CN1582050A - Method for realizing mobile node switching in mobile IP - Google Patents
Method for realizing mobile node switching in mobile IP Download PDFInfo
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- CN1582050A CN1582050A CN 200410042315 CN200410042315A CN1582050A CN 1582050 A CN1582050 A CN 1582050A CN 200410042315 CN200410042315 CN 200410042315 CN 200410042315 A CN200410042315 A CN 200410042315A CN 1582050 A CN1582050 A CN 1582050A
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Abstract
Mobile node compares current detected channel information of selected physical layer with preset trigger condition, and determines whether the base station of satisfying triggering condition belongs to current located sub network of the mobile node in order to decide whether it is needed to trigger network layer switching. If trigger is needed, then switching indication is sent to network layer, and dual links are built for each mobile node. When witching indication being received in network layer, disconnecting only one link in already built dual links, mobile node builds a new link. Then, using new built link, mobile node carries out network registration to home and network layer switching. Then, the other link is disconnected and another new connection in new sub network is built. The method can actively trigger startup of switching network layer precisely from low layer so as to raise switching speed and reduce package loss under condition of uninterrupted communication.
Description
Technical field
The present invention relates to mobile IP handoff technique, be meant a kind of method that the mobile node realization is switched in mobile IP 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 scheme that locomotive function is provided on global Internet, makes mobile node (MN) still can keep ongoing communication when handoff links.The IP routing mechanism that mobile IP provided can be connected on any link mobile node with a permanent IP address.
The release of mobile IP technology, make the mobile subscriber in across a network moves and roams, realized revising the requirement that all resources in the former network still can be continued to use in the original IP address of computer, it has shielded the user and has moved the influence that middle IP access network variation is brought.Briefly, mobile IP has realized level and smooth move and roaming function of mobile subscriber in network.
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 (Home Address), 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, HomeAgent) 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 external agent 13 and the external agent 14 that belong to field network 1 and field network 2 respectively among Fig. 1.
When mobile node A roams into field network or when field network 1 roamed into field network 2, according to the mobile IP protocol of standard, the handoff procedure of mobile node A may further comprise the steps from home network:
A. after mobile node A finds oneself to enter new network, disconnect original link earlier and connect, set up new link with the base station of new network with the agency and be connected; Mobile node A obtains a Care-of Address from Foreign Agent then, this Care-of Address can be the foreign agent care-of address that obtains from act on behalf of broadcast, or, be example below with the foreign agent care-of address according to the co-located care-of address that certain configuration rules obtain.
B. mobile node A sends login request message to current Foreign Agent, the Care-of Address that contains acquisition in this request message, Foreign Agent is done validity check to login request message, if check and pass through, then Foreign Agent is transmitted to the register requirement of mobile node A transmission the home agent of mobile node A; If check and do not pass through, then Foreign Agent is directly to mobile node A loopback registration reply message, and the indication registration failure finishes current flow process.
C. after the home agent of mobile node A is received login request message, carry out validity check, if message is effective, then home agent is with home address and the Care-of Address binding of mobile node A, and loopback registration reply message, indication is succeeded in registration, and begins to prepare to encapsulate the message that sends to mobile node A as tunnel portal; If message is invalid, then loopback registration reply message is indicated registration failure.
D. Foreign Agent is done validity check after receiving registration reply message again, pass through if check, then Foreign Agent upgrades the tabulation of visit mobile node, gives mobile node A with the registration reply forwards, and begins to prepare to seal off the message that sends to mobile node A as tunnel exit; If check and do not pass through, then Foreign Agent is transmitted registration reply message and is given mobile node A, the indication registration failure.
E. after mobile node A receives registration reply message,, then begin operate as normal if succeed in registration; Otherwise, can be according to initiating register requirement after the error message adjustment again.
Through behind the above-mentioned handoff procedure, the message that sends of oriented mobile node A all be routed to the home network of mobile node A, intercept and capture this message by home agent after, with the Care-of Address of mobile node A registration as tunnel exit, its own IP address sends message encapsulation back as tunnel portal.After Foreign Agent is received message and opening, check the visit mobile node tabulation of self,, then message is handed to mobile node A according to Care-of Address if mobile node A is present in the tabulation.
From above-mentioned handoff procedure as can be seen, have only when mobile node after the switching of low layer is finished, just begin network layer and switch.More particularly be exactly, only just can carry out network layer after physical layer and link layer have disconnected legacy network to be connected, to have set up new connection switches, and original connection has been broken before network layer is switched, but network layer can not be discovered, therefore, the cycle stretch-out that this handoff procedure will inevitably make communicating interrupt, cause handover delay and integrated communication to recover, and then cause packet loss.And, if the communicating interrupt overlong time can exert an influence to the application that real-time is had relatively high expectations, make that roaming is opaque to upper layer application, influence the result of use of mobile IP.
For shortening handover delay, reducing packet loss, industry has proposed a lot of different solutions respectively.Mainly comprise: 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.But in such scheme, no matter be to realize switching fast or realizing taking over seamlessly, all be confined to improvement to network layer switching processing process, can not thoroughly solve low layer and switch to finish and just can carry out the problem that network layer is switched, the therefore simple switching time that shortens network layer is to the influence that improves whole switch speed and not obvious.
