CN100334918C - Method for implementing seamless switching between mobile nodes in mobile IP - Google Patents
Method for implementing seamless switching between mobile nodes in mobile IP Download PDFInfo
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- CN100334918C CN100334918C CNB2004100487767A CN200410048776A CN100334918C CN 100334918 C CN100334918 C CN 100334918C CN B2004100487767 A CNB2004100487767 A CN B2004100487767A CN 200410048776 A CN200410048776 A CN 200410048776A CN 100334918 C CN100334918 C CN 100334918C
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Abstract
The present invention discloses a method for implementing seamless switching between mobile nodes in a mobile IP, which comprises: after the current mobile node determines to carry out switching and obtains the information of a new ecdemic proxy, a registering request is sent to the new ecdemic proxy according to the obtained information; after the new ecdemic proxy receives the registering request, the new ecdemic proxy informs the original ecdemic proxy to forward the data to be sent to the current mobile node to the new ecdemic proxy, and besides, a tunnel between the new ecdemic proxy and the original ecdemic proxy is established; after the original ecdemic proxy receives the notice, the original ecdemic proxy informs the current mobile node to carry out the switching, establishes the tunnel between the original ecdemic proxy and the new ecdemic proxy and captures and forwards the data sent to the current mobile node to the new ecdemic proxy, and the new ecdemic proxy buffers the received data; the new ecdemic proxy sends the buffered data to the current mobile node and stops buffering the data after the switching; the new ecdemic proxy informs the original ecdemic proxy to stop forwarding the data after receiving a registering response, and the new ecdemic proxy and the original ecdemic proxy disassemble the tunnel. The method can ensure that the packets can not be lost in the switching process of mobile nodes, and the switching time delay is shortened.
Description
Technical field
The present invention relates to mobile IP handoff technique, be meant a kind of method of the mobile node realization seamless switching that in mobile IP, two layers of triggering is combined with the Foreign Agent caching mechanism especially.
Background technology
Along with internet (Internet) swift and violent popularized, the fast development of a large amount of uses of portable equipment, Wireless Telecom Equipment and people are to the dependent increase of network, the mobile subscriber wishes can be with a kind of flexible way more access enterprise networks network resource and Internet resource anywhere or anytime, that is to say, the user has produced the ambulant demand of main frame, wishes that main frame need not to interrupt existing communicating to connect when changing its present position.For this reason, internet engineering task group (IETF) has defined mobile IP (Mobile IP), mobile IP is the network layer solution that a support main frame moves, its main thought is: on the basis of not changing existing network routing mode and other fixed host computer software and hardware, provide a kind of position to follow the tracks of and IP datagram literary composition forwarding mechanism, when certain main frame moved, the IP datagram literary composition that is sent to this main frame can be forwarded to the current position of this main frame safely.
Mobile IP is a kind of Internet agreement of expansion, and its proposition is to realize anywhere or anytime that in order to guarantee mobile device not need to change the IP address network connects and communication.Fig. 1 is the basic network topology diagram that each entity is formed among the mobile IP, mobile node 10 shown in the figure is meant a mobile computer or router, also can be described as mobile host (MH), still can communicate after this mobile node 10 moves with original IP address; Correspondent Node shown in the figure (CN) 11 is the computer of communicating by letter with mobile node 10, also can be described as Correspondent Node main frame (CH).
Referring to shown in Figure 1, at mobile node 10, the home network of mobile node 10 is called home network (HN), and the network at place was called field network (FN) when mobile node 10 was in roaming state, comprised two field networks among Fig. 1.The permanent IP address of distributing to mobile node 10 is called home address (HomeAddress), and this address does not change with the variation of node location; In home network, the link of mobile node 10 home networks is called home link (HL); The router that operates on mobile node 10 home networks is called home agent (HA, Home Agent) 12, be responsible for preserving the mobile node current position information, also be responsible for simultaneously intercepting and capturing the message that sends to mobile node, and message is forwarded to the current position of mobile node with tunnel style.In field network, the link of the field network at mobile node 10 places is called foreign link (FL); The router that operates on the field network is called Foreign Agent (FA), it is mobile node sends message in field network default router, the tunnel de-encapsulation services also is provided sometimes, comprises the Foreign Agent 13 and the Foreign Agent 14 that belong to field network 1 and field network 2 respectively among Fig. 1.
