CN1301035C - Method for realizing network layer switching in mobile IP - Google Patents
Method for realizing network layer switching in mobile IP Download PDFInfo
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- CN1301035C CN1301035C CNB2004100423163A CN200410042316A CN1301035C CN 1301035 C CN1301035 C CN 1301035C CN B2004100423163 A CNB2004100423163 A CN B2004100423163A CN 200410042316 A CN200410042316 A CN 200410042316A CN 1301035 C CN1301035 C CN 1301035C
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Abstract
The present invention discloses a method for realizing network layer switching in mobile IP. The present invention has the key point that double chain paths used for communication are established between a mobile node and the existing base station. The method comprises the following steps: step a, after a network layer determines that switching operation is required, one of the established double chain paths is broken, and connection of a new chain path is established between the existing mobile node and a target base station which needs to be switched to; step b, the mobile node carries out registration to a hometown agent through the newly established chain path, and network layer switching operation is carried out; step c, after the registration is completed, connection of the other chain path between the existing mobile node and the original base station is broken, and connection of a chain path is established between the existing mobile node and the target base station which needs to be switched to. The method can ensure that in the switching process of the mobile node, communication can not be interrupted. Therefore, the switching speed is enhanced, and the packet loss ratio in the switching process is reduced.
Description
Technical field
The present invention relates to mobile IP handoff technique, be meant a kind of method that network layer is switched that in mobile IP, realizes 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.
It still is example with Fig. 1, when mobile node 10 roams into field network 1 or when field network 1 roams into field network 2 from home network, network will take place and switch in mobile node 10, common handoff procedure is: mobile node 10 according to current detection to INFORMATION DISCOVERY self enter new network after, mobile node 10 can be by receiving acting on behalf of broadcast or obtaining a Care-of Address by DHCP modes such as (DHCP) of Foreign Agent transmission, with these Care-of Address sign mobile node 10 present located positions.This Care-of Address can be a foreign agent care-of address, i.e. the IP address of Foreign Agent; Also can be co-located care-of address, an IP address of promptly distributing on the field network.After obtaining Care-of Address, mobile node 10 is registered to the home agent of oneself by the route forwarding function that Foreign Agent provides again, the own present care-of address of notice home agent.Home agent that is to say, when the position of mobile node changes, all will register to home agent again, upgrade its positional information, so that can be known the mobile node current position information at any time.
Because mobile IP is the network layer solution, handoff procedure recited above all carries out in network layer, but in fact, mainly occur on two aspects in the switching between the heterogeneous networks in the mobile node roam procedure: the one, the switching on the level physical network comprises the processing on physical layer and the link layer; Another is to register, reconfigure sequence of operations such as route on network layer according to mobile IP protocol.In the standard mobile IP protocol, have only when mobile node and finish in the switching of low layer, promptly disconnect with being connected of former network after, just begin to carry out the switching of network layer, like this, can make communicating interrupt, 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.
Want to solve handover delay to using the influence that is produced, just need to realize seamless switching.So-called seamless switching comprises two aspects: switch fast and take over seamlessly.Wherein, the purpose of switching fast is to reduce or eliminate the delay that mobile node is set up new communication path; The purpose that takes over seamlessly is to reduce the Loss Rate of packet.
At present, at quick switching with take over seamlessly, industry has proposed a lot of different solutions respectively:
Solving on the quick switching problem, main thought is: with the function distribution of home agent, implement local registration, reduce hour of log-on.Mainly comprise two class modes: hierarchical mobility management and based on the mobile management of particular host route, wherein, the mode of hierarchical mobility management comprises: solutions such as MIP-RR, IDMP; Mode based on the mobile management of particular host route comprises: solutions such as cellular ip, HAWAII.Aforesaid way all is that wireless access network is divided into one by one wireless domains, realizes the localization of registration in wireless domains.The difference of dual mode just is: the agreement of transmitted in packets in the wireless domains, and preceding a kind of mode is used conventional mobile IP protocol, and a kind of mode in back is used the agreement based on the particular host route.
