JP4035026B2 - Access network and IP mobility control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to mobile communication, and more particularly to an access network for mobile communication that connects a mobile terminal and an ISP (Internet Service Provider) in a mobile communication network. as well as The present invention relates to an IP mobility control method.
[0002]
[Prior art]
As with fixed IP (Internet protocol) communication, high-speed IP communication is expected to spread in wireless LANs and the like, and it is considered that voice communication will also become communication by IP support in the future. Also, wireless IP network communication in the public, such as hot spots, is showing signs of widespread use. In mobile communication in such a wireless IP network, it is indispensable to switch base stations at high speed by moving terminals. Yes. As one of such terminal mobility controls, Mobile IP (Mobile IP) is being studied for standardization at the Internet Engineering Task Force (IETF), an organization that performs standardization at the IP level (non-patented). Reference 1).
[0003]
[Non-Patent Document 1]
Mobility Support in IPv6: draft-ietf-mobileIP-IPv6-18.txt
[0004]
FIG. 20 simply shows a mobility control method for a mobile terminal using mobile IP. It is assumed that the mobile terminal 10 is connected to a base station 21 that is one of hot spots provided by a certain ISP # 2 and performs communication. The hot spot network is composed of a plurality of base station nodes 20 to 2n (only 20 to 22 are shown in the figure) and relay stations 30 to 33, and is connected to the Internet through a connection station 40 placed at a connection point with another network. It shall be connected. In this example, the mobile terminal 10 communicates with a node (CN) in the Internet through the base station 21 and the connection station 40. The IP address of the mobile terminal 10 is (A), the CN IP address is (B), and the home agent (hereinafter referred to as HA) in the mobile IP is the base station 21. When the mobile terminal 10 is under the base station 21, it is assumed that normal IP communication is performed.
[0005]
A process when the mobile terminal 10 moves will be described with reference to FIG. When the communication is switched from the subordinate of the base station 21 to the subordinate of the base station 22, the mobile terminal 10 acquires an IP address (Care of Address) from the base station 22. Further, the base station 22 notifies the base station 21 that the mobile terminal 10 has moved under the base station 22. The base station 21 that has received the notification generates an IP tunnel with the base station 22.
Communication after moving is as follows. The packet transmitted from the CN to the mobile terminal 10 is transferred to the base station 21 that is the HA of the mobile terminal 10 through the path as before. The base station 21 transfers the packet to the mobile terminal 10 via the base station 22 using the IP tunnel generated when the mobile terminal 10 moves. The mobile terminal 10 transfers the packet to the CN through the base station 22. At this time, the mobile terminal is notified that the mobile terminal is currently under the control of the base station 22.
[0006]
At the next opportunity, the CN recognizes that the position of the mobile terminal 10 is under the base station 22 and communicates with the mobile terminal 10 through the base station 22 without passing through the base station 21.
[0007]
[Problems to be solved by the invention]
However, the IP support system based on mobile IP needs to follow the complicated signaling procedure as described above. In addition, there is a problem that a triangular path is generated between the CN, the HA, and the mobile terminal, and overhead due to the IP tunnel occurs between them. In addition, it is possible to send a packet directly to the destination by notifying the communication partner of his / her position, but this is necessary to inform the communication partner of his / her current CoA, and the position information is the communication partner. There is a problem that may be known. In addition, processing at the layer 3 level, such as acquiring an IP address or configuring an IP tunnel, occurs, and the procedure is complicated, so high-speed mobility control that is essential for high-speed mobile communication such as moving by car is possible. There is a problem that it is difficult. Specifically, a momentary interruption in units of several seconds may occur when the location registration is changed. For this reason, it is difficult to apply to micromobility that frequently moves in a small area.
[0008]
Also, consider a case where the operator providing this hot spot does not take the form of directly accommodating the user as an ISP, but takes the transport form of lending a network to the ISP as a mobile communication operator. A mobile communication operator having this network has a radio base station, accommodates subscribers, and provides transport services to and from ISPs. From the perspective of the ISP, this mobile network functions as an access network. Such an access network is shared by a plurality of external networks (for example, ISP # 1, ISP # 2, etc.). The packet transfer with the user terminal of the ISP # n must be via the ISP # n regardless of the destination address.
[0009]
In such a network, when mobile IP is applied, the address used by the mobile terminal is a care-of address given from the mobile network, and the ISP to which the packet belongs is identified and controlled from the destination address or source address of the packet. I can't do it. For this reason, it is difficult to efficiently provide multicast forwarding within the access network and provide a multicast service that supports mobility. In addition, since mobile IP is control in the IP layer, it also depends on the IP version. When configuring a network, it is necessary to support IPv4 and IPv6.
