JP4532311B2 - Mobile communication control apparatus, mobile communication control system and method - Google Patents

Description

  The present invention relates generally to a mobile communication control apparatus, a mobile communication control system, and a method for realizing high-speed and seamless HO when an object having a communication function is handed over (HO) in an IP mobility environment. Is.

  Today, so-called n-casting is attracting attention as a method for realizing high-speed HO in mobile IPv6. In this method, a packet addressed to a mobile terminal (MN) is copied at a certain point and transferred to the current location of the MN and an access router (AR) as a destination candidate. As an implementation method of n-casting, an n-casting method that extends FMIP (Fast Handovers for Mobile IPv6) as disclosed in Non-Patent Documents 1 and 2 has also been proposed.

  That is, in this method, as shown in FIG. 5, when the MN 100 notifies the PAR (Previous Access Router) 101 of FBU (Fast Binding Update) to inform that it will move soon (# 100), the PAR 101 Exchanges messages for tunneling with a destination access candidate NAR (New Access Router) 102. That is, since the MN 100 includes the address to be used next in the FBU and notifies the PAR 101, the PAR 101 notifies the NAR 102 of the HI (Handover Initiate) (movement destination care-of address (CoA) notification) including the address (# 101). The NAR 102 creates an entry for the destination CoA (# 102), and notifies the PAR 101 of a HACK (Handover Acknowledgment) (movement destination CoAOK) indicating that the creation is completed (# 103). When receiving this HACK, the PAR 101 notifies the MN 100 of FBACK (Fast Binding Acknowledgment) (movement destination CoA confirmation notification) (# 104). Thereafter, the packet is transmitted to the current CoA in PAR 101 also to MN 100, but is tunneled from PAR 101 to NAR 102 to the destination CoA (# 105), and MN 100 moves the tunneled packet to NAR 102. Buffering is performed until it is done (# 106). When receiving an FNA (Fast Neighbor Advertisement) notifying that the mobile station has moved from the moved MN 100 (# 107), the NAR 102 sends the buffered packet and the packet sent thereafter to the MN 100. Transfer (# 108).

    In this example, the packet is duplicated and transferred from the PAR 101. However, the packet may be duplicated and transferred from a HA (Home Agent) or a MAP (Mobility Anchor Point) having a home agent function in the hierarchical mobile IP. Yes.

  On the other hand, as an existing technology of the same kind as this, in Patent Document 1, the HA and the communication partner manage a plurality of CoAs and transfer duplicate packets to the MN, thereby reducing the IP packet loss and reducing the processing load of the MN. Techniques to do this are disclosed. Further, in Patent Document 2, when the MN exists over at least two areas, the dynamic addresses MA1 and MA2 are notified to the management server in real time, and the management server sends a packet from the host to the MN. A mobile communication system is disclosed in which, when dynamic addresses MA1 and MA2 are assigned, packets are transferred using these dynamic addresses as headers.

EI Malki, Hesham Soliman, “Simultaneous Bindings for Mobile IPv6 Fast Handoffs”, draft-elmalki-mobileip-bicasting-v6-0.5.txt ”, Oct 2003. Robert Hsieh, Zhe Guang Zhou, and Seneviratne, “S-MIP: A Seamless Handoff Architecture for Mobile IP.”, In Proceedings of INFOCOM, San Francisco, USA, 2003. JP 2004-228754 A JP 2002-084562 A

  However, in the n-casting method in which FMIPs described in Non-Patent Documents 1 and 2 are extended, high-speed HO cannot be realized unless the MN transmits a connection notification message to the NAR immediately after moving. Furthermore, when HA or MAP (Mobility Anchor Point) is the base point of n-casting, the HO delay time at the destination AR (NAR: New Access Router) is simply transferred to the destination CoA candidate. High-speed HO cannot be realized because it depends on the generation timing of the Neighbor Cache (NC).