Aspect taking over seamlessly, need the grouping cache forwarding mechanism, be divided into clean culture forwarding and multicast forwarding.Clean culture is transmitted and is meant: the current base station agency is Foreign Agent buffered packet data message in handoff procedure, be transmitted to new base station agency after switching, but the packet forward between the agency of new and old base station may need the long time; Multicast forwarding then adopts the grouped data report of multicast protocol forwarding cache, for example each mobile node has a multicast address, when mobile node during to new base station agency of trademark registration, the base station agency that this new base station Agent Requirements is adjacent adds multicast group, buffered packet in advance, but this scheme exists multicast address conflict and neighbours to need the problem of manual configuration, if adopt overseas agency (DFA) to distribute the mode of multicast address to solve the problem of multicast address conflict, but have the neighbor discovery mechanisms of lack of wisdom and the overhead issues of multicast state equally to mobile node.
In addition, no matter be to realize switching fast or realizing taking over seamlessly in the such scheme, it all is the solution that is confined to network layer, though be to make every effort to shorten the time of delay that network layer is switched, but the Millisecond just during this period of time that switches of network layer in fact, and the communicating interrupt process is a second level, if it is also not obvious to the influence that improves whole switch speed to shorten the switching time of network layer merely.Therefore, there are some research institutions to propose link layer and network layer 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 and realizes the method that network layer is switched among a kind of mobile IP, can guarantee that communication is not interrupted in mobile node switching process, thereby improve switch speed, has reduced the packet loss in the handoff procedure.
For achieving the above object, technical scheme of the present invention is achieved in that
Realize the method that network layer is switched among a kind of mobile IP, set up the dual link that is used to communicate by letter between the base station under mobile node and its are current, this method may further comprise the steps:
A. after network layer is determined to switch, disconnect in the dual link of being set up, between current mobile node and the target BS that will switch to, set up a new link and be connected;
B. mobile node is registered by chain road direction home agent newly-built among the step a, and carries out the network layer switching;
C. 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 new link and be connected with another link between the former base station.
In the such scheme, when mobile node when home network switches to field network, step b specifically comprises:
B11. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
B12. mobile node is set up the tunnel, sends register requirement by newly-built chain road direction home agent;
B13. 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 c finish for: mobile node is received the registration reply that home agent is sent.
When mobile node when a field network switches to another field network, step b specifically comprises:
B21. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
B22. 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;
B23. 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;
B24. 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;
B25. 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 c is finished and is received home agent for: mobile node and delete the registration reply of sending behind the former Care-of Address.
When mobile node switches when going back home network from field network, step b specifically comprises:
B31. mobile node sends gratuitous ARP message in home network, and sends the cancel register request to home agent;
B32. 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 c.
For 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, when mobile node was in the field network, home agent was only bound the Care-of Address of current mobile node place network; Two links that mobile node and current base station are set up are in the consolidated network, and a public Care-of Address.
For such scheme, this method also comprises: the trigger parameter that chosen in advance will detect, and corresponding triggering condition is set; Then before the execution in step a, this method also further comprises: current mobile node detects the selected information of triggering parameters of all base stations of current discovery; Judge that whether detected trigger parameter information satisfy the trigger condition of setting, if satisfy, then judge again current satisfy trigger condition the base station whether belong to self current place subnet, if do not belong to, then the trigger network layer switches; If do not satisfy trigger condition or belong to current place subnet, then continue to detect.
So, 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; Then describedly judge whether that belonging to current sub network is: the base station information that current mobile node will satisfy all base stations of the base station information of base station of trigger condition and self storage 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, described selected trigger parameter is received signal intensity or is signal to noise ratio.Described base station information is Base Station Identification ID or is the service set SSID of subnet under the base station.
Realize the method that network layer is switched among a kind of mobile IP provided by the present invention, have following advantage and characteristics:
1) the present invention has introduced the notion of dual link in mobile IP switches, that is: mobile node keeps the communication of two wireless links simultaneously, a link is used to set up new connection in handoff procedure, another link is used to keep former connection simultaneously, keep data communication, so, just can guarantee that communication is not interrupted in the handoff procedure, thereby reduce packet loss.
2) in the present invention, when mobile node was in non-switch step, two links of parallel use so, can make full use of hardware resource, improve bandwidth, and reach the purpose of load balancing.
3) in the present invention, 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, thereby before legacy network is unavailable, insert when realizing former network and new two networks of network, fundamentally improve switch speed, and effectively reduce packet loss, be a kind of effective means that realizes seamless switching among the mobile IP.
