JP3928443B2 - Mobile communication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile data communication system, and more particularly to a technique for maintaining a connection while a terminal is moving between networks.
[0002]
[Prior art]
With the spread of small and lightweight terminals such as notebook PCs and PDAs (Personal Digital Assistants) and the explosive spread of the Internet, an environment where terminals can be used outside the home or office has been improved and terminals have been used. Email and Internet access are becoming common.
In addition, VoIP (Voice over IP) that realizes voice communication by packetizing data obtained by digitizing analog sound information and sending it over an IP network, or ALL that communicates by placing all data in an IP frame in a mobile communication network IP networks are attracting attention.
[0003]
Generally, an IP network is configured by connecting a plurality of networks (called sub-networks) with different network numbers to each other, and the IP address group assigned to each sub-network is different for terminals connected to the sub-network. An IP address is given from a group of unique IP addresses assigned to each network. In general, packets transferred between sub-networks are forwarded based on a network number, and therefore a terminal needs to be assigned a different IP address each time it moves to another sub-network.
[0004]
When a terminal using IPv4, which is currently widely used as an Internet communication protocol, moves between sub-networks, the packet addressed to the IP address used in the sub-network before moving is the sub-network of the network number before moving. Therefore, the connection cannot be maintained by using the IP address used in the sub-network before moving in the sub-network having a different network number after moving.
[0005]
IPv6, which expands the address space to 128 bits, is becoming popular as an Internet communication protocol. In IPv6, it is called Mobile IPv6 (draft-ietf-mobileip-ipv6-13.txt), which makes it possible to continue the connection even if the terminal moves to another subnetwork to solve the above problem Technology has been proposed, and standardization is under discussion at the Internet Engineering Task Force (IETF).
[0006]
In Mobile IPv6, a terminal defines a subnetwork (called a home network) to which the terminal normally belongs in the subnetwork. A terminal is assigned a home address as an IP address used in the home network, and a home agent device (referred to as an HA device) having a function of managing location information of a terminal that uses the subnetwork as the home network is placed in the subnetwork.
[0007]
Each subnetwork is assigned a prefix of the IPv6 address as a prefix address. Each subnetwork is provided with at least one router called an advertising router. The advertising router advertises an advertisement including the prefix address of the subnetwork (called Router Advertisement) to the terminals in the subnetwork through the base station, and determines which prefix address the terminal has moved to or belongs to the subnetwork. Inform. Also, when there is a request for notification of information on a subnetwork currently belonging from a terminal in the subnetwork, a response is made by the advertisement.
[0008]
Each terminal obtains the prefix address of the current subnetwork from the above advertisement in the destination subnetwork, and assigns the address using the IPv6 auto configuration function or DHCP (Dynamic Host Configuration Protocol). Generate a care-of address that is temporarily used in the subnetwork.
The terminal notifies the generated care-of address to the HA device. After that, the HA device captures and encapsulates the IPv6 packet that reaches the home address of the terminal, sends it to the care-of address, and the terminal encapsulates the address that reaches the care-of address. Unencapsulate the received packet and receive the IPv6 packet that arrives at the home address.
[0009]
[Problems to be solved by the invention]
In this way, the HA device uses the Mobile IPv6 technology to forward packets that are addressed to the home address of the terminal's home network to the care-of address, so that the terminal can continuously receive packets addressed to the home address. It is possible to move while maintaining the connection with the communication partner.
[0010]
However, when the terminal moves to another subnetwork, it cannot detect that the terminal has moved to another subnetwork until it receives the prefix address of the subnetwork information transmitted from the advertising router in the destination subnetwork. Also, until a care-of address is generated and registered in the HA device, packets sent to the terminal via the HA device are not sent to the new care-of address.
[0011]
For this reason, movement between sub-networks occurs when data is actually flowing, such as when a terminal is moving at high speed or when movement (handoff) between base stations occurs frequently in a mobile network. If it happens frequently, packet loss occurs frequently. When packet loss occurs frequently, the communication quality deteriorates, such as throughput drops and sound is interrupted in VoIP.
[0012]
Accordingly, a further improved mobile data communication technique is required.
[0013]
[Means for Solving the Problems]
The present invention provides a mobile data communication technique capable of reducing packet loss even when a terminal moves at high speed or hands off a base station in a mobile network.
According to the present invention, it is possible to provide a system using the above-described technology and an HA device, an advertising router, a base station, a router, and a terminal device that constitute the system.
[0014]
The embodiment of the present invention will be specifically described.
When a cell can receive a radio wave from one base station, one or more cells form a subnetwork (102), and one or more subnetworks form a mobile network. And
The terminal according to the present invention includes a receiving unit capable of receiving radio waves from a plurality of base stations by using a radio communication technology such as CDMA (Code Division Multiple Access), and the advertising router is a base station in each subnetwork. It is possible to receive subnetwork information transmitted through the plurality of subnetworks.
