JP2001016253A - Method for interrupting remaining tcp connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve a load of an exchange for mobile terminals when an IP address of a mobile terminal is changed attended with its movement by generating a TCP segment to interrupt a TCP connection for a received packet and transmitting the TCP segment to an IP network in the case that a destination address of the received packet is not assigned and contents of its data part point out TCP segment. SOLUTION: In the case that no destination address is assigned to a packet received from an IP network and contents of a data part of the packet point out a TCP segment, a TCP segment to interrupt a TCP connection pointed out by the TCP segment of the contents of the data part is generated and transmitted to the IP network. A packet exchange PDSN 105 is provided with containing channel I/Fs 201a-201c to contain BSC and a network I/F 202 to control a network channel to a PDGN and also with a packet buffer 203 to temporarily store packets received from each channel, a CPU 204 and a memory 205 or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to land mobile communication covering a service area with a plurality of radio zones, and more particularly to packet communication on mobile communication.

[0002]

2. Description of the Related Art At present, there is a portable telephone system called a second generation. NTT DoCoMo Technical Journal Vol. 5 No. According to No. 2 “Special Edition on Mobile Packet Communication System”, this system allows a terminal to connect to the Internet and perform packet communication via a mobile phone network. The gateway to the IP network has a certain IP address, and a packet addressed to an IP address having the same network number as the address is transmitted to the IP network.
In the P network, it is routed to this gateway.

[0003] Therefore, a terminal that wants to connect to the Internet via the gateway is provided with a gateway I
It is necessary to assign an IP address having the same network number as the P address. Opportunities to be assigned include a method of fixedly assigning an IP address to a subscriber when subscribing a service, and a method of dynamically assigning when a terminal requests communication with an IP network (packet service). When dynamically assigning, while the terminal uses the packet service, the terminal can continue to use the same IP address regardless of where it moves within the service area of the mobile phone system, but the packet service is terminated. In some cases, there is no guarantee that the same IP address will be assigned even if the packet service is requested again.

On the other hand, a mobile phone system called a third generation is under development. This system is called IMT-2000. Cdma2000 under development in the United States
It is a kind of MT-2000.

[0005] In cdma2000, a terminal sends a PDSN.
The packet transfer is performed by a routing method peculiar to the mobile network up to the packet switch called “Phone Switch”, but from the PDSN to the PDGN which is the gateway to the Internet,
Similarly to the Internet, packet transfer is performed by IP routing. Therefore, each PDSN has an IP address in the same way as the gateway in the second generation, and the IP address limits the IP addresses that can be used by terminals located under the PDSN.

[0006]

In cdma2000, when a terminal moves within a service area of a portable telephone system while performing packet communication, an IP address may have to be changed in some cases. That is, different P
This is a case where a terminal moves between service areas managed by the DSN. In cdma2000, when a terminal requests a packet service, a path for packet communication from the terminal to the PDSN is set by a protocol specific to a mobile network, a PPP link is established between the terminal and the PDSN, and an IP address of the terminal is assigned by IPCP. .

Therefore, even when the terminal moves between PDSNs while performing packet communication with the Internet, a PPP link is established again between the terminal and the destination PDSN, and a new IP address is assigned. At this time, packets destined for the terminal that has already disappeared are being sent from the Internet to the source PDSN. These packets uselessly increase the load on the PDSN, and if the server in the Internet to which the access is made prohibits simultaneous multiple access by the same user, the terminal can use a new IP address from under the destination PDSN. Even if an attempt is made to access the server, the TCP connection times out (generally 3 minutes) on the server side and cannot be accessed until the previous access ends.

[0008]

A dynamic assignment means for dynamically assigning an IP address to a mobile terminal which performs packet communication via the mobile exchange, and
Address allocation state determining means for determining whether or not the destination address of the packet received from the IP network has been allocated; TCP determining means for determining that the content of the data portion of the received packet is a TCP segment;
A disconnection instruction segment creating means for disconnecting the TCP connection indicated by the segment is provided. If the destination address of the packet received from the IP network is not assigned and the content of the data part of the packet is a TCP segment, A TCP segment for disconnecting the TCP connection indicated by the TCP segment is created and transmitted to the IP network.