  The same kind of problem exists in the techniques disclosed in Patent Documents 1 and 2 above. That is, in the techniques according to Patent Documents 1 and 2 described above, the NC is not generated simply by copying and forwarding the packet to the destination address, or the state of the NC can be transmitted from the link. Since it is not established as a state, the packet is discarded by the AR. Furthermore, when buffering is performed using a destination candidate, it is necessary to notify the AR of the fact after the terminal detects the movement.

  Here, with reference to FIG. 6 and FIG. 7, the reason why the packet does not reach the MN 100 simply by sending a packet to the destination candidate address (movement destination CoA) will be described in detail.

  In the above prior art, even if n-casting is performed, the NAR 102 cannot immediately create an NC entry, and the NAR 102 discards the packet addressed to the destination CoA. However, in order to create an NC by the NAR 102, it is necessary for the NAR 102 to receive an NA (Neighbor Advertisement) for NS (Neighbor Solicitation) and to resolve the MAC address of the destination CoA. While the packet addressed to the destination CoA is broadcast, the NAR 102 issues NS to resolve the address, but it does not continue to issue NS for all packets addressed to the destination CoA. , RETRANS_TIMER (default is 1 s) every predetermined interval. Therefore, as shown in FIG. 6, when the MN 100 detects its movement after the first NS is issued from the NAR 102 until the next NS is issued, an NC entry is generated and the packet is transferred. There is a problem that there is a delay before starting. In other words, since the MN 100 can return the NA for the NS after the end of the movement detection, a delay occurs in the time when the packet addressed to the destination CoA can be received depending on the timing when the NS is issued and the timing of the movement detection. It will end up.

  This problem is further complicated if the address generation process is not completed as shown in FIG. IPv6 has an automatic address generation function. RA (Router Advertisement) advertises the address of the new router, network prefix, etc. When the MN 100 detects its movement due to the change of the RA network prefix, the destination CoA that the MN 100 will use in the future is duplicated by NS. Check if it is not. If there is no response for a predetermined time (RETRANS_TIMER: 1 s by default), it can be confirmed that there is no duplication (address generation complete). Thereafter, it is possible to respond to the NS for address resolution from the NAR. After the response, the NC entry creation is completed, and communication can be performed for the first time. As described above, in IPv6, an address automatic generation step is entered, and further delay occurs.

  The object of the present invention is to detect movement of a mobile terminal by allowing a mobile terminal to receive a packet addressed to a destination CoA immediately after the mobile terminal moves under the control of a new access router. The purpose is to realize high-speed handover regardless of accuracy. In addition, since the packet addressed to the destination CoA can be received without considering the movement timing of the mobile terminal, a low-delay handover can be realized.

In order to achieve the above object, according to a first aspect of the present invention, there are provided first and second access routers capable of communicating with a mobile terminal, wherein the first access router includes a first care-of address. A notification is transmitted to the second access router, and when the second access router receives the first notification, it generates a cache entry for the new care-of address , activates the generated cache entry, Is transmitted to the first access router, and when the first access router receives the second notification from the second access router , it transmits a third notification to the mobile terminal. Upon receiving the third notification, it establishes a state where it can receive n-casting packets from the first access router and the second access router. Establishing a second access router and the link is a mobile communication control system, characterized in that to start the second access router and packet communication.

  According to a second aspect of the present invention, in the first aspect, the first access router holds a peripheral AR table related to a peripheral access router, and refers to the peripheral AR table to move the mobile terminal to a destination. There is provided a mobile communication control system further characterized by determining a candidate second access router.

  In a third aspect of the present invention, in the second aspect, the first access router manages the interface information of the access router in the peripheral AR table and receives the interface information held by the mobile terminal from the mobile terminal. In this case, the interface information of the access router is compared with the interface information held by the received mobile terminal, and the first interface information desired to be used for the access router that matches the interface information held by the mobile terminal is added. There is provided a mobile communication control system further characterized by transmitting a notification to the second access router.