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 because the realization of this scheme also is based on single-link, three layers switch and two layers of switching between time cooperate just very importantly, if former link disconnects before finishing network layer and switching, so, still can cause the interruption of communication, cause packet loss.
Summary of the invention
In view of this, main purpose of the present invention is to provide a kind of method that the mobile node realization is switched in mobile IP, can not only make initiatively trigger network layer startup switching exactly of low layer, the raising switch speed; And, can guarantee that communication is not interrupted in handoff procedure, reduce the packet loss in the handoff procedure.
For achieving the above object, technical scheme of the present invention is achieved in that
The method that mobile node realize to switch among a kind of mobile IP, key be, sets up two for each mobile node and be connected with link that current sub network communicates, and this method is further comprising the steps of:
A. current mobile node detects the selected physical layer channel information of all base stations of current discovery;
B. judge that whether detected selected physical layer channel information satisfies the trigger condition of setting, if do not satisfy, then returns step a; If satisfy, judge again then whether current base station of satisfying trigger condition belongs to the current place of described mobile node subnet, if do not belong to, then send and switch indication to network layer; Otherwise return step a;
C. after network layer is received and switched indication, disconnect in two links having set up between current mobile node and the former subnet base station, and between current mobile node and the target BS that will switch to, set up a new link and be connected;
D. current mobile node is registered by chain road direction home agent newly-built among the step c, and carries out the network layer switching;
E. after registration is finished, disconnect current mobile node and be connected, and between current mobile node and the target BS that will switch to, set up another link and be connected with another link between the former subnet base station.
This method further comprises: current mobile node obtains and stores all base station informations of current subnet of living in, and obtains the base station information of current all base stations of finding in real time; Judge described in the step b then whether the base station satisfy trigger condition belongs to the current place of described mobile node subnet and be: the base station information of base station information and all base stations of self storing that current mobile node will satisfy the base station of trigger condition mates, if all do not match, the base station of then satisfying trigger condition does not belong to the current place of current mobile node subnet, otherwise belongs to the current place of current mobile node subnet.
In the such scheme, when mobile node switched to field network from home network, steps d is described carried out network layer and switches and specifically comprise:
D11. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
D12. mobile node is set up the tunnel, sends register requirement by newly-built chain road direction home agent;
D13. after home agent is received register requirement, set up and lead to the tunnel of this Care-of Address, send registration reply, and send Proxy Address Resolution Protocol ARP message;
Then the described registration of step e finish for: mobile node is received the registration reply that home agent is sent.
When mobile node switched to another field network from a field network, steps d is described carried out network layer and switches and specifically comprise:
D21. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
D22. mobile node is set up the tunnel after obtaining Care-of Address, sends register requirement by newly-established chain road direction home agent, and carries the indication that keeps former Care-of Address in this register requirement;
D23. home agent keeps former Care-of Address after receiving new register requirement, stores the new Care-of Address that carries in the register requirement simultaneously, and sends registration reply to mobile node;
D24. after mobile node is received registration reply, send the cancel register request from the link that keeps between mobile node and the former base station;
D25. after home agent is received the cancel register request, delete former Care-of Address, and send registration reply to mobile node;
Then the described registration of step e is finished and is received home agent for: mobile node and delete the registration reply of sending behind the former Care-of Address.
Mobile node switches when going back home network from field network, and steps d is described carries out network layer and switch and specifically comprise:
D31. mobile node sends gratuitous ARP message in home network, and sends the cancel register request to home agent;
D32. after home agent is received the cancel register request, delete the Care-of Address and the tunnel of mobile node, and return registration reply to mobile node;
Then the tunnel of setting up between deletion and the Foreign Agent is finished to after: mobile node receives the registration reply that home agent sends in the described registration of step e.
In the such scheme, in handoff procedure, mobile node filters a repeating data according to existing protocol after receiving the repeating data that sends over from different links.
In the such scheme, before mobile node switches or switch finish after, two links that mobile node and current base station are set up are in the consolidated network, and a public Care-of Address.
In the such scheme, the triggered time that the trigger condition that sets causes is in advance in the time that physical layer automaticallyes switch.The trigger condition of described setting is the threshold value of selecting the physical layer channel information that will detect that sets in advance.Described selected physical layer channel information is received signal intensity or is signal to noise ratio.
In the such scheme, described base station information is Base Station Identification ID or is the service set SSID of subnet under the base station or the MAC Address of base station.So, the described base station information that obtains specifically comprises: mobile node sends the login request message that carries all base station informations indications of acquisition request to the agency of current place subnet, and the agency who receives described register requirement returns the registration reply message of the information that carries all base stations in the current sub network to the mobile node of initiating register requirement.Wherein, the described request indication of obtaining all base station informations is positioned in the extension field of login request message; The information of described all base stations is positioned in the extension field of registration reply message.
The method that the mobile node realization is switched in mobile IP provided by the present invention has following advantage and characteristics:
1) the present invention utilizes the trigger condition that the relevant information of detected physical layer channel is switched as network layer, the network layer switching is carried out in the low layer switching in advance, can shorten the time of network layer switching judging, fundamentally improve switch speed, and effectively reduce packet loss.
