JP2001230816A - Mobile ip visitor list eliminating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of a conventional mobile IP visitor list eliminating method that has uselessly maintained a resource such as a memory because a terminal is left registered in an FA visitor list although no IP packet communication is made after interruption of a PPP even when the PPP is interrupted without registration release of a mobile IP by the terminal. SOLUTION: In the case that a channel I/F (201) contained in a PDSN (105) detects interruption of an IP low-order layer connection, the I/F (201) eliminates a terminal address (401) of a terminal which has used the connection from a visitor list (400).

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,
In particular, it relates to packet communication on mobile communication.

[0002]

2. Description of the Related Art IM which is a third generation mobile phone system
Standardization of T-2000 is an international organization 3GPP, 3GPP
Under two. In IMT-2000, a mobile terminal can perform packet communication with an IP network via an IMT-2000 network. In the system under consideration in 3GPP2, PDSN (Packet Data Serving Node) is sent from the terminal.
Is connected by PPP to the packet exchange called
By using the DSN as a router, packet communication with the IP network is realized. The IP address of a mobile terminal can be fixedly assigned to the terminal or dynamically assigned each time the terminal connects to the IMT-2000 network. In the former case, the Internet Engineering Task Force (IETF) defines the IP address. It is assumed that mobile IP (RFC2002) is used.

[0003] Mobile IP is a protocol for allowing a terminal such as a PC to freely move between subnets in an IP network without changing the IP address. If the subnet to which the terminal is originally connected is called a home network and the other subnets are called an external network, a home agent (HA) is assigned to the home network and a foreign agent (F) is assigned to the external network.
A) is provided. The HA and the FA periodically notify their IP addresses in the subnet where they are located so that the terminals themselves can detect the movement of the terminals between subnets. Upon detecting the movement, the terminal notifies the FA of its own IP address and HA address, and the FA requests the HA of the terminal to transfer the IP packet addressed to the terminal to the FA (movement registration). Thereby, the IP address for the terminal arriving at the home network
The terminal can receive the packet on the external network. That is,
After the HA performs proxy reception on the home network, the HA sets them in a packet addressed to the FA and transfers the packet to the FA. The FA extracts a packet addressed to the terminal from the received packet and transfers it to a terminal in the subnet. The period (lifetime) during which a series of these transfer procedures is applied to packets addressed to terminals arriving at the home network
Is determined by the HA at the time of transfer registration, and is notified to the FA and the terminal. During the lifetime, the FA registers the terminal's IP address in a list called a visitor list,
Is used to determine whether the packet addressed to the terminal received from the terminal is transmitted into the subnet or discarded by the FA. The IP address of the terminal is deleted from the visitor list when the lifetime has expired and when the terminal has performed mobile registration with the lifetime value set to zero (deregistration).

In the IMT-2000, a PDSN is provided with an FA function. The HA is located in a terminal having an IMT-2000 network as a home, but the terminal is in the other network.
It may exist on a network or a fixed IP network. Same P
Terminal movement between radio base stations (BTS) under DSN is as follows:
It is managed by mobility management specific to the mobile communication network.
The inter-movement is managed by mobile IP. When a terminal starts packet communication, it first establishes a PPP connection with the PDSN, and then performs mobile registration. The PPP is disconnected when the terminal actively requests the disconnection. However, the PPP is also disconnected when the IP packet has not been transmitted / received for a certain period of time, or when there is a communication failure due to radio abnormality. When the terminal actively requests the disconnection, the terminal cancels the registration in advance, so that the IP of the terminal can be obtained from the visitor list in the FA.
The address can be deleted.

[0005]

When the PPP is disconnected without the terminal deregistering, the terminal is registered in the FA visitor list despite the fact that no IP packet communication is performed after the disconnection. As a result, resources such as a memory are continuously wasted.

[0006]

A plurality of mobile terminals perform wireless communication with a plurality of wireless base stations connected to a mobile switching system, and perform packet communication with an IP network via the mobile switching system using a mobile IP protocol. Lower layer connection disconnection detecting means for detecting a disconnection of a protocol existing under IP in a section from a mobile terminal to a mobile exchange in a mobile exchange having a mobile IP foreign agent of a mobile packet communication network. If the connection disconnection is detected by the IP lower layer connection disconnection detecting means, the IP address of the mobile terminal that has been performing packet communication on the connection is deleted from the visitor list of the foreign agent.

[0007] Alternatively, the mobile exchange is provided with a timer for measuring an elapsed time from the detection of the disconnection of the IP lower layer connection, and when the time measured by the timer exceeds a threshold value T, Delete the mobile terminal's IP address.

