JP3293761B2 - Packet routing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a packet routing method, and more particularly to a technique for appropriately routing a packet transmitted from a terminal when the terminal moves between a plurality of packet communication networks.

[0002]

2. Description of the Related Art In communication between data terminals such as personal computers, IP packet communication is currently widely used. This IP packet communication (IP: Internet P
In the (rotocol), an IP packet is routed to a destination terminal using an IP address including information on an area (subnetwork) in which the terminal exists.

[0003] Therefore, when a terminal moves across different sub-networks, the IP assigned to the terminal is changed.
In order to transfer IP packets to the terminal without changing the address, IETF (Internet Engineering Tas
k Force), the technology of tunneling by encapsulating IP packets is being studied.

FIG. 10 shows the IETF RFC 2002 “I.
FIG. 11 is a diagram for explaining the operation when the terminal moves in “P Mobility Support”.
01 is an IP network for transferring IP packets, 10
Reference numeral 2 denotes a mobile terminal, and reference numeral 103 denotes a subnetwork in which the mobile terminal 102 originally exists. The mobile terminal 102 is assigned an IP address including information on the subnetwork 103, for example, A1. Here, “A” included in the IP address is a network address for identifying the subnetwork 103. 104 is the mobile terminal 102
Is an example of a subnetwork to which the subnetwork 104 moves, and here, the network address for identifying the subnetwork 104 is “B”. Reference numeral 105 denotes a data terminal which communicates with the mobile terminal 102, and C1 is assigned as an IP address. Reference numeral 106 denotes an H having a home agent (HA) which is a function for managing the movement of the mobile terminal 102 having an IP address including the subnetwork address A.
A device 107 is an FA device having a foreign agent (FA) that is a function of managing mobile terminals that have moved to the sub-network B. An arrow 108 indicates a transfer route of the IP packet from the data terminal 105 to the mobile terminal 102, and an arrow 201 indicates a transfer route of the IP packet from the mobile terminal 102 to the data terminal 105.

FIG. 11 is a diagram showing a state of encapsulation and decapsulation of an IP packet in an IP packet transfer route from the data terminal 105 to the mobile terminal 102. FIG. FIG. 4 is a diagram showing an IP packet when transmitting. Hereinafter, transfer of an IP packet when the mobile terminal 102 moves between sub-networks will be described with reference to FIGS.

[0006] First, the data terminal 105 is connected to the mobile terminal 102.
When the IP packet is transferred to the
The P packet 301 is transmitted. In this case, the IP header 3
A1 that is the IP address assigned to the mobile terminal 102 is set as the destination IP address 306 of
The IP address C1 of the data terminal 105 is set in the P address 307 and transmitted to the IP network 101. The HA device 106 recognizes that the mobile terminal 102 has moved to the sub-network 104 by a predetermined method, and upon receiving the IP packet 301 addressed to the mobile terminal 102, as shown in FIG. An IP packet 302 having an IP header 305 (encapsulated) for enabling transfer to a position where the mobile terminal 102 exists in the IP network 101 is generated. That is, the subnetwork 104 to which the mobile terminal 102 has moved
An IP header 305 with the IP address Bn including the network address B of the destination as the destination IP address 308 is provided. The HA device 106 performs the encapsulation process and transmits the IP packet 30 to the IP network 101 again.
Send 2.

[0007] Then, the IP packet 302 is delivered to the FA device 107 via the IP network 101. Here, the FA device 107 removes the IP header 305 of the IP packet 302 (decapsulation), and converts the IP packet 303 shown in FIG.
Pass to. As described above, when the mobile terminal 102 moves across the sub-network, the I
The P packet 301 will be transferred.

On the other hand, from the mobile terminal 102 to the data terminal 10
In the case where an IP packet is transmitted to
The packet 401 is transmitted to the IP network 101. That is, the destination IP address 403 of the IP header 402 contains the IP address C1 of the data terminal 105.
Is set, and the mobile terminal 1
02 IP address A1 is set. The IP packet 401 is transferred through the IP network 101 and transmitted to the target data terminal 105.