2) the present invention has introduced the notion of dual link in mobile IP switches, that is: each mobile node keeps the communication of two wireless links simultaneously, when mobile node enters the overlapping network overlay area that may switch, judge whether need to carry out the network layer switching in the still spendable situation of legacy network, then a link is used for connecting as needs with new network, and another link is used to keep and being connected of former network, thereby before legacy network is unavailable, insert when realizing former network and new two networks of network, so, just can guarantee that communication is not interrupted in the handoff procedure, thereby reduce packet loss.
3) the present invention will utilize the switching of physical layer channel information trigger network layer to be used in combination simultaneously with setting up the dual link technology, and fundamentally improve switch speed, and effectively reduce packet loss, be a kind of effective means that realizes seamless switching among the mobile IP.
When 4) mobile node among the present invention utilizes physical layer channel information as trigger condition, information according to all base stations in the current wireless subnet, judge whether self switches between different sub-network, so, not only improved the accuracy of switching judging, and avoided switching owing to the frequent triggering of low layer handover information causes the blindness of network layer.
5) in the present invention, when mobile node is in non-switch step, can walks abreast and use two links, so, can make full use of hardware resource, improve bandwidth, and reach the purpose of load balancing.
6) the present invention is the expansion to the standard mobile IP protocol, only existing the processing is a little changed, and is compatible fully with the standard mobile IP system, therefore, realizes simple and conveniently, and is easy to carry out function expands on existing mobile IP system.
Description of drawings
Fig. 1 is the basic network topology diagram that each entity is formed among the mobile IP;
The process chart that Fig. 2 realizes for the present invention;
The triggering schematic diagram on opportunity of physical layer channel information when the mobile node that Fig. 3 defines for the present invention switches;
Fig. 4 moves to the handoff procedure schematic diagram of field network from home network for mobile node among the present invention;
The handoff procedure schematic diagram that Fig. 5 moves between two field networks for mobile node among the present invention;
Fig. 6 returns the handoff procedure schematic diagram of home network from field network for mobile node among the present invention;
Fig. 7 is the network topology structure figure of the present invention's one specific embodiment.
Embodiment
Core concept of the present invention is: mobile node as trigger condition, and in conjunction with the base station information of current network, need to judge whether the trigger network layer to switch the relevant information of physical layer channel.And for each mobile node is set up dual link, when mobile node was in non-switching state, the dual link that the mobile node utilization is set up walked abreast and carries out communication; When mobile node is in switching state, only disconnect in the dual link, just, utilize a link to keep former connection, utilize another link establishment newly to connect simultaneously, when mobile node re-register finish after, will keep the link of former connection to disconnect again, and set up again a mobile node and new new connection between the subnet base station.
The prerequisite that the present invention realizes is: physical layer channel information of chosen in advance is as trigger parameter, and at the selected good trigger condition of physical layer channel information setting, here, selected physical layer channel information is to judge whether to carry out to choose the used physical layer parameter information of physical layer switching from mobile node; And, between the current subnet of living in of mobile node and its base station, set up the dual link that is used to communicate by letter.Based on this, implementation procedure of the present invention may further comprise the steps referring to shown in Figure 2:
Step 201: mobile node detects the selected physical layer channel information of current all base stations of finding in real time.
Wherein, described physical layer channel information is that mobile node judges whether to carry out the used physical layer 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 etc.; Can from above-mentioned parameter information, choose any one kind of them as selected physical layer channel information, common optionally connected collection of letters intensity or signal to noise ratio.Such as: as selected physical layer channel information, mobile node just detects the state of signal-to-noise of current all base station signals of finding in real time with signal to noise ratio.
Step 202: mobile node judges whether detected selected physical layer channel information satisfies the trigger condition of setting, if satisfy, then execution in step 203; Otherwise, return step 201.
Here, described trigger condition can be the threshold value of the selected physical layer channel information that sets in advance, such as: selected signal to noise ratio is selected physical layer channel information, trigger condition is SIR1 for snr threshold is set, so, if the current snr value of mobile node satisfies trigger condition exactly greater than SIR1.Set trigger condition must guarantee to utilize this trigger condition and triggered time of causing in advance in the time that link layer automaticallyes switch, as shown in Figure 3, the initial moment that the moment 32 switches for network layer in the prior art, the triggering moment that the moment 31 switches for the network layer that is provided with among the present invention.
Step 203～204: mobile node judges whether the base station of satisfying trigger condition belongs to new subnet, if do not belong to, then returns step 201, if belong to, then sends to network layer and switches indication.
Here, mobile node can judge whether the base station of satisfying trigger condition belongs to self current place subnet by comparing base station information.In this case, in step 201, mobile node also will obtain the base station information of current all base stations of finding simultaneously; And mobile node is also wanted timing search, obtains and store all base station informations of current place subnet.Wherein, described base station information is meant the information that can identify each base station subnet ownership, and promptly current base station belongs to the identification information of which subnet, such as: service set (SSID) of subnet or the like under base station IDs, the base station.The time cycle of described timing search can be set arbitrarily according to actual conditions, such as: the rate travel according to mobile node is set; If the time cycle is set to zero, then search in real time.
