as the first threshold value, the second threshold value, and the third threshold value, respectively. Further, the first to third threshold values are not limited to the values of 680 Mbps, 650 Mbps, and 480 Mbps, respectively and these values can be appropriately determined. 
         [0178]    In  FIG. 14 , it is determined that the line shown with positive slope hatching is in the “congestion state”. Further, in  FIG. 14 , it is determined that the line shown with horizontal line hatching is in the “quasi-congestion state”. 
         [0179]    In  FIG. 14 , a priority path (Path) and a priority traffic are stored in the storage unit  62  with respect to each of the access-network devices (the wireless base stations eNB 1  to eNB 2  and the switches SW 1  to SW 8 ). For example, the priority path (Path) and the priority traffic are set according to an instruction from an administrator terminal of the access network  1 . 
         [0180]    In a case in which the access-network device to which the priority path is set has a plurality of the paths, the priority path is preferentially used among a plurality of the paths for data transmission. 
         [0181]    The priority traffic shows information such as priority service, VLAN, DSCP (Differentiated Services Code Point) or the like when the access-network device to which the priority traffic is set transmits the data. 
         [0182]    For example, when the access-network device to which the priority traffic is set is in the congestion state, the management unit  63  transmits a band control instruction or a priority control instruction indicating that the traffic other than the priority traffic is lowered to the access-network device. When the access-network device receives the band control instruction or the priority control instruction, the access-network device controls the traffic according to the band control instruction or the priority control instruction. 
         [0183]      FIG. 15  is a figure showing an example of a format of the LLDP frame used in each exemplary embodiment or each modification example. 
         [0184]    As shown in  FIG. 15 , a state of the own device and band information of the line between the own device and the adjacent device is newly set in Vendor Specific TLV (Type, Length, Value) of the LLDP. 
         [0185]    Further, even when the expansion of the LLDP frame as shown in  FIG. 15  is not performed, the management unit  63  can perform the predetermined traffic control based on the information which can be acquired from the existing standard MIB. Therefore, the above-mentioned each exemplary embodiment can be applied to the existing access network. 
         [0186]    Further, the access network that is a monitoring target monitored by the BRM  3  is not limited to EUTRAN (Evolved Universal Terrestrial Radio Access Network) for LTE (Long Term Evolution). For example, the access network that is a monitoring target monitored by the BRM  3  may be UTRAN (Universal Terrestrial Radio Access Network) of 3GPP (3rd Generation Partnership Project). Further, the access network that is a monitoring target monitored by the BRM  3  may be GERAN (Enhanced Data Rates for GSM Radio Access Network) of GSM (Global System for Mobile Communications) (registered trademark). Further, the access network that is a monitoring target monitored by the BRM  3  may be the Internet. In this case, it is desirable that the wireless base station eNB can support Multiple RAT (Radio Access Technology) access network connection. 
         [0187]    Further, in the above-mentioned each exemplary embodiment, the wireless base station eNB may be realized by using a computer. In this case, the computer reads a program recorded in a recording medium such as a computer-readable CD-ROM (Compact Disk Read Only Memory), executes it, and performs each function of the wireless base station eNB. The recording medium is not limited to the CD-ROM and another medium can be appropriately used. 
         [0188]    Further, in the above-mentioned each exemplary embodiment, the switch SW may be realized by the computer. 
         [0189]    In this case, the computer reads a program recorded in a computer-readable recording medium, executes it, and performs each function of the switch SW. 
         [0190]    In each exemplary embodiment described above, the configuration shown in the figure is shown as an example. Therefore, the present invention is not limited to the configuration shown in the figure. 
         [0191]    A part of or all of the above-mentioned each exemplary embodiment can be described as the following supplementary note. However, the present invention is not limited to the following supplementary note. 
         [0192]    (Supplementary note 1) An access-network device installed in an access network including 
         [0193]    a control unit which sets a communication tunnel between a management device for managing the access-network and the access-network device after the access-network device is installed in the access network and 
         [0194]    a communication unit which transmits a layer 2 message including information managed by the access-network device via the communication tunnel. 
         [0195]    (Supplementary note 2) The access-network device described in Supplementary note 1 wherein the information includes information indicating a communication state of the access-network device. 