[0009]

SUMMARY OF THE INVENTION IP network 10
In the device which transfers the IP packet within 1, for example, the IP router 109, the packet is delivered to the target terminal using the destination IP address of the IP header. However, when routing the IP packet, the IP router may check whether the subnetwork address included in the source IP address of the IP header exists in the direction in which the IP packet was received, in order to eliminate illegal routing. is there. When such an IP router 109 exists in the IP packet route 201 from the mobile terminal 102 to the data terminal 105, the subnetwork address included in the source IP address and the destination subnetwork address in which the mobile terminal exists Therefore, the IP router 109 determines that the routing is illegal, and the IP packet is discarded and does not reach the data terminal 105.

[0010] The present invention has been made in view of the above problems, and has as its object to provide a transmission source I of a received IP packet.
If the P address does not exist in the direction in which the IP packet was received, the I
It is an object of the present invention to provide a packet routing method capable of normally delivering data transmitted from a mobile terminal to a destination even when a P router exists on an IP network.

[0011]

In order to solve the above-mentioned problems, a first invention is provided corresponding to a first sub-network and performs communication between the first sub-network and an IP network. A first communication relay device for relaying, and a mobile terminal provided corresponding to the second sub-network and assigned an IP address belonging to the first sub-network, A second communication relay device that receives data transmitted by the mobile terminal and sends out an IP packet based on the data to an IP network; and a packet routing method using the second communication relay device. Receiving data from a mobile terminal, based on the data, information on an IP address which is a final destination of the data and information on an IP address assigned to the mobile terminal. A capsule having a data body that includes an IP header having an IP address belonging to the first sub-network as a destination IP address and an IP address belonging to the second sub-network as a source IP address. Transmitting the encapsulated IP packet to the IP network, and receiving, at the first communication relay device, an encapsulated IP packet transmitted from the second relay device based on the encapsulated IP packet. A decapsulated IP packet is transmitted to the IP network in which an IP address, which is a final destination of the packet, is set as a destination IP address and an IP header having an IP address assigned to the mobile terminal as a source IP address is added. Things.

According to a second aspect of the present invention, in the first aspect, the second communication relay device uses an IP based on data received from the mobile terminal instead of the encapsulated IP packet under a predetermined condition. IP, the final destination of the packet
The IP packet for direct transmission, which has an IP header with the address as the destination IP address and the IP address assigned to the mobile terminal as the source IP address, is
It is sent to the P network.

[0013] In a third aspect based on the second aspect, when the second relay device receives data from the mobile terminal, the second relay device transmits an IP address that is a final destination of the data to a destination IP address. And the IP address assigned to the mobile terminal as a source IP address.
A test IP packet attached with a P header is transmitted to the IP network, and either the encapsulated IP packet or the direct transmission IP packet is transmitted to the IP network based on whether or not there is a response to the test IP packet. Is to determine.

According to a fourth aspect of the present invention, in the second or third aspect, the second relay device selects one of the encapsulated IP packet and the direct transmission IP packet for data having a predetermined destination and transmission source. Is stored in a memory indicating whether the packet is to be transmitted to the IP network, and whether the encapsulated IP packet or the direct-transmission IP packet is to be transmitted to the IP network is determined based on the selection information. Things.

In a fifth aspect based on the fourth aspect, the second relay device sends a predetermined test IP packet based on the selection information to an IP network, and sends a response to the test IP packet. The selection information stored in the memory is updated based on the presence / absence.

According to a sixth aspect of the present invention, there is provided a first communication relay device provided corresponding to a first sub-network, for relaying communication between the first sub-network and an IP network; When a mobile terminal provided corresponding to the network and assigned an IP address belonging to the first sub-network has moved into the service area,
A second communication relay device that receives data transmitted by the mobile terminal and sends out an IP packet based on the data to an IP network; and a packet routing method using the second communication relay device. An IP header that receives data from the mobile terminal and, based on the data, sets an IP address that is a final destination of the data as a destination IP address and sets an IP address assigned to the mobile terminal as a source IP address I for direct delivery with
A P packet is sent to an IP network, and an IP address which is a final destination of the data is set as a destination IP address.
A test IP packet with an IP header having the P address as a source IP address is transmitted to the IP network, and if there is no response to the test IP packet,
For data received from the mobile terminal, an IP address belonging to the first sub-network is included in a data body including information of an IP address which is a final destination of the data and information of an IP address assigned to the mobile terminal. Sending an encapsulated IP packet to an IP network, the IP packet having an address as a destination IP address and an IP header having an IP address belonging to the second sub-network as a source IP address, and transmitting the first communication relay; When the device receives the encapsulated IP packet sent from the second relay device, based on the encapsulated IP packet, the device determines the final destination of the IP packet.
A decapsulated IP packet having an IP header having a P address as a destination IP address and an IP address assigned to the mobile terminal as a source IP address is transmitted to an IP network.

