Method of operating a mobile telecommunications network

[0001] [Technical field to which the invention belongs] The present invention relates to a method of operating a mobile communication network, and more particularly to a method of assigning an address to a packet directed to a mobile node in a foreign network. [0002] [Conventional technology] In 3rd generation communication networks such as GPRS (General Packet Radio Service) and EDGE (Enhanced Date-rate for GSM Evolution), when a mobile node enters the holoin network, the network connectivity becomes mobile Internet protocol. Maintained by using (Mobile IP). On the other hand, in the home network, a home agent (HA) is set up and the location information of the mobile node is obtained by the binding update technique, that is, the registration of the information sent into the HA by the mobile node. To hold. [0003] Mobile IP has two modes of operation. The first mode is shown in FIG. The mobile node is held as mobile node 14 (MN14) in a network different from its own home network. The mobile node (MN) 14 is communicating with the corresponding node 12. Corresponding node (CN) 12 sets the home agent (HA) 16 in its home network and the holoin agent (FA) 18 in the holoin network. The holloin agent 18 assigns a unique IP address, that is, a Care of Address (CoA), to a mobile node that has entered the holloin network. This address is sent to Home Agent 16 using the association information update technique. [0004] Packets destined for the mobile node are encapsulated by the home agent 16 and passed through the holoin agent 18 along the tunnel 20 and further sent to the mobile node 14. In such an encapsulation process, an extra IP header containing the care of address of mobile node 14 is added to each packet. This is known as the FA-COA operating mode. [0005] In the second mode of operation, FA18 does not exist. The mobile node 14 is assigned its own COA, and the encapsulated packet passes through the home agent 16 and directly enters the mobile node 14 (without going through the FA). This is known as the Colocated Care of Address mode of working (CO-COA). [0006] In both FA-COA and CO-COA modes, the encapsulation process requires extra headers and shortens the payload. As a result, transmission efficiency is reduced and the use of expensive system and network resources, such as wireless links, is inefficient. Furthermore, this encapsulation process hides the flow identification and makes service class differences impossible. As a result, the mechanisms that provide quality of service (QoS), such as RSVP (Resoure reSerVation Protocol) Int Serve, must be modified. [0007] Such drawbacks of encapsulation can be avoided by using non-encapsulation Mobile IP technology. This is disclosed in the applicant's European patent application No. 99301437.2. (Filing date: February 26, 1999, title of invention: Non-encapsulation Mobile IP). In this technique, the current CoA of the mobile node is used as the destination address and the original source address or CN address is retained. In FA-COA mode, this allows you to remove headers that are at least 20 bytes long, introduces only 2 bytes of headers, and does not introduce headers in CO-COA mode. The downside, however, is that firewalls or exit filtering in your home network will reject such packets. The reason is that they have a different source address than the home network address. [0008] [Problems to be Solved by the Invention] An object of the present invention is to solve the drawbacks of the prior art and to provide a new packet addressing method capable of providing QoS. [0009] [Means for solving problems] The present invention has the features described in claim 1. That is, the operation of the 3rd generation mobile communication system in which the packet is addressed to the mobile node (MN, 28) that is currently associated with the holoin network and communicates with the corresponding node (CN, 24). In the method (A) The step of setting the home agent (HA, 26) in the corresponding node (24) and assigning the care-off address (CoA) to the mobile node (22), (B) The source address of the packet header is the home agent (HA) address, the destination address is the care of address (CoA), and the corresponding node identification code (CNID, 40) and the mobile node identification code (MNID, 42). It is characterized by having a step of changing the packet header so as to include. The home agent usually modifies the packet header. [0010] BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 2a, the mobile node 28 has a hololive agent 30. Corresponding node 24 has a home agent 26. Figure 2a shows the FA-COA mode. Figure 2b shows the CO-COA mode. Therefore, there is no FA and the packet goes directly to the mobile node 28. [0011] Compared to FIG. 1, FIGS. 2a, 2b do not have a tunnel from the home agent 26 to either the holoin agent 30 or the mobile node 28. [0012] In Figure 3a, the packet is still addressed to the mobile node in the holoin network, and this packet is the source address 32 as the IP address of the corresponding node 24 and the mobile node (MN) as the home address 34. It has the home address of the mobile node 28. Figure 3a also shows the payload 38 and the other fields 36. [0013] In FIG. 3b, in the header according to the present invention, the source address 32 is the address of the home agent (HA) 26, and the home address 34 of the mobile node (MN) is the COA of the mobile node (MN) 28. The header has two new fields, CNID40 and MNID42, which contain the identifier ID of the corresponding node 24 and the identifier ID of the mobile node 28, respectively. [0014] When the network is operating in FA-COA mode, as shown in Figure 2a, the holoin agent 30 receives the readdressed (readdressed) packet, and the FA30 uses the MNID42 to separate. Distinguish from the mobile node of, using its FA30 at the same time, and the packet is delivered to the mobile node 28. [0015] When the re-addressed packet is received by the holoin agent 30 (FA-COA mode in FIG. 2a) or directly by the mobile node 28 (CO-COA mode in FIG. 2b), the CNID 40 is FA. 30 or MN28 uses it to retrieve the original source address, that is, the address of the corresponding node 24. The holoin agent 30 or mobile node 28 then recalculates the checksum of the packet and distributes it to the application. [0016] Next, considering CNID40, this unique identifier is assigned by the home agent 26 as soon as it detects a packet addressed to the address of the mobile node. Home agent 26 adds an entry to the address mapping table for CNID40 and CN24. This is maintained by Home Agent 26. The home agent 26 then sends the