When the terminal moves between cells belonging to different sub-networks, the sub-networks are different because the prefix addresses included in the plurality of sub-network information transmitted by the advertising router transmitted from the base station are different. It has a detection part which detects that it is moving between.
[0015]
When the terminal is close to the base station near the cell center, the radio wave from one base station is strong and the signal strength sufficient for data communication is obtained, so the subnetwork information transmitted from one base station is received, A care-of address generator for generating a care-of address to be registered in the HA device from the prefix address of the sub-network information is provided.
The HA device includes a transfer unit that receives a packet sent to the home address of the terminal on behalf of the terminal on the home network and transfers the packet to the care-of address.
The terminal receives the packet sent to the care-of address by the receiving unit, so that the terminal can receive the packet delivered to the home address even at the destination.
[0016]
When a terminal moves within a cell and reaches the vicinity of a cell boundary forming a different subnetwork, the terminal receives radio waves of other subnetwork information from other advertising routers by the base station forming the cell. And a plurality of pieces of subnetwork information can be received.
[0017]
It is assumed that the sub-network information transmitted through the base station is different for each sub-network or different for each base station.
Further, the subnetwork information includes routing address information that is an address necessary for a packet to be transferred to each subnetwork, in addition to a prefix address necessary for generating a care-of address.
A part of the routing address information of the adjacent base station or subnetwork is set according to a predetermined rule.
[0018]
When the terminal receives a plurality of different subnetwork information near the boundaries of a plurality of cells each belonging to a different subnetwork, the terminal converts the plurality of information into one information that can be later decomposed and identified according to a predetermined rule. It has a processing unit that synthesizes and registers the location with the care-of address in the HA device.
[0019]
More specifically, each bit of the predetermined portion of the routing address is assigned in advance to a different subnetwork. The base station or the sub-network transmits the predetermined portion with the assigned bit set to “1” and the other bits set to “0”.
A common prefix address is given to the routing addresses of several sub-networks, and the routers in the mobile communication network can recognize one address group to which these routing addresses belong by this common prefix address. Set to.
[0020]
When a terminal receives a plurality of subnetwork information from a plurality of base stations near a cell boundary, if the prefix addresses of the routing addresses are the same and 1 is set to different bits of the predetermined part, A processing unit that generates a logical sum (OR) of the routing addresses as a routing header address and registers it in the HA device together with the care-of address.
[0021]
One of the IPv6 extension headers is called a Routing Header. The Routing Header includes a list of addresses through which the packet passes on the route from the transmission source to the destination, and the transmission source sets the first address of the list as the Destination Address of the IPv6 packet and transmits it. When the packet reaches the first address in the list, the node sets the next address in the list in Destination Address and forwards the packet to the next relay point. When the relay node performs the above processing, the packet reaches the final address of the list.
[0022]
When a routing header address is registered together with a care-of address in the HA device, the HA device uses an IPv6 Routing Header so that the packet reaches the home address via the registered routing header address and care-of address. And a transfer processing unit that performs packet transfer.
[0023]
The router in the mobile communication network is used when the address set in the Destination Address part of the packet transferred from the HA device is one of the address groups to which the routing address belongs and the specific part of the predetermined part is specified. When only 1 bit is set to “1”, a transfer processing unit that performs normal routing is provided.
[0024]
In addition, the transfer processing unit, when the address set in the Destination Address is one of the address group to which the routing address belongs, and "1" is set in the plurality of bits of the predetermined portion Breaks down the packet so that “1” is set in any one bit of the predetermined portion, and checks whether it is necessary to route each from a different interface of the router. If necessary, the transfer processing unit disassembles the routing address, copies other parts, and routes from each interface.
As a result, when a handoff that moves to another sub-network occurs, the terminal is connected to a base station of another sub-network that is considered to be a destination in advance in addition to the base station that is currently communicating before the hand-off occurs. It becomes possible to route the addressed packet. For this reason, it is possible to receive a packet addressed to the terminal immediately after execution of handoff, and to reduce packet loss even at the time of handoff.
[0025]
Further, as another aspect, the advertising router in each subnetwork in the mobile communication network is the first subnetwork information (referred to as main subnetwork information) for transferring packets in the subnetwork to the subnetwork information In addition, the second or higher subnetwork address information (referred to as subsubnetwork information) may be transmitted.
In this case, if the terminal receives radio waves from one base station, the terminal generates a care-of address based on the main subnetwork information. If radio waves are received from a plurality of base stations and the prefix parts of the received sub-subnetwork information are equal, a care-of address is generated based on the prefix parts and registered in the HA device.
[0026]
The routing table of the router in the mobile communication network includes routing information so that packets having the prefix portion of the sub-subnetwork information are multicast-routed to each base station that transmits the sub-subnetwork information. You only have to set it.
The effect similar to the above can be obtained also by this aspect.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a configuration diagram of a mobile data communication system according to the present embodiment.