According to a seventh aspect of the present invention, there is provided a first communication relay device provided corresponding to the first sub-network, for relaying communication between the first sub-network and the IP network; When a mobile terminal provided corresponding to the network and assigned an IP address belonging to the first sub-network has moved into the service area,
A second communication relay device that receives data transmitted by the mobile terminal and sends out an IP packet based on the data to an IP network; and a packet routing method using the second communication relay device. Receiving data from the mobile terminal, based on the data, the data body including the information of the IP address that is the final destination of the data and the information of the IP address assigned to the mobile terminal, the first body The IP address belonging to the sub-network is set as the destination IP address and the IP address belonging to the second sub-network is set as the source IP address.
Encapsulated IP packet with P header attached to IP
A test I which is transmitted to the network and has an IP header which is the final IP address of the data as a destination IP address and an IP address assigned to the mobile terminal as a source IP address.
P packet is sent to the IP network, and the test IP
If there is a response to the packet, for data received from the mobile terminal within a predetermined period thereafter, the IP address that is the final destination of the data is set as the destination IP address, and the IP address assigned to the mobile terminal is A direct sending IP packet attached with an IP header as a source IP address is sent to the IP network, and if there is no response to the test IP packet, data received from the mobile terminal within a predetermined period thereafter is When the encapsulated IP packet is transmitted to an IP network, and the first communication relay device receives the encapsulated IP packet transmitted from the second relay device, based on the encapsulated IP packet, The IP address that is the final destination of the IP packet is defined as the destination IP address. I assigned to the mobile terminal
A decapsulated IP packet with an IP header having a P address as a source IP address is transmitted to an IP network.

In an eighth aspect based on any one of the third, fifth, sixth and seventh aspects, an echo packet based on an ICMP (Internet Control Message Protocol) is used as the test IP packet.

[0019]

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

Embodiment 1 FIG. 1 is a diagram showing a transfer route of an IP packet in the packet routing method according to the first embodiment. FIG. 2 is a diagram showing a state of encapsulation / decapsulation of an IP packet transmitted from the mobile terminal 102 to the data terminal 105. Note that the configuration of the network shown in FIG. 1 is almost the same as the configuration of the network already shown in FIG. 10, and the corresponding components are denoted by the same reference numerals and description thereof is omitted here.

First, the mobile terminal 102 is connected to the data terminal 10.
5 when transmitting an IP packet to the I.5 packet shown in FIG.
P packet 501 is transferred to FA device 107 (second relay device)
Send to Here, in the IP header 504 of the IP packet 501, the mobile terminal 10 is added to the destination IP address 506.
The IP address C1 of the data terminal 105, which is the final destination of the data transmitted from the IP packet 501, is set to the IP address A1 of the mobile terminal 102, which is the sender of the IP packet 501, in the source IP address 507. Is set. When receiving the IP packet 501, the FA device 107 adds an IP header 505 to the IP packet 501 shown in FIG.
Generate IP added to this IP packet 502
In the header 505, one IP address An in the address space in the subnetwork where the mobile terminal 102 originally exists is set as the destination IP address 508, and the source I
One IP address Bn in the address space in the subnetwork where the FA device 107 exists is set as the P address.

Here, the IP packet 502 is transferred to the FA
When the device 107 transmits to the IP network 101,
As described above, the IP router 109 may check the header 505 of the IP packet. However, according to the present packet routing method, the source I of the IP packet 502
Since the P address 509 is set to Bn, it is determined that this routing is normal because the subnetwork 104 (network address B) exists on the route from which the IP packet 502 has been transmitted. And
Since the destination IP address 508 is An, the IP packet 502 is transmitted to the subnetwork 102 (network address A).

Thereafter, the IP packet 502 is transmitted to the HA device 1
06 (first relay device). HA device 106
Recognizes that the IP packet 502 is encapsulated, removes the IP header 505, and returns to the I shown in FIG.
A P packet 503 is generated, and the IP packet 503 is transmitted to the IP network 101 again. The IP packet 503 is delivered to the data terminal 105 (IP address C1) which is the final destination by the destination IP address 506.