According to a fourth aspect of the present invention, there is provided a method using first and second access routers capable of communicating with a mobile terminal, wherein the first access router sends a first notification including a new care-of address. When the second access router receives the first notification, it generates a cache entry for the new care-of address , activates the generated cache entry, and sends the second notification to the second notification router. The first access router transmits a third notification to the mobile terminal when the first access router receives the second notification from the second access router, and the mobile terminal transmits the third notification to the third access router . Upon receiving the notification, to establish a state capable of receiving packets of n-casting method from the first access router and said second access router, the second action Establishing a Suruta link, to start the second access router and packet communication, the mobile communication control method, characterized in that a.

  Therefore, according to the present invention, after the mobile terminal moves under the control of the new access router, the packet addressed to the destination CoA arrives immediately and the mobile terminal can receive it immediately. Regardless of this, it is possible to provide a mobile communication control apparatus, a mobile communication control system, and a method that realize high-speed handover.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a basic conceptual diagram of a mobile communication control system according to a first embodiment of the present invention.

  As shown in the figure, in this system, an access router (PAR; Previous Access Router) 1 before movement, an access router (NAR; New Access Router) 2 as a movement destination candidate, and a mobile terminal (MN; Mobile Node) ) 3 can communicate freely. When n-casting is started, PAR1 transfers the packet addressed to the current CoA that is the current transfer destination, and transmits the packet addressed to the destination CoA to the destination candidate NAR2 of MN3. And MN3 starts reception immediately after link establishment.

  More specifically, the NAR 2 in the n-casting range generates an NC (Neighbor Cache) entry before the start of n-casting, so that packets can be transmitted to the new link by the n-casting method. . Further, the MN 3 holds the destination CoA within the n-casting range before the start of n-casting. Normally, the MN 3 is set so as to receive only packets addressed to one CoA. Since one CoA is a CoA currently used, packets addressed to the destination CoA cannot be received. However, since this method is set so as to be able to receive packets addressed to all the destination CoAs (the destination CoA is established even if a trigger is not issued after the move since the receivable state at the destination CoA is established). The packet addressed can be received.

  Hereinafter, the processing sequence of the mobile communication control system according to the first embodiment of the present invention will be described in detail with reference to the flowchart of FIG.

  This also corresponds to the mobile communication control method according to the first embodiment.

  When entering this processing sequence, first, MN 3 transmits RtSolPr (Router Solicitation for Proxy) to PAR 1 (# 1). This RtSolPr is for inquiring the IP address of NAR2 from the link address of the access point (AP) from which MN3 can receive radio waves. The PAR 1 holds a correspondence between the link address of the access point and the IP address of the AR that accommodates the access point as a table. When PAR1 receives this RtSolPr, it refers to the above table, identifies the IP address of NAR2 as the MN3 destination candidate from the link address of the access point, and notifies PrRtAdv (Proxy Router Advertisement) to MN3 (# 2 ). When receiving this RrRtAdv, the MN 3 transmits an FBU (Fast Binding Update) indicating movement to the PAR 1 (# 3).

  The above is a message sequence defined by FMIP that inquires about the destination destination NAR2 and generates an address (movement destination CoA) in the destination destination NAR2. In general FMIP, the timing for issuing an FBU is important. However, the timing is not particularly important if the FBU can be issued before HO as in the first embodiment.

  Subsequently, PAR1 transmits HI (Handover Initiate) to NAR2 (# 4). Here, when there are a plurality of destination candidates, there is a method of transmitting HI to each NAR candidate.

  The NAR 2 that has received this HI generates a “reachable” NC for the destination CoA. In this example, the NC includes at least a unicast address (destination CoA), a link layer address (MN3 MAC address), a flag indicating whether it is a router or a host (host), an NC state (Reachable), and an interface (Ethernet (Registered trademark) etc.).

  The unicast address of NC (movement destination CoA) and the link layer address of MN are notified from PAR1 to NAR2 by HI. The NAR 2 uses the link layer address of the destination CoA and MN notified from the PAR by the HI, further sets a flag indicating the host, and generates an NC entry with the NC state as Reachable.

  Along with the generation of the NC, the NAR 2 secures the destination CoA. Here, securing the destination CoA means responding when a duplicate address detection (Duplicate Address Detection) is performed so that a different terminal does not use the destination CoA (an NS for the address is issued from another terminal). (Neighbor Advertisement) (# 5).