In FIG. 1, in order to manage the location of the terminal (105), the HA device (101) receives a location registration request from the terminal (105) and manages the location of the terminal, and the terminal (105) is connected to the home network (107). And a processing unit that captures and encapsulates the IP packet addressed to the terminal (105) and transfers it to the registered care-of address when it exists in another sub-network (102, 114, 116). Reference numeral (108) denotes a network management device, which performs maintenance / operation management of routers and base stations in the mobile data communication system and makes settings for the routers by the operation of the administrator.
[0028]
(106, 111) is a router, which transfers IP packets.
(103, 113, 115) is an advertising router, which is arranged in each sub-network (102, 114, 116) of the mobile communication network, and the terminal is located with respect to the terminal (105) that has moved to the sub-network (102, 114, 116). The sub-network information is advertised through the respective base stations (104, 112, 117). The base station (104, 112, 117) communicates with the terminal (105) in the cell (109, 118, 119) by radio. Each subnetwork may be composed of a plurality of cells. The router (106) may be an advertising router, or an advertising router may be installed in the base station.
The terminal (105) receives the subnetwork information included in the advertisement message of the advertisement router (103) through the base station (104), generates a care-of address and a routing address, and registers it in the HA device (101) have.
[0029]
(110) is an IP network such as the Internet connected to a mobile network.
[0030]
FIG. 2 shows an example of the configuration of sub-network information transmitted by the advertising router (103), which is transmitted using a kind of Router Advertisement Message of ICMPv6 packet shown in the technical document RFC2461 published by IFTF. .
In this embodiment, a router advertisement message (Router Advertisement Message) defined in RFC2461 is extended to notify a terminal of a routing address.
[0031]
(208) indicates the type of the ICMP message, and 134 in the case of an advertisement message. (203) is a part that stores information about the prefix address included in the subnetwork information in the Router Advertisement Message, and (211) is the upper bit length indicating the prefix part of the prefix address shown in (212). Yes. (204) is a portion obtained by extending the Router Advertisement Message according to the present embodiment, and stores information on the routing address.
(213) indicates that the option part of (204) is routing address information, (216) is an area in which the routing address is stored, and (215) is a high-order part indicating the prefix part of the routing address (216). Indicates the bit length. A plurality of routing addresses (216) may exist in one ICMP message.
[0032]
The terminal (105) stores the home address in the home network (107), knows the prefix address of the network to which it currently belongs by looking at the prefix address (212) in the Router Advertisement Message, and belongs to the home network. It is possible to know whether the subnetwork has been moved by comparing with the care-of address.
[0033]
As the routing address (216) transmitted from the advertising router (103) to the terminal (105) through the base station (104), for example, an address in which “1” is set only in one of the lower 64 bits is set. In a routing address transmitted from a base station (for example, (112)) forming cells belonging to different sub-networks, “1” is set to different bits.
[0034]
FIG. 3 shows a configuration example of the routing address shown in (216).
(301) indicates the prefix part of the routing address, and (302) indicates an Interface ID. In the interface ID (302), 1 is set to 1 bit allocated in advance and 0 is set to the other bits at the time of transmission from one base station (104). The advertising router (113) belonging to the other subnetwork (114) adjacent to the subnetwork (102) passes through the base station (112), and the prefix part (301) is equal, and 1 is different for each bit of the interface ID (302). The routing address that is set is being sent.
[0035]
An example of generating a routing address when the terminal (105) receives a plurality of pieces of subnetwork information is shown.
When the terminal (105) moves from the home network to the subnetwork (102) in the mobile communication network and receives the ICMP Router Advertisement Message including the subnetwork information from the advertising router (103) through the base station (104). Reference is made to the prefix address (212) included in the subnetwork information.
[0036]
The terminal (105) detects that the sub-network has moved because the prefix address (212) of the sub-network being visited is different from the prefix address of the home network held by the terminal (105).
[0037]
If the terminal (105) has received one type of the above ICMP Router Advertisement Message, Mobile IPv6 (draft-ietf-mobileip -ipv6-13.txt) to generate a mobile IPv6 care-of address and register it in the HA device (101) using the Mobile IPv6 Binding Update packet.
[0038]
The routing address (216) of the routing address information part (204) is composed of an upper prefix part (301) masked by the prefix length (215) and a lower Interface ID (302) excluding the prefix part. When the prefix length (215) is 64, the Interface ID is 128-64 = 64 bits, and 1 is set to any one bit as described above.
When the terminal (105) receives a plurality of ICMP Router Advertisement Messages with different prefix information (203) from a plurality of sub-networks (102) (114) through a plurality of base stations (104) (112), Select one of the prefix information used up to or received prefix information. Then, the care-of address is similarly generated from the selected prefix information and registered in the HA device (101).
Also, when the terminal (105) includes a plurality of routing addresses (216) having the same prefix part (301) and different Interface ID (302) in a plurality of received ICMP Router Advertisement Messages, the terminal (105) Select a routing address. Further, the logical sum of each selected routing address is calculated, and a routing header address in which “1” is set in a plurality of bits of the Interface ID (302) is generated and registered in the HA device (101).