At present, mobile IP technology still can not extensive use, because some technical problems fail to solve, wherein handoff delay is exactly one of problem anxious to be solved to a great extent, because the existence of handoff delay causes a lot of real-times to require very strong service not use in mobile IP.Handoff delay among the mobile IP can cause the problem of two aspects: being the interruption of communication in the handoff procedure on the one hand, is exactly because the data-bag lost that communicating interrupt causes on the other hand.In order to shorten the communicating interrupt time, to reduce packet loss, industry has proposed the seamless switching that a lot of different solutions realize mobile IP, mainly comprises: realize the scheme switched fast, for example cellular ip etc.; The scheme that realization takes over seamlessly, for example grouping cache forwarding mechanism; Also have two layers and three layers of method that switching combines.
Solving on the quick switching problem, a kind of thought is the function distribution home agent, implement local registration, mainly comprise: hierarchical mobility management and based on mobile management two classes of particular host route, the former has technology such as MIP-RR and IDMP, the latter has technology such as cellular ip, HAWAII, all is that wireless access network is divided into several wireless domains, realizes the localization of registration in wireless domains.What both were different is the agreement of transmitted in packets in the wireless domains, and the former uses conventional mobile IP protocol, and the latter uses the agreement based on the particular host route.These modes all only are based on three layers of proposition switching times of minimizing, and in fact the handoff delay of mobile host is made up of two layers of switching and the time-delay of three layers of switching two parts, and the time-delay that reduces by three layers of switching merely can not tackle the problem at its root.
So, there are some research institutions to propose link layer and network layer switching are combined again, utilize link layer to come the trigger network layer to carry out pre-registration, make and when two layers of switching are finished, also finish three layers of switching, thereby realize switching fast.This scheme mainly contains: an Internet draft--" the quick switching in the mobile IPv 4 " that Ericsson proposes.The main thought of this scheme is: register in advance when mobile node is in overlapping region, utilize the new Foreign Agent of original chain road direction to register.But the realization of this scheme need three layers switch and two layers of switching between time accurately cooperate, otherwise still can cause the interruption and the packet loss of communication.
For solution takes over seamlessly problem, industry has mainly proposed employing grouping cache and forwarding mechanism, utilizes the data that Foreign Agent buffer memory in mobile node switching process mails to mobile node to realize not packet loss of handoff procedure.But, because only at three layers of switching, caused former Foreign Agent (oFA) to know for sure when beginning for mobile node data cached.And in traditional caching mechanism, the size of buffering area is difficult to determine that rationally if buffering area is too small, in case mobile node finds that the time of new Foreign Agent is long, the data of buffering area will be overflowed, and mobile node will packet loss; If buffering area is excessive, the data in the buffering area comprise the data of having received before mobile node switches probably, and this will cause mobile node to receive the packet of repetition, also needs to increase extra filtration treatment.These problems all make the method for only using Foreign Agent to transmit data as the mobile node buffer memory by network layer have a lot of drawbacks, and infeasible.
Owing to only utilize network layer to realize that there is above problem in caching mechanism, also the someone proposes to introduce the caching mechanism that two layers of information trigger, but the trigger message that utilizes in these mechanism that proposed comes the triggering (trigger) of automatic network, that is to say, need expand the function and/or the message of access point (AP).And mobile node is in passive state when adopting network trigger, and it really begins time of switching to be difficult to control, and this is to realizing that caching mechanism also causes some problems.
Summary of the invention
In view of this, the method that main purpose of the present invention is to provide mobile node among a kind of mobile IP to realize seamless switching can guarantee neither can or not receive duplicate packages again by packet loss in the process that mobile node switches, has shortened handoff delay simultaneously.