So, described judgement is exactly: mobile node will be current all interior base station informations of base station information and the current place subnet of self storing that satisfy the base station of trigger condition mate, if on mating, illustrate that then the base station of satisfying trigger condition does not all belong to new subnet, so just return step 201, if all do not match, then explanation has the base station of satisfying trigger condition to belong to new subnet, so just initiatively the trigger network layer switches, that is: send to network layer and switch indication.
Why to judge further whether the base station of satisfying trigger condition belongs to new subnet, that is: why want simultaneously in conjunction with base station information judge whether to carry out network layer switch be because: if only rely on selected physical layer channel information to trigger, might only finish the switching between different base station in the same subnet, that is to say, if only according to the switching of this trigger condition trigger network layer, may cause a lot of meaningless switchings, have a strong impact on network performance, consume system resources.Therefore, what determine appearance in this step is the base station of new wireless sub network, just starts network layer and switches, otherwise switch with regard to not carrying out network layer, so can reduce unnecessary switching.
Mobile node obtains base station information can a lot of modes, and dual mode commonly used is:
A) because the standard mobile IP protocol leaves extension field to the definition of registration message, shown in table one, table two, table one is the message format of login request message, table two is the message format of registration reply message, therefore, can utilize the extension field of registration message between Foreign Agent and the mobile node about the transmission of base station information.
| 0 | 1 | ??2 | ????3 | |||||||
| Type (Type) | S | ?B | ?D | ?M | ?G | ?R | ?T | ?X | Life cycle (Lifetime) | |
| Home address (Home Address) | ||||||||||
| Home agent (Home Agent) | ||||||||||
| Care-of Address (Care-of Address) | ||||||||||
| Describe (Identification) | ||||||||||
| Extension field (Extensions) ... | ||||||||||
Table one
| 0 | ????1 | ??2 | ????3 |
| Type (Type) | ????Code | Life cycle (Lifetime) | |
| Home address (Home Address) | |||
| Home agent (Home Agent) | |||
| Extension field (Extensions) ... | |||
Table two
In this case, the process that mobile node obtains base station information in the current network is: mobile node sends login request message to the agency of current place network, the indication of all base station informations in the current network is transmitted in the request of carrying in this register requirement, and described indication is placed in the extension field of login request message; After the agency of the current place of mobile node network receives register requirement, carry the registration reply message of all base station informations in the current network to the mobile node loopback, same, all base station informations also are placed in the extension field of registration reply message.
So, the concrete extended method of registration message is: add one in the extension field of login request message, and be that this sets a particular value, represent mobile node request Foreign Agent to transmit the information of base station in this subnet, such as: set a type item, and types value is defined as 39, as shown in Table 3.Certainly, if certain mobile node is in home network, can send the register requirement that carries the certain kinds offset to home agent equally.
| ????0 |
| Type |
Table three
Correspondingly, in the extension field of registration reply message, add one, be used to carry the information of all base stations of current sub network, as shown in Table 4.
| ????0 | ????1 | ????2 | ????3 |
| Type | Byte number | Quantity | |
| The flag information of base station 1 | |||
| The flag information of base station 2 | |||
| ????...... | |||
| The flag information of base station n | |||
Table four
In the table four, type is represented to carry base station information in this registration reply message, and types value is identical with types value in the login request message, such as: types value is 39; The number of base station in this subnet of quantitaes; Byte number is represented a required byte number that takies of base station information, is assumed to four bytes in the table four; The flag information of base station 1 to base station n is a base station information, can be the ID, MAC Address etc. of base station, so long as information that can certain base station of unique identification can.
For preventing that the base station number in the current network of living in from changing, for example: close a base station, increase a situation such as base station newly, except that the other places agency regularly upgraded, mobile node can also regularly ask Foreign Agent to transmit the information of all base stations in the current sub network.Because the register requirement in the standard mobile IP protocol also is to want timed sending, therefore can directly utilize register requirement regularly to come regularly to ask base station information.
In a single day mobile node enters new field network, and the base station information of former field network just will be replaced by the information of new field network.But for the base station information of home network, mobile node must be preserved always, because for network layer, the processing of coming back to hometown is distinguishing with switching between different field networks.
B) be the different SSID of adjacent radio network configuration, for example: if network 1 is adjacent with network 2, then the SSID of configuration network 1 is Ssid1, and the SSID of network 2 is Ssid2.Mobile node with the reciprocal process of base station in, from the message that the base station issues, extract the SSID of subnet under it.
Certainly, in actual applications, the mode that mobile node obtains base station information is not limited only to above-mentioned two kinds.
Step 205: after network layer is received the switching indication that low layer sends, system discharges the connection that link is current, promptly disconnect original connection of any link in the dual link, bear whole communications of current sub network by another link, and a link that disconnects is used for setting up and new being connected of wireless sub network base station.
Step 206: with set up being connected of new base station finish after, mobile node is registered to home agent by newly-established connection, and carries out network layer and switch.Specifically, mobile node set up with new subnet in being connected between acting on behalf of, and register to home agent.Here, if mobile node is to enter new field network, so, the agency in the new subnet is exactly new Foreign Agent, if mobile node is the network of coming back to hometown, so, the agency in the new subnet is exactly a home agent.