[0010]
Therefore, the present invention can communicate while moving in the network while using the same IP address without affecting the IP address of the mobile terminal at all, and the micro mobility that frequently moves in a small area. Mobile communication access network that can be applied to as well as An object is to provide a mobility control method.
[0011]
The present invention also provides a very inexpensive Ethernet for the relay device. (Registered trademark) An access network for mobile communications that can use switches and can support mobility at low cost as well as An object is to provide a mobility control method.
[0012]
The present invention also provides an access network for mobile communication that can solve the problem of knowing the position of a mobile terminal by a communication partner. as well as An object is to provide an IP mobility control method.
[0013]
The present invention also provides a mobile communication access network that can efficiently deliver multicast packets from an ISP and can receive a multicast service while moving. as well as An object is to provide an IP mobility control method.
[0014]
The present invention also provides an access network for mobile communications that eliminates unnecessary multicast delivery from a mobile terminal and can support multicast from an ISP while ensuring security. as well as An object is to provide an IP mobility control method.
[0015]
[Means for Solving the Problems]
To achieve the above object, according to the present invention, in order to relay between a mobile terminal and an external IP network to which a user of the mobile terminal belongs, a connection station connected to the external IP network to which the user belongs, A plurality of radio base stations to which the mobile terminal can be connected, a plurality of relay stations connecting the connection station and the plurality of radio base stations, and a network management unit that manages the radio base station and the mobile terminal An access network,
Tunnel transfer means for transferring packets transmitted and received by the mobile terminal using a tunnel having an identifier between the connection station and the radio base station is provided, and the network management unit sets a route of the tunnel Access having centralized tunnel setting means, and centralized tunnel assignment means for changing the mapping between the mobile terminal and the base station that accommodates the mobile terminal by following the mobile terminal that moves and changes the mapping between the tunnel and the mobile station A network is provided.
[0016]
According to the present invention, the tunnel transfer means comprises a relay station that transfers packets in the plurality of relay stations as an Ethernet (R) switch, and the tunnel is a tag VLAN (Virtual Local) defined by IEEE802.1q. There is provided an access network that is configured with an area network and uses VLANID (sometimes simply referred to as VID) as an identifier of the tunnel.
[0017]
Further, according to the present invention, the access network connecting station physically or logically distinguishes the external connection ports connecting each external IP network, and the centralized tunnel setting means is an initial part of the access network. An access network is provided in which all point-to-point tunnels connecting each connection port of the connection station and each base station are set in advance at the time of setting.
[0018]
Further, according to the present invention, the centralized tunnel setting means further adds a tree-shaped point-to-multipoint tunnel connected to all the base stations with the connecting station as a vertex for each external IP network. An access network characterized by being set is provided.
[0019]
Further, according to the present invention, the centralized tunnel allocating means includes a user ID for identifying the mobile terminal and a point-to-point tunnel identifier used by the mobile terminal, the base station from which the mobile terminal has moved, and It is set in a connection station, and the base station and the connection station determine the user ID from a packet received from the mobile terminal and the external IP network, and add the set tunnel identifier and transfer the packet. An access network is provided.
[0020]
Further, according to the present invention, the centralized tunnel allocating unit adds the multicast and broadcast packets received from the external IP network to the point-to-multipoint tunnel identifier for each external IP network set by the centralized tunnel setting unit. An access network is provided, wherein the access network is assigned and set only to the connection station, and the connection station adds the tunnel identifier set to the multicast and broadcast packets received from the external IP network and forwards the packet. The
[0021]
Further, according to the present invention, the centralized tunnel assigning means validates the point-to-multipoint tunnel identifier assigned for the external network to which the user belongs to the base station to which the mobile terminal has moved. An access network is provided, characterized in that a packet having a point-to-multipoint tunnel identifier received from the access network side at the base station is transferred to the mobile terminal side only when the identifier is valid.
[0033]
According to the present invention, in order to relay between a mobile terminal and an external IP network to which a user of the mobile terminal belongs, a connection station connected to the external IP network to which the user belongs can be connected to the mobile terminal. Mobility using an access network comprising a plurality of radio base stations, a plurality of relay stations connecting the connection station and the plurality of radio base stations, and a network management unit for managing the radio base station and the mobile terminal In the control method,
A tunnel transfer step of transferring a packet transmitted / received by the mobile terminal using a tunnel having an identifier between the connection station and the radio base station, and the tunnel path is set by the network management unit A centralized tunnel setting step, and a centralized tunnel allocation step of changing the mapping between the mobile terminal and the base station that accommodates the mobile terminal by following the mobile terminal that moves and changes the mapping of the tunnel and the mobile terminal An IP mobility control method is provided.