For achieving the above object, technical scheme of the present invention is achieved in that
Mobile node is realized the method for seamless switching among a kind of mobile IP, and this method may further comprise the steps:
A. after current mobile node is determined to switch, obtain the information of new Foreign Agent earlier by former Foreign Agent, the information according to the new Foreign Agent that is obtained sends register requirement to new Foreign Agent then;
B. after new Foreign Agent is received register requirement, this register requirement is transmitted to home agent; The extremely new Foreign Agent of the data forwarding of notifying former Foreign Agent will send to current mobile node, and set up self to the tunnel between the former Foreign Agent;
C. after former Foreign Agent is received the notice of new Foreign Agent, notifying current mobile node to carry out link layer switches, set up self to the tunnel between the new Foreign Agent, and intercept and capture all data forwarding that mail to current mobile node and give new Foreign Agent, the data of issuing current mobile node that new Foreign Agent buffer memory is received;
D. after current mobile node link layer switching is finished, notify new Foreign Agent to switch and finish, new Foreign Agent will send to current mobile node for current mobile node data in buffer, and stop data cached; And, after new Foreign Agent is received the registration reply that home agent returns, the data of notifying former Foreign Agent to stop forwarding current mobile node, the tunnel between both sides remove.
This method further comprises: each Foreign Agent is safeguarded a binding table that stores the base station information of adjacent Foreign Agent; Then the described mobile node of the step a information of obtaining new Foreign Agent specifically comprises: current mobile node sends apply for information to former Foreign Agent, carries the identification information of the purpose base station that will switch in this message; After former Foreign Agent was received apply for information, the binding table of inquiry self maintained obtained the information of new Foreign Agent, and gives current mobile node with the information-reply that is obtained.
Wherein, the base station information in the described binding table is a Base Station Identification, or is the MAC Address of base station.So, this method further comprises: the base station information in each Foreign Agent timing search subnet, judge whether base station information changes, if having, then notify all adjacent Foreign Agents to carry out the renewal of binding table, all receive that the Foreign Agent of update notification upgrades the binding table of self; Otherwise, do not process.
In the such scheme, steps d further comprises: new Foreign Agent sends the agent advertisement that carries current mobile node Care-of Address after receiving that notice is finished in current mobile node switching to current mobile node.
In the such scheme, after steps d Central Plains Foreign Agent is received and stopped forwarding notice, through removing self after one section time-delay again to the tunnel between the new Foreign Agent.
In the such scheme, the interacting message between former Foreign Agent and the new Foreign Agent adopts the UDP message.
Mobile node is realized the method for seamless switching among the mobile IP provided by the present invention, adopt two layers of triggering to combine with Foreign Agent buffer memory forwarding mechanism, utilize the relevant information of detected physical layer channel to determine whether to switch by mobile node on the one hand, and begin to carry out as nFA with the moment that the trigger network layer switches the initial moment of metadata cache; On the other hand in the network layer handoff procedure, between the oFA of current mobile node and nFA, set up the tunnel, oFA will mail to the data forwarding of current mobile node to nFA, by all issue the data of mobile node in the nFA buffer memory handoff procedure, remove this tunnel after finishing switching.This scheme has following advantage and characteristics:
1) owing to adopts the mechanism of two layers of switching of mobile node ACTIVE CONTROL, can accurately trigger Foreign Agent and transmit the opportunity of data for the mobile node buffer memory, thereby the assurance mobile node neither can or not received duplicate packages by packet loss yet in whole handoff procedure, does not need the extra processing that duplicate packages is filtered that increases yet.
2) the present invention can realize that quick and smooth switches, and makes the handoff delay of mobile node be substantially equal to the time-delay that link layer switches, thereby has shortened the time of communicating interrupt, i.e. handoff delay in the handoff procedure greatly.
3) the present invention is by mobile node active searching AP information, and the ACTIVE CONTROL switching time makes work such as prediction that mobile node can switch and judgement, avoids blindly switching.
4) the present invention is by mobile node ACTIVE CONTROL switching time, before making mobile node have the sufficient time to finish to switch with oFA and nFA between alternately, thereby ensured the realization of two layers of triggering and FA caching mechanism.