CNID 40 and the corresponding CN24 IP address to the holoin agent 30 (in FA-COA mode) or to the mobile node 28 (in CO-COA mode). At that time, a registration response message or another CNID notification message is used. [0017] When CNID40 is received by the holoin agent 30 or mobile node 28, an entry is added to the CNID40 to CN24 IP address mapping table, which is maintained by FA30 or MN28. [0018] Information about MN28 and MNID42 will be exchanged as well. [0019] When each packet destined for mobile node 28 arrives at home agent 26, HA26 examines the Smapping table of CNID40 and CN address to find the CNID40 that corresponds to the source address of the packet. HA26 then replaces the original source address with the HA address and the destination address with the COA of the mobile node 28. The home agent 26 adds CNID40 and MNID42, adjusts the checksum of the packet, and sends the packet. [0020] When the packet arrives at the holoin agent 30 or mobile node 28, it examines the CNID to CN table, replaces the source address of home agent 26 with the actual address of the corresponding node 24, and replaces the destination address with the home address of the mobile node. Replace with. In FA-COA mode, check the table from MNID to MN. Adjust the checksum and distribute the packet to mobile node 28 (in FA-COA mode) or to the application (in CO-COA mode). [0021] [0021] The CNID and MNID formats are so short and simple that the added fields do not significantly increase the header length. [0022] The method of assigning a header of a packet of the present invention to a mobile node in a holoin network has a short header and a long payload, as described in the above-mentioned patent application (No. 99301437.2). Since the HA address is used as the source address, problems that occur during exit filtering caused by using a source address different from the home network address can be avoided. Since the destination address is returned before the packet is distributed, the application to which the packet is distributed does not need to be rebuilt, and it is possible to avoid stopping or restarting the application. [0023] Yet another advantage of the present invention is that it is not necessary to change only the source and destination addresses of the header and other information, such as the information that identifies the traffic flowing from the home agent 26 to the current COA of the mobile node 28. Therefore, standard QoS, such as RSVP, can be applied without changing the QoS service to the mobile node. [0024] The QoS session will be described below using RSVP as an example. [0025] In FIG. 4, the corresponding node 24 and the mobile node 28 are related to the home network 50, and the mobile node 28 and the holoin agent 30 are related to the holoin network 52. RSVP sessions are configured as two parts: session 1 and session 2 in the figure. Session 1 runs between the corresponding node 24 and the home agent 26, and session 2 runs between the home agent 26 and the mobile node 28. [0026] Session 1 is set up as a normal RSVP session in a non-mobile environment and has a path message sent from the corresponding node 24 to the home agent 26. The difference in the configuration of the present invention is from the home agent 26 to the corresponding node 24. The return RESV message is that it will not start until the session is complete. [0027] Session 2 covers the mobile node 28 and is dynamically applied as the mobile node moves from one network to another. [0028] When the home agent 26 receives a PATH message from the mobile node 28 such that the source and destination addresses are the corresponding node 24 and the mobile node 28, respectively, the home agent 26 intercepts the packet and sends the PATH message to the RSVP proxy server. Corrects or regenerates the path message by readdressing the packet. Packets pass through several nodes or network routers (routers 54, 56 in the figure). The PATH message is a terminal-to-terminal message. The proxy server is attached to or independent of the home agent 26. [0029] In the holoin network 52, the foreline proxy server, or the server equivalent to that in the mobile node 28 or the holoin agent 30, uses the COA address of the mobile node 28 as the source address and has the HA destination address depending on the operation mode. Prepare a message. This message contains flow identification information such as protocol ID and source / destination port number, and the message is shipped. The RESV message is routed as a path message through the same routers 54 and 56 for each hop, but in the opposite direction, the source address and destination address for each hop are appropriately changed by the routers 54 and 56. [0030] When the RESV message is received by the home agent 26 or an equivalent server such as the home network proxy server, the RESV message is modified or replayed with the home address of the mobile node 28 as the source address and the corresponding node 24 as the destination address. That is, session 2 is completed. Session 1 RESV messages are sent in the traditional way. [0031] When the corresponding node 24 or the home network proxy server receives the RESV message, the request sends back a RESV confirmation message to confirm the entire RSVP session. [0032] Port crash avoidance control is required for session 2 of the RSVP session to compensate for flow-specific identification and to differentiate this class of services when the mode of operation is FA-COA. And a known technique is applied. [0033] If there is a number in parentheses after the constituent requirements of the invention in the claims, it is intended to make the invention easier to understand by associating the constituent requirements with the examples, and is used to interpret the claims. It shouldn't be. [Simple explanation of drawings] FIG. 1 is a diagram showing a mobile communication network in a conventional FA-COA operation mode. FIG. 2 a: A diagram showing a mobile communication network of the present invention operating in FA-COA mode. b: The figure which shows the mobile communication network of this invention operating in CO-COA mode. FIG. 3 a: A diagram showing a packet header format according to the prior art. b: The figure which shows the packet header format which concerns on this invention. FIG. 4 is a diagram representing an RSVP session. [Explanation of symbols] 12 Supported nodes 14 Mobile node 16 Home Agent 18 Holloin Agent 20 tunnel 24 Corresponding node 26 Home Agent 28 mobile node 30 Holloin Agent 32 source address 34 MN home address 36 Other fields 38 Payload 40 CNID 42 MNID 50 home network 52 Holloin Network 54, 56 routers