CN101521622A - Method and device for determining maximum transmission unit - Google Patents

Abstract

The invention discloses a method for determining a maximum transmission unit, pertaining to the technical field of communication and comprising the following steps of: determining a target access network of a mobile node, and determining the maximum transmission unit of the mobile node in accordance with the target access network and according to the negotiation result of the maximum transmission unit of the mobile node. For instance, during the transportation process of the mobile node among different access networks, according to the negotiation result of the maximum transmission unit of the mobile node between the service access network and the target access network, the maximum transmission unit of the mobile node is determined. For another instance, during the transportation process of the mobile node among different access networks, according to the negotiation result of the maximum transmission unit of the mobile node between the service access network and the home agent, the maximum transmission unit of the mobile node is determined. The technical proposal reduces service response time and raises the service response speed.

Description

Method and device for determining maximum transmission unit

technical field

The invention relates to the technical field of network communication, in particular to a method for determining a maximum transmission unit and a device for determining a maximum transmission unit.

Background technique

Maximum Transmit Unit (Maximum Transmission Unit, MTU) specifies the maximum length of the message that the IP layer and the upper layer allow to send. The MTU is related to a specific physical link, and each node can be configured with an MTU.

The MTU of a node has many functions. For example, when the source node sends a data message, it needs to determine the size of the data message according to the MTU to fragment the data message; The MTU of the node establishes the tunnel between the source end node and the destination end node, etc. The MTU actually set by the source node should not exceed the path MTU (Path MTU, PMTU). If the MTU of the source node exceeds the MTU of the nodes in the data transmission path, that is, exceeds the PMTU, the data packet will be discarded.

The source end node can obtain its MTU according to the default setting or learning method. When the source node sends a data packet according to its MTU, and the size of the data packet exceeds the MTU of a node in the data transmission path, the source node can learn the MTU according to the information returned by the node, and renew the MTU according to the learned MTU. Send datagram.

In the process of realizing the present invention, the inventor finds that: Mobile Node (mobile node, MN) may migrate between different access networks, and the migration of the access network may cause the MTU of the MN to change. However, in the current In the technical solution, after the migration of the MN, the MTU before the migration is still used, which will cause the data packets sent by the source end node to be discarded, the source end node to re-learn the MTU, and re-establish the tunnel between the source end node and the destination end node And other problems, ultimately delaying the business response time.

Contents of the invention

The embodiment of the present invention provides a method and a device for determining the maximum transmission unit, which shortens the service response time and improves the service response speed.

The method for determining the maximum transmission unit provided by the embodiment of the present invention includes:

Determine the target access network of the mobile node, and determine the maximum transmission unit of the mobile node according to the negotiation result of negotiating the maximum transmission unit of the mobile node for the target access network.

The device for determining the maximum transmission unit provided by the embodiment of the present invention includes:

A determining module, configured to determine the target access network of the mobile node;

A negotiating module, configured to determine the maximum transmission unit of the mobile node according to the negotiation result of negotiating the maximum transmission unit of the mobile node for the target access network;

A storage module, configured to store the maximum transmission unit of the mobile node determined by the negotiation module.

From the description of the above technical solution, it can be seen that by negotiating the MTU of the MN before or during the migration of the MN in different access networks, the MTU of the MN can be updated in time, and the discarding of data packets and the relearning of the source end node can be avoided as much as possible. MTU, re-establishment of data transmission channels and other issues, thereby shortening the service response time and improving the service response speed.

Description of drawings

FIG. 1 is a schematic diagram of a method for determining an MTU according to an embodiment of the present invention;

FIG. 2 is a schematic flowchart of a method for determining an MTU according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a MN trigger negotiation process in an embodiment of the present invention;

FIG. 4 is a schematic diagram of an HA triggering negotiation process in an embodiment of the present invention;

5 is a schematic diagram of a gateway-triggered negotiation process in an embodiment of the present invention;

Fig. 6 is a schematic flowchart of a method for determining an MTU by a security gateway according to an embodiment of the present invention.