To enter new field network is example, after mobile node connects with new Foreign Agent, again by registering between new Foreign Agent and home agent, registration process comprises: at first, mobile node will obtain new Care-of Address from new Foreign Agent, register to home agent then, new Care-of Address is sent to home agent; Home agent not at once former Care-of Address deletion, but keeps two registration bindings after the registration of receiving new Care-of Address, each data message that sends to mobile node is delivered to each Care-of Address of mobile node by the tunnel.In such cases, mobile node can be received the data of repetition by dual link, and so, mobile node is just according in the existing protocol processing mode of repeating data being filtered a repeating data.
Step 207: after the registration of the stable formation of new link, mobile node is finished, system discharges original connection of another link, and between mobile node and new wireless sub network base station and set up another link between the agency of mobile node and new wireless sub network and be connected, recover normal communication process afterwards.
The switching of mobile node can be divided into three kinds of situations: mobile node from home network move to that field network, mobile node move between different field networks, mobile node is from the field network network of coming back to hometown.
Mobile node adopts a link registration, the mode of another link communication in the handoff procedure when leaving home network and switch.As shown in Figure 4, link 40 link for keeping original connection to proceed to communicate by letter, link 41 newly is connected the link of registering for disconnecting setting up between original connection and the Foreign Agent.The handoff procedure of mobile node when home network moves to field network may further comprise the steps:
A1. work as mobile node and shift out home network, when entering a field network, this mobile node inserts field network with any link in two links self setting up, after new connection is set up, mobile node connects the Care-of Address that obtains in the new network by this, such as: utilize link 41 to obtain Care-of Address.
B1. set up the tunnel between mobile node and the Foreign Agent, send register requirement by newly-built chain road direction home agent, that is: mobile node is registered to home agent via link 41, path 42,43,44.
C1. after home agent is received register requirement, set up the tunnel that leads to this Care-of Address, send registration reply, and send Proxy Address Resolution Protocol (ARP) message.Here, the purpose that sends ARP message is that this mobile node of explanation has left home network, and all data messages that are sent to this mobile node can receive the back forwarding by home agent.
D1. after mobile node is received the registration reply that home agent sends, new stable formation that connect is described, then, inserts again in the field network, finish switching keeping another link of original connection also to disconnect in the home network.
Mobile node is when leaving a field network and enter another field network, and home agent adopts the mode of multiple bindings in the handoff procedure, stores two Care-of Address simultaneously for this mobile node that is:, binds two routes simultaneously.Referring to shown in Figure 5, mobile node handoff procedure when mobile between different field networks may further comprise the steps:
A2. mobile node is when field network 1 roams into field network 2, a link in two links will setting up with field network 1 disconnects, insert in the field network 2, after new connection was set up, mobile node connected the Care-of Address that obtains in the new network by this.
B2. mobile node is set up the tunnel after obtaining Care-of Address, sends register requirement by newly-established chain road direction home agent.It should be noted that: this moment, register requirement needed to be provided with " S " position.In the standard mobile IP protocol login request message form of defined as shown in Table 1, wherein, the S bit is represented binding information simultaneously, if S set just illustrates that mobile node requirement home agent keeps the binding information before it.
C2. registered a Care-of Address owing to mobile node on home agent, home agent is not deleted former Care-of Address after receiving new register requirement, and just adds one again, and sends registration reply to mobile node.After this, home agent is all delivered to each data message of being received, send to this mobile node each Care-of Address of mobile node by the tunnel.
D2. after mobile node is received registration reply, send the cancel register request message from former link.
E2. home agent is received the cancel register request, deletes former configuration Care-of Address, and sends registration reply.After this, home agent is just only transmitted data to new Care-of Address.
F2. mobile node is received registration reply, will also disconnect with original another link that is connected of maintenance in the field network 1, inserts again in the field network, finishes switching.
When mobile node returned home network from field network, handoff procedure adopted a link registration, the mode that another link continuation communicates by field network.As shown in Figure 6, the handoff procedure of mobile node when field network is come back to hometown network may further comprise the steps:
A3. mobile node is when field network returns home network, a link in two links will setting up with field network disconnects, insert in the home network, after new connection is set up, mobile node sends gratuitous ARP message in home network, and sends the cancel register request to home agent.
Here, the purpose that sends ARP message is to notify this mobile node network of having come back to hometown.
B3. after home agent is received the cancel register request, delete the Care-of Address and the tunnel of mobile node, and return registration reply to mobile node.
C3. after mobile node is received the registration reply that home agent sends, the tunnel of setting up between deletion and the Foreign Agent, and with keeping another link of original connection also to disconnect in the field network, insert again in the home network, finish switching.
In Fig. 4, Fig. 5, Fig. 6, dotted line is represented unidirectional tunnel, and solid line is represented registration message, and chain-dotted line is represented normal communication data, and the rectangle on the solid line is represented the tunnel.
Before mobile node switches or switch finish after, if this mobile node is in the field network, home agent is just only bound the Care-of Address of current mobile node place network, therefore, all data messages that send to this mobile node all is forwarded on this Care-of Address.At this moment, two links that mobile node is set up all in same subnet, a public Care-of Address.Though two links are arranged, can pass through a virtual link layer, make its IP address of common use carry out communication, thereby upper layer application can not be recognized the existence of dual link.In actual applications, two links of mobile node can be respectively realize by two network interface cards, have only an IP address at the upper layer application mobile node of mobile node, but the datagram that its sends are transmitted by two links.When specifically utilizing any bar link to send, can select according to the busy idle condition of link, such as: when needing to select, judge the busy not busy situation of two links earlier, utilize the light link of wherein load to send, thereby can improve bandwidth, can realize load balancing again.