With the above processing, according to the present packet routing method, the IP packet 501 transmitted from the mobile terminal 102 is delivered to the data terminal 105 along the route indicated by the arrow 108 in FIG. It can be reliably delivered to the final destination without being discarded by the disposed IP router 109.

Embodiment 2 In FIG. 1, a mobile terminal 102 that has moved to a subnetwork 104 is a data terminal 1
When the IP packet 501 shown in FIG. 2A is transmitted at 05, the FA device 107 receives the IP packet 501. According to the packet routing method according to the second embodiment described below, FA apparatus 107 determines whether or not to encapsulate IP packet 501 from destination IP address 506 and source IP address 507 of IP packet 501. I do.

This determination is based on the information as to whether or not the IP packet 501 is discarded by the transmission source IP address 507 on the route to which the IP packet 501 is transferred. Therefore, the FA device 107, for example, has the same format as the IP packet 501 (the IP header 5 having the same content).
In the IP packet (with “04”), an indication that the IP packet is a test IP packet is displayed in the data portion, and transmitted to the IP network 101. Then, the IP packet 501 is transmitted to the IP network 101
When the data terminal 105 arrives at the data terminal 105, the data terminal 105 generates an IP packet indicating that the response has been made and returns it to the FA device 107. FA device 107
Receives such a response from the data terminal 105,
It is determined that direct transmission of an IP packet from the device 107 to the data terminal 105 is possible, and the IP packet received from the mobile terminal 102 is transmitted to the IP network 101 without encapsulation. In this case, the IP packet is transmitted to the target data terminal 105 without passing through the HA device 106.
To reach. If no response is returned, the FA device 107
The mobile terminal 1 determines that direct transmission of the P packet is impossible.
02 is encapsulated and transmitted in the same manner as in the first embodiment.

Here, the FA device 107 is connected to the mobile terminal 102.
First, the communication protocol shown in FIG. 4 is set to the data terminal 10 to determine whether or not the IP packet received from the
5 is implemented. The figure shows the configuration of a protocol implemented in the data terminal 105. A data link layer 702 is provided above a physical layer 701, and a network layer 703, a transport layer 704, and an application layer 705 are further above that. They are provided in order. In the data terminal 105, in particular, in addition to the Internet protocol (IP) 706, the ICMP 7
07 is used.

Then, the FA device 107 sets an echo packet in the ICMP type 604 in the ICMP header 603, and sends the ICMP packet 601 to the IP network 1
01. The data terminal 105 that has received the ICMP packet 601 (echo packet) sets the ICMP type
The packet 601 is returned. When receiving the ICMP packet 601 (echo reply packet), the FA device 107 transfers the IP packet received from the mobile terminal 102 without encapsulation. Note that, when the message reply unit 607 in the ICMP packet 601 transmits the echo reply, the content set by the echo is set as it is, so that the echo and the echo reply can be corresponded by this content.

Next, FIG. 5 shows an example of a communication sequence according to the present packet routing method. First, mobile terminal 1
02 transmits an IP packet addressed to the data terminal 105 (S801). The FA device 107 transmits an echo packet when receiving the packet (S802). When this echo packet is transferred in the IP network 101 and reaches the data terminal 105, the data terminal 105 returns an echo reply packet (S803). FA device 107
Receives the echo reply packet, the F
The A device 107 sends the IP packet received from the mobile terminal 102 to the IP network 101 without encapsulation (S804). On the other hand, when the mobile terminal 102 transmits an IP packet to the data terminal having the IP address D1 (S805), the FA device 107 transmits an echo packet to D1 (S806). This echo packet is discarded in the IP network 101 and no echo reply is returned. For this reason, the FA device 107 encapsulates the IP packet received from the mobile terminal 102, and
The data is transmitted to the IP network 101 via the device 106 (S807).

As described above, when an IP packet transmitted from the mobile terminal 102 is transmitted to the IP network 101 and the possibility of being discarded in the IP network 101 is small, the IP packet is efficiently encapsulated without being encapsulated. The data can be transmitted to the target data terminal 105 through a simple route. Further, when there is a possibility that the IP packet is discarded in the IP network 101, the IP packet can be reliably transmitted to the target data terminal by encapsulating the IP packet and passing it through the HA device 106. Further, by using ICMP echo and echo reply packets to determine whether transfer is possible, it is not necessary to add a function to the data terminal.