Detailed ways

No matter for the same type of access network or for different types of access networks, the size of the MTU of different access networks may be different. When the MN migrates (ie, moves or switches) between different access networks, if the MTU of the MN is not updated in time, it may cause problems such as discarding of data packets, re-learning of the MTU by the MN, and re-establishment of data transmission paths by network nodes. Therefore, when the MN migrates between different access networks, if the MTU of the MN can be changed in time and the MTU can be set for the data transmission path of the MN in time, the above problems can be effectively avoided.

In the embodiment of the present invention, the MN's MTU of the MN for the target access network can be determined in time by negotiating the MTU of the MN for the target access network before or during the migration of the MN in different access networks. The negotiation process needs to consider the support capability of the target access network for the MTU. The MTU determined through negotiation can be applied in the terminal node, and can also be applied in the network node. The terminal nodes here are MN, Correspondence Node (communication node, CN) and so on. The network nodes here are Home Agent (Home Agent, HA), GW, base station, router in the access network, etc. The MTU determined through negotiation can be used in processes such as subsequent data message sending and data transmission path setting, thereby reducing service delay time and jitter as much as possible. Reducing the service delay time means reducing the terminal delay time.

The negotiation process in the embodiments of the present invention can be performed between networks, or between a terminal node and the network. The negotiation process between networks, such as the process of negotiating the MN's MTU between the serving access network and the target access network, and the negotiation of the MN's MTU between the access network and the core network (such as with the HA in the core network) process and so on. The negotiation process between the terminal node and the network, such as the MN MTU negotiation process between the MN and the core network, the MN MTU negotiation process between the CN and the core network, and the negotiation between the access network and the CN The process of the MTU of the MN and so on. The negotiation subject can be determined according to actual network application requirements, and the embodiment of the present invention does not limit the specific expression form of the negotiation subject.

The negotiation process in the embodiment of the present invention can be performed before the MN migrates in different access networks, and can also be performed during the migration process of the MN in different access networks. Because some nodes in the network (such as routers in the access network) can learn the support capabilities of different access networks to MTU before the MN migrates, therefore, the implementation of the present invention can discover the support capabilities of different access networks to MTU At the same time, the negotiation process of the MN's MTU is carried out, so that during the MN migration process or after the MN migration, the terminal node and/or network node can apply the negotiated MN's MTU in time to avoid possible service delays and jitters .

For different access networks, the process of negotiating the MN's MTU can be implemented in various ways. For example, for an IPv4 network, when the MN moves between different access networks, the MN's MTU can be carried in the In the context information, it is transferred between the serving access network and the target access network to negotiate and determine the MTU of the MN. For another example, when the MN moves between different access networks, the MN's MTU can be carried in newly added signaling, and the newly added signaling can be transmitted between the serving access network and the target access network, Determine the MTU of the MN through negotiation.

The negotiation process between the serving access network and the target access network can be performed between the serving gateway and the target gateway, or between the serving gateway, the target gateway, and the target base station. At this time, the signaling used in the process of negotiating the MTU of the MN may be any one or more of handover signaling, relocation signaling, context transfer signaling, and newly defined protocol messages.

The negotiation process between the access network and the core network can be performed between the serving access gateway and the HA, or between the target access gateway and the HA. At this point, the MTU process of negotiating the MN can use any one or more of data messages, Internet Control Message Protocol (Internet Control Message Protocol, ICMP) messages, and newly defined protocol messages.

The negotiation process between the terminal node and the core network can be performed between the MN and the HA, or between the CN and the HA. At this moment, the MTU process of MN can adopt any one or more in data message, Internet ControlMessage Protocol (Internet Control Message Protocol, ICMP) message, newly defined protocol message.

The negotiation process between the terminal node and the access network can be performed between the MN or CN and the gateway (such as a security gateway).

The implementation process of negotiating the MTU of the MN between the serving access network and the target access network may be as follows: a node in the serving access network sends a signaling carrying MTU information of the negotiating MN to a node in the target access network to indicate a request for negotiation The MTU of the MN, the negotiated MTU information of the MN in the embodiment of the present invention may include: the current MTU of the MN, or may include the current MTU of the MN while also including: the capability range of the MTU supported by the service access network, and Is it possible to reset either or both of the MTUs. After receiving the MTU of the MN, the node in the target access network judges whether to allow the MTU, and after judging that the MTU is allowed, sends a signaling carrying information about allowing the MTU to the node in the serving access network. After the MTU is disallowed, a signaling carrying the MTU disallowed and suggested new MTU information may be sent to the node in the serving access network. The process for the node in the target access network to determine whether to allow the MTU may be: the target gateway in the target access network performs signaling interaction with the target base station to determine whether to allow the MTU. The process for the node in the target access network to determine whether to allow the MTU may also be: the target gateway in the target access network independently determines whether to allow the MTU without considering the signaling interacted with the target base station. That is to say, the target base station may or may not participate in MTU negotiation.