Below with reference to Fig. 7 also in conjunction with specific embodiments, describe in detail and set up the handoff procedure that dual link combines with the switching of low layer active trigger network layer, Fig. 7 is the network topology structure figure of mobile node 70 mobile IP systems of living in.As shown in Figure 7, this mobile IP system is a WLAN (wireless local area network) that adopts 802.11 agreements, and this WLAN (wireless local area network) comprises three subnets: home network, field network 1 and field network 2.Link to each other by router between three subnets, comprise an agency in each subnet, that is: home agent, Foreign Agent 1 and Foreign Agent 2.Each subnet comprises two base stations again respectively, i.e. access point AP1～AP6, and six imaginary circles among Fig. 7 are represented the overlay area of AP1～AP6 respectively.Wherein, access point AP1 and AP2 belong to home network, and access point AP3 and AP4 belong to field network 1, and access point AP5 and AP6 belong to field network 2.Chain-dotted line among Fig. 7 is represented the motion track of mobile node 70, as can be seen, mobile node 70 is from home network, roam into field network 1 earlier, roam into field network 2 by field network 1 again, this moving process comprises three kinds of switchings: the switching from the home network to the field network, the switching between two field networks and from the come back to hometown switching of network of field network.
In the present embodiment, mobile node 70 is selected two 802.11 wireless network card simulated dual link for use, and the network layer switching is initiatively triggered according to the physic channel information that is detected by low layer.
Mobile node 70 begins to be positioned at home network, and when mobile node 70 moved to the overlapping area of coverage 71 of AP2 and AP3, two layers were triggered and start, and informing network layer mobile node 70 will move to field network 1 from home network, and the trigger network layer begins to switch.At this moment, mobile node 70 will be connected disconnection with a link in two links setting up between the AP2, connect with AP3; And another link still keeps and being connected of AP2.After mobile node 70 and the link establishment of AP3 were got up, mobile node 70 connected the Care-of Address 1 that obtains in the field network 1 by this; And set up the tunnel according to Care-of Address 1, send register requirement by chain road direction home agent with AP3.
Home agent is set up the tunnel that leads to Care-of Address 1 after receiving register requirement, and sends registration reply to mobile node 70, sends proxy ARP message simultaneously; After mobile node 70 is received registration reply, will and AP2 between the link that keeps also disconnect, this link is inserted AP3, as the second link between mobile node 70 and the AP3, so, promptly finished from the home network to the field network 1 whole handoff procedure.
Is that the MAC Address of AP is an example with signal to noise ratio as selected physical layer channel information and base station information, described two layers of detailed process that triggers startup are: mobile node 70 enters the boundary part of home network and field network 1, during promptly from AP2 immigration AP3, along with the distance from AP3 becomes near, mobile node 70 can find that the signal to noise ratio of AP3 has satisfied the trigger condition of setting, promptly reaches predefined snr threshold; Simultaneously, the MAC Address of AP3 is searched for and obtained to mobile node 70, with the MAC Address of all AP in the current sub network of the MAC Address of AP3 and self current preservation relatively, at this moment, what mobile node 70 self was preserved is the MAC Address of AP1 and AP2, so the MAC Address of the MAC Address of discovery AP3 and all AP of self current preservation does not all match, can determine that then AP3 belongs to new subnet, so the just initiatively switching of trigger network layer of mobile node 70.
When mobile node 70 when motion track moves to the overlapping area of coverage 72 of AP4 and AP6, two layers are triggered and start, informing network layer mobile node 70 has been about to enter new field network, the trigger network layer begins to switch.Mobile node 70 will be connected disconnection with a link in two links setting up between the AP4, connect with AP6, but still keep a link to be connected with AP4; And mobile node 70 obtains Care-of Address 2 in the field network 2 by connecting with AP6.Mobile node 70 is set up the tunnel, sends register requirement by the chain road direction home agent with AP6, and this moment, register requirement needed to be provided with " S " position.Here, if be the MAC Address of AP with signal to noise ratio as selected physical layer channel information and base station information, described two layers of detailed process that triggers to start are similar with mobile nodes 70 to the AP3 switching.
Though mobile node 70 had been registered a Care-of Address 1 on home agent, but after home agent is received and is carried the new registration request that is provided with the S position, do not delete Care-of Address 1, but Care-of Address 2 is added in the binding table, and send registration reply to mobile node 70.After this, home agent each data message that will send to mobile node 70 is all delivered on Care-of Address 1, Care-of Address 2 these two Care-of Address by the tunnel.After mobile node 70 is received registration reply, by and AP4 between chain road direction home agent send the cancel register request.After home agent is received the cancel register request, delete Care-of Address 1, and return registration reply to mobile node 70, expression Care-of Address 1 has been deleted.After this, home agent has just only been transmitted data to Care-of Address 2.Mobile node 70 after receiving registration reply, will and AP4 between link disconnect, and this link is inserted among the AP6, as the second link between mobile node 70 and the AP6, so far finish from field network 1 to field network 2 whole handoff procedure.