[0034]
Further, according to the present invention, the tunnel transfer step is implemented by an Ethernet (R) switch that relays packets in the plurality of relay stations, and the tunnel is configured by a tag VLAN defined by IEEE802.1q. An IP mobility control method using VLANID as an identifier of the tunnel is provided.
[0035]
Further, according to the present invention, the access network connecting station physically or logically distinguishes the external connection ports connecting each external IP network, and the centralized tunnel setting step includes the initial step of the access network. An IP mobility control method is provided in which all point-to-point tunnels connecting each connection port of the connection station and each base station are set in advance at the time of setting.
[0036]
According to the present invention, the centralized tunnel setting step further adds a tree-shaped point-to-multipoint tunnel connected to all the base stations with the connecting station as a vertex for each external IP network. An IP mobility control method characterized by being set in advance is provided.
[0037]
Further, according to the present invention, the concentrated tunnel assignment step includes: a user ID for identifying the mobile terminal; a point-to-point tunnel identifier used by the mobile terminal; It is set in a connection station, and the base station and the connection station determine the user ID from a packet received from the mobile terminal and the external IP network, and add the set tunnel identifier and transfer the packet. An IP mobility control method is provided.
[0038]
According to the present invention, the centralized tunnel assignment step includes a multicast identifier and a broadcast packet received from the external IP network in a point-to-multipoint tunnel identifier for each external IP network set by the centralized tunnel setting step. An IP mobility control method comprising: assigning and setting this only to the connecting station, wherein the connecting station adds a tunnel identifier set to multicast and broadcast packets received from the external IP network and forwards the packet. Provided.
[0039]
According to the present invention, the concentrated tunnel assignment step validates the point-to-multipoint tunnel identifier assigned for the external network to which the user belongs to the base station to which the mobile terminal has moved. An IP mobility control method is provided, characterized in that a packet having a point-to-multipoint tunnel identifier received from the access network side at the base station is forwarded to the mobile terminal side only when the identifier is valid The
[0040]
DETAILED DESCRIPTION OF THE INVENTION
An outline of an access network used as an example of an embodiment of the present invention is shown in FIG. The access network includes base stations 20 to 22 that accommodate subscriber wireless mobile terminals (also simply referred to as mobile terminals) 10, relay stations 30 to 33 that relay packets, and ISPs that provide Internet connection services to subscribers. The connection station 40 is connected to a network. In this embodiment, mobile communication between such an ISP network and the mobile terminal 10 that is a subscriber of the ISP will be described.
[0041]
<First Embodiment>
This access network is a network that connects a subscriber and its ISP, and each subscriber can connect to a favorite ISP individually. Since the subscriber's IP is distributed by the ISP, the packet of each subscriber whose IP address is distributed by each ISP is appropriately transferred through the ISP described above in the access network. For this reason, the access network forms a layer 2 tunnel. In detail, this access network is logically composed of two planes.
[0042]
One is a transfer plane in FIG. 1B for transferring data packets from a subscriber terminal to the ISP, and the second is a control plane in FIG. 1A for executing network monitoring and management. Hereinafter, two planes will be described. The transfer plane is composed of a network using a tunnel technology for transparently transmitting a layer 2 (data link layer) network in the OSI model. Ethernet (R) is provided as an interface for connecting the subscriber and ISP. On the other hand, the control plane is composed of layer 3 (network layer) in the OSI model, constitutes a closed IP network inside the access network, and executes transmission of control information between devices by normal IP routing. A network management unit 50 that manages the entire network is connected to one of the radio base stations.
[0043]
Next, the concept of mobility control according to the present invention will be described with reference to FIG. In this embodiment, VLAN is used as a tunnel configuration method. In this case, the VID in the VLAN tag is used as a label that is a tunnel identifier. It is assumed that the mobile terminal 10 is communicating with ISP # 1 under the base station 21. At this time, in the access network, the mobile terminal uses a VLAN (VID = 10) having a single route from the base station 21 through the relay stations 33 and 30 to the port to which the ISP # 2 of the connection station 40 is connected. The packet transmitted and received by the network 10 is transferred to and from the ISP by layer 2 through this VLAN. At this time, a VLAN tag defined by IEEE802.1q as a VLAN identifier is added between the base station 21 and the connection station 40.
[0044]
In the access network, a VLAN that connects each ISP and the base station is set in advance by the network management unit through the control plane. When the mobile terminal 10 moves to a new base station 22, a VLAN (VID) having a single route from the base station 22 to the port to which the ISP # 2 of the connection station 40 is connected via the relay stations 32 and 31. = 20) and forwarded to ISP by layer 2. Thus, every time the mobile terminal 10 moves to a new area, it continues communication using an appropriate VLAN tunnel set in the access network.