[0039]
The function of the terminal (105) in each embodiment may be realized by the CPU executing a program stored in the memory in the terminal (105), or the hardware in the terminal (105). The program executed by the CPU may be realized by using hardware.
[0040]
The generation of the routing header address will be described in detail with reference to FIG.
4 (a) and 4 (b) illustrate the routing address information unit (204) in FIG. 2, and the terminal (105) can be accessed from both the base station (104) and the base station (112).
It is an example of routing address information (204) of each received ICMP Router Advertisement Message.
Since the prefix length (401) of the routing header information part received from the advertising router (103) in the subnetwork (102) through the base station (104) is 64 bits, the prefix part (402) of the routing address is 5EFF: 45DE: 7300: AB23 Similarly, since the prefix length (403) of the routing address information received from the advertising router (113) in the subnetwork (114) through the base station (112) is 64 bits, the prefix part (404) is 5EFF: 45DE: 7300: AB23 Therefore, the prefix part (402) and the prefix part (404) are equal.
[0041]
Further, the interface ID (405) of the routing address received from the advertising router (103) in the subnetwork (102) through the base station (104) is 0: 80: 0: 0, and the subnetwork through the base station (112) The interface ID (406) of the routing address received from the advertising router (113) in (114) is 0: 0: 0: 2.
[0042]
Therefore, the terminal (105) calculates the logical sum of the routing addresses received from the advertising router (103) in the sub-network (102) and the advertising router (113) in the sub-network (114), and FIG. As shown in c), the synthesized routing header address 5EFF: 45DE: 7300: AB23: 0000: 0000: 0080: 0002 is obtained, and this routing header address is registered in the HA device (101).
[0043]
In this embodiment, after the terminal (105) shown in Mobile IPv6 (draft-ietf-mobileip-ipv6-13.txt) moves from the home network (101), it moves from the destination subnetwork (102) to the HA device ( 101) extends the format of the Binding Update packet used when performing location registration.
[0044]
FIG. 5 illustrates an extended format.
[0045]
As specified in Mobile IPv6, the home address option part of the Binding Update packet stores the home address of the terminal (105) that sent this packet, and the source IPv6 address is stored in the destination subnetwork (102). A care-of address temporarily used by the terminal (105) is set.
(503) is a sub-option included in the option of the Binding Update packet, which is a part extended by the present embodiment to store the routing header address.
(513) indicates that the suboption stores the routing header address, (514) indicates the length of the suboption, and (515) indicates the prefix length of the routing header address shown in (516). , (516) indicate addresses to be added to the routing header when the HA device (101) captures and transfers a packet addressed to the home address of the terminal (105).
[0046]
By using the Binding Update packet shown in FIG. 5, the terminal (105) gives the HA device (101) a routing header address (516) in addition to the care-of address set in the source IPv6 address of the Binding Update packet. Register.
[0047]
FIG. 13 shows a hardware configuration example of the HA device or router. (1501) is a CPU, (1502) is a memory, (1503) (1504) and (1505) are network interfaces, and (1506) is a switch.
A CPU (1501), a memory (1502), and network interfaces (1503 to 1505) are connected to each other through a switch (1506). When the CPU (1501) operates as an HA device, the CPU (1501) operates according to the HA device program stored in the memory (1502), and sends the Binding Update packet from the mobile terminal (105) to the network interface (1503) to The location of the mobile terminal is managed by receiving at (1505).
[0048]
The memory (1502) stores a table (described later with reference to FIG. 6) for managing terminal location information, and is used for the source IPv6 address included in the BindingUpdate packet from the terminal (105). The table is created and updated based on the care-of address, the routing header address (516), and the home address stored in the home address option.
[0049]
When the terminal (105) is moving, an entry is created in the table of FIG. 6, and when the HA device (101) captures a packet addressed to the terminal (105), the captured packet is, for example, The CPU (1501) encapsulates and performs processing of transferring through the network interfaces (1503) to (1505) based on the location information for each terminal registered in FIG.
[0050]
FIG. 6 is a configuration example of the location management table of the terminal (105) provided in the HA device (101).
In FIG. 6, (601) is the home address in the home network (107) of the terminal (105), and (602) is temporarily used by the terminal (105) in the destination subnetwork (102) (114). (603) is a routing header generated based on the routing address (402) (405) (404) (406) included in the subnetwork information received by the terminal (105) in the destination subnetwork. Address.
(604) shows the validity period of the location management information of the terminal (105) held by the HA device (101), and the Binding Update packet is sent from the terminal (105) before the validity period expires If there is no entry and the entry is not updated, it is deleted.
[0051]
When the Binding Update packet shown in FIG. 5 is sent from the terminal (105) to the HA device (101), the HA device (101) extracts the home address of the terminal (105) from the home address option of the Binding Update packet ( 601), the care-of address used by the terminal (105) at the destination is extracted from the source IP address of the Binding Update packet and used for the (602) entry, and the routing header address (516) Is extracted and used for the entry of (603) to manage the location information of the terminal (105).