5) the present invention does not need AP function and message are expanded, and realizes simple, convenient, flexible.
Description of drawings
Fig. 1 is the basic network topology diagram that each entity is formed among the mobile IP;
Fig. 2 is the specific implementation flow chart of the inventive method;
Fig. 3 is the network topology structure schematic diagram of one embodiment of the invention.
Embodiment
The method that a kind of accurate trigger network layer switches has been proposed in another patent application of the applicant, its main thought is: mobile node with the relevant information of physical layer channel as trigger condition, and, need to judge whether the trigger network layer to switch in conjunction with the base station information of current network.
Wherein, the relevant information of physical layer channel is meant as trigger condition: mobile node regularly detects the state of self current place wireless network, obtain relevant physical layer channel information, the therefrom selected trigger parameter that will detect, and at trigger parameter definition trigger condition, so, when finding new base station, just judge whether the trigger parameter of newfound base station satisfies trigger condition.Described physical layer channel information is that mobile node judges whether to carry out the used parameter information of physical layer switching, comprises the ID of the current base station that is connected to, available Basic Service Set tabulation, the signal strength signal intensity that receives, signal to noise ratio or the like; Can choose any one kind of them or several as trigger parameter from above-mentioned physical layer channel information, normally selected received signal intensity or signal to noise ratio are as trigger parameter; Described trigger condition is meant and preestablishes selected trigger parameter corresponding threshold, such as: selected signal to noise ratio is a trigger parameter, and it is SIR1 that trigger condition is set to set snr threshold, so, if greater than SIR1, just starting, triggers the current snr value of mobile node.Here, set trigger condition must guarantee to utilize this trigger condition and triggered time of causing in advance in the time that physical layer automaticallyes switch.
Because the switching between the different base station in the same subnet may be just finished in above-mentioned triggering, therefore, the present invention is also in conjunction with the base station information in the subnet of the current place of mobile node, with the base station information of current sub network as basis for estimation, mobile node judges simultaneously whether emerging base station belongs to new wireless sub network, then start the network layer switching if belong to new wireless sub network, switch otherwise do not carry out network layer.
The specific implementation step of this accurate trigger network layer changing method comprises:
A. current mobile node detects the selected information of triggering parameters of all base stations of current discovery;
B. judge that whether detected trigger parameter information satisfy the trigger condition of setting, if satisfy, execution in step c then; Otherwise, return step a;
C. current mobile node judges whether current base station of satisfying trigger condition belongs to self current place subnet, if do not belong to, then initiatively the trigger network layer switches; Otherwise return step a.
Based on this, core concept of the present invention is: in conjunction with the mechanism of above-mentioned two layers of triggering, when the trigger network layer switches, between the oFA of this mobile node and nFA, set up the tunnel, be responsible for the data that buffer memory is transmitted to this mobile node by nFA, after finishing switching, stop the buffer memory of nFA, and remove the tunnel between oFA and the nFA the forwarding data.Wherein, oFA by mobile node before switching the former Foreign Agent of connection network; NFA by mobile node switch the back the new Foreign Agent of connection network.
Referring to shown in Figure 2, the specific implementation that MN switches among the present invention may further comprise the steps:
Step 201:MN is by the relevant information of current all the AP signals that receive of active detecting, and whether judgement produces two layers of triggering, if, then produce two layers of triggering signal, initiatively the trigger network layer switches; Otherwise, return step 201 and continue to detect.
Step 202: after producing two layers of triggering, MN sends FA information query message FA-request to oFA, inquires about the information of the nFA under the purpose AP that self will switch to, carries the identification information of purpose AP in this message.
Here, the message format that FA-request message can employing table one provides, what its utilized is the expansion of proxy requests in the standard mobile IP protocol.In the table one, type (Type)=20 shows that this message is used to inquire the information of the affiliated FA of AP; Byte number shows the byte number that each AP identification information will take, and is defaulted as 4 in this table; Reserved field (Reserved) is 0; The identification information of AP may be the ID of AP or MAC Address etc.
| 0 | 1 | 2 | 3 | ||||||||||||||||||||||||||||
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | |
2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
| Type | Byte number | Reserved field | |||||||||||||||||||||||||||||
| The identification information of AP | |||||||||||||||||||||||||||||||
Table one
After step 203:oFA receives the FA information query message that MN sends, can be in the binding table of self maintained the FA under the search purposes AP, and obtain the information of this nFA, transmit a reply message FA-reply to MN then, with the information notification MN of nFA.