[0045]
Since VLAN 3 tunneling does not cause any layer 3 processing, users do not need to receive a new network care-of address as in the case of using mobile IP, and continue communication using the same IP address as it is. Is possible. However, this operation is limited to movement within the access network, and when moving the access network itself, movement is controlled using mobile IP. For this reason, the ISP controls the mobile mobility with respect to the macro mobility that moves the access network by placing the HA in the ISP that distributes the IP address to the subscriber.
[0046]
A method for changing the label during movement will be described in detail with reference to FIG. In this access network, each base station periodically advertises area information including an area ID. The mobile terminal always receives this area information, and grasps the current area based on the received area ID. When a base station for communication is changed after receiving a new area ID by moving, a subscriber location registration request packet is transmitted to register the new base station with itself. Although this packet is an Ethernet (R) packet, it is a special packet for controlling mobility in the access network, and is not an IP packet but a protocol packet in layer 2. For this reason, the packet has a movement control packet ID for indicating this.
[0047]
The destination address of the Ethernet (R) packet is a broadcast or multicast address that does not specify a base station. For this reason, the mobile terminal does not need to individually identify the address of the base station and output the packet. The new base station that has received the subscriber location registration request recognizes the subscriber location registration request from the mobile control packet ID and the user ID, and uses the control plane to request the subscriber route indication to the network management unit. Send. In the subscriber route instruction request, the source MAC address of the received Ethernet (R) packet and the area ID of the own device are sent as the user ID indicating the user. When receiving the subscriber route instruction request, the network management unit searches the ISP described above from the user ID in the table shown in FIG. 5, and extracts the VID described above from the already set VLAN table from the ISP and the area ID.
[0048]
When the VID newly assigned to the user is determined, the network management unit notifies the new base station of the VID assigned to the user ID as a subscriber route instruction response using the control plane. In addition, a user ID and a VID to be changed are notified as a subscriber route instruction for a connection station that is a connection point with the ISP. When the new base station that has received the subscriber route indication response adds a new VID table that maps to the user ID to the table shown in FIG. 6, and subsequently receives a packet from the user, the specified VID Is inserted into the packet and sent to the transfer plane. For packets from within the access network, the VLAN tag is deleted and transmitted to the subscriber.
[0049]
On the other hand, the connecting station that has received the subscriber route instruction changes the VID mapped to the user ID in the table shown in FIG. 7 to the VID specified by the subscriber route instruction. From now on, for packets received from the ISP side, the user table is searched from the destination MAC address of the Ethernet (R) packet, a VLAN tag having the newly changed VID is inserted into the packet, and is sent to the transfer plane. It becomes like this. For packets from within the access network, the VLAN tag is deleted and transmitted to the ISP.
[0050]
Next, the area information advertisement receiving process in the mobile terminal will be described in detail with reference to FIG. The mobile terminal always scans each base station to grasp the state of the radio wave and receives an area information advertisement output from each base station. When a certain area information advertisement is received (step S81), it is first checked whether or not the received area ID has been registered in the own terminal (step S82). If the area ID has not been registered, the area ID is registered in the own terminal (step S83). Next, the reception intensity is newly registered (step S84). When the area information advertisement of the already registered area ID is received, only the reception strength is updated (from step S82 to step S84). If the reception strength of the updated area ID is greater than the reception strength of the area ID currently used for communication by a set threshold value α or more (YES in step S85), the mobile terminal sends a subscriber location registration request to a new area. Transmit to the base station having the ID (step S86). Otherwise, the process ends (from step S85 to end).
[0051]
This area information advertisement does not have to be a layer 2 packet such as an Ethernet (R) packet, and may be in a form in which communication can be performed by the wireless unit. An example of the base station management table held in the mobile terminal at this time is shown in FIG. The base station management table includes a receiving area ID, its reception intensity, and a flag for each area ID. The meaning of the flag is 0: The area advertisement is received, but the reception strength is low and is not used for communication. 1: State currently used for communication. 2: Current reception intensity of the area ID exceeds a threshold value, indicating a state in the middle of making a subscriber location registration request. With this table, the mobile terminal manages the base station with which the mobile terminal communicates.
[0052]
Next, processing at the time of packet reception from the subscriber-side radio apparatus in the base station will be described in detail with reference to FIG. When the base station receives a packet from the subscriber-side wireless device (step S91), it first checks whether the packet has a mobility control packet ID (step S92). If it does not have a mobility control packet ID, The table shown in FIG. 6 is searched using the source MAC address as the user ID (step S93), and if not registered in the table, the packet is discarded (step S97). If it is registered in the table, a VID is obtained from the table (step S94), a VLAN tag having this VID is created, inserted into a packet, and transmitted to the transfer plane on the access network side (step S95). If it has a movement control packet ID (YES in step S92), a subscriber location registration request process is executed (step S96).