[0052]
When the HA device (101) is connected to the LAN, packets addressed to the home address (601) of the terminal (105) registered in the location management table shown in FIG. Use to capture. The captured packet is encapsulated and sent to a care-of address in the subnetwork where the terminal (105) exists. If the routing header address to the terminal (105) is also registered in the HA device (101), first set the routing header address as the destination address and use the IPv6 packet routing header function to Is set so that it is further forwarded to the care-of address at the destination.
[0053]
Next, the operation of the router in the mobile communication network will be described.
[0054]
The advertising router (103) enters the cell (109) through the base station (104), for example, 2001: 4555: 7300: AB23: 0000: 0000: 0000: 0000 as the prefix address (212) of the subnetwork (102), It is assumed that 5EFF: 45DE: 7300: AB23: 0000: 0000: 0080: 0000 as the routing address (216) and 64 as the prefix length (215) of the routing address are transmitted,
The advertising router (113) enters the cell (118) through the base station (112), for example, 2001: 0000: 3333: ABCD: 0000: 0000: 0000: 0000 as the prefix address (212) of the subnetwork (114), It is assumed that 5EFF: 45DE: 7300: AB23: 0000: 0000: 0000: 0002 as the routing address (216) and 64 as the prefix length (215) of the routing address are transmitted,
The advertising router (115) enters the cell (119) through the base station (117), for example, 2001: 0000: 3333: 5555: 0000: 0000: 0000: 0000 as the prefix address (212) of the subnetwork (116), It is assumed that 5EFF: 45DE: 7300: AB23: 0040: 0000: 0000: 0000 as the routing address (216) and 64 as the prefix length (215) of the routing address are transmitted.
[0055]
The boundary between the cell (109) formed by the base station (104) belonging to the subnetwork (102) and the cell (118) formed by the base station (112) belonging to the subnetwork (114). If the subnetwork information from both base stations (104) and (112) can be received in the vicinity, the terminal (105) and the routing address (402) (405) from the subnetwork (102) Assume that two routing addresses (404) and (406) are received from the subnetwork (114). If both routine addresses are masked with the prefix length 64 of the routing address, both prefix parts (402) and (404) are equal, so the logical sum of both is calculated and the routing address is 5EFF: 45DE: 7300: AB23: 0000 : 0000: 0080: 0002 is generated, and this routing header address is registered in the HA device (101).
[0056]
When the router is configured using the hardware configuration diagram shown in FIG. 13, the CPU (1501) operates according to the router program stored in the memory (1502). Packets received from the network interfaces (1503) to (1505) are temporarily stored in the memory (1502). The CPU (1502) searches the routing table or multicast routing table stored in the memory (1502) according to the packet destination address, determines the network interface that outputs the received packet, and determines the received packet. Send out from the interface. The CPU (1502) also executes other packet copy processing necessary for multicast routing.
[0057]
In the routing table stored in the router's memory (1502) in the Internet (110), packets with the same prefix as the prefix part of the above routing address will be sent to the router (111) as a gateway to the mobile network. Assume that it is set to be forwarded.
When the prefix of the destination address of the packet received from the HA device (101) matches the prefix part of the routing address and “1” is set in a plurality of bits of Interface ID, the router (106) Generates and transmits a packet having a destination address in which “1” is set for each bit of the Interface ID.
[0058]
Alternatively, the router (106), based on the multicast routing table as shown in FIG. 7, for the packet matching the prefix part determined from the destination address (901) and the prefix length (905) of the destination address, (902 ) (903) (904) The packet may be copied and transmitted to the destination shown in each interface column. In that case, the IP address of the receiving destination may be copied as it is, or an address in which “1” is set only in the bit indicating the sub-network to be transferred from each interface to the Interface ID. It may be set as.
[0059]
Each advertising router (103), (113), and (115) receives a packet with a routing header encapsulated and transferred from the HA device (101) to the mobile terminal (105), for example, the destination address shown in FIG. If it has the same prefix part as determined from (901) and the prefix length of the destination address (905), the routing header included in the packet is processed, the destination address is changed to the care-of address, and each base The base station sends it to the terminal (105) existing in the cell formed by itself.
[0060]
The operation when the terminal (105) hands off from the cell (109) in the subnetwork (102) to the cell (118) in the subnetwork (114) will be described with reference to FIG.
The terminal (105) first receives the subnetwork information from the advertising router (103) in the cell (109) served by the base station (104) (1001),
Location registration is performed by generating a care-of address and sending a Binding Update to the HA device (101) via the base station (103) (1002).
[0061]
When the HA device (101) receives the Binding Update, it returns a Binding Acknowledge of confirmation to the terminal (105) (1003),
Thereafter, the HA device (101) captures the packet addressed to the home address of the terminal (105) (1004),
The encapsulated data is transferred to the care-of address and delivered to the terminal (105) (1005) (1006).