[0009] Alternatively, a dynamic assigning means for dynamically assigning an IP address to a mobile terminal which performs packet communication via the mobile exchange, and a data portion of a packet transmitted / received between the mobile terminal and the IP network include a TC.
In the case of a P segment, a TCP connection management means for analyzing the TCP segment to manage the TCP connection state and a disconnection instruction segment creating means for disconnecting the TCP connection are provided, and the assignment of the IP address to the mobile terminal is eliminated. Then, a disconnection instruction segment is transmitted to the remaining TCP connection that has not been released.

[0010] In order to reduce the load of the mobile exchange accompanying the transmission of the disconnection instruction segment, the content of the packet addressed to the IP address not allocated to the mobile terminal is changed to TCP.
If the segment indicates a connection establishment request, the connection is not established yet, the disconnection instruction segment is not transmitted, and the received packet is discarded.

[0011] Further, the IP address free time measuring means for measuring the unassigned time of the IP address not assigned to the mobile terminal to the mobile exchange, and the fact that the TCP connection is lost after the TCP segment is no longer received. A TCP connection expiration time storage means is provided for storing the time until deemed to be deemed. If the IP address vacancy time is equal to or longer than the TCP connection expiration time, a disconnection instruction is issued even if a TCP segment addressed to the IP address is received. Discard the received packet without sending the segment.

A TCP connection storing means for storing, in the mobile switching center, a source address, a source port, a destination address, and a destination port of a received packet to be transmitted with the disconnection instruction segment to the IP network; Counting a packet having a source address, a source port, a destination address, and a destination port to be stored in the connection storage means; a packet count means on the disconnected connection; and storing an interval value of the disconnection instruction segment transmission by the number of packets; An interval packet number storage unit is provided, and the received packet is discarded without transmitting the disconnection instruction segment from the transmission of the disconnection instruction segment to the reception of packets of the number of interval packets on the same TCP connection.

A TCP connection storage means for storing, in the mobile exchange, a source address, a source port, a destination address, and a destination port of a reception packet to be transmitted with the disconnection instruction segment to the IP network; Measure the elapsed time since sending the disconnect instruction segment,
There is provided an elapsed time measuring unit after the transmission of the disconnection instruction and an interval time storage unit for storing the interval value of the transmission of the disconnection instruction segment in time, and the same TCP is transmitted from the transmission of the disconnection instruction segment to the lapse of the interval time.
Even if a packet is received on the connection, the received packet is discarded without transmitting the disconnect instruction segment.

[0014]

An embodiment of the present invention will be described below.

FIG. 1 shows the configuration of a mobile packet communication network 100 under development with cdma2000. The PC 101 is connected to the MS 102 via a wired line, and transmits an IP packet to the MS 102.
102 or received from MS 102. MS1
Reference numeral 02 denotes a mobile device accommodated in the mobile packet communication network 100, and performs wireless communication with the BTS 103 using the CDMA method. The BTS 103 is a wireless base station device,
4 is connected by a wired line. Mobile packet communication network 1
Each of the BTSs in 00 forms a wireless zone, and the wireless zone covers the area in a plane, thereby forming a service area of the mobile packet communication network 100.
The BTS 103 performs simultaneous communication with a plurality of MSs 102 located in a wireless zone formed by the BTS 103. The BSC 104 is a base station controller and accommodates a plurality of BTSs 103. Layer 2 of the wireless protocol between the MS 102 and the BTS 103 actually terminates at the MS 102 and the BSC 104. The PDSN 105 is a mobile switching center for packets and accommodates a plurality of BSCs 104. MS102 to P
Up to the DSN 105, a connection-oriented communication path is set up, and then IP packets are transmitted and received. Therefore, IP routing based on the header information of the IP packets is not performed in this range.