  When the above processing is completed, the NAR 2 returns a Hack (Handover Acknowledge) to the PAR 1 (# 6). When PAR1 receives this HAck, it sends Fback (Fast Binding Acknowledgment) to MN3 (# 7). Upon receiving this FBack, the MN 3 establishes a receivable state, and after that, n-casting is performed, and after establishing a link with the NAR 2, a packet addressed to the destination CoA can be received immediately. (# 8, # 9). After the MN 3 moves, the NAR 2 stops securing the destination CoA after receiving an FNA (Fast Neighbor Advertisement) (# 10, # 11). Thus, a series of processing sequences is completed.

  If PAR1 holds a peripheral AR table, NAR2 can be determined with reference to the table. In that case, it is necessary to notify the MN 3 of the destination address (destination CoA) by PrRtAdv or FBack described above. When PAR1 determines NAR2 by referring to the neighboring AR table, when there are a plurality of candidates for the destination CoA, MN3 sends all FBU messages for NAR2 that manage the candidate destination CoA to PAR1. There is no need to send it out, and it is only necessary to send one FBU message to PAR1, so that control traffic can be reduced. An AR that accommodates an access point that cannot receive radio waves can also be a destination candidate.

  Here, an NC interface instruction method will be described.

  Since RtSolPr is a message for inquiring about the address of NAR2 from the link address that can be received, the type of interface held by NAR2 may be registered in the NC even if not specified. On the other hand, as described above, PAR1 holds the peripheral AR table, and when NAR2 is specified by referring to the table, the interface information held by MN3 is added to FBU, and PAR1 is stored in the AR table. It is only necessary to manage the interface information of the AR together and transmit the HI to which the interface information desired to be used is added to the AR matching the interface information held by the MN 3.

  As described above, in the mobile communication control system and method according to the first embodiment, the n-casting packet addressed to the destination CoA is transferred to the new link as it is without being buffered by the NAR2. MN3 can receive the packet addressed to the destination CoA immediately after establishing the link with NAR2. To realize this method, it is necessary to add two new functions to the existing n-casting. The first function is to generate an NC for MN3 in NAR2 at an early stage in order to transfer an n-casting packet to a new link. The second function is directed to the destination CoA regardless of whether MN3 detects movement. It is a function to receive the packet of unconditionally. This first function can be realized by generating the NC for MN 3 as the state “REACHABLE” after the NAR 2 receives the HI from the PAR 1. And this 2nd function is realizable because MN3 has the state which receives the packet addressed to movement destination CoA after receiving FBack from PAR1. Because of the realization of these functions, this proposed method allows the packet addressed to the destination CoA to arrive immediately after the MN moves under the control of the new access router, and the MN can receive it immediately. High-speed HO can be performed. Furthermore, since the packet addressed to the destination CoA can be received without considering the timing of movement of the mobile terminal, a low-delay handover can be realized.

  In the above embodiment, one NAR2 is written, but the present invention can be applied to the case where there are two or more NAR2. In that case, the MN 3 transmits a plurality of FBUs (corresponding to the number of NAR2), or the PAR refers to the peripheral AR table and transmits the HI to the plurality of NAR2.

  In the above embodiment, packets are branched from PAR1, but the role of PAR1 is handled by HA (Home Agent) or MAP (Mobility Anchor Point) with home agent function in hierarchical mobile IP. Also good.

(Second embodiment)
Next, FIG. 3 is a conceptual diagram of a mobile communication control device and a mobile communication control system according to the second embodiment of the present invention. In the present embodiment, the mobile communication control device corresponds to a mobility control device, and details will be described later. As shown in FIG. 3, the mobile communication network 16 is provided with a plurality of routing devices 13a to 13e. Among these routing devices 13a to 13e, in particular, 13b to 13d correspond to access routers (AR). The MN 12 can communicate with a communication partner terminal (CN) via the routing devices 13a to 13e. Hereinafter, the reference numeral 13 is used to collectively refer to the routing devices 13a to 13e.