Embodiment 3 FIG. 6 is a diagram showing a communication sequence by the packet routing method according to the third embodiment. As shown in the figure, first, the mobile terminal 102 transmits an IP packet addressed to the data terminal 105 (S9).
01). Then, the FA device 107 transmits an echo packet having an IP header including the same destination IP address and source IP address as the IP packet to the IP network 1.
01 (S902), and if an echo reply packet for the echo packet is received (S903),
It is determined that the IP packets from IP addresses A1 to C1 can be transmitted without encapsulation. Then, the FA device 107 transmits the IP packet received from the mobile terminal 102 to the destination without encapsulation (S904), and selection information indicating that the IP packet from the IP address A1 to C1 can be transmitted without encapsulation. Is stored in a built-in memory (not shown). Thereafter, when an IP packet addressed to the data terminal 105 is received from the mobile terminal 102 (S90
5), the FA device 107 transmits the IP packet without encapsulation from the selection information previously stored in the memory (S90).
6). The FA device 107 deletes this selection information from the memory when, for example, the transmission of the IP packet having the same destination and the same transmission source has not been performed for a certain period of time. When the mobile terminal 102 moves out of the sub-network 104 under the control of the FA device 107, the mobile terminal 102
From the memory.

As described above, it is possible to determine whether to perform encapsulation of an IP packet without sending a test IP packet each time an IP packet is received.

Embodiment 4 of the Invention FIG. 7 is a diagram showing a communication sequence by the packet routing method according to the fourth embodiment. As shown in the figure, when the mobile terminal 102 transmits an IP packet addressed to the data terminal 105, and the FA device 107 receives it (S1001), the FA device 107 sends an echo packet to the IP network 101 (S1001). In step S1002, the received IP packet is sent to the IP network 101 as it is (S10).
03). The FA device 107 is connected to the data terminal 105
When an echo reply packet is received from the
4) The previously transmitted IP packet is normally transmitted to the data terminal 1
It is determined that the packet has arrived at 05, and, for example, in the same manner as in Embodiment 3 described above, the same destination and transmission source IP packets are transmitted without being encapsulated.

The mobile terminal 102 receives the IP address D1
Sends an IP packet to the data terminal of the FA device 1
07 (S1005), the FA device 10
7 transmits an echo packet to the IP network 101 and converts the received IP packet into an IP
Send to network 101 (S1006, S100
7). In the IP network 101, the echo packet and I
When the P packet is discarded, the FA device 107 does not receive the echo reply packet.
HA device 1 by encapsulating the IP packet received from
The message is transmitted again via the command line 06 (S1008). Thereafter, the FA device 107 performs, for example, in the same manner as in the above-described third embodiment,
Thereafter, IP packets of the same destination and source are encapsulated and then transmitted to the IP network 101.

As described above, the I transmitted by the mobile terminal 102
When it is not necessary to take a redundant route, the P packet can be delivered through an optimal route, and can be appropriately transmitted to the target data terminal 105 while reducing the probability of waiting for a response of the test IP packet. .

Embodiment 5 of the Invention FIG. 8 is a diagram showing a communication sequence by the packet routing method according to the fifth embodiment. As shown in the figure, when the mobile terminal 102 transmits an IP packet addressed to the data terminal 105 and the FA device 107 receives it (S1101), the FA device 107 sends an echo packet to the IP network 101 (S1101). (S1102), the received IP packet is encapsulated and transmitted to the IP network 101 (S1103). The FA device 107 is connected to the data terminal 105
When an echo reply packet is received from the
4), it is determined that the IP packet of the same destination and the transmission source can be transmitted to the target data terminal without encapsulation, and thereafter, the IP packet is transferred without encapsulation (S1105, S1106).

Further, when the mobile terminal 102 receives the IP address D1
When the IP packet is transmitted to the data terminal having the IP address and received by the FA device 107 (S1107), the FA device 107 similarly transmits the echo packet to the IP network 10
1 (S1108), and encapsulates the received IP packet and transmits it to the IP network 101 (S1109). Here, for example, when the echo packet is discarded in the IP network 101, the FA
Since the device 107 does not receive the echo reply packet corresponding to the echo packet, it determines that encapsulation is necessary when transmitting the IP packet to the target data terminal, and thereafter, the IP address of the same destination and the same source The packet is encapsulated and sent to the IP network 101 (S1110, S1111).

As described above, the I transmitted by the mobile terminal 102
The P packet can be transmitted to the target data terminal without waiting for the response of the test IP packet, and the subsequent IP packet of the same destination and transmission source can be delivered by the optimal route.