[0008]

An embodiment of the present invention will be described below.

FIG. 1 shows the configuration of a mobile packet communication network 100 under development in IMT-2000. 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 one or a plurality of BSCs 104. MS1
From 02 to PDSN 105, a connection-oriented communication path is set up, and IP packets are transmitted and received on the path. Therefore, in this section, IP routing based on the header information of the IP packet is not performed. Meanwhile, PD
Since IP routing is performed from the SN 105 to the GW 106 and the Internet 107, a global IP address is assigned to each PDSN. Also PDS
N105 terminates the PPP from the PC 101, and transmission and reception of IP packets in this section are performed on the PPP connection. The GW 106 is a gateway to the Internet 107 of the mobile packet communication network 100. The GW 106 connects to a plurality of PDSNs 105. Internet 107
Has a subnet 112 to which the PC 101 is originally connected.
(Home Agent) 111 exists. Note that the PC 101 in this example is a subnet 1 outside the IMT-2000 network.
12 is the home network, but the IMT-2000 network 10
In the case of a PC whose home network is 0, an HA exists in the IMT-2000 network 100. In this case, HA is PDSN1
05, it is necessary to connect with GW106.

The PC 101 is MS102, BTS103,
IP packet communication can be performed with a server on the Internet 107 via the BSC 104, PDSN 105, and GW 106. The MSC 108 is a mobile switch for circuit switching, and is connected to the HLR 110. GMSC
Reference numeral 109 denotes a gateway exchange for circuit switching, which is an IMT-20.
The 00 network 100 is connected to another circuit switching network via this. The HLR 110 manages location information for calling the MS 102 when a packet addressed to the PC 101 is routed from the Internet 107 to the PDSN 105 by mobile IP. When an IP packet arrives at the PDSN 105 from the Internet 107, the BSC 1 under the BSC 1 obtains the identification number of the MS 102 from the destination address.
04, and sends an incoming call request. BSC 104 is MSC10
8 is notified of the identification number of the MS 102, and the MSC 108
The LR 110 is searched, and the MS 102 is paged 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. PC 101 is then PDSN 10
Establish up to 5 PPP connections.

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 GW 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 them, and a control bus 20
Consists of six. The accommodation line I / F 201 controls a communication path setting protocol on the accommodation line and performs PPP control. PP
In the P control, the IP of the PC 101 received from the PC 101
The address is notified to the CPU 204 via the control bus 206, and the CPU 204 stores the PP stored in the memory 205.
Register in the P-IP address management table. FIG. 3 shows the PPP-IP address management table 300.

[0013] PPP-IP address management table 300
Is an IP address 301 of the PC 101 and an accommodation line number 3 indicating which accommodation line the PC 101 is accommodated in.
02.

When a PPP connection is established, the CPU 204
Stores the IP address 301 of the PC 101 and the accommodation line number 302 in an unused column (indicated by “-” in the figure) in the PPP-IP address management table 300.

When the accommodating line I / F 201 notifies the CPU 204 of the disconnection of the PPP connection due to factors such as the end of packet communication, the CPU 204 reads the corresponding IP address 30 from the PPP-IP address management table 300.
1 and the accommodated line number 302 are deleted.

The network I / F 202 receives or transmits packets 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 controls the PPP-IP address management table 30
0, the accommodation line number 302 is obtained from the destination address of the received packet, and the corresponding accommodation line I / F 20
1 is transmitted. However, the destination address of the packet received from the network line is PDSN10.
5, if it is an encapsulated packet, it is determined whether the destination address of the IP packet in the encapsulated packet has been mobile-registered by the Mobile IP protocol, and only when the packet has been registered, the PPP-I
The P address management table 300 is referred to. The determination as to whether or not the movement has been registered is made by searching for a visitor list stored in the memory 205. FIG. 4 shows visitor list 4
00 is shown.

The visitor list 400 has the terminal address 40
1, HA address 402, lifetime 403, remaining time 404, and deletion waiting time 405. The terminal address 401 is the IP address of the PC 101 to be registered when the mobile IP mobile registration is successful. The HA address 402 is the IP address of the HA of the PC 101. The lifetime 403 is a time for maintaining the registration, and stores a value notified from the HA when the mobile registration is successful. The remaining time 404 indicates the remaining time for maintaining the registration.
, The corresponding terminal address 401, HA address 402, lifetime 403, and remaining time 404 are deleted. The initial value of the remaining time 404 is the value of the lifetime 403, and the value is periodically reduced as time passes. The deletion wait time 405 is set when the disconnection of the PPP connection is detected, and is reduced as time elapses. When it reaches zero, the corresponding terminal address 401,
HA address 402, lifetime 403, remaining time 40
4. The deletion waiting time 405 is deleted.