On the other hand, PDSN 105 to PDGN 10
6. Since IP routing is performed up to the Internet 107, a global IP address is assigned to each PDSN. In the PDSN 105, the MS 10
The protocol on the second side and the protocol on the Internet 107 side are converted. The PDGN 106 is a gateway to the Internet 107 of the mobile packet communication network 100. The PDGN 106 connects to a plurality of PDSNs 105. PC 101 is MS102, BTS103, BSC1
04, a PDSN 105, and a PDGN 106 can perform IP packet communication with a server on the Internet 107. The MSC 108 is a mobile switch for circuit switching, and is connected to the HLR 110. HLR110
When a packet addressed to the PC 101 is routed from the Internet 107 to the PDSN 105, the MS
It manages the position information for calling out 102.

From the Internet 107 to the PDSN 105
When an IP packet arrives at the destination, the destination address MS1
A request for an incoming call is transmitted to the subordinate BSC 104 for the identification number of 02. The BSC 104 sends the MS 102 to the MSC 108.
The MSC 108 searches the HLR 110, and performs paging of the MS 102 via the BSC 104 and the BTS 103. When the MS 102 responds to the paging, a communication path between the MS 102 and the PDSN 105 is set.

FIG. 2 is a diagram showing a configuration example of the PDSN 105. The PDSN 105 includes an accommodation line I / F 201 that accommodates the BSC 104, a network I / F 202 that controls a network line to the PDGN 106, a packet buffer 203 for temporarily storing packets received from each line, a CPU 204, A memory 205;
A packet bus 207 for connecting these components and a control bus 206 are provided. The accommodation line I / F 201 performs control of a communication path setting protocol on the accommodation line and PPP link control. In the PPP link control, a request for an IP address to be assigned to the PC 101 is sent to the CPU via the control bus 206.
Then, the CPU 204 refers to the IP address assignment table stored in the memory 205 and notifies the accommodation line I / F 201 of a vacant IP address. FIG. 3 shows the IP address assignment table 300.

The IP address assignment table 300 includes a PC
IP address 3 to dynamically assign to 101
01, an in-use flag 302 indicating whether the IP address has been allocated (in use), and a PC 10 using the IP address when the IP address is in use.
1 is accommodated in an accommodation line number 303 indicating which accommodation line is accommodated, and an allocation release time 304 indicating a time when the used IP address is released.

The CPU 204 notifies the IP address for which the in-use flag 302 in the IP address allocation table 300 is not used to the accommodation line I / F which has requested the allocation,
Set busy flag 302 to busy, accommodation line number 30
3 is stored.

When the accommodating line I / F 201 requests the CPU 204 to release the IP address due to a factor such as the end of the packet communication, the CPU 204 sets the in-use flag 302 corresponding to the IP address to unused, and sets the allocation release time 3
04 is stored with the current time.

The network I / F 202 receives or transmits a packet from a network line. When a packet is received, the received packet is stored in the packet buffer 203 via the packet bus 207.
The CPU 204 refers to the IP address assignment table 300, and sets the destination address of the received packet to the IP address 301.
Is obtained, and the packet is transmitted to the corresponding accommodation line I / F 201.

When the accommodated line I / F 201 receives a packet from the accommodated line, the packet is stored in the packet buffer 203 via the packet bus 207, and is stored in the network I / F.
202. In this example, the network I / F 202
There is only one, but when there are a plurality, it is necessary to select a network I / F based on the destination address of the packet, and a routing table for that is stored in the memory 205 as in the IP address assignment table 300.

FIG. 5 shows that the PC 101 is connected to the Internet 10.
7 is a sequence diagram when starting packet communication with a server 504 in FIG. MS1 to which PC 101 is connected
When a packet communication request is transmitted to MS 102
Establishes a communication path to PDSN1 (503) (5
05). When the communication path is established, the MS 102
A path establishment response is transmitted to 101. After that, PC 101
Establishes a PPP link with the PDSN1 (503) using the LCP protocol (506). When the establishment of the PPP link is completed, the PC 101 assigns the IP address used by the PC 101 to the PDSN 1 (50
Ask 3). Thus, the PC 101 can perform IP communication with the server 504 in the Internet. This figure shows an example in which a TCP connection is established (508) between the PC 101 and the server 504 over IP.