Wherein, the message format that FA-reply message can employing table two provides, what its utilized is the expansion of agent advertisement in the standard mobile IP protocol.In the table two, type is 21, shows it is the nFA information of replying the MN inquiry; Byte number shows the byte number of describing nFA information, owing to be that IP address with nFA replies to MN, so byte number should be 4; Reserved field is 0.
| 0 | 1 | 2 | 3 |
| Type | Byte number | Reserved field | |
| The IP address of nFA | |||
Table two
Mention oFA inquiry in this step and obtain the information of the nFA under the purpose AP, that is to say, MN need be in the information that just obtains nFA after two layers of triggering, before switching, and this information is actual to be obtained from oFA.Here, can adopt FA to safeguard the mechanism of binding table, use the binding table of being safeguarded to store the AP information of adjacent FA.Be achieved in that specifically each FA safeguards a binding table, write down the AP information in the adjacent FA subnet; Each FA oneself wants the AP information in the timing search subnet, if find to change, just sends AP_updata message to adjacent FA; Each FA must upgrade the AP information in self binding table after receiving the AP_updata message of adjacent FA.So, MN just can learn the information of nFA by inquiry oFA after obtaining two layers of triggering.
Here and since in the standard mobile IP protocol not about FA between the definition of interactive information, so AP_updata is self-defining a kind of message, this message adopts the UDP message.Wherein, the UDP territory comprises: source port and destination interface, source port are variable, and destination interface is fixed as 500; Each territory of UDP head as shown in Table 3.In the table three, the type thresholding is 1, shows it is the message of an exchange AP information; Length field is used for describing the identifier figure place of AP information, thinks four bytes here; The number of AP information of carrying in this message of number domain representation such as AP sign.
| 0 | 1 | 2 | 3 |
| Type | Length | Number | |
| The sign of AP1 | |||
| The sign of AP2 | |||
| …… | |||
Table three
Step 204:MN receives after the answer message of oFA, extracts the information of nFA from reply message, and sends register requirement to nFA, and this register requirement can mail to nFA by original old link.
Step 205:nFA receives after the register requirement from MN, wait operation through authentication after, this register requirement is transmitted to HA.NFA can send transfer request message transmit-request to oFA, and the data that notice oFA can begin to transmit MN are to nFA, and nFA can set up self to the tunnel between the oFA afterwards, and prepares the data that mail to MN that buffer memory oFA forwards.
Wherein, transmit-request message is self-defining a kind of message, because there is not the definition about interactive information between the FA in the existing mobile IP protocol.This message adopts the UDP message format, and the UDP territory comprises: source port and destination interface, source port are variable, and destination interface is fixed as 500; Each territory of UDP head as shown in Table 4, in the table four, the type thresholding is 2, explanation is the message that nFA notice oFA begins to transmit the MN data, length field and keep thresholding and be 0.
| 0 | 1 | 2 | 3 |
| Type | Length | Keep | |
| …… | |||
Table four
Step 206:oFA can send one and reply message Handoff-ack to MN after receiving the notice of nFA, and notice MN can begin two layers and switch.After this tunnel between oFA foundation and the nFA begins to intercept and capture the data that mail to MN and is forwarded to nFA.Begin MN from this moment and can stop to receive data, the data that mail to MN will all be forwarded to nFA by oFA, and be got up by the nFA buffer memory.
Wherein, the message format that Handoff-ack message can employing table five provides, what its utilized is the expansion of agent advertisement in the standard mobile IP protocol.In the table five, type is 22, shows it is the message that oFA notice MN begins to switch; Byte number is 0; Reserved field is 0.
| 0 | 1 | 2 | 3 |
| Type | Byte number | Reserved field | |
Table five
After step 207:MN receives the notice of oFA, begin two layers of switching, this switches by the own ACTIVE CONTROL of MN.