[0053]
Next, subscriber location registration request processing will be described with reference to FIG. When the subscriber location registration is received from the mobile terminal (step S101), it is checked whether the user ID is a registered user ID using the transmission source MAC address as the user ID using the table of FIG. 6 (step S102). If registered, a subscriber location registration response is transmitted to the mobile terminal (step S105). If the user ID is not registered, the user ID is provisionally registered (step S103), and a subscriber route instruction request including the user ID and area ID is transmitted to the network management unit using the control plane (step S104).
[0054]
Next, processing in the network management unit will be described in detail with reference to FIG. When receiving the subscriber route instruction request (step S111), the network management unit extracts the user ID from the packet, and searches the network management database using the user ID as a key (step S112). It is assumed that a user who can access this network is registered in advance, for example, when the subscriber applies for the wireless IP network service, the user ID is registered in the network management database. If the user ID is not registered, an error process is performed because the user is not registered (step S118).
[0055]
If the user ID has already been registered, no VID has been assigned to the user, and a new user has connected to this access network, the registered user's connection destination ISP using the table of FIG. The VLAN path set in the transfer plane in the access network is searched using the area ID of the received subscriber route instruction request as a key, and the VID is assigned to the user (NO in step S113 → step S115). After setting in the internal table, a subscriber route instruction response including the user ID and VID is transmitted to the new base station indicated by the area ID (step S116).
[0056]
Also, a subscriber route instruction including the user ID and VID is transmitted to the connecting station (step S117). If the VID has already been assigned (YES in step S113), the registered user is compared with the area ID currently set from the table in FIG. 5 and the area ID included in the subscriber route instruction request is moved. If the area IDs are the same, the base station has transmitted a subscriber route instruction request even though the area has not been moved, so error processing is performed (step S118). ) If the area IDs are different (YES in step S114), a VID assigned to the user is derived using the table of FIG. 5 (step S115), and a subscriber route instruction request response and a subscriber route instruction are transmitted (step S115). S116, step S117).
[0057]
Next, the packet reception operation at the connecting station will be described with reference to FIGS. FIG. 12 shows the operation when a packet is received from the access network side. When the connecting station receives a packet from the access network side (step S121), it checks whether the packet is a transfer plane packet (step S122). This is the reception port (physical port number or logical port) of the control plane and transfer plane. It can be easily realized by separating the number). In the case of a transfer plane packet, the ISP port of the output destination is searched from the VID setting table according to the VID value using the table of FIG. 7 (step S126), the VLAN tag is deleted, and the packet is transferred (step S127). ).
[0058]
In the case of a control plane packet, it is determined from the destination MAC address whether the packet is addressed to the own device (step S123). If the packet is not addressed to the own device, the packet is discarded (step S128). In the case of a packet addressed to its own device, it is determined whether or not it is a subscriber route instruction (step S124). In the case of a subscriber route instruction, a subscriber route instruction reception process is executed (step S125). Processing according to other received packets is performed (step S129). Since this part is not related to the present invention, the processing will not be described.
[0059]
Next, the subscriber route instruction receiving process will be described with reference to FIG. When the subscriber route instruction packet is received (step S131), the user ID registration table of FIG. 7 is searched using the user ID included in the packet as a key (step S132). If the user ID is a new ID, the user ID and VID are New registration is performed (step S133). When the user ID is registered, the VID written in the table is changed to the VID included in the received subscriber route instruction and updated (step S134).
[0060]
FIG. 14 shows the operation when the connecting station receives a packet from the ISP side. Upon receiving the packet from the ISP side (S141), the connecting station searches the user ID registration table of FIG. 7 using the destination MAC address as the user ID (S142). If there is no user ID as a result of the search, the packet is discarded (S145). When the VID is obtained from the user ID, an output port is obtained from the VID setting table (S143), a VLAN tag including the VID is inserted into the packet, and the packet is output to the output port (S144). Through the operation of the various devices described above, the mobile terminal does not change its own IP address at all by the process of changing the tunnel using the tunnel identifier set in the access network corresponding to the area where the user has moved. Communication can be continued while moving in an area within the access network.