FIG. 6 shows a format of an IP packet transmitted and received between the PC 101 and the server 504. The integer value at the top of the format represents a bit number. In the IP packet 600, Version 601 of the first 4 bits is IP
Indicates the version of the header. In this figure, the header format of version 4 is shown.
Coding. IHL 602 indicates the length of the IP header in units of 4 octets. For example, if the IP header has no option 613, the Destination Address 61
Since up to 2 is a header, 5 is coded. Ty
The pe of Service 603 indicates the service quality given to this packet. Total Length 604 indicates the total length of the IP packet in octets. Identification60
Reference numeral 5 denotes information for reconstructing the original data on the receiving side when the data to be transmitted by the PC 101 or the server 504 is divided into a plurality of packets. Flags606
Is used for control when dividing data into a plurality of packets. Fragment Offset 607 indicates the position in the original data when the data is divided into a plurality. Time to Live
608 indicates the remaining time that the packet can exist in the network. Protocol 609 indicates an upper layer protocol of IP, and is 6, for example, in the case of TCP. Header Checksum 610 indicates a checksum of the IP header. Source Address 611 indicates the IP address of the source of the IP packet. Destination Address
612 indicates the destination address of the IP packet. Option
s613 is used to indicate option information not included in the standard header. Option 613 in IP header
May not be included. Padding 614 is for adjusting the length of the IP header to a multiple of 4 octets, and is included when Options 613 does not become a multiple of 4 octets. In the DATA 615, information necessary for an upper layer of the IP is set.

FIG. 7 shows the format of a TCP segment. The integer value at the top of the format indicates a bit number.
source Port 701 indicates the port number of the sending host. D
destination Port 702 indicates the port number of the receiving host. The Sequence Number 703 is data to be transmitted on the TCP connection (DATA 71 of each TCP segment 700).
When the serial number is assigned to each octet, the number of the first octet of DATA 718 in the segment is indicated. Acknowledgment Number
Reference numeral 704 denotes the Sequence Number of the next segment expected to be received when the transmission host of the TCP segment receives data from the communication partner. Data Of
The fset 705 indicates the length of the TCP header in units of 4 octets, and is 5 for a segment that does not include the Options 716, for example. Reserved 706 codes zero. URG 707 indicates whether Urgent Pointer 715 has been set. ACK708 is Acknowledgment Nu
Indicates whether mber 704 is set.

[0027] The PSH 709 receives the T
This bit is for requesting the CP to immediately pass DATA 718 to the upper layer. The RST 710 is a bit for instructing the TCP receiving this segment to reset the connection. SYN 711 is a bit indicating a segment for establishing a TCP connection. FIN 712 is a bit indicating that the segment is for releasing a connection. Wi
ndow 713 indicates that the sending host of this segment is Acknowle
The data amount indicated by dgment Number 704 indicates the amount of data that can be received as the first octet. Checksum 714
Is the checksum of the TCP segment. Urgent P
ointer 715 indicates that the emergency information is DATA 718 of this segment.
When starting with, the data amount is indicated in octets. Options 716 are used to indicate the maximum segment length that can be received. Padding 717 is for adjusting the TCP header to be an integral multiple of 4 octets.

In the DATA 718, necessary information is set in the upper layer.

FIG. 8 shows that the PC 101 and the MS 102 are PDs.
FIG. 11 is a sequence diagram for disconnecting a TCP connection before the movement when moving between SNs. First, PC 101
S102, BTS1 (501), BSC1 (502),
It is assumed that TCP communication has been performed with the server 504 via the PDSN 1 (503). Here, MS 102 is PD
PDS from BTS1 (501) under SN1 (503)
When moving to the BTS2 (801) under the control of the N2 (803), the MS 102 transmits a handoff request to the network and the PDS
The communication path up to N1 (503) is disconnected (804).
The PDSN 1 (503) releases the IP address assigned to the PC 101 (805). MS1
02 is the destination BTS2 (801), BSC2 (80
A communication path to PDSN2 (803) is established via 2) (806). The MS 102 notifies the PC 101 of the completion of establishment, and the PC 101 establishes a PPP link (807), assigns an IP address (808), and establishes a TCP connection (809) with the PDSN 2 (803) to obtain a new IP address. Server 5 using B
04.