Step 208:MN is by two layers of information of active inquiry, learns that two layers of switching finish, and after promptly new link has been connected, sends message informing nFA oneself at once and inserted subnet under the nFA.
After step 209:nFA receives the notification message of MN, at once data buffer memory, that issue MN are sent to MN, and stop to MN data cachedly, and beginning directly will be mail to the data forwarding of MN and be given MN.NFA can send the Care-of Address notice MN of an agent advertisement with MN simultaneously, and so far, MN has just recovered normal communication.
Step 210: after nFA received that HA issues the registration reply of MN, nFA just can send transmission and stop request message transmit-stop-request, and notice oFA stops forwarding the data of MN.
Because registration process and the handoff procedure of MN are executed in parallel among the present invention, so,, switch when registration is finished probably and also do not finish if HA is very near apart from MN.Therefore in actual applications, step 209 and 210 order may be put upside down, but this does not influence treatment mechanism of the present invention.
Wherein, transmit-stop-request message is self-defining a kind of message, because there is not the definition about interactive information between the FA in the existing mobile IP protocol.This message adopts the UDP message format, and the UDP territory comprises: source port and destination interface, source port are variable, and destination interface is fixed as 500; Each territory of UDP head as shown in Table 6, in the table six, the type thresholding is 3, explanation is the message that nFA notice oFA stops forwarding the MN data, length field and keep thresholding and be 0.
| 0 | 1 | 2 | 3 |
| Type | Length | Keep | |
| …… | |||
Table six
After step 211:oFA receives and stops forwarding notice, when confirming to no longer include the data that mail to MN, will remove the tunnel between self and the nFA, and send one and reply message transmit-stop-reply to nFA.Here, why need to be confirmed to be, do not remove the tunnel between oFA and the nFA, some late packet can't be received, can cause packet loss equally if do not confirm horse back because data may have time-delay owing to congested in transmission course.Usually the method that adopts is: the tunnel between oFA and the nFA is removed in time-delay a little while again, and concrete delay time can be determined according to network condition.
Wherein, transmit-stop-reply message is self-defining a kind of message, because there is not the definition about interactive information between the FA in the existing mobile IP protocol.This message adopts the UDP message format, and the UDP territory comprises: source port and destination interface, source port are variable, and destination interface is fixed as 500; Each territory of UDP head as shown in Table 7, in the table seven, the type thresholding is 4, explanation is that FA replys transmit-stop message, length field and keep thresholding and be 0.
| 0 | 1 | 2 | 3 |
| Type | Length | Keep |
| …… | ||
Table seven
Step 212:nFA receives and replys after the message, removes the tunnel between self and the oFA, so far finishes the whole process that MN switches, and enters normal communication flow.
From above-mentioned flow process as can be seen, the present invention has shifted to an earlier date the registration of MN, mainly consider 2 points: on the one hand, consider from aspects such as safety and services, nFA must pass through providing service for MN after the work such as a series of authentications of MN, and the present invention needs nFA just data cached for MN before MN does not switch, and therefore must the information of MN be informed nFA in advance by register requirement.On the other hand, it is the time that MN transmits data that registration in advance will be shortened oFA, has improved the efficient of transfer of data.
Fig. 3 is the mobile IP network topological diagram that an embodiment is adopted, and it is that example describes that present embodiment moves in WLAN (wireless local area network) with MN.Comprise two subnets among Fig. 3, promptly subnet 1 and subnet 2 comprise two wireless base station: AP1 and AP2 in the subnet 1, and base station a: AP3 is arranged in the subnet 2, and three broken circles are represented the overlay area of AP1, AP2 and AP3 respectively.Pocket computer is MN31, and the motion track of MN31 moves to AP3 from AP2 shown in chain-dotted line 32.For MN31, subnet 1 and subnet 2 all are its field networks, and the agency in the subnet 1 is FA1, and the agency in the subnet 2 is FA2, when MN31 when subnet 1 switches to subnet 2, FA1 is equivalent to oFA, FA2 is equivalent to nFA.