The implementation process of negotiating the MTU of the MN between the access network and the core network may be as follows: during the migration process of the MN between the serving access network and the target access network, the node in the serving access network sends a message carrying Negotiate the signaling or data message of the MN's MTU information, and negotiate the MN's MTU information as described in the above method implementation. After receiving the signaling or data message, the nodes in the core network determine the MTU information of the MN.

The implementation process of negotiating the MTU of the MN between the terminal node and the core network can be as follows: After the node in the core network perceives that the MN is migrating between access networks, it obtains the MTU supported by the serving access network and the target access network, and determines the MTU of the service access network. After there is a difference between the MTU supported by the access network and the target access network, by triggering the PMTU learning process of the MN's peer node (such as other MNs, or CNs, etc.), the MN's MTU change information is notified to the MN's peer Nodes; the nodes in the core network can also notify the peer node of the MN of the change information of the MTU of the MN by directly sending a notification to the peer node of the MN.

The implementation process of determining the MTU in the embodiment of the present invention will be described below with reference to the accompanying drawings.

Figure 1 shows two gateways (GW), the gateway connected to the MN is the serving access gateway, and the gateway connected to the CN is the target access gateway. It should be noted that the CN in FIG. 1 is marked in the target access network of the MN, and of course the CN may not be in the target access network of the MN.

When the MN in Figure 1 needs to migrate from the serving access network to the target access network, the serving gateway in the serving access network determines that after the MN migrates in different access networks according to the information it receives, it can migrate to the target access network. The target gateway in the ingress network sends information such as the obtained MN's MTU to negotiate the MN's MTU with respect to the target access network.

The serving gateway in Figure 1 can also negotiate the MTU of the MN with the HA, and the negotiation process can be triggered by the gateway (that is, the gateway initiates the negotiation process); CN can also negotiate the MN’s MTU with the HA, and the negotiation process can be triggered by the HA (that is, the negotiation process is initiated by the HA); the MN can also negotiate the MTU of the MN with the HA, and the negotiation process can be triggered by the MN (that is, the negotiation process is initiated by the MN); the MN can also negotiate the MTU of the MN with the CN, and the negotiation process can be Triggered by the MN (that is, the MN notifies the CN of the MTU for the target access network). The network node in the embodiment of the present invention can also set the data transmission path for the MN according to the negotiated MTU, and the network node can also process the data message according to the negotiated MTU, such as the network node according to the negotiated MTU. The data packet is segmented forwarded, directly forwarded, discarded, notified to modify the size of the data packet, etc. The specific implementation process of using the MTU to set the data transmission path may adopt an existing implementation manner, and the embodiments of the present invention do not limit the specific implementation process of using the MTU to set the data transmission path.

FIG. 2 is a schematic diagram of a specific implementation flow of determining an MTU according to an embodiment of the present invention.

In Fig. 2, in step 1), the MN sends handover signaling, such as a handover request message, to the serving base station. The handover request message may or may not include the current MTU of the MN.

Step 2), after receiving the handover signaling, the serving base station sends the handover signaling to the serving gateway, such as sending a handover request message to the serving gateway. Likewise, the handover request message may or may not include the current MTU of the MN.

Step 3), after receiving the handover signaling, the serving gateway sends the handover signaling to the target gateway, such as sending a handover request message to the target gateway. The handover request message may include MTU information to be negotiated, such as the current MTU of the MN, the capability range of the MTU supported by the serving access network, and whether the MTU can be reset.

Step 4), the target gateway may send handover signaling to the target base station, such as sending a handover request message to the target base station, so that the target base station performs handover control. The handover request message may include the current MTU of the MN, or may not include the MTU of the MN. Moreover, the target base station may participate in the MTU negotiation of the MN, or may not participate in the MTU negotiation of the MN.