  Among these routing devices 13a to 13e, the duplication / transfer device 13a having a function of duplicating and forwarding the packet from the MN 3 has network location information and geographical location information by the mobility control device 15 as a management device together with the duplication / transfer range. Is determined dynamically in consideration of In FIG. 3, there is one copy transfer apparatus 13a, but there may be a plurality of copy transfer apparatuses. This mobile communication control system includes at least a mobility control device 15, a copy transfer device 13a, and access routers 13b to 13d.

  The mobility control device 15 does not need to be a single physical device, and may be configured by a plurality of device groups as long as it is established as a logical mobility control plane. By configuring the mobility control device 15 in the mobility control plane, one function can be efficiently realized as a whole without being aware of the physical medium arrangement. In other words, even when distributed to a plurality of physical device groups, the device groups operate as a single unit, thereby exhibiting the same function as when one physical device is provided with all.

  Here, the detailed configuration of the mobility control device 15 is as shown in FIG.

  That is, as shown in FIG. 4, the mobility control device 15 includes a collection function 15a, a distribution function 15b, an optimum area formation function 15c, an area database (hereinafter abbreviated as DB) 15d, a network location information DB 15e, a geography A location information DB 15f, an MN interface DB 15g, and an AR interface DB 15h.

  In such a configuration, the collection function 15a collects information necessary for optimal area formation by the optimal area formation function 15c from the MN 12 and the routing device 13. That is, the collection function 15a receives, for example, an optimum area formation request from the MN 12. The network location information DB 15e stores information related to the network location relationship and network topology of devices related to Mobile IP such as the routing device 13 and the mobility control device 15 in the network, and the geographic location information DB 15f stores the routing device 13 ( (In some cases, only AR) is stored.

  The MN interface DB 15g stores the identifier of the MN 12 (home address or NAI (Network Address Identifier)), the interface possessed by the MN 12, its MAC address, and optionally the priority of interface use. ing. The AR interface DB 15h stores an AR identifier (IP address), an owned interface, its MAC address, and a network prefix in association with each other.

  It is assumed that the network location information DB 15e, the geographical location information DB 15f, the MN interface DB 15g, and the AR interface DB 15h exist in advance.

  The optimum area forming function 15c refers to the network location information DB 15e and the geographic location information DB 15f, and determines which range (network) is to be n-casted via which replication transfer device 13a. In addition, when the replication transfer device 13a for efficiently performing replication transfer range and replication transfer suitable for the situation (current location, movement characteristics, communication characteristics, etc.) of the MN 12 is obtained and stored in the area DB 15d in advance. First, the replication transfer range and the replication transfer device 13a are determined by referring to the area DB 15d. Information including information on the determined copy transfer range and copy transfer device 13a is referred to as "optimal area information". The distribution function 16 notifies the routing device 13 that should notify the optimum area information.

  Further, NC interface information is determined with reference to the MN interface DB 15g and the AR interface DB 15h.

  Hereinafter, the processing sequence by the mobile communication control system according to the second embodiment of the present invention will be described in detail with reference to FIG. 3 and FIG. This processing sequence also corresponds to the mobile communication control method according to the second embodiment of the present invention.

  When the MN 12 determines that n-casting is necessary from its own state (# 11), it requests n-casting to the collection function 15a of the mobility control device 15 (# 12). This n-casting request is issued when the AR 13 detects a high-speed movement of the MN 12 and sends it to the mobility control device 15, or the mobility control device 15 (for example, HA) manages the state of the MN 12 together, and the mobility control device 15 There is a case where a request is issued (for example, when the CoA of the MN 12 is changed) or a request is issued from the CN when the communication from the CN 11 (communication partner terminal) is started.