[0062]
When the terminal (105) moves near the boundary between the cell (109) and the cell (118) and is ready to receive radio waves from both the base station (104) and the base station (112), the terminal (105) The sub-network information of the sub-network (102) sent from the advertising router (103) and the sub-network information of the sub-network (114) sent from the advertising router (113) are received (1007) (1008 )
[0063]
The terminal (105) examines the routing address in addition to the prefix address used to generate the care-of address, and performs an OR operation on each bit of the routing address received from both base stations in addition to the care-of address. The address is generated as a routing header address, and each is registered in the HA device (101) (1009).
[0064]
Upon receiving the Binding Update, the HA device (101) returns a Binding Acknowledge of confirmation to the terminal (105), and stores the routing address in addition to the care-of address. (1010)
After that, the HA device (101) captures the packet addressed to the terminal (105) (1011),
Encapsulate. The encapsulated packet is sent to the routing address first, then to the care-of address, so that the destination address is the above-mentioned routing header address generated by the terminal (105), and the routing header is A care-of address is set and transferred (1012).
[0065]
When a packet in which a routing address prefix is set as a destination address is transferred to the router (106) in the mobile communication network, the packet is sent to an address in which the interface ID of the packet is set bit by bit. The packet is copied and transmitted. (1013) (1016)
The advertising router (103) (113) that is sending the routing address processes the routing header when the above-mentioned copied packet is sent, sets the care-of address to the destination address, (1014) (1017) sent to base station (104) (112)
The base station (104) (112) sends the packet to the terminal (105) (1015) (1018).
[0066]
Therefore, before the terminal (105) starts handoff to the cell (118), the packet can be transferred in advance to the cell (118) considered to be the handoff destination. In addition, the terminal (105) can receive a packet addressed to the care-of address before and after the movement, thereby realizing a handoff with less packet loss.
[0067]
If the terminal (105) moves further and can only receive radio waves from the base station (112) (1019),
The terminal (105) generates a care-of address based only on the subnetwork information of the subnetwork (114) received from the advertising router (113) through the base station (112) to the HA device (101), and binds the HA device to the HA device with Binding Update. Register location (1020),
The HA device (101) returns a location registration confirmation (1021) to the terminal (105) by Binding Acknowledge.
[0068]
Thereafter, the HA device (101) captures the packet addressed to the terminal (105) (1022),
It is encapsulated, transferred to the care-of address, and delivered to the terminal (105) (1023) (1024).
[0069]
Next, as another embodiment, an example will be described in which a part of the prefix address included in the subnetwork information transmitted from the advertising router (103) of FIG. 1 through the base station (104) is used as the subnetwork instruction unit. According to this embodiment, it is not necessary to newly provide a field for the subnetwork instruction section as in the first embodiment.
[0070]
FIG. 9 is a configuration example of prefix information sent by the advertising router.
The lower 64 bits are the interface ID (1103) of the advertising router. The upper 64 bits are the prefix part (1101), and for example, the lower 16 bits of the prefix part are used as the subnetwork instruction part (1102).
[0071]
When the terminal receives the subnetwork information included in the Router Advertisement Message transmitted by the advertising router, the terminal can know the prefix of the subnetwork to which the terminal belongs from the prefix address and the prefix length (211).
[0072]
A care-of address generation method when the terminal (1205) receives subnetwork information included in the advertisement message transmitted by the advertisement router from a plurality of base stations will be described with reference to FIG.
In this embodiment, the lower 16 bits of the prefix part (1101) is the subnetwork instruction part (1102), and the terminal (1205) knows its position in advance or can know it from information from the advertising router. And
[0073]
The terminal (1205) holds 3EF0: 35FA: 7823: AB76: 0080: 35FF: FEBC: 12E8 as the home address in the home network, and the lower 64 bits of the terminal are uniquely assigned to each terminal as an Interface ID. , And used when generating a care-of address in the destination network.
[0074]
The terminal (1205) receives the first advertisement message (1206) transmitted from the advertisement router (103) through the base station (104) at the destination and receives the prefix address and prefix length of the prefix information in the first advertisement message (1206). 5EFF: 45DE: 7300: 0040: 0000: 0000: 0000: 0000 is generated as a first care-of address prefix from the field.
[0075]
Similarly, the terminal (1205) receives the second advertisement message (1207) transmitted by the advertisement router (113) through the base station (112), and includes the prefix address and prefix length fields of the prefix information therein. To 5EFF: 45DE: 7300: 0001: 0000: 0000: 0000: 0000 as a second care-of address prefix.
[0076]
The terminal (1205) compares the two, and when the prefix 5EFF: 45DE: 7300 excluding the subnetwork directive matches, performs the logical OR operation of both prefixes, and combines 5EFF: 45DE: 7300: 0041: Let 0000: 0000: 0000: 0000 be a prefix indicating two subnetworks.
[0077]
Further, the terminal (1205) uses the IPv6 Auto Configuration function, and uses the synthesized prefix and the interface ID uniquely assigned to the terminal (1205) as the care-of address (1211), and 5EFF: 45DE : 7300: 0041: 0080: 35FF: FEBC: 12E8 is generated and registered in the HA device (101).