Step 5), after receiving the handover request message sent by the target gateway, the target base station makes a handover decision, and sends a handover response message to the target gateway according to the handover decision result.

Step 6), the target gateway judges whether to allow the MN to move to the target access network according to the received handover response message, and determines whether to allow the current MTU of the MN, and if the current MTU of the MN is not allowed, the target gateway suggests a new MTU.

It should be noted that the target gateway can consider the signaling transmitted by the target base station in the process of judging whether to allow the current MTU of the MN. At this time, the target base station has participated in the negotiation process of the MN's MTU; In the process of MN's current MTU, the signaling interacted with the target base station is not considered. At this time, the target base station does not participate in the negotiation process of the MN's MTU; that is, the target base station can directly determine whether to allow the MN to move to the target access network. And determine whether to allow the current MTU of the MN, in the case of not allowing the current MTU of the MN, the target gateway proposes a new MTU, at this time, the target gateway and the target base station have no signaling interaction about MTU negotiation, and the target base station does not participate in the MN's MTU negotiation MTU negotiation process.

Then, the target gateway sends handover signaling such as a handover response message to the serving gateway. The handover response message may contain response result information for the MTU negotiation requested by the serving gateway. For example, the response result information may include: whether the target access network accepts the MTU size of the MN sent by the serving network, the MTU suggested by the target gateway, etc. information.

Step 7), after the serving gateway acquires the negotiated MTU from the received handover response message, it carries the negotiated MTU of the MN in the handover signaling and sends it to the serving base station. For example, the serving gateway sends a handover response message carrying the negotiated MTU to the serving base station.

It should be noted that after the MTU determined by negotiation, the serving gateway and the target gateway can configure the data transmission path of the MN; moreover, the serving gateway and the target gateway can also configure the received data message according to the negotiated MTU. Perform processing, such as discarding data packets exceeding the negotiated MTU, segmenting the data packets according to the negotiated MTU, and notifying to modify the size of the data packets.

Step 8), after receiving the handover response message, the serving base station sends handover signaling to the MN, such as sending a handover response message.

Figure 2 also includes the transmission of uplink data packets and the transmission of downlink data packets. The uplink data message is the data message sent by the MN to the CN. The downlink data message is the data message sent from the CN to the MN. The single dotted line in FIG. 2 indicates the transmission process of the uplink data message, and the double dotted line indicates the transmission process of the downlink data message.

The application of the negotiated MTU in the uplink data packet transmission process may include: the MN sends the data packet to the target gateway, and the target gateway determines the size of the data packet after receiving the data packet to be sent to the CN. If the negotiated MTU is exceeded, the target gateway may discard the data message, or the target gateway may segment the received data message according to the negotiated MTU, and then send the segmented data message. After the target gateway determines that the size of the data packet does not exceed the negotiated MTU, the target gateway can continue to forward the data packet.

The application of the negotiated MTU in the process of transmitting downlink data packets may include:

Step 9), after the serving gateway receives the data message that needs to be sent to the MN, after judging that the size of the data message exceeds the negotiated MTU, the serving gateway can discard the data message, or the serving gateway can according to the negotiation The determined MTU segments the received data message, and then sends the segmented data message. After the serving gateway determines that the size of the data packet does not exceed the negotiated MTU, the serving gateway can continue to forward the data packet, for example, forward the data packet to the serving base station.

It should be noted that, in step 9), the operation performed by the service gateway after receiving the data message can be selected differently in different networks. For example, in an IPv6 network, the service gateway determines the size of the data message After the negotiated MTU is exceeded, the data message can be directly discarded; that is, in the IPv6 network, the serving gateway may not be required to segment the data message. Possibility to fragment datagrams for a given MTU.

In addition, it should be noted that the serving gateway may also perform MTU negotiation with the HA after receiving the handover signaling sent by the serving base station. Of course, after receiving the handover signaling sent by the target gateway, the serving gateway can also negotiate the MTU negotiation of the MN with the HA again, and the HA can configure the data transmission path of the MN after negotiating the determined MTU; moreover, the HA The received data packets can also be processed according to the negotiated MTU, such as discarding data packets exceeding the negotiated MTU, or segmenting the data packets according to the negotiated MTU, and notifying to modify the data packets text size etc. For example, when a peer node such as CN sends a data packet to the MN through the HA, the HA may use the MTU negotiated and determined by the serving gateway to send the data packet to the serving gateway.