When mobile node 70 when motion track moves to the overlapping area of coverage 73 of AP5 and AP2, two layers are triggered and start, informing network layer mobile node 70 will be from field network 2 network of coming back to hometown, the trigger network layer begins to switch.At this moment, mobile node 70 will be connected disconnection with a link in two links setting up between the AP5, connect with AP2, keep and be connected still with another link of AP6.Here, if be the MAC Address of AP with signal to noise ratio as selected physical layer channel information and base station information, described two layers of detailed process that triggers to start are similar with mobile nodes 70 to the AP3 switching.
After getting up with the link establishment of AP2, mobile node 70 illustrates and oneself comes back to hometown, and send the cancel register request by sending gratuitous ARP message in the home network with being connected of AP2 foundation.After home agent is received the cancel register request, the Care-of Address 2 and the tunnel of deletion mobile node 70, and to mobile node 70 transmission registration replys.After mobile node 70 is received registration reply, the deletion tunnel, and will be connected also disconnection with the link that AP5 keeps, insert on the AP2 of home network, as the second link between mobile node 70 and the AP2, so far finish from the come back to hometown whole handoff procedure of network of field network 2.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.
Claims (13)
1, the method that mobile node realize to switch among a kind of mobile IP is characterized in that, sets up two for each mobile node and is connected with link that current sub network communicates, and this method is further comprising the steps of:
A. current mobile node detects the selected physical layer channel information of all base stations of current discovery;
B. judge that whether detected selected physical layer channel information satisfies the trigger condition of setting, if do not satisfy, then returns step a; If satisfy, judge again then whether current base station of satisfying trigger condition belongs to the current place of described mobile node subnet, if do not belong to, then send and switch indication to network layer; Otherwise return step a;
C. after network layer is received and switched indication, disconnect in two links having set up between current mobile node and the former subnet base station, and between current mobile node and the target BS that will switch to, set up a new link and be connected;
D. current mobile node is registered by chain road direction home agent newly-built among the step c, and carries out the network layer switching;
E. after registration is finished, disconnect current mobile node and be connected, and between current mobile node and the target BS that will switch to, set up another link and be connected with another link between the former subnet base station.
2, method according to claim 1 is characterized in that, this method further comprises: current mobile node obtains and stores all base station informations of current subnet of living in, and obtains the base station information of current all base stations of finding in real time;
Judge described in the step b then whether the base station satisfy trigger condition belongs to the current place of described mobile node subnet and be: the base station information of base station information and all base stations of self storing that current mobile node will satisfy the base station of trigger condition mates, if all do not match, the base station of then satisfying trigger condition does not belong to the current place of current mobile node subnet, otherwise belongs to the current place of current mobile node subnet.
3, method according to claim 1 is characterized in that, when mobile node switched to field network from home network, steps d is described carried out network layer and switch and specifically comprise:
D11. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
D12. mobile node is set up the tunnel, sends register requirement by newly-built chain road direction home agent;
D13. after home agent is received register requirement, set up and lead to the tunnel of this Care-of Address, send registration reply, and send Proxy Address Resolution Protocol ARP message;
Then the described registration of step e finish for: mobile node is received the registration reply that home agent is sent.
4, require 1 described method according to power, it is characterized in that, when mobile node switched to another field network from a field network, steps d is described carried out network layer and switches and specifically comprise:
D21. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
D22. mobile node is set up the tunnel after obtaining Care-of Address, sends register requirement by newly-established chain road direction home agent, and carries the indication that keeps former Care-of Address in this register requirement;
D23. home agent keeps former Care-of Address after receiving new register requirement, stores the new Care-of Address that carries in the register requirement simultaneously, and sends registration reply to mobile node;
D24. after mobile node is received registration reply, send the cancel register request from the link that keeps between mobile node and the former base station;
D25. after home agent is received the cancel register request, delete former Care-of Address, and send registration reply to mobile node;
Then the described registration of step e is finished and is received home agent for: mobile node and delete the registration reply of sending behind the former Care-of Address.
5, method according to claim 1 is characterized in that, mobile node switches when going back home network from field network, and steps d is described carries out network layer and switch and specifically comprise:
D31. mobile node sends gratuitous ARP message in home network, and sends the cancel register request to home agent;
D32. after home agent is received the cancel register request, delete the Care-of Address and the tunnel of mobile node, and return registration reply to mobile node;
Then the tunnel of setting up between deletion and the Foreign Agent is finished to after: mobile node receives the registration reply that home agent sends in the described registration of step e.
According to each described method of claim 1 to 5, it is characterized in that 6, in handoff procedure, mobile node filters a repeating data according to existing protocol after receiving the repeating data that sends over from different links.
7, according to each described method of claim 1 to 5, it is characterized in that, before mobile node switches or switch finish after, two links that mobile node and current base station are set up are in the consolidated network, and a public Care-of Address.
8, method according to claim 1 and 2 is characterized in that, the triggered time that the trigger condition that sets causes is in advance in the time that physical layer automaticallyes switch.
9, method according to claim 1 and 2 is characterized in that, the trigger condition of described setting is the threshold value of selecting the physical layer channel information that will detect that sets in advance.
10, method according to claim 1 and 2 is characterized in that, described selected physical layer channel information is received signal intensity or is signal to noise ratio.