         [0196]    (Supplementary note 3) The access-network device described in Supplementary note 2 wherein the information further includes information indicating a communication state of a communication device which communicates with the access-network device at a layer 2 level. 
         [0197]    (Supplementary note 4) A management device which manages an access network including 
         [0198]    a communication unit which receives a layer 2 message including information managed by an access-network device from the access-network device installed in the access network via a communication tunnel set between the management device and the access-network device. 
         [0199]    (Supplementary note 5) The management device described in Supplementary note 4 wherein the communication unit receives the layer 2 message from each of a plurality of the access-network devices via the communication tunnel set between the management device and the access-network device. 
         [0200]    (Supplementary note 6) The management device described in Supplementary note 5 further including a storage unit which stores information included in each layer 2 message. 
         [0201]    (Supplementary note 7) The management device described in Supplementary note 6 wherein the communication unit controls communication of the access network by using the information stored in the storage unit. 
         [0202]    (Supplementary note 8) A communication system including an access-network device installed in an access network and a management device which manages the access network wherein 
         [0203]    the access-network device includes 
         [0204]    a control unit which sets a communication tunnel between the management device and the access-network device after the access-network device is installed in the access network and 
         [0205]    a first communication unit which transmits a layer 2 message including information managed by the access-network device via the communication tunnel and 
         [0206]    the management device includes a second communication unit which receives the layer 2 message from the access-network device via the communication tunnel. 
         [0207]    (Supplementary note 9) The communication system described in Supplementary note 8 wherein 
         [0208]    the communication system further includes 
         [0209]    a second access-network device different from the access-network device; 
         [0210]    the second access-network device includes 
         [0211]    a second control unit which sets the communication tunnel between the second access-network device and the management device after the second access-network device is installed in the communication system and 
         [0212]    a third communication unit which transmits the layer 2 message including second information managed by the second access-network device via the communication tunnel; and 
         [0213]    the second communication unit of the management device receives the layer 2 message including the second information. 
         [0214]    (Supplementary note 10) The management device described in Supplementary note 9 further including a storage unit which stores the information included in the layer 2 message including the information and the second information included in the layer 2 message including the second information. 
         [0215]    (Supplementary note 11) An information provision method performed by an access-network device installed in an access network comprising: 
         [0216]    a control step in which a communication tunnel is set between a management device for managing the access-network and the access-network device after the access-network device is installed in the access network and 
         [0217]    a transmission step in which a layer 2 message including information managed by the access-network device is transmitted via the communication tunnel. 
         [0218]    (Supplementary note 12) A management method performed by a management device which manages an access network comprising 
         [0219]    a reception step in which a layer 2 message including information managed by an access-network device is received from the access-network device installed in the access network via a communication tunnel set between the management device and the access-network device. 
         [0220]    (Supplementary note 13) A program which causes a computer to perform 
         [0221]    a control procedure in which a communication tunnel is set between a management device which manages an access network and the computer after the computer is installed in the access network and 
         [0222]    a transmission procedure in which a layer 2 message including information managed by the computer is transmitted via the communication tunnel. 
         [0223]    (Supplementary note 14) A program which causes a computer to perform 
         [0224]    a reception procedure in which a layer 2 message including information managed by an access-network device is received from the access-network device installed in an access network via a communication tunnel set between the computer and the access-network device. 
         [0225]    The invention of the present application has been described above with reference to the exemplary embodiment (and the example). However, the invention of the present application is not limited to the above mentioned exemplary embodiment (and the example). Various changes in the configuration or details of the invention of the present application that can be understood by those skilled in the art can be made without departing from the scope of the invention. 
         [0226]    This application claims priority from Japanese Patent Application No. 2013-236576 filed on Nov. 15, 2013, the disclosure of which is hereby incorporated by reference in its entirety. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               100  communication system 
               1  access network 
               2  EPC network 
               3  BRM (management device) 
               41  wireless communication IF 
               42  network IF 
               43  communication processing unit 
               44  communication tunnel control unit 
               45  and  45   a  LLDP processing unit 
               51  network IF 
               52  communication processing unit 
               53  communication tunnel control unit 
               54  and  54   a  LLDP processing unit 
               61  network IF 
               62  storage unit 
               63  management unit 
               10 A to  10 C network 
             eNB 1  to eNB 2  wireless base station 
             SW 1  to SW 8  switch