Embodiment 6 of the Invention FIG. 9 is a diagram showing a communication sequence by the packet routing method according to the sixth embodiment. In this packet routing method, FA
It is assumed that device 107 stores, for example, with the same configuration as in the third embodiment, that the IP packet whose destination IP address is C1 and whose source IP address is A1 does not require encapsulation. In this state, an echo packet is sent out to the IP network 101 after a certain period of time (S1201), and the echo reply to the
When the device 107 receives the data (S1202), the storage contents are held. If an IP packet whose destination IP address is C1 and whose transmission source IP address is A1 is received from the mobile terminal 102 (S1203), the IP packet is transmitted without encapsulation (S1204).

On the other hand, the FA device 107 sends out an echo packet to the IP network 101 after a predetermined time (S12).
05) If no echo reply is received, the FA device 107 recognizes that the IP packet whose destination IP address is C1 and whose source IP address is A1 needs to be encapsulated. And thereafter, the destination IP
If an IP packet whose address is C1 and whose source IP address is A1 is received from the mobile terminal 102 (S12)
06), the IP packet is encapsulated and transmitted to the IP network 101 (S1207).

As described above, even when the route of the IP packet is changed in the IP network 101 and the IP packet is transferred via a different IP router, optimal routing can be performed.

[0042]

As described above, according to the first aspect of the present invention, when a mobile terminal exists in the area covered by the second relay device, the second relay device has the mobile terminal. Receives data transmitted to the terminal and, based on the data, sets an IP header belonging to the first sub-network as a destination IP address and an IP address belonging to the second sub-network as a source IP address. Since the attached encapsulated IP packet is sent to the IP network, the IP packet can be reliably forwarded from the second relay device to the first relay device without being discarded in the middle of the IP network. . Further, according to the first aspect of the present invention, based on the encapsulated IP packet received from the second relay device, the first relay device sends the final IP address of the IP packet to the destination IP address. Since a decapsulated IP packet having an IP header and an IP address (belonging to the first subnetwork) assigned to the mobile terminal as a source IP address is sent to the IP network, the IP address is transmitted to the IP network. The IP packet can be reliably forwarded from the first relay device to the final destination without being discarded in the middle of the network.
As a result, according to the first aspect of the invention, an IP packet based on data transmitted from a mobile terminal can be reliably delivered to a final destination without being discarded in an IP network.

According to the second aspect of the present invention, the second relay device transmits the IP packet for direct transmission based on data received from the mobile terminal to the IP network under a predetermined condition determined by, for example, a destination or a transmission source. Therefore, when it is determined that the IP packet is not discarded in the IP network, the IP packet can be delivered to the destination by an efficient route without encapsulation.

According to the third aspect of the present invention, the second relay device transmits the test IP packet to the IP network when receiving data transmitted from the mobile terminal,
Depending on whether or not there is a response from the terminal which is the destination of the test IP packet, the encapsulation in the second relay device /
Since the non-execution is determined, the encapsulation processing can be performed as needed.

According to the fourth aspect of the present invention, in the second relay device, the selection information is stored in a memory, and whether or not to perform the encapsulation processing is determined based on the selection information. Therefore, every time data is received from the mobile terminal, encapsulation is performed without sending a test IP packet /
Non-implementation can be determined.

According to the fifth aspect of the present invention, a predetermined test IP packet is transmitted to the IP network at predetermined intervals, for example, and the selection information stored in the memory is updated. Changes the route of the IP packet and sends the IP packet through a different IP router.
Even when P packets are transferred,
Optimal routing can be performed.

According to the sixth aspect of the present invention, when receiving data from a mobile terminal, the second relay device transmits the test I
The P packet and the direct transmission IP packet based on the received data are both transmitted to the IP network, and if a response to the test IP packet is not received, the encapsulated IP packet based on the same data is transmitted again to the IP network. Therefore, when data received from the mobile terminal does not need to take a redundant route, the data is transmitted through an optimal route, and the probability of transmitting an IP packet after waiting for a response to a test IP packet is reduced. And send it to the destination.

According to the seventh aspect of the present invention, when receiving data from the mobile terminal, the second relay device performs the encapsulation IP based on the test IP packet and the received data.
When a response to the test IP packet is received together with the test packet, data having the same destination and source as the test IP packet is transmitted without encapsulation thereafter, and the test is performed. If a response to the test IP packet is not received, the data having the same destination and source as the test IP packet
Since the packet is encapsulated and transmitted, the IP packet transmitted by the mobile terminal can be transmitted to the destination without waiting for the response of the test IP packet, and the data of the same destination and the same transmission source thereafter. Can be delivered by an optimal route.