On the other hand, the PDSN 1 (503) and the server 50
During period 4, MS 102 used A before moving.
The TCP connection to the IP address and the port p remains. If the server 504 sends a TCP segment to PDSN1 (503) on this connection, PDSN1 (503) makes a decision 810,
In order to release this connection, RST 710 is set to 1 T
The IP packet 600 having the CP segment 700 in the DATA 615 is transmitted to the server 504. As a result, the server 504 sets the TCP for the IP address A and the port p.
The connection can be released (811). In this example, the RST 710 uses one segment, but the FIN 712 may use one segment.

FIG. 9 is a diagram showing the contents of the judgment 810. First, when an IP packet is received from a network line (901), the Destination of the IP packet 600 is received.
Address 612 is the I of IP address assignment table 300
It is determined whether the in-use flag 302 is unused as the P address 301 (902). If the IP packet is being used, the IP packet is sent to the accommodation line indicated by the accommodation line number 303.
PP framing and transmission (913, 91)
4). If the in-use flag 302 is not used in step 902, it is determined whether the upper layer protocol is TCP by looking at the Protocol 609 of the IP packet 600 (90).
3). If it is not TCP, the received packet is discarded (91
1) Then, the process related to the IP packet ends.

If it is determined in step 903 that the upper layer protocol is TCP, the elapsed time since the release of the IP address is obtained from the difference between the current time and the allocation release time 304 of the IP address allocation table 300. It is determined whether the value is greater than the value Td (904). The threshold value Td here is a time when it is considered that the TCP connection has already been independently released by the server 504 when the transmission and reception of the TCP segment are not performed for the time Td or more. If the elapsed time since the release of the IP address is longer than Td, the received packet is discarded (911), and the process ends. If the elapsed time since the release of the IP address is equal to or less than Td in step 904, it is determined whether SYN 711 of the received TCP segment is 1 and ACK 708 is 0 (90).
5). If this is true, this TCP segment is one for which the server 504 is requesting the establishment of a TCP connection, and thus the TCP connection has not been established. Discard the packet (911),
The process ends.

In step 905, the received TCP
When the segment is not a connection establishment request from the server 504, it is considered that the server 504 maintains the TCP connection and has transmitted the TCP segment using the connection. In that case, basically, the RST 710 creates (909) an IP packet including one TCP segment and sends it to the network (91).
0), the server 504 transmits a packet transmitted to the IP address A before the RST 710 receives the 1 TCP segment and disconnects the connection, by the PDS
There is a possibility that N1 (503) receives a plurality of RST packets after transmission, and RST
Since it is useless for 710 to send one TCP segment, processing block 912 suppresses it. The processing block 912 uses the connection management table 400 shown in FIG.

The connection management table 400 includes a mobile terminal IP address 401, a mobile terminal port 402,
Communication partner IP address 403 and communication partner port 404
, Number of received packets after RST transmission 405, and RST transmission time 4
06. Initialization of the connection management table
IP address 301 in IP address assignment table 300
Is in use, the mobile terminal port 402, communication partner IP address 403, communication partner port 404, number of received packets after RST transmission 405, R
This is performed by clearing the ST transmission time 406 to zero.

In the processing block 912 of FIG. 9, first, in order to determine whether or not the same TCP connection segment as the reception segment has been received after releasing the IP address, the connection information (the mobile terminal IP address 401, Mobile terminal port 4
02, communication partner address 403, communication partner port 40
In 4), it is checked whether or not there is one that matches the connection of the received packet (915). If not, as connection information in the connection management table 400, for the mobile terminal IP address 401 that matches the Destination Address 612 of the received packet,
Address 611 is set to the communication partner IP address 403 and DATA
Destination Port of TCP Segment 700 in 615
702 to the mobile terminal port 402 and Source Port 701
Are respectively stored in the communication partner ports 404. Also, RS
A value larger than a certain threshold N is set to the number of received packets 405 after T transmission, and a time Tth before the current time is set to the RST transmission time 406 (916).
Move to step 906.