The implementation process of negotiating the MTU of the MN in the embodiment of the present invention will be described below by taking the CN of the MN as an example with reference to the accompanying drawings.

Negotiation Embodiment 1: In the case that the MN can know the CN of the peer node communicating with it and the lifetime of the MTU, the MN triggers a negotiation process and negotiates the MTU with the CN.

The MN can obtain all the CNs it has communicated with by recording the information of the CNs it has communicated with. Of course, the MN can also obtain the CN information from the network device. The lifetime of the MTU can be maintained by the MN.

In Figure 3, when the MN migrates to a new access network, or during the migration process of the MN between access networks, the MN can obtain its new address from the access gateway or foreign agent before migration, that is, the MN can be in The address that can be used in the target access network is obtained before accessing the target access network, and the address may be called a care-of address. At the same time, the MN can also obtain the MTU value of the migrated access network from the access gateway or external agent before migration. The MN can use the MTU as an option parameter of the IP data message, and send the IP data message to the CN, and the CN can learn the MN's MTU from the received IP data message. The CN can cache the MTU of the MN, and when the CN needs to send a data packet to the MN, it can segment the data packet according to the MTU. The above option parameters may include: the care-of address used by the MN's external network and the MTU value of the MN's external network.

If the IP data message sent by the MN is forwarded by the HA, the HA can parse out the current MTU of the MN from the IP data message, and maintain the correspondence between the MN's MTU and the care-of address. In this way, each CN that needs to communicate with the MN can learn the MTU of the MN through information interaction with the HA.

The MN in Figure 3 may also not use the method of sending IP data packets to negotiate the MTU with the CN, but instead notify the CN by sending an ICMP oversized error message. message, and send ICMP messages to each CN according to the recorded information.

In the first negotiation embodiment above, the MN can negotiate with the CN when the MTU of the serving access network before migration and the MTU of the target access network after migration change; When the MTU of the target access network after migration does not change, it is not necessary to negotiate with the CN.

Negotiation Embodiment 2: The HA triggers the negotiation process, and negotiates the MTU of the MN with the CN.

In Fig. 4, the HA can know the access network migration of the MN at any time. The HA can obtain the MTU supported by the target access network through the tunnel establishment negotiation process with the target gateway. HA can also learn the MTU based on pre-configuration and information obtained from the policy center. The HA can also learn the MTU according to the interaction with the MN. After learning the MTU supported by the target access network, the HA can negotiate the MTU with the CN in two different ways.

Mode 1: The HA triggers the process of the CN learning the MTU, and responds to the request in the process of the CN learning the MTU on behalf of the MN. For example, when the CN wants to communicate with the MN through the HA, if the size of the data packet sent by the CN exceeds the MTU value supported by the target access network, the HA can send an ICMP oversized error message to the CN on behalf of the MN. And discard the data message, the CN can learn the MTU of the MN after receiving the ICMP oversized error message.

In addition, in the first method, the HA may not discard the data packet, but force the data packet sent by the CN to be segmented according to the MTU supported by the target access network, and the segmented data packet The text is sent to the MN. After sending the data message, it sends an ICMP oversized error message to the CN on behalf of the MN.

Method 2: The HA directly notifies the CN of the MTU.

Since the HA can directly maintain the corresponding relationship between the MN's care-of address and the CN, when the HA determines that the MTU supported by the target access network before migration is different from the MTU supported by the serving access network before migration, it can directly use the care-of address Corresponding relationship with CN, determine each CN that needs to be notified, and notify the MTU supported by the target access network to the CN. The HA can notify each CN by sending an IP data message carrying an MTU parameter option to the CN. The update address in this parameter option can be the home address of the MN and the MTU supported by the target access network.

Negotiation Embodiment 3: The gateway in the access network triggers the negotiation process.

In Fig. 5, GWB notifies the neighbor gateway GWA of the change of the MTU of the MN by using a routing protocol, and the CN sends a data message with the destination address of the MN to the GWA. After receiving the data message and determining the MTU of the MN after the size change of the data message, the GWA discards the data message and sends an ICMP oversized error message to the CN. The changed MTU of the MN is learned after the error message.