[0078]
The operation of this embodiment will be described with reference to FIG.
The router (106) that forwards the packet in the mobile communication network creates a routing table based on the routing information received from the other router by the router (106) and the routing information of the own router, and the routing information between the other routers. Replace.
When the router (106) has its own router or the routing information received from another router, and the part of the prefix address of the subnetwork information advertised by the advertising router excluding the subnetwork instruction part, A processing unit is provided for adding a logical sum operation result of prefix addresses of a plurality of matching subnetwork information to the routing table.
[0079]
In the routing table of each router (106) in the mobile communication network, a packet in which a plurality of bits in the subnetwork instruction part of the destination address is set to “1”, and any one bit in the subnetwork instruction part is “ The IP address set to “1” is set to be transferred to the advertising router that advertises as the prefix part (1101).
[0080]
When an IP packet (1208) addressed to the terminal (1205) in which a plurality of bits in the subnetwork instruction section (1102) of the destination address is set to “1” is sent to the router (106), the router (106) The unit (1102) generates a plurality of packets having a prefix set to “1” bit by bit and transmits the packets to the corresponding subnetwork (1209) (1210).
[0081]
At this time, if the next-hop routers match for a plurality of packets, that is, for a plurality of packets whose next transfer destination is the same router, one copied packet is transmitted. In this state, the terminal (105) has a packet in which only one bit is set to “1” as a care-of address, in addition to the one in which a plurality of bits of the subnetwork instruction unit (1102) are set to “1”. It is set so that it can be received (1211).
[0082]
As described above, when the terminal (1205) becomes ready to receive radio waves from the plurality of base stations (104) (112) near the boundary of the subnetwork (102) (114), the terminal (1205) becomes a destination before the handoff occurs. Packets can be routed to base stations in other possible sub-networks. Therefore, it is possible to receive a packet addressed to the terminal (1205) immediately after the occurrence of handoff, and it is possible to execute a handoff with little packet loss.
[0083]
FIG. 11 shows an operation when the terminal receives the subnetwork information from the base station.
When the terminal receives the subnetwork information from the advertising router via the base station, it stores this (1301),
Compare prefix addresses obtained from multiple subnetwork information received in a certain time (1302)
If the subnetwork instruction units are different, an OR operation is performed and this is used as a prefix address to generate a care-of address (1303).
[0084]
Check whether the generated care-of address is different from the one registered last time (1304),
Check if the lifetime has expired since the last registration (1305)
When it corresponds to either one, a Binding Update is transmitted to the HA device to perform location registration (1306).
[0085]
FIG. 12 shows the operation when the router device (106) receives a packet addressed to a care-of address or having a routing address.
When the router receives a packet for transfer within the mobile communication network (1401),
Check the destination IP address in the packet and if it matches the prefix part used in the care-of address (1403),
Check whether multiple bits are set in the subnetwork directive (1404)
If only 1 bit is set, normal transfer processing is performed (1409).
[0086]
When multiple bits are set, the address of the subnetwork indicator is disassembled into addresses set for each matching bit (1407)
Copy the packet for each interface that has a matching prefix in the routing table (1408),
The packet is transmitted (1409).
[0087]
【The invention's effect】
According to the present invention, it is possible to route packets to a handoff destination base station in advance before handoff is performed, and to reduce packet loss during handoff.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a mobile communication network using the present embodiment.
FIG. 2 is a packet format example for advertising subnetwork information.
FIG. 3 is a configuration example of a routing address using the present embodiment.
FIG. 4 is an example of generation of a routing header address using the present embodiment.
FIG. 5 is a configuration example of a location registration packet.
FIG. 6 is a configuration example of a location management table in the HA device.
FIG. 7 is a configuration example of a multicast routing table in a router.
FIG. 8 is a sequence diagram when the terminal performs handoff.
FIG. 9 is a configuration example of prefix information in another embodiment.
FIG. 10 is a diagram for explaining the operation of another embodiment.
FIG. 11 is a flowchart when the terminal performs location registration.
FIG. 12 is a flowchart when a router transfers a packet.
FIG. 13 is a configuration example of an HA device and a router.
[Explanation of symbols]
101 ... HA equipment, 102, 114, 116 ... Subnetwork, 103, 113, 115 ... Advertising router, 104, 112, 117 ... Base station, 105 ... Terminal, 106 ... Router, 107 ... Home network, 108 ... Network management device, 109, 114, 119 ... Cell, 110 ... Internet 204 ... ICMPv6 routing address Option part, 301 ... Routing address prefix part, 302 ... Interface ID, 401 ... Prefix length, 402 ... Prefix part, 403 ... Interface ID, 503 ... IPv6 Binding Update Routing header address suboption extension part, 601 ... Home address, 602 ... Care-of address, 603 ... routing header address, 604 ... lifetime, 901 ... destination address, 902 ... first transmission interface, 903 ... second transmission interface, 904 ... third transmission interface, 905 ... prefix length, 1101 ... prefix part 1102 ... Subnetwork instruction unit, 1103 ... Interface ID, 1206 Subnetwork information, 1207 ... subnetwork information, 1208 ... IP packet, 1209 ... copied IP packet, 1210 ... copied IP packet, 1211 ... can receive the care of address.