According to the invention of claim 8, since the echo packet of ICMP is used as the test IP packet, the function for transmitting the response packet to the destination data terminal is not added separately. It is possible to select whether to perform encapsulation using existing technology.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a system to which a packet routing method according to the present invention is applied.

FIG. 2 is a diagram showing a state in which an IP packet transmitted from a mobile terminal is encapsulated by a packet routing method according to Embodiment 1 of the present invention.

FIG. 3 is a diagram showing an ICMP packet used in a packet routing method according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a protocol configuration to be implemented in a data terminal that is a destination of an IP packet in the packet routing method according to the second embodiment of the present invention.

FIG. 5 is a diagram showing a communication sequence by a packet routing method according to Embodiment 2 of the present invention.

FIG. 6 is a diagram showing a communication sequence by a packet routing method according to Embodiment 3 of the present invention.

FIG. 7 is a diagram showing a communication sequence by a packet routing method according to Embodiment 4 of the present invention.

FIG. 8 is a diagram showing a communication sequence by a packet routing method according to Embodiment 5 of the present invention.

FIG. 9 is a diagram showing a communication sequence by a packet routing method according to Embodiment 6 of the present invention.

FIG. 10 is a diagram showing a transfer route of an IP packet in a packet routing method according to a conventional example.

FIG. 11 is a diagram illustrating a state in which an IP packet transmitted from a data terminal to a mobile terminal is encapsulated by a packet routing method according to a conventional example.

FIG. 12 is a diagram illustrating an example of a configuration of an IP packet transmitted from a mobile terminal by a packet routing method according to a conventional example.

[Explanation of symbols]

101 IP network, 102 Mobile terminal, 103
Subnetwork (first subnetwork), 10
4 subnetworks (second subnetworks), 1
05 data terminal, 106 HA device (first relay device), 107 FA device (second relay device), 502
IP packet (encapsulated IP packet), 503 I
P packet (decapsulated IP packet), 601 I
CMP packet (echo packet, echo reply packet).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-129488 (JP, A) JP-A-6-104926 (JP, A) JP-A-5-235942 (JP, A) JP-A-6-104 46063 (JP, A) JP-A-6-69963 (JP, A) JP-A-6-237270 (JP, A) JP-A-6-337824 (JP, A) JP-A-7-170286 (JP, A) Fumio Teraoka, Protocol for Realizing Mobile Transparent Communication, IEICE Journal, Japan, The Institute of Electronics, Information and Communication Engineers, April 25, 1997, No. 875, p. 344-349 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/56 100 H04L 12/28 300

Claims (8)