[0061]
<Second Embodiment>
The outline of the second embodiment of the present invention will be described with reference to FIG. In the second embodiment, a multicast tree is configured in the access network for each ISP in order to perform efficient packet delivery in the access network for multicast packets from the ISP. As shown in FIG. 15 (a), the multicast tree is configured such that all base stations are connected in a tree shape with the external connection port of the connection station serving as a connection point with the ISP as a vertex. Such a multicast tree is configured in advance by a network management unit, and is set in each node as one VLAN segment. Further, as shown in FIG. 15 (b), the unicast packet and the multicast packet from the mobile terminal are configured by a point-to-point VLAN in which the ISP and the base station are set as in the first embodiment. Mapped to tunnel.
[0062]
Next, the transfer table possessed by the connecting station will be described with reference to FIG. The user ID registration table and the VLAN setting table are the same as in the first embodiment. In the second embodiment, a multicast table is newly added for multicast. This table is composed of the VID mapped to each ISP and the port number on the access network side. A tree that connects all base stations with the connection point as the apex is constructed, but the tree configuration for each ISP is centrally managed by the network management unit, so it is possible to have a different tree configuration for each ISP. is there. For this reason, the port numbers on the access network side set in this table are not necessarily the same.
[0063]
Next, processing when a packet from the ISP side is received by the connecting station will be described with reference to FIG. First, when a packet is received from the ISP side (step S171), it is checked whether the destination address of the packet is multicast or broadcast (step S172). If it is multicast or broadcast, the ISP is specified from the receiving port (step S172). In step S173, a VID and a port to be output are specified from the multicast table (step S174), and a VLAN tag having the VID is inserted into the packet and output to the port (step S177). If there are a plurality of output ports at this time, the packet is duplicated and transmitted.
[0064]
If the destination is unicast, it is checked whether the destination MAC address is registered in the user ID (step S175). If it is registered, the VID and output port are specified (step S176), and the VLAN tag is inserted and transmitted. (Step S177). If the destination is unicast and the user ID is not registered, the packet is discarded (step S178). Through such processing, packets are transferred using different VLANs for unicast and multicast. In each relay station, multicast and broadcast packets are broadcast and transferred in the same VLAN, in the same way as in the normal Ethernet (R) switch. Therefore, all base stations can receive the same packet.
[0065]
Next, processing at the base station will be described. First, the base station table will be described with reference to FIG. The packet forwarding table from the mobile terminal is the same as in the first embodiment. In the second embodiment, a multicast packet forwarding table from the access network is added to this. This consists of a VID indicating a multicast tree from each ISP and a flag. The flag indicates whether the packet having the VID can be transferred to the mobile terminal side (flag 1) or discarded (flag 2). Since the multicast tree from each ISP is set in advance by the network management unit, the VID elements are held by the number of ISPs connected to the access network in any base station. The default value of the flag at the first setting is discard of 2.
[0066]
In the second embodiment, at the time of processing of the subscriber location registration request of the mobile terminal, during the subscriber route instruction response from the network management unit in the sequence of FIG. A VID indicating a point-to-point tunnel for multicast from the ISP is set together with a VID indicating a point-to-point tunnel indicating a packet and a unicast packet from the ISP. Upon receiving this, the base station sets the VID in the packet transfer table from the mobile terminal and sets the above-mentioned VID flag in the multicast packet transfer table to 1 (transfer possible). That is, when this multicast forwarding table is 1, it indicates that there is a mobile terminal of the multicast ISP under the control. When there is no ISP mobile terminal as described above, the network management unit issues an instruction to set the flag to 2.
[0067]
The packet transfer process using this table will be described with reference to FIG. The base station that has received the packet from the relay station side (step S191) first checks whether the destination address of the packet is multicast or broadcast (step S192). If it is multicast or broadcast, the multicast packet forwarding table Then, it is checked whether the received packet can be transferred (step S193). If the packet can be transferred, the VLAN tag is deleted and the packet is transferred (transmitted) (step S194), and the VID flag of the received packet is discarded. If there is, the packet is discarded (step S195). If the received packet is unicast (NO in step S192), the VLAN tag is deleted and the packet is transferred (transmitted) (step S194).
[0068]
In this way, only a multicast from the ISP side is transferred using a tunnel in which a special point-to-multipoint VLAN segment is configured in a tree shape, so that a multicast service served by the ISP can be received while moving through the access network. It becomes possible. Also, by filtering at each base station, an ISP multicast packet in which no mobile terminal exists under the base station is discarded for each base station, and it is possible to reduce useless traffic.
[0069]
【The invention's effect】
As described above, according to the present invention, in a network that supports the movement of a terminal, a tunnel using a label is formed, the packet of the mobile terminal is transferred through the tunnel, and when the terminal moves in an area, By changing the tunnel to the tunnel for the area, it is possible to communicate while moving in the network while using the same IP address without affecting the IP address of the mobile terminal.