In addition, the access network gateway may also directly notify the HA or CN of the negotiated MTU. For example, the access network gateway may notify the HA or CN through the process of establishing a tunnel with the HA, or through the proxy binding process of the mobile IP performed by the MN through the GW. Of course, the access network gateway can also use newly defined procedures and protocols to notify the HA or CN. The access network gateway can expand the existing tunnel protocol to make the message carry information such as the MN's MTU. The access network gateway here may be the target gateway. The tunnel here may be an IP tunnel or an IPSEC tunnel.

Another MTU negotiation process is described below.

The technical solutions provided by the embodiments of the present invention can be applied to mobile IP tunnels, and can also be applied to other tunnels, such as IPSEC tunnels.

As shown in Figure 6, the mobile node MN needs to be able to communicate with the private network behind the security gateway. In this case, the mobile node will contain at least two addresses: one address is the IP address of the public network, and the address will follow the mobile node's IP address. Changes due to the migration of the access network; the other address is a relatively fixed private address allocated by the security gateway.

The mobile node will use the IP address of the public network to establish a dynamic IPSEC tunnel connection with the security gateway. After the tunnel is successfully established, the data packets sent by the mobile node to the private network using the private address will be encapsulated by the IPSEC tunnel. After the data message arrives at the security gateway, it is decapsulated, and the decapsulated data message is sent to the corresponding terminal node in the private network.

Since the private address of the mobile node is assigned by the security gateway, the corresponding relationship between the private address of the mobile node and the MTU of the access network where the mobile node is currently located can be maintained on the security gateway. The maintenance process is as follows:

1) When the mobile node needs to negotiate with the security gateway to establish an IPSEC tunnel connection, the mobile node notifies the security gateway of the MTU and private address of the current access network through the tunnel.

2) After the security gateway receives the MTU information and the private address, it judges whether the private address is correctly allocated, and if it is correctly allocated, maintains the correspondence between the private address and the MTU, and starts to establish a tunnel connection at the same time.

3) If the terminal node in the private network sends a data message exceeding the MTU to the mobile node, the destination address of the data message is the private address of the mobile terminal. When the data packet passes through the security gateway, the security gateway searches for the MTU corresponding to the destination address. When the security gateway finds that the tunnel-encapsulated IP data packet exceeds the MTU, it directly responds to the terminal node with an ICMP oversized error message to notify End nodes in the private network modify the size of datagrams.

4) When the mobile node switches to another access network, the public network address of the mobile node will be updated. At this time, the IPSEC tunnel needs to be re-established, so that the corresponding MTU can also be refreshed in time on the security gateway side.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be realized by means of software plus a necessary hardware platform, and of course all can be implemented by hardware, but in many cases the former is better implementation. Based on this understanding, all or part of the contribution made by the technical solution of the present invention to the background technology can be embodied in the form of software products, and the computer software products can be stored in storage media, such as ROM/RAM, magnetic disks, optical disks, etc. , including several instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute the methods described in various embodiments or some parts of the embodiments of the present invention.

The device for determining the maximum transmission unit provided by the embodiment of the present invention includes a determination module, a negotiation module and a storage module.

The determining module determines a target access network of the mobile node. The determining module can know the target access network of the mobile node before the mobile node is migrated, and can also know the target access network of the mobile node during the migration process of the mobile node. The determining module may use an existing method to determine the target access network of the mobile node. When the devices provided by the embodiments of the present invention are located in different nodes, the process for the determining module to obtain the target access network of the mobile node will be different, specifically as described in the above method embodiments.

After the determination module determines the target access network of the mobile node, for the target access network, the negotiation module determines the maximum transmission unit of the mobile node according to the negotiation result of the maximum transmission unit negotiation of the mobile node, and outputs it. The negotiation module can actively trigger the MTU negotiation process, or passively participate in the MTU negotiation process according to the received message. When the devices provided by the embodiments of the present invention are located in different nodes, the way the negotiation module participates in the MTU negotiation process will be different, as described in the above-mentioned method embodiments for details.

The storage module receives and stores the maximum transmission unit of the mobile node output by the negotiation module. The maximum transmission unit stored in the storage module can be used for the setting of the data transmission path, and can also be used for processing the data message. Specifically, it is as described in the above manner of the above method.

