WO2013077722A1

WO2013077722A1 - Dynamic gateway selection in ip mobility by ranking gateways according to a priority score

Info

Publication number: WO2013077722A1
Application number: PCT/MY2012/000174
Authority: WO
Inventors: Ariff Abdullah MOHD; Faheem Mohd Ezani MOHD; Haseeb Shariq
Original assignee: Mimos Berhad
Priority date: 2011-11-24
Filing date: 2012-06-29
Publication date: 2013-05-30
Also published as: MY169842A

Abstract

The present invention relates to a method of selecting an access gateway from a plurality of detected gateways in a mobile node, in particular in mobile IP. The mobile node is provided with more than one gateway to access a telecommunication network. The mobile node carries several egress interfaces and each of these interfaces is capable of connecting the mobile node to the home agent as long the correct gateway is presented. In the prior art, the mobile node only binds to a specific gateway selected by or assigned to the user without considering other gateway made available for binding. This might lead to crowding a single gateway and competing for the limited bandwidth while leaving other available gateways idle is waste of network resources. This problem is overcome by the application in that the mobile node dynamically selects (106) and binds ((107) to the best gate¬ way which is the gateway with