In step 915, if there is a connection that matches the received packet, the flow directly proceeds to step 906. In step 906, the number of received packets after RST transmission 405 in the connection management table 400 is compared with the threshold value N, and if it is larger than N, the number of received packets after RST transmission 405 is set to zero (908), and the RST 710
Creates an IP packet including a TCP segment of 1 (909). If the number of received packets 405 after RST transmission is smaller than the threshold value N in step 906, the RS
After T transmission, the value of the number of received packets 405 is incremented, and the received packet is discarded without creating a packet with RST 710 of 1 (911).

The threshold value N adjusts the frequency at which the RST 710 transmits one packet. The larger the value of N, the more the transmission of the RST packet to the same connection is suppressed.
In step 909, the RST packet is created as follows. Version 4 is set to 4. 5 is set in IHL602. Type of Service 603 is 1 in binary
Set 1100000. 4 for Total Length 604
Set 0. Flags 606 is set to zero. Fragm
The ent Offset 607 is set to zero. Protocol609
Is set to 6. The Source Address 611 contains the mobile terminal IP address 401 of the connection management table 400.
Set. A destination IP address 403 is set in the Destination Address 612. Options 613, Paddi
ng 614 is not included in the IP header. TC in DATA615
For the P segment 700, the mobile terminal port 402 is set in the Source Port 701. Destination Port
In 702, a communication partner port 404 is set. Sequence
Acknowledgment Nu of the received segment is included in Number703.
Set mber704. Data Offset 705 is set to 5. URG707, ACK708, PSH709, SYN71
1, FIN 712 is set to zero. RST 710 is set to one. Options 716, Padding 717 and DATA 718 are T
Not included in CP segment 700. After creating the RST packet, the packet is sent to the network line (910), the received packet is discarded (911), and the process ends.

Although FIG. 9 has been described as the determination 810 in FIG. 8, it may be FIG. FIG. 10 is the same as FIG. 9 except that the processing block 912 is replaced by a processing block 1012. Processing block 1012
In, steps 1015 and 1016 are the same as steps 915 and 916, respectively. Step 1006
RST transmission time 4 in the connection management table 400
If the difference between 06 and the current time is equal to or greater than threshold value Tth, RS
The current time is set to the T transmission time 406 (1008), and the RST
710 creates an IP packet containing one TCP segment (909). If the difference between the RST transmission time 406 and the current time is smaller than the threshold value Tth in step 1006, the received packet is discarded without creating a packet whose RST 710 is 1 (911). The threshold Tth is
The RST 710 adjusts the frequency at which one packet is transmitted. As Tth increases, the RS for the same connection increases.
Transmission of T packets is suppressed.

As described above, the residual T based on the sequence of FIG.
Having described the CP connection disconnection method, another implementation method is shown in FIG. FIG. 11 is a sequence diagram for disconnecting the TCP connection before the movement when the PC 101 and the MS 102 move between PDSNs as in FIG. 8, but the difference from FIG.
The point is that when the connection is released by the DSN 1 (503), the judgment 1101 is performed, and the reset request is transmitted to all the TCP connections that are not released at that time.

In this method, the PDSN1 (503) needs to manage the TCP connection relating to the PC 101 in advance, and uses the connection management table 400 for that purpose. The usage of the connection management table 400 here is completely different from the usage in FIG. 8, and first, when the PC 101 and the server 504 establish a TCP connection (508) in FIG. Address6
For the mobile terminal IP address 401 that matches 12,
The source address 611 of the received packet is set to the communication partner IP address 403, and the TCP segment 70 in the DATA 615 is set.
0 Destination Port 702 to mobile terminal port 402
Then, the source port 701 is stored in the communication partner port 404, respectively. The number of received packets 405 after RST transmission and the RST transmission time 406 are not used. When the PC 101 and the server 504 release the TCP connection, they are cleared to zero.