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 interface.
202. In this example, the network I / F 202
Is only one, but if there is more than one, it is necessary to select a network I / F based on the destination address of the packet, and the routing table for that is
Like the IP address management table 300, it is stored in the memory 205.

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 notifies its own IP address to the PDSN 1 (503) by the IPCP protocol (507). When a PPP connection is established, P
DSN1 (503) sends the IP address of PDSN1 (FA) to PC 101 as part of the mobile IP protocol.
Is notified (508). The PC 101 transmits a move registration request message addressed to the FA (509). FIG. 6 shows the format of the move registration request message.

The mobile registration request message 600 is an IP packet having a UDP segment.

The IHL 601 indicates the length of the IP header in units of 4 octets, whereby the start position (Source port 604) of the UDP header can be determined. Source Address
602 is a source IP address of the IP packet,
When the PC 101 transmits this message, the PC 101
Is set. Destination Address 603
Is the IP address of the destination of the IP packet, and the address of the FA is set.

Source Port 604 is a UDP port number assigned by the transmission source. Destination Port 605 is the UDP port number of the destination.
A value = 434, which means that the protocol is used, is set. Length 606 indicates the total length of the UDP segment in octets. Checksum 607 is a checksum for detecting a transmission error of the UDP segment. Type60
8 and thereafter are UDP data portions, in which information for mobile IP is set. Type 608 indicates what kind of message of the mobile IP, and 1 is set for a mobile registration request. Li
fetime 609 indicates the registration validity period desired by the PC 101 in seconds. Home Address 610 is the IP address of PC 101. Home Agent 611 is HA1 of PC 101
11 IP addresses. Care-of Address 612
Is an IP address that is a destination when the HA 111 encapsulates a packet addressed to the PC 101 and transmits the packet.
The PC 101 sets the address of the FA notified by the FA address notification (508) in FIG.

In FIG. 5, when the PDSN 1 (503) receives the move registration request (509), the PDSN 1 (503)
me Agent 611 is the Destination Address 6 in the IP header.
03, the IP address of PDSN1 is set in Source Address 602, and a transfer registration request in which 434 is set in Source Port 604 is transmitted to HA 111 (51).
0). When HA 111 receives the mobility registration request from PDSN 1 (503), Home Address 610 in the message is received.
, And a set of Care-of Address 612 and Lifetime 609 is internally stored, and a transfer registration response is transmitted to PDSN1 (503) (511).

At this time, if the value of the Lifetime 609 is too long as the registration maintenance period in the HA, a smaller value can be stored. FIG. 7 shows the format of the move registration response message.

The mobile registration response message 700 has substantially the same format as the mobile registration request message 600,
708 is set to 3 indicating that this is a mobile registration response, and Co
Set a value indicating whether registration was successful or unsuccessful in de712,
me709 sets the value determined by the HA. When the HA sends a movement registration response to the PDSN1, the Source Address 70
2 sets the address of the HA, and Destination Address 703 sets the address of PDSN1.

In FIG. 5, PDSN1 (503) is H
When the mobile registration response is received from A111, it is determined whether registration has been permitted in the HA by referring to Code 712 in the message. If the code is a successful registration, Home Addre
It searches whether ss710 (IP address of PC 101) is already registered as terminal address 401 of visitor list 400. If not registered, leave blank in the list
Home Address 710, Home Agent 711, Lifetime 70
9 is set to the terminal address 401, the HA address 402, and the lifetime 403, respectively. Remaining time 404
Is set to the same value as the lifetime 403. If the Home Address 710 already exists in the visitor list 400, a value similar to the above is set in the corresponding column. Also, the deletion waiting time 405 is cleared because it may be set. Thereafter, PDSN1 (503) transmits a mobile registration response to PC 101 (512). Source Add at this time
ress702 is the IP address of PDSN1, Destination
Address 703 is the IP address of PC 101, Source Po
rt 704 is 434, Destination Port 705 is PC10
1 is Source Port 60 of the move registration request message 600
Set the value set to 4. When the PC 101 receives the mobile registration response from the PDSN 1 (512), it becomes possible to freely perform IP communication with the server 504 in the Internet 107.