4) 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;
Fig. 3 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. 4 moves between two field networks for mobile node among the present invention;
Fig. 5 returns the handoff procedure schematic diagram of home network from field network for mobile node among the present invention;
Fig. 6 is the schematic diagram that concerns between double center chain of the present invention road and the upper layer application;
Fig. 7 is the network topology structure figure of the present invention's one specific embodiment.
Embodiment
Core concept of the present invention is: 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, after new link network layer switching finished, to keep the link of former connection to disconnect again, set up new a connection equally.
Each mobile node all comprises two states: a kind of is that mobile node is in the state in the handoff procedure; Another kind is that mobile node is before switching or be in the state of normal communication after switching.
The prerequisite that the present invention realizes is: set up the dual link that is used to communicate by letter under mobile node and its are current between the base station.
Based on this prerequisite, mobile node utilizes process that dual link realizes that network switches as shown in Figure 2 among the present invention, may further comprise the steps:
Step 201: when the judgement of mobile node network layer need be switched, system discharges the current connection of article one link, promptly disconnect original connection of any link in the dual link, bear whole communications of current network by the second link, article one link then is used for connecting with the base station of new wireless sub network.
Step 202: bottom be set up being connected of physical layer and link layer finish after, mobile node carries out network layer and switches and register by newly-built chain road direction home agent.Promptly by registering between new Foreign Agent and home agent, comprising: at first, mobile node will obtain new Care-of Address from new Foreign Agent, register to home agent then, and 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 203: new link is stable form after, system discharges original connection of second link, and base station in second link and the new wireless sub network and the current Foreign Agent of mobile node are connected, and so far recovers normal communication process.
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 3, link 30 link for keeping original connection to proceed to communicate by letter, link 31 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 31 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 31, path 32,33,34.
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 4, 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.
| 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
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 5, 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. 3, Fig. 4, Fig. 5, 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.As shown in Figure 6, 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.
In the above dual link handoff procedure, the foundation of new link need be carried out under the still spendable situation of original link, therefore the method that a kind of trigger network layer that proposes in can another patent application in conjunction with the applicant switches triggers the foundation of new link in the dual link.The main thought of this method is: current mobile node detects the selected information of triggering parameters of all base stations of current discovery, and obtain the base station information of current all base stations of finding in real time, and current mobile node also obtains and stores all base station informations of current subnet of living in; Then, current mobile node judges that whether detected trigger parameter information satisfy the trigger condition of setting, if satisfy, again according to base station information judge current satisfy trigger condition the base station whether belong to self current place subnet, if do not belong to, then the trigger network layer switches; If do not satisfy trigger condition or belong to current place subnet, then continue to detect.That is: the base station information that will satisfy all base stations of the base station information of base station of trigger condition and self storage 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, and the trigger network layer switches; Otherwise, belong to the current place of current mobile node subnet, continue to detect.
Wherein, described physical layer channel information 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 therefrom choose any one kind of them as trigger parameter; Trigger condition is meant and preestablishes selected trigger parameter corresponding threshold; Base station information is meant the information of each base station of energy unique identification, such as: SSID of subnet or the like under base station IDs, the base station.Mobile node can utilize the existing information in the existing message, obtains all base station informations of current network of living in as the SSID of subnet under the base station; But or utilize the extended field in the existing message to carry required base station information, as utilize the extension field of registration message to carry all base station IDs.
Below with reference to Fig. 7 and in conjunction with a specific embodiment, 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, and as can be seen, mobile node 70 roams into field network 1 earlier from home network, roams into field network 2 by field network 1 again, is come back to hometown by field network 2 at last.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.
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 trigger parameter 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; At this moment, the MAC Address of AP3 is searched for and obtained to mobile node 70 again, with the MAC Address of all AP in the current sub network of the MAC Address of AP3 and self current preservation relatively, find that the MAC Address of AP3 and all AP of self current preservation all do not match, therefore, can determine that AP3 belongs to new subnet, the then 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.
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.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.
Present embodiment switches network layer and switches the scheme of carrying out in low layer in advance and combine with the scheme of setting up dual link, has not only shortened network layer switching time greatly, has fundamentally improved switch speed; And, for various switch instances, can both in whole handoff procedure, guarantee to communicate by letter and not interrupt, avoided packet loss.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.