The TCP connection is established by SYN7.
The TCP segment 11 is 1 is the PC 101-server 50
It can be recognized by detecting transmission and reception between the four. In addition, connection release is performed by FIN 712.
Can be recognized by detecting the transmission and reception of the TCP segment having a value of 1 between the PC 101 and the server 504. FIG. 12 shows the content of the determination 1101 when the IP address is released while the connection information is stored in the connection management table 400.

In FIG. 12, when release of an assigned IP address occurs (1201), it is determined whether a connection is registered in the connection management table 400 (1202). If it has not been registered, the process ends with the in-use flag 302 of the IP address assignment table 300 unused (1206). If a TCP connection has been registered in step 1202, RST (710) is applied to all registered connections.
Creates a packet containing one TCP segment (120
3) Send to the network line (1204). Thereafter, in the connection management table 400, the mobile terminal IP address 40 corresponding to the released IP address
For 1, the mobile terminal port 402, the communication partner IP address 403, and the communication partner port 404 are cleared to zero (1
205), the in-use flag 302 of the IP address assignment table 300 is set to unused (1206).

[0043]

According to the present invention, the load on the mobile exchange when the IP address is changed due to the movement of the mobile terminal is reduced.

Further, it is possible to re-access a server in which a plurality of simultaneous accesses by the same user are prohibited at a destination in a short time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a mobile packet communication network.

FIG. 2 is a diagram showing the configuration of a mobile switching center for packets.

FIG. 3 is a diagram showing an IP address assignment table.

FIG. 4 is a diagram showing a connection management table.

FIG. 5 is a sequence diagram when the PC 101 starts packet communication with the server 504 in the Internet 107.

FIG. 6 is a diagram showing a format of an IP packet.

FIG. 7 is a diagram showing a format of a TCP segment.

FIG. 8 is a sequence diagram in which, when the PC 101 and the MS 102 move between PDSNs, a TCP connection before the movement is disconnected by using a packet reception from the Internet as a trigger.

FIG. 9 is a flowchart when the PDSN 105 receives an IP packet from a network line in FIG. 8, and illustrates a case where the transmission interval of the TCP RST segment is controlled by the number of received packets.

FIG. 10 is a flowchart when the PDSN 105 receives an IP packet from a network line, and shows a flowchart in the case where the transmission interval of the TCP RST segment is controlled by time.

FIG. 11 is a sequence diagram in which, when the PC 101 and the MS 102 move between PDSNs, the release of the IP address is used as a trigger to disconnect the TCP connection before the movement.

FIG. 12 is a flowchart when an IP address is released in FIG. 11;

[Explanation of symbols]

101 PC, 102 MS, 105 PDSN, 10
7 Internet, 300 IP address assignment table, 400 Connection management table, 600 IP
Packet, 700 TCP segment, 708 AC
K, 710 ... RST, 711 ... SYN.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H04Q 7/26 7/30 (72) Inventor Tetsuhiko Hirata 1099 Ozenji Temple, Aso-ku, Aso-ku, Kawasaki-shi, Kanagawa Hitachi, Ltd. Inside the System Development Laboratory (72) Inventor Shoji Fukuzawa 1099 Ozenji Temple, Aso-ku, Kawasaki City, Kanagawa Prefecture Inside the Hitachi System Development Laboratory Company (72) Susumu Matsui 1099 Ozenji Ozenji, Aso-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor ▲ Taka ▼ Yosuke Hashi 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Communication Systems Division, Hitachi, Ltd. 5K030 GA03 HA08 HC09 HC14 HD05 HD06 JL01 JT09 5K033 CC01 DA05 DA19 EC03 5K067 AA11 BB21 CC08 DD11 DD26 EE02 EE10 EE16

Claims (8)