When the PC 101 transmits an IP packet to the server 504, the IP address of the server 50 is used as the destination IP address.
4 is set and transmitted. Server 504 is PC
101, the PC 1 is used as the destination address.
01 is routed to the home subnet 112 of the PC 101 in order to set and transmit the address.
111 encapsulates the packet in a packet addressed to PDSN1 (503) and transmits it to PDSN1 until the lifetime expires. PDSN1 (503) extracts the contents of the packet received from the HA, and
If it is a packet addressed to 1, the packet is transmitted to the PC 101. Even when an IP packet is transmitted from the PC 101 to the server 504, a method of encapsulating a packet addressed to the HA by the FA (PDSN1) and transmitting the contents packet to the server by the HA is also defined as a mobile IP ( RFC2344; Reverse Tunneling for Mobile I
P), there is also a method using this. In this case, PDSN1
In (503), the source address of the packet received from the PC 101 is set to the terminal address 401 of the visitor list 400.
, And obtains the HA address 402, sets the received packet in the data portion of the IP packet addressed to the HA address 402, and transmits it to the HA.

FIG. 8 is a sequence diagram when the information of the PC 101 is deleted from the visitor list 400 according to the present invention. When the PC 101 is communicating with the server 504, the PD
When the accommodated line I / F 201 of the SN 1 (503) detects the disconnection of the PPP, the accommodating line number 302 and the IP address 301 that have detected the disconnection are deleted from the PPP-IP address management table 300 (80).
1) further searches the visitor list 400 using the deleted IP address as a key, and sets a value T in the corresponding deletion waiting time 405 (802). T decreases periodically, and when it becomes zero (803), information such as the corresponding IP address 401 is deleted from the visitor list 400 (8).
04).

Thereafter, if the PC 101 attempts to perform packet communication again, the PPP connection is established and the mobile registration is newly performed as shown in FIG. 5, so that the data of the visitor list 400 is deleted when the PPP disconnection is detected. No problem at all. In addition, PDS can be deleted by deleting unnecessary data.
It is possible to increase the number of terminals that can receive the mobile registration in N1. On the other hand, if the PC 101 tries to perform packet communication before the deletion waiting time 405 becomes zero, the column for the PC 101 is set in the visitor list 4 in advance.
00, the service is not rejected because there is no free area in the visitor list 400.

FIG. 9 shows PDSN1 when PPP disconnection is detected.
It is a flowchart of FIG. When the disconnection of the PPP connection is detected (901), an IP address 301 is obtained from the accommodating line number 302 in the PPP-IP address management table 300 where the disconnection is detected (902). After that, the IP address 301 and the accommodation line number 302 obtained from the PPP-IP address
Delete from the IP address management table 300 (90
3). Further, the IP address obtained earlier is searched in the visitor list 400, and the value T is set to the corresponding deletion waiting time 405 (904). The value T is periodically reduced, and when it becomes zero, the terminal address 401, the HA address 402, and the lifetime 40 are read from the visitor list 400.
3. The remaining time 404 is deleted (905).

[0031]

According to the present invention, it is possible to reduce waste of resources such as memories in the PDSN.

[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 a PPP-IP address management table.

FIG. 4 is a diagram showing a visitor list.

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 a move registration request message.

FIG. 7 is a diagram showing a format of a movement registration response message.

FIG. 8 is a sequence diagram when a PPP connection is disconnected when the PC 101 performs packet communication with a server 504 in the Internet 107.

FIG. 9 shows that in FIG. 8, PDSN1 (503)
FIG. 4 is a diagram illustrating a flowchart when a disconnection is detected.

[Explanation of symbols]

101 PC, 105 PDSN, 201 accommodation line I
/ F, 400: visitor list, 401: terminal address,
405: deletion waiting time, 600: transfer registration request message, 700: transfer registration response message.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K030 HA08 HC01 HC09 JL01 JT09 LA08 LC18 5K067 AA41 BB21 CC08 DD13 EE02 EE16 HH11 HH32 9A001 CC07 JJ12 KK56 LL09

Claims (2)

[Claims] 1. A mobile packet in which a plurality of mobile terminals perform wireless communication with a plurality of wireless base stations connected to a mobile switch, and perform packet communication with an IP network using the mobile IP protocol via the mobile switch. In the communication network, the mobile exchange having a mobile IP foreign agent is provided with an IP lower layer connection disconnection detecting means for detecting a disconnection of a protocol existing under IP in a section from the mobile terminal to the mobile exchange, A mobile IP visitor, wherein when a connection disconnection is detected by an IP lower layer connection disconnection detecting means, an IP address of a mobile terminal that has been performing packet communication on the connection is deleted from a visitor list of the foreign agent. How to delete a list. 2. The mobile IP visitor list deletion method according to claim 1, wherein said mobile switching center is provided with a timer for measuring an elapsed time after detecting a disconnection of an IP lower layer connection, And deleting the IP address of the mobile terminal when the time measured by (1) exceeds a threshold value (T).