[0070]
Also, by configuring the tunnel using VLAN, it is possible to use a very inexpensive Ethernet (R) switch for the relay device, and it is possible to construct an access network that supports mobility at low cost.
[0071]
In the present invention, since it is the network management unit in the access network that notifies the movement, the problem that the position of the mobile terminal is known to the communication partner can also be solved.
[0072]
Furthermore, according to the second aspect of the present invention, it is possible to efficiently deliver multicast packets from the ISP by configuring the VLAN segment of the multicast tree that connects all base stations from the connecting station on the tree. It is possible to receive a multicast service while moving. Also, all packets from the mobile terminal and unicast packets from the ISP are tunneled by the VLAN of each base station, unlike the multicast VLAN, so that unnecessary multicast delivery from the mobile terminal is eliminated, and security is ensured with the ISP. Multicast from can be supported.
[Brief description of the drawings]
FIG. 1A is a diagram showing a structure of an access network according to a first embodiment of the present invention using a control plane;
(B) The figure which shows the structure of the access network concerning the 1st Embodiment of this invention with a transfer plane
FIG. 2A is a diagram showing a concept of mobility control in the first embodiment of the present invention (state before movement);
(B) The figure which shows the concept of the mobility control in the 1st Embodiment of this invention (state after a movement)
FIG. 3 is a diagram showing a tunnel change sequence when a terminal moves in mobility control according to the first embodiment of the present invention;
FIG. 4 is a diagram showing a configuration example of a base station management table of a mobile terminal in mobility control according to the first embodiment of the present invention.
FIG. 5 is a diagram showing a configuration example of a management table of a network management unit in mobility control according to the first embodiment of the present invention.
FIG. 6 is a diagram showing a configuration example of a transfer table of a base station in mobility control according to the first embodiment of the present invention.
FIG. 7 is a diagram illustrating a configuration example of a transfer table of a connection station in mobility control according to the first embodiment of the present invention.
FIG. 8 is a flowchart showing area information advertisement reception processing in mobility control according to the first embodiment of the present invention;
FIG. 9 is a flowchart showing packet reception processing at the base station in mobility control according to the first embodiment of the present invention;
FIG. 10 is a flowchart showing subscriber location registration request reception processing at the base station in mobility control according to the first embodiment of the present invention.
FIG. 11 is a flowchart showing packet reception processing in the network management unit in mobility control according to the first embodiment of the present invention;
FIG. 12 is a flowchart showing packet reception processing from the access network side at a connection station in mobility control in the first embodiment of the present invention;
FIG. 13 is a flowchart showing subscriber route instruction reception processing at the access network connection station in the first embodiment of the present invention;
FIG. 14 is a flowchart showing packet reception processing from the ISP side in the mobility control connection station in the first embodiment of the present invention;
FIG. 15A is a diagram illustrating an access network structure corresponding to multicast in mobility control in the second embodiment of the present invention, and illustrates a path for multicast packets from an ISP; FIG. 6 is a diagram showing the structure of an access network corresponding to multicast in mobility control in the second embodiment of the invention, and showing a unicast / multicast from a mobile terminal and a unicast path from an ISP
FIG. 16 is a diagram illustrating a configuration example of a forwarding table of a connection station corresponding to multicast in mobility control according to the second embodiment of the present invention.
FIG. 17 is a flowchart showing packet reception processing from the ISP side in a connection station corresponding to multicast in mobility control in the second embodiment of the present invention;
FIG. 18 is a diagram illustrating a configuration example of a forwarding table of a base station corresponding to multicast in mobility control according to the second embodiment of the present invention.
FIG. 19 is a flowchart showing packet reception processing from a relay station at a base station corresponding to multicast in mobility control according to the second embodiment of the present invention;
FIG. 20A is an explanatory diagram of an access network using a conventional mobile IP (state before movement).