  When the mobility control device 15 receives this n-casting request, the optimum area forming function 15c refers to the network location information DB 15e and the geographic location information DB 15f, and to which copy transfer range (network), which copy transfer device. It is determined whether n-casting is performed via 13a (# 13). Next, the mobility control device 15 instructs the AR 13 in the replication transfer range 14 to create an NC (Reachable) for the MN 12 and secure the destination CoA (# 14). Specifically, the mobility control device 15 uses the link layer address of MN12, the destination CoA in AR13, the MN12 as a host, and the interface type of AR13 as information for generating the NC of MN12 in AR13. Notify AR13. The link layer address of the MN can be acquired from the n-casting request, and the destination CoA is determined by the optimum area forming function. The interface type of the AR 13 is determined with reference to the MN interface DB 15g and the AR interface DB 15h. Upon receiving this instruction, the AR 13 generates an NC for the MN 12 in a state (Reachable) based on the information for generating the NC, and secures the destination CoA.

  Then, the replication transfer device (replication node) 13a is instructed to replicate and forward the packet addressed to the home address (HoA) of the MN 12 or to the CoA registered in the HA (# 15). The mobility control device 15 notifies the MN 12 of the completion of n-casting setting and the destination CoA (s) in the replication transfer range 14. After this, since the AR 13 holds the NC of the MN 12 and the MN 12 is ready to receive the packet addressed to the destination CoA, the duplicated and forwarded packet is not transferred after the MN 12 moves under the new access router. Since the packet addressed to the destination CoA arrives immediately and the MN can receive it immediately, high-speed HO can be performed regardless of the movement detection accuracy of the MN 12 (# 16, # 17).

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and it is needless to say that various improvements and modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, IPv6 having an automatic address generation function has been described as an example. However, the present invention is not limited to this and is applicable to IPv4. Specifically, the NC is described as an example as the “table for managing the correspondence between the physical address and the IP address of the mobile terminal” described in the claims, but when applied to IPv4, the NC Will be replaced by ARP Cache.

1 is a configuration diagram of a mobile communication control system according to a first embodiment of the present invention. It is a flowchart which shows the process sequence by the mobile communication control system which concerns on the 1st Embodiment of this invention. It is a block diagram of the mobile communication control apparatus and mobile communication control system which concern on the 2nd Embodiment of this invention. 2 is a detailed configuration diagram of a mobility control device 15. FIG. It is a conceptual diagram of the n-casting system which expanded FMIP concerning a prior art. It is a conceptual diagram for demonstrating the problem of a prior art. It is a conceptual diagram for demonstrating the problem of a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... PAR, 2 ... NAR, 3 ... MN, 11 ... CN, 12 ... MN, 13 ... Routing device, 13a ... Duplicate transfer device, 14 ... Duplicate transfer range, 15 ... Mobility control device, 16 ... Mobile network.

Claims (4)

Comprising first and second access routers that can communicate with a mobile terminal;
The first access router transmits a first notification including a new care-of address to the second access router. When the second access router receives the first notification, the first access router caches the new care-of address. Create an entry, activate the generated cache entry , send a second notification to the first access router, and the first access router receives the second notification from the second access router Then , a third notification is transmitted to the mobile terminal, and when the mobile terminal receives the third notification, the mobile terminal can receive n-casting packets from the first access router and the second access router. establishing a, establishing the second access router and the link, starts the second access router and packet communication, transfer, characterized in that Communication control system.   The first access router holds a peripheral AR table related to peripheral access routers, and further determines a second access router that is a destination candidate of the mobile terminal by referring to the peripheral AR table. The mobile communication control system according to claim 1.   When the first access router manages the interface information of the access router in the peripheral AR table and receives the interface information held by the mobile terminal from the mobile terminal, the first access router holds the interface information of the access router and the received mobile terminal And a first notification to which the interface information desired to be used is added to the access router that matches the interface information held by the mobile terminal is transmitted to the second access router. The mobile communication control system according to claim 2. A method using first and second access routers capable of communicating with a mobile terminal,
The first access router transmits a first notification including a new care-of address to the second access router. When the second access router receives the first notification, the first access router caches the new care-of address. Create an entry, activate the generated cache entry , send a second notification to the first access router, and the first access router receives the second notification from the second access router Then, a third notification is transmitted to the mobile terminal, and when the mobile terminal receives the third notification, it can receive n-casting packets from the first access router and the second access router. establishing a state, establishing the second access router and the link, starts the second access router and packet communication, it is characterized in that Mobile communication control method.

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