The device provided by the embodiment of the present invention may be located in a mobile node, may be located in a gateway, may also be located in a home agent, and may also be located in a communication node. The gateway here may be a serving gateway in the serving access network of the mobile node, a target gateway in the target access network of the mobile node, or a security gateway.

Although the present invention has been described by way of example, those of ordinary skill in the art know that there are many variations and changes in the present invention without departing from the spirit of the invention, and the claims of the application document of the present invention include these variations and changes.

Claims (11)

1. A method for determining the maximum transmission unit, comprising: Determine the target access network of the mobile node, and determine the maximum transmission unit of the mobile node according to the negotiation result of negotiating the maximum transmission unit of the mobile node for the target access network. 2. The method according to claim 1, wherein said determining the maximum transmission unit of said mobile node comprises: determining a maximum transmission unit provided by a network node for said mobile terminal; and/or Determine the maximum transmission unit that the mobile node needs to use. 3. The method according to claim 1, characterized in that the method specifically comprises: determining the maximum transmission unit of the mobile node according to the negotiation result of the maximum transmission unit of the mobile node between the serving access network and the target access network; And/or the method specifically includes: determining the maximum transmission unit of the mobile node according to the negotiation result of the maximum transmission unit of the mobile node between the serving access network and the core network; And/or the method specifically includes: determining the maximum transmission unit of the mobile node according to the negotiation result of the maximum transmission unit negotiation between the mobile node/communication node and the core network; And/or the method specifically includes: determining the maximum transmission unit of the mobile node according to the negotiation result of the maximum transmission unit of the mobile node between the mobile node and the communication node; And/or the method specifically includes: The maximum transmission unit of the mobile node is determined according to the negotiation result of the maximum transmission unit of the mobile node between the access network and the communication node. 4. The method according to claim 3, wherein the determining the maximum transmission unit of the mobile node according to the negotiation result of the maximum transmission unit of the mobile node between the serving access network and the target access network comprises: The serving gateway determines that the mobile node migrates in different access networks according to the received information, and the serving gateway sends a signaling carrying the current maximum transmission unit of the mobile node to the target gateway; After receiving the signaling, the target gateway judges whether to allow the current maximum transmission unit of the mobile node; After determining the permission, send the information of allowing the current maximum transmission unit of the mobile node to the serving gateway; After determining that it is not allowed, send the suggested maximum transmission unit to the serving gateway. 5. The method according to claim 4, wherein the signaling sent by the serving gateway to the target gateway also carries one or more of the following: the range of the maximum transmission unit supported by the serving access network, whether to allow Reset the maximum transmission unit. 6. The method according to claim 4, wherein the target gateway determining whether to allow the current maximum transmission unit of the mobile node comprises: The target gateway directly determines whether to allow the current maximum transmission unit of the mobile node; and/or The target gateway judges and determines whether to allow the current maximum transmission unit of the mobile node according to the signaling interaction with the target base station. 7. The method according to claim 4, 5 or 6, wherein the signaling includes one or more of the following: handover signaling, migration signaling, and context transfer signaling. 8. The method according to claim 3, wherein the determining the maximum transmission unit of the mobile node according to the negotiation result of the maximum transmission unit of the mobile node/communication node and the core network comprises: The mobile node learns the maximum transmission unit supported by the target access network, and sends the maximum transmission unit supported by the target access network to the home agent; and/or The home agent learns the maximum transmission unit supported by the target access network, and sends the maximum transmission unit of the target access network to the communication node. 9. The method of claim 1, further comprising: performing data transmission path setting according to the maximum transmission unit of the mobile node determined through the negotiation; And/or perform data packet processing according to the maximum transmission unit of the mobile node determined through the negotiation. 10. A device for determining a maximum transmission unit, comprising: A determining module, configured to determine the target access network of the mobile node; A negotiating module, configured to determine the maximum transmission unit of the mobile node according to the negotiation result of negotiating the maximum transmission unit of the mobile node for the target access network; A storage module, configured to store the maximum transmission unit of the mobile node determined by the negotiation module. 11. The apparatus of claim 10, wherein the apparatus is located at one or more of a mobile node, a gateway, a home agent, and a correspondent node.

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