[Claims] 1. A mobile packet communication network in a mobile packet communication network in which a plurality of mobile terminals perform radio communication with a plurality of radio base stations connected to the mobile exchange and perform packet communication with an IP network via the mobile exchange. Dynamic assignment means for dynamically assigning an IP address to a mobile terminal that performs packet communication via the mobile exchange; and address assignment for determining whether a destination address of a packet received from the IP network has been assigned to the mobile terminal. State determination means, TCP determination means for determining that the content of the data portion of the received packet is a TCP segment, and disconnection instruction segment creation means for disconnecting the TCP connection indicated by the received TCP segment, The destination address of the packet received from the network is not assigned to the mobile terminal, and If the contents of over data unit is TCP segment, residual TCP disconnection method characterized by creating a disconnection instruction segments for cutting the TCP connection indicated by the TCP segment, and transmits to the IP network. 2. The mobile switching system of the mobile packet communication network, wherein a plurality of mobile terminals perform wireless communication with a plurality of radio base stations connected to the mobile switching system and perform packet communication with an IP network via the mobile switching system. Dynamic assigning means for dynamically assigning an IP address to a mobile terminal that performs packet communication via the mobile exchange; and when a data segment of a packet transmitted and received between the mobile terminal and the IP network is a TCP segment, TC that analyzes the TCP segment and manages the TCP connection state
P connection management means and disconnection instruction segment creation means for disconnecting a TCP connection are provided, and when the assignment of an IP address to a mobile terminal is canceled, the T
If there is a CP connection, the TC
A method for disconnecting a residual TCP connection, comprising creating and transmitting a disconnection instruction segment for disconnecting a P connection. 3. The residual TCP connection disconnection method according to claim 1, wherein the disconnection instruction segment is a TCP segment in which an RST bit of a control flag in a TCP header is set to 1. The remaining TCP connection disconnection method. 4. The residual TCP connection disconnection method according to claim 1, wherein the destination address of the packet received from the IP network is not assigned to the mobile terminal, and the content of the data portion of the packet is TCP. If the TCP segment is a segment indicating a request to establish a TCP connection, the disconnection instruction segment for disconnecting the TCP connection indicated by the TCP segment is set to IP.
A method for disconnecting a residual TCP connection, wherein the method does not transmit to a network. 5. The residual TCP connection disconnection method according to claim 4, wherein the SYN flag of the control flag and the ACK flag of the TCP segment included in the packet received from the IP network are 0. To the TCP segment
A method of disconnecting a residual TCP connection, which is determined to be a segment indicating a connection establishment request. 6. The method for disconnecting a residual TCP connection according to claim 1, wherein the mobile switch measures an unassigned time of an IP address not assigned to a mobile terminal. IP address free time measuring means, and TC for storing the time from when the TCP segment is no longer received until the TCP connection is deemed to have disappeared.
If the IP connection free time becomes equal to or longer than the TCP connection deemed time, a TC to the IP address is provided.
A method for disconnecting a residual TCP connection, wherein a disconnection instruction segment for disconnecting a TCP connection indicated by the received TCP segment is not transmitted to an IP network even when a P segment is received. 7. The method for disconnecting a residual TCP connection according to claim 1, wherein the source of a received packet whose disconnection instruction segment is to be transmitted to an IP network is transmitted to the mobile switching center. TCP connection storage means for storing the address, source port, destination address, and destination port, and counting of packets having the source address, source port, destination address, and destination port stored in the TCP connection storage means A packet count unit on the disconnected connection, and an interval packet number storage unit for storing the interval value of the transmission of the disconnection instruction segment by the number of packets, when the value counted by the packet count unit on the disconnected connection reaches the number of interval packets. To send the disconnect instruction segment Residual TCP disconnection process, characterized by. 8. The method for disconnecting a residual TCP connection according to claim 1 or 3, or 4 or 5 or 6, wherein a source of a received packet whose transmission instruction segment is to be transmitted to an IP network to the mobile exchange. A TCP connection storage unit that stores an address, a source port, a destination address, and a destination port; a TCP connection storage unit that measures an elapsed time after transmitting the disconnection instruction segment; Interval time storage means for storing the interval value of the instruction segment transmission in time is provided, the destination address of the packet received from the IP network is not assigned to the mobile terminal, and the content of the data portion of the packet is a TCP segment. And the elapsed time after the transmission of the disconnection instruction regarding the TCP connection indicated by the TCP segment If the value measured by the measurement means exceeds the value stored in the interval time storage means, a disconnection instruction segment for disconnecting the TCP connection indicated by the TCP segment is created and transmitted to the IP network. The remaining TCP connection disconnection method.