11, method according to claim 2 is characterized in that, described base station information is Base Station Identification ID or is the service set SSID of subnet under the base station or the MAC Address of base station.
12, method according to claim 2, it is characterized in that, the described base station information that obtains specifically comprises: mobile node sends the login request message that carries all base station informations indications of acquisition request to the agency of current place subnet, and the agency who receives described register requirement returns the registration reply message of the information that carries all base stations in the current sub network to the mobile node of initiating register requirement.
13, method according to claim 12 is characterized in that, the indication that described request is obtained all base station informations is positioned in the extension field of login request message; The information of described all base stations is positioned in the extension field of registration reply message.
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| CNB2004100423159A CN1324924C (en) | 2004-05-17 | 2004-05-17 | Method for realizing mobile node switching in mobile IP |
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| CNB2004100423159A CN1324924C (en) | 2004-05-17 | 2004-05-17 | Method for realizing mobile node switching in mobile IP |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007045177A1 (en) * | 2005-10-19 | 2007-04-26 | Huawei Technologies Co., Ltd. | Method, system and appatatus for realizing mobile protocol deregistering |
| CN100456742C (en) * | 2006-04-30 | 2009-01-28 | 国家数字交换系统工程技术研究中心 | Mobile Internet protocol route processing method and system and router |
| CN101878669A (en) * | 2007-11-30 | 2010-11-03 | 朗讯科技公司 | Switching as possible of multimode mobile unit to keep the method for radio bearer and MIP session continuity |
| CN101931938A (en) * | 2009-06-26 | 2010-12-29 | 华为技术有限公司 | Method, device and system for forwarding data in inter-network switching |
| CN101345696B (en) * | 2007-07-12 | 2011-03-16 | 中国科学院声学研究所 | Fast switching method for proxy mobile IP |
| CN101682631B (en) * | 2007-05-30 | 2013-05-22 | 高通股份有限公司 | Method and apparatus for communication handoff |
| CN104270811A (en) * | 2008-09-23 | 2015-01-07 | 高通股份有限公司 | Method And Apparatus For Reducing Successive Pre-registration Attempts By Access Terminals |
| CN108900248A (en) * | 2018-06-27 | 2018-11-27 | 中国联合网络通信集团有限公司 | The distribution method and device of access point in a kind of visible light wireless communication system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7492787B2 (en) * | 2002-03-29 | 2009-02-17 | Fujitsu Limited | Method, apparatus, and medium for migration across link technologies |
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- 2004-05-17 CN CNB2004100423159A patent/CN1324924C/en not_active Expired - Fee Related
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2007045177A1 (en) * | 2005-10-19 | 2007-04-26 | Huawei Technologies Co., Ltd. | Method, system and appatatus for realizing mobile protocol deregistering |
| US7961681B2 (en) | 2005-10-19 | 2011-06-14 | Huawei Technologies Co., Ltd. | Method, system and apparatus for performing mobile internet protocol deregistering |
| US8112084B2 (en) | 2005-10-19 | 2012-02-07 | Huawei Technologies Co., Ltd. | Method, system and apparatus for performing mobile internet protocol deregistering |
| CN100456742C (en) * | 2006-04-30 | 2009-01-28 | 国家数字交换系统工程技术研究中心 | Mobile Internet protocol route processing method and system and router |
| CN101682631B (en) * | 2007-05-30 | 2013-05-22 | 高通股份有限公司 | Method and apparatus for communication handoff |
| CN101345696B (en) * | 2007-07-12 | 2011-03-16 | 中国科学院声学研究所 | Fast switching method for proxy mobile IP |
| CN101878669A (en) * | 2007-11-30 | 2010-11-03 | 朗讯科技公司 | Switching as possible of multimode mobile unit to keep the method for radio bearer and MIP session continuity |
| CN101878669B (en) * | 2007-11-30 | 2015-08-19 | 朗讯科技公司 | Switching with the method keeping radio bearer and MIP session continuity as possible of multiple mode mobile units |
| CN104270811A (en) * | 2008-09-23 | 2015-01-07 | 高通股份有限公司 | Method And Apparatus For Reducing Successive Pre-registration Attempts By Access Terminals |
| US9883477B2 (en) | 2008-09-23 | 2018-01-30 | Qualcomm Incorporated | Method and apparatus for reducing successive pre-registration attempts by access terminals |
| CN104270811B (en) * | 2008-09-23 | 2018-09-28 | 高通股份有限公司 | The method and apparatus that continuous pre-registration for reducing access terminal is attempted |
| CN101931938B (en) * | 2009-06-26 | 2013-09-25 | 华为技术有限公司 | Method, device and system for forwarding data in inter-network switching |
| CN101931938A (en) * | 2009-06-26 | 2010-12-29 | 华为技术有限公司 | Method, device and system for forwarding data in inter-network switching |
| CN108900248A (en) * | 2018-06-27 | 2018-11-27 | 中国联合网络通信集团有限公司 | The distribution method and device of access point in a kind of visible light wireless communication system |
| CN108900248B (en) * | 2018-06-27 | 2019-10-11 | 中国联合网络通信集团有限公司 | The distribution method and device of access point in a kind of visible light wireless communication system |
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