Claims (10)
1, realize the method that network layer is switched among a kind of mobile IP, it is characterized in that set up the dual link that is used to communicate by letter under mobile node and its are current between the base station, this method may further comprise the steps:
A. after network layer is determined to switch, disconnect in the dual link of being set up, between current mobile node and the target BS that will switch to, set up a new link and be connected;
B. mobile node is registered by chain road direction home agent newly-built among the step a, and carries out the network layer switching;
C. 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 new link and be connected with another link between the former base station.
2, method according to claim 1 is characterized in that, when mobile node switched to field network from home network, step b specifically comprised:
B11. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
B12. mobile node is set up the tunnel, sends register requirement by newly-built chain road direction home agent;
B13. 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 c finish for: mobile node is received the registration reply that home agent is sent.
3, method according to claim 1 is characterized in that, when mobile node switched to another field network from a field network, step b specifically comprised:
B21. mobile node by with target BS between the link set up be connected and obtain new Care-of Address;
B22. 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;
B23. 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;
B24. 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;
B25. 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 c is finished and is received home agent for: mobile node and delete the registration reply of sending behind the former Care-of Address.
4, method according to claim 1 is characterized in that, when mobile node went back home network from the field network switching, step b specifically comprised:
B31. mobile node sends gratuitous ARP message in home network, and sends the cancel register request to home agent;
B32. 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 c.
According to each described method of claim 1 to 4, it is characterized in that 5, in handoff procedure, mobile node filters a repeating data according to existing protocol after receiving the repeating data that sends over from different links.
6, method according to claim 1 is characterized in that, before mobile node switches or switch finish after, when mobile node was in the field network, home agent was only bound the Care-of Address of current mobile node place network; Two links that mobile node and current base station are set up are in the consolidated network, and a public Care-of Address.
7, according to each described method of claim 1 to 4, it is characterized in that this method also comprises: the trigger parameter that chosen in advance will detect, and corresponding triggering condition is set; Then before the execution in step a, this method also further comprises:
Current mobile node detects the selected information of triggering parameters of all base stations of current discovery; Judge that whether detected trigger parameter information satisfy the trigger condition of setting, if satisfy, then judge again current satisfy trigger condition the base station whether belong to self current place subnet, if do not belong to, then the trigger network layer switches; If do not satisfy trigger condition or belong to current place subnet, then continue to detect.
8, method according to claim 7 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;
Then describedly judge whether that belonging to current sub network is: the base station information that current mobile node will satisfy all base stations of the base station information of base station of trigger condition and self storage 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.
9, method according to claim 7 is characterized in that, described selected trigger parameter is received signal intensity or is signal to noise ratio.
10, method according to claim 8 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.
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| CNB2004100423163A CN1301035C (en) | 2004-05-17 | 2004-05-17 | Method for realizing network layer switching in mobile IP |
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| CNB2004100423163A CN1301035C (en) | 2004-05-17 | 2004-05-17 | Method for realizing network layer switching in mobile IP |
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| 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 |
| CN101610553B (en) * | 2008-06-17 | 2011-04-27 | 福建工程学院 | Method for quick multi-wireless module switching |
| CN107889172A (en) * | 2016-09-29 | 2018-04-06 | 中兴通讯股份有限公司 | The method, apparatus and system of cell switching |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1343430A (en) * | 1999-03-09 | 2002-04-03 | 诺基亚网络有限公司 | IP routing optimization in access network |
| US20020067704A1 (en) * | 2000-12-01 | 2002-06-06 | Telefonaktiebolaget Lm Ericsson (Publ) | Method for ensuring reliable mobile IP service |
| CN1452369A (en) * | 2002-04-13 | 2003-10-29 | 三星电子株式会社 | Method and device for managing Internet protocol in mobile network by transformation of network address |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1343430A (en) * | 1999-03-09 | 2002-04-03 | 诺基亚网络有限公司 | IP routing optimization in access network |
| US20020067704A1 (en) * | 2000-12-01 | 2002-06-06 | Telefonaktiebolaget Lm Ericsson (Publ) | Method for ensuring reliable mobile IP service |
| CN1452369A (en) * | 2002-04-13 | 2003-10-29 | 三星电子株式会社 | Method and device for managing Internet protocol in mobile network by transformation of network address |
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