(57) [Claims] 1. A first communication relay device which is provided corresponding to a first sub-network, relays communication between the first sub-network and an IP network, and corresponds to a second sub-network. When a mobile terminal to which an IP address belonging to the first sub-network is assigned moves to a service area, the mobile terminal receives data transmitted by the mobile terminal, and performs I-based communication based on the data.
A second communication relay device for transmitting a P packet to an IP network, wherein the second communication relay device receives data from the mobile terminal, and based on the data, and IP address information which is the final destination of data, the assigned to the mobile terminal, the previous SL IP address information belonging to the first sub-network, to the data body including the first sub-network An encapsulated IP packet having an IP address belonging to the second sub-network and a source IP address attached thereto as destination information using IP address information belonging to the Sending, at the first communication relay device, from the second relay device
Encapsulation I sent over the IP network
When receiving a P packet, based on the encapsulated IP packet, the IP that is the final destination of the IP packet
An IP address belonging to a first sub-network assigned to the mobile terminal and having a destination IP address
A packet routing method characterized by transmitting a decapsulated IP packet to which an IP header having an address information as a source IP address is attached, to an IP network. 2. An IP address which is a final destination of an IP packet based on data received from the mobile terminal in place of the encapsulated IP packet under a predetermined condition in the second communication relay device. 2. A direct sending IP packet with an IP header attached to a destination IP address and an IP address assigned to the mobile terminal as a source IP address is transmitted to an IP network. Packet routing method. 3. When the second relay device receives data from the mobile terminal, an IP address which is a final destination of the data is set as a destination IP address and assigned to the mobile terminal. In the first sub-network
A test IP packet attached with an IP header having an IP address belonging to the source IP address is transmitted to an IP network, and the encapsulated IP packet or the direct transmission IP is transmitted based on whether or not there is a response to the test IP packet. 3. The packet routing method according to claim 2, wherein it is determined which of the packets is to be transmitted to the IP network. 4. Selection information indicating which of the encapsulated IP packet and the direct transmission IP packet should be transmitted to the IP network for the data having a predetermined destination and a transmission source in the second relay device. 4. The method according to claim 2, further comprising: storing in the memory which of the encapsulated IP packet and the direct transmission IP packet is to be transmitted to an IP network based on the selection information. 5. Packet routing method. 5. The second relay device transmits a predetermined test IP packet based on the selection information to an IP network, and stores the predetermined test IP packet in the memory based on whether or not there is a response to the test IP packet. The packet routing method according to claim 4, wherein the selection information is updated. 6. A first communication relay device provided corresponding to a first sub-network, for relaying communication between the first sub-network and an IP network, and corresponding to a second sub-network. When a mobile terminal to which an IP address belonging to the first sub-network is assigned moves to a service area, the mobile terminal receives data transmitted by the mobile terminal and transmits an IP packet based on the data to an IP. A second communication relay device for sending to a network, wherein the second communication relay device receives data from the mobile terminal, and based on the data, The IP address that is the destination is the destination IP address, and the first subnet assigned to the mobile terminal is
A direct sending IP packet having an IP header with an IP address belonging to the network as a source IP address is sent to the IP network, and the final IP address of the data is set as a destination IP address. The first subnet assigned to the mobile terminal;
A test IP packet attached with an IP header having an IP address belonging to the network as a source IP address is transmitted to the IP network. If there is no response to the test IP packet, data received from the mobile terminal is sent. , The information of the IP address that is the final destination of the data and the IP belonging to the first sub-network assigned to the mobile terminal.
In the data body including address information, an IP address belonging to the first sub-network is set as a destination IP address, and an IP address belonging to the second sub-network is included.
An encapsulated IP packet with an IP header having a P address as a source IP address is transmitted to an IP network, and the first communication relay device performs encapsulation transmitted from the second relay device. When receiving IP packets,
Based on the encapsulated IP packet, an IP address that is a final destination of the IP packet is set as a destination IP address, and the first IP address assigned to the mobile terminal .
Decapsulated IP with IP header attached to IP address belonging to subnetwork as source IP address
A packet routing method for transmitting a packet to an IP network. 7. A first communication relay device which is provided corresponding to a first sub-network and relays communication between the first sub-network and an IP network, and corresponds to a second sub-network. When a mobile terminal to which an IP address belonging to the first sub-network is assigned moves to a service area, the mobile terminal receives data transmitted by the mobile terminal and transmits an IP packet based on the data to an IP. A second communication relay device for sending to a network, wherein the second communication relay device receives data from the mobile terminal, and based on the data, data body including said first IP address of the information belonging to the subnetwork assigned to IP address information and the mobile terminal is a destination An encapsulated IP packet having an IP address belonging to the first sub-network as a destination IP address and an IP header having an IP address belonging to the second sub-network as a source IP address. And the IP address, which is the final destination of the data, is set as the destination IP address, and the IP address belonging to the first sub-network assigned to the mobile terminal is
A test IP packet with an IP header having the P address as a source IP address is transmitted to the IP network, and if there is a response to the test IP packet, the packet is received from the mobile terminal within a predetermined period thereafter. With respect to the data, an IP header having an IP address that is a final destination of the data as a destination IP address and an IP address belonging to the first subnetwork allocated to the mobile terminal as a source IP address is attached. If there is no response to the test IP packet, the encapsulated IP packet is transmitted to the IP network for data received from the mobile terminal within a predetermined period thereafter. Transmitted by the first communication relay device from the second relay device. When receiving the encapsulated IP packet,
Based on the encapsulated IP packet, an IP address that is a final destination of the IP packet is set as a destination IP address, and the first IP address assigned to the mobile terminal .
Decapsulated IP with IP header attached to IP address belonging to subnetwork as source IP address
A packet routing method for transmitting a packet to an IP network. 8. An ICM as the test IP packet
8. The packet routing method according to claim 3, wherein an echo packet based on P is used.