(B) Explanatory diagram of an access network using a conventional mobile IP (state after movement)
[Explanation of symbols]
10-11 mobile terminals
20-22 base station
30-33 relay station
40 connected stations
50 Network management unit

Claims (14)

In order to relay between a mobile terminal and an external IP network to which the user of the mobile terminal belongs, a connection station connected to the external IP network to which the user belongs, and a plurality of radio base stations to which the mobile terminal can be connected; An access network comprising a plurality of relay stations connecting the connection station and the plurality of radio base stations, and a network management unit for managing the radio base station and the mobile terminal,
Tunnel transfer means for transferring packets transmitted and received by the mobile terminal using a tunnel having an identifier between the connection station and the radio base station is provided, and the network management unit sets a route of the tunnel Access having centralized tunnel setting means, and centralized tunnel assignment means for changing the mapping between the mobile terminal and the base station that accommodates the mobile terminal by following the mobile terminal that moves and changes the mapping between the tunnel and the mobile station network. The tunnel forwarding means comprises a relay station that forwards packets in the plurality of relay stations as an Ethernet (registered trademark) switch, a tunnel as a tag VLAN defined by IEEE802.1q, and serves as an identifier for the tunnel. The access network according to claim 1, wherein VLANID is used.   The access network connecting station physically or logically distinguishes the external connection ports connecting each external IP network, and the centralized tunnel setting means is configured so that each of the connecting stations can be configured at the time of initial setting of the access network. The access network according to claim 1 or 2, wherein all point-to-point tunnels connecting a connection port and each of the base stations are set in advance.   The centralized tunnel setting means further adds a tree-shaped point-to-multipoint tunnel connected to all the base stations with the connecting station as a vertex for each external IP network, and sets in advance. The access network according to claim 3.   The centralized tunnel allocating means sets a user ID for identifying the mobile terminal and a point-to-point tunnel identifier used by the mobile terminal in a base station and a connecting station from which the mobile terminal has moved, 5. The base station and the connecting station determine the user ID from packets received from the mobile terminal and the external IP network, and forward the packet with a set tunnel identifier added thereto. The access network according to any one of the above.   The centralized tunnel allocating unit allocates multicast and broadcast packets received from the external IP network to a point-to-multipoint tunnel identifier for each external IP network set by the centralized tunnel setting unit, and only to the connection station The packet is forwarded by adding the tunnel identifier set to the multicast and broadcast packets received from the external IP network at the connection station. Access network.   The centralized tunnel assigning means performs a setting for validating a point-to-multipoint tunnel identifier assigned for an external network to which the user belongs to a base station to which the mobile terminal has moved, and the base station 7. The access network according to claim 6, wherein a packet having a point-to-multipoint tunnel identifier received from the access network side is transferred to the mobile terminal side only when the identifier is valid. In order to relay between a mobile terminal and an external IP network to which the user of the mobile terminal belongs, a connection station connected to the external IP network to which the user belongs, and a plurality of radio base stations to which the mobile terminal can be connected; In an IP mobility control method using an access network composed of a plurality of relay stations connecting the connection station and the plurality of radio base stations, and a network management unit for managing the radio base station and the mobile terminal,
A tunnel transfer step of transferring a packet transmitted / received by the mobile terminal using a tunnel having an identifier between the connection station and the radio base station, and the tunnel path is set by the network management unit A centralized tunnel setting step, and a centralized tunnel allocation step of changing the mapping between the mobile terminal and the base station that accommodates the mobile terminal by following the mobile terminal that moves and changes the mapping of the tunnel and the mobile terminal A method for controlling IP mobility. In the tunnel transfer step, a relay station that transfers packets in the plurality of relay stations is realized by an Ethernet (registered trademark) switch, a tunnel is configured by a tag VLAN defined by IEEE802.1q, and the identifier of the tunnel is used. The IP mobility control method according to claim 8 , wherein VLANID is used. The access network connecting station physically or logically distinguishes external connection ports connecting each external IP network, and the centralized tunnel setting step includes the steps of each of the connecting stations at the initial setting of the access network. IP mobility control method according to claim 8 or 9, wherein the a connection port in which advance all sets up a tunnel point-to-point connecting the base station. In the centralized tunnel setting step, for each external IP network, a tree-shaped point-to-multipoint tunnel connected to all the base stations with the connecting station as a vertex is further added and set in advance. The IP mobility control method according to any one of claims 8 to 10, characterized in that : In the centralized tunnel assignment step, a user ID for identifying the mobile terminal and a point-to-point tunnel identifier used by the mobile terminal are set in a base station and a connecting station that the mobile terminal has moved under, the base station and the connecting station determines the user ID from the packet received from the mobile terminal and the external IP network, from the claims 8 11, characterized in that forwarding by adding the set tunnel identifier packet The IP mobility control method according to any one of the above. In the centralized tunnel assignment step, multicast and broadcast packets received from the external IP network are assigned to the point-to-multipoint tunnel identifier for each external IP network set in the centralized tunnel setting step, and only to the connection station 13. The packet transmission is performed according to any one of claims 8 to 12 , wherein this is set, and the connecting station adds the tunnel identifier set to the multicast and broadcast packets received from the external IP network and forwards the packets. IP mobility control method. In the concentrated tunnel assignment step, a setting is made to enable a point-to-multipoint tunnel identifier assigned for an external network to which the user belongs to a base station to which the mobile terminal has moved. 14. The IP mobility control method according to claim 13 , wherein a packet having a point-to-multipoint tunnel identifier received from the access network side is forwarded to the mobile terminal side only when the identifier is valid.

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