Claims (8)

A terminal having means for receiving radio waves from a plurality of base stations; a home network to which the terminal belongs; a plurality of sub-networks to which the terminal is moved;
In each subnetwork, an advertising router that advertises information of the subnetwork to the terminal via the base station;
Means for managing the location information of the terminal and registering a routing address which is an address temporarily used in a movement destination sub-network of the terminal; and when the terminal is moved and the routing address is registered, A home agent device comprising: means for capturing a packet addressed to the terminal that has arrived at a home address that is a destination in the home network of the terminal, and transferring the packet to the destination subnetwork according to the registered routing address Prepared,
The advertising router includes means for advertising the interface ID and prefix portion of the routing address from the base station as the subnetwork information,
When the terminal moves to the subnetwork and receives a plurality of routing addresses having the same prefix part and different interface IDs, the terminal combines the plurality of routing addresses into one routing header address, A mobile communication system comprising means for registering with the home agent device. The mobile communication system according to claim 1, wherein
A different bit is assigned to the Interface ID for each subnetwork,
The advertising router includes means for transmitting the subnetwork information including a routing address in which a bit assigned to each subnetwork is set to “1”.
The terminal calculates a logical sum of the interface IDs of the routing addresses included in the received plurality of subnetwork information when the prefix portions of the routing addresses included in the received plurality of subnetwork information match, and calculates A mobile communication system comprising means for setting a result as the synthesized routing header address. The mobile communication system according to claim 2, wherein
The home agent device
Means for storing a combination of the care-of address sent from the terminal, the routing header address, and the home address of the terminal;
Means for setting the care-of address as a routing header address of a packet sent to the home address of the terminal;
Means for encapsulating a packet in which the care-of address is set, and setting the routing header address as a destination address;
A mobile communication system comprising means for sending the encapsulated packet. The mobile communication system according to claim 1, wherein
The router in the mobile communication network is
A packet in which the routing header address received from the home agent device is set as a destination address, and one bit of the Interface ID is “1” from a packet in which “1” is set in a plurality of bits of the Interface ID. Means to generate and send a packet with a recipient address set to, or
The advertisement that advertises an address in which any one bit of the Interface ID is set to “1” for a packet having the same prefix as the routing address of the subnetwork information advertised by the advertising router. A mobile communication system comprising a routing table configured to be transferred to a router. The mobile communication system according to claim 1, wherein
A part of the prefix part of the subnetwork information advertised by the advertising router is used as a subnetwork instruction bit, and a different bit is assigned to each subnetwork.
The base station in the sub-network comprises means for transmitting sub-network information with the assigned bit set to “1”,
The terminal calculates a logical sum of the prefix portions of the received plurality of subnetwork information when the portions of the received prefix portions of the plurality of subnetwork information match the portion excluding the subnetwork instruction bit portion. A means for generating a care-of address with the operation result as a prefix part and registering it with the home agent device is provided
When a plurality of subnetwork instruction bits of a destination address of a packet to be transferred are set to “1”, a router in the mobile communication network sets any one bit of the subnetwork instruction unit to “1”. A mobile communication system comprising a routing table that is set to be transferred to an advertising router that advertises a set address as a prefix part of subnetwork information. The mobile communication system according to claim 1, wherein
A plurality of routers for transferring the packets in the mobile communication network;
The advertising router in each subnetwork comprises means for advertising main subnetwork information for forwarding packets into the subnetwork and subnetwork information including subsubnetwork information,
When the terminal receives the subnetwork information from one base station, the terminal receives the subnetwork information from a plurality of base stations and means for generating a care-of address based on the main subnetwork information. Means for generating a care-of address based on the prefix part, and means for transmitting the generated care-of address to the home agent device if the prefix parts of the plurality of sub-subnetwork information received are equal. With
The router that forwards the packet includes a routing table that is set so that a packet having a prefix portion of the sub-subnetwork information is multicast-routed to each base station that is transmitting the sub-subnetwork information. Body communication system. The mobile communication system according to claim 4 or claim 5 or claim 6,
A mobile communication system, wherein the terminal includes means for receiving and processing packets addressed to a plurality of care-of addresses. The mobile communication system according to claim 5 is:
A plurality of routers for transferring the packets in the mobile communication network;
Any of the routers creates a routing table based on the routing information received from other routers and the routing information of its own router, and exchanges routing information between other routers;
If the routing information of the own router or received from other routers matches the part of the subnetwork information advertised by the advertising router excluding the subnetwork instruction part, the matching multiple A mobile communication system comprising means for adding a logical sum calculation result of the prefix part of the subnetwork information to the routing table.

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