So, MN31 switches to AP3 from AP2, and just the handoff procedure that switches to the FA2 subnet from the FA1 subnet specifically is such:
1) MN31 will switch to AP3 from AP2 by two layers of certain trigger policy decision.Here, described two layers of certain trigger policy are meant: MN31 as trigger condition, and in conjunction with the AP information of current network, need to judge whether the trigger network layer to switch the relevant information of physical layer channel.
2) after MN31 determines to switch to AP3 from AP2, send FA-request message, inquire the information of the FA that AP3 is affiliated, carry the identification information of AP3 in this message to FA1.
3) after FA1 receives FA-request, inquire about the AP information binding table of self, learn that AP3 belongs to FA2, carry the FA-reply of FA2 IP address to MN31 so send.
Here, FA1 and FA2 are safeguarding a binding table, store the AP information of adjacent FA in this binding table.That is to say that FA1 knows an AP--AP3 in the FA2 subnet, and write down the sign of this AP3, this sign can be ID or MAC Address; FA2 knows that also two AP--AP1, AP2 are arranged in the FA1 subnet simultaneously, and the sign of record AP1 and AP2, and this sign can be ID or MAC Address equally.
In addition, FA1 and the FA2 AP in can this subnet of timing search if find the situation that the AP increase and decrease arranged or change, can send AP_updata message immediately to adjacent FA, upgrades the binding table among the adjacent FA.
4) MN31 just sends registration message to FA2 by original link after receiving FA-reply.
5) after FA2 receives the register requirement of MN31, after work such as checking, distribute a Care-of Address, and this register requirement is forwarded to HA to MN31; Simultaneously FA2 will set up the tunnel between self and the FA1, and carries out the data cached preparation for MN31; FA2 also will send a transmit-request message to FA1, and notice FA1 can begin to transmit the data of MN31 to FA2.
6) after FA1 receives transmit-request message, send handoff-ack message to MN31, notice MN31 begins two layers of switching; Simultaneously FA1 sets up the tunnel between self and the FA2, and the data forwarding that begins to issue MN31 is given FA2.
7) after MN31 received the handoff-ack of FA1, ACTIVE CONTROL began two layers of switching.
8) MN31 is by two layers of information of active inquiry, learn that two layers of switching are finished after, send an Agent Solicitation at once, the extended field of this Agent Solicitation will provide the IP address of FA1, notice FA2, MN31 has inserted in this subnet.
9) after FA2 receives the Agent Solicitation of MN31, send agent advertisement, notify its Care-of Address to MN31; Simultaneously will be in the buffering area send to MN31, and stop to MN31 data cachedly, give MN31 but directly transmit data for the MN31 data in buffer.
On the other hand, FA2 is after receiving that HA replies to the registration reply of MN31, and FA2 is transmitted to MN31 with this registration reply; FA2 sends transmit-stop-request message to FA1, and notice FA1 stops forwarding the data of MN31.
10) FA1 is receiving transmit-stop-request message, and after waiting for certain hour, removes the tunnel between self and the FA2, sends transmit-stop-reply to FA2.Here, wait for that certain hour is exactly in order to prevent that long packet of some transmission time from causing packet loss because of stopping transmitting.
11) after FA2 receives transmit-stop-reply message, remove the tunnel between self and the FA1, so far switch and finish.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.
Claims (7)
1, the method for mobile node realization seamless switching among a kind of mobile IP is characterized in that this method may further comprise the steps:
A. after current mobile node is determined to switch, obtain the information of new Foreign Agent earlier by former Foreign Agent, the information according to the new Foreign Agent that is obtained sends register requirement to new Foreign Agent then;
B. after new Foreign Agent is received register requirement, this register requirement is transmitted to home agent; The extremely new Foreign Agent of the data forwarding of notifying former Foreign Agent will send to current mobile node, and set up self to the tunnel between the former Foreign Agent;
C. after former Foreign Agent is received the notice of new Foreign Agent, notifying current mobile node to carry out link layer switches, set up self to the tunnel between the new Foreign Agent, and intercept and capture all data forwarding that mail to current mobile node and give new Foreign Agent, the data of issuing current mobile node that new Foreign Agent buffer memory is received;
D. after current mobile node link layer switching is finished, notify new Foreign Agent to switch and finish, new Foreign Agent will send to current mobile node for current mobile node data in buffer, and stop data cached; And, after new Foreign Agent is received the registration reply that home agent returns, the data of notifying former Foreign Agent to stop forwarding current mobile node, the tunnel between both sides remove.
2, method according to claim 1 is characterized in that, this method further comprises: each Foreign Agent is safeguarded a binding table that stores the base station information of adjacent Foreign Agent; Then the described mobile node of the step a information of obtaining new Foreign Agent specifically comprises: current mobile node sends apply for information to former Foreign Agent, carries the identification information of the purpose base station that will switch in this message; After former Foreign Agent was received apply for information, the binding table of inquiry self maintained obtained the information of new Foreign Agent, and gives current mobile node with the information-reply that is obtained.
3, method according to claim 2 is characterized in that, the base station information in the described binding table is a Base Station Identification, or is the MAC Address of base station.
4, method according to claim 2, it is characterized in that, this method further comprises: the base station information in each Foreign Agent timing search subnet, judge whether base station information changes, if have, then notify all adjacent Foreign Agents to carry out the renewal of binding table, all receive that the Foreign Agent of update notification upgrades the binding table of self; Otherwise, do not process.
5, method according to claim 1 is characterized in that, steps d further comprises: new Foreign Agent sends the agent advertisement that carries current mobile node Care-of Address after receiving that notice is finished in current mobile node switching to current mobile node.
6, method according to claim 1 is characterized in that, after steps d Central Plains Foreign Agent is received and stopped forwarding notice, through removing self after one section time-delay again to the tunnel between the new Foreign Agent.
7, method according to claim 1 is characterized in that, the interacting message between former Foreign Agent and the new Foreign Agent adopts the UDP message.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| US8842631B2 (en) | 2005-11-30 | 2014-09-23 | Qualcomm Incorporated | Data state transition during handoff |
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| CN1992659B (en) * | 2005-12-28 | 2010-05-05 | 华为技术有限公司 | Method of implementing data lossless transmission in the process of R3 re-anchoring |
| CN101422064B (en) * | 2006-02-09 | 2012-01-04 | 思达伦特网络有限责任公司 | Fast handoff support for wireless networks |
| CN100596095C (en) * | 2006-02-23 | 2010-03-24 | 华为技术有限公司 | Hierarchical mobility IPv6 rapid switching method and system |
| CN101132612B (en) * | 2006-08-22 | 2010-11-17 | 华为技术有限公司 | Network entity emigration method for grouping core network |
| US8532663B2 (en) | 2007-01-17 | 2013-09-10 | Qualcomm Incorporated | Configuring a base station to act as a regional mobility agent |
| US8125954B2 (en) * | 2007-05-04 | 2012-02-28 | Futurewei Technologies, Inc. | System for FA relocation with context transfer in wireless networks |
| US8830950B2 (en) | 2007-06-18 | 2014-09-09 | Qualcomm Incorporated | Method and apparatus for PDCP reordering at handoff |
| CN100593929C (en) * | 2007-08-21 | 2010-03-10 | 中国科学院计算技术研究所 | Mobile switch method of wireless packet network |
| CN101686507B (en) * | 2008-09-22 | 2012-07-04 | 中兴通讯股份有限公司 | Switching method for user to cross base stations in high speed downlink packet access technology |
| US8457071B2 (en) | 2010-08-31 | 2013-06-04 | Cisco Technology, Inc. | Reducing latency and packet loss related to handoffs of mobile video traffic |
| CN102893662A (en) * | 2011-02-25 | 2013-01-23 | 华为技术有限公司 | Method for managing a data path, mobility controller and communication system |
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| CN104023364A (en) * | 2014-05-28 | 2014-09-03 | 北京邮电大学 | Virtual access point-based wireless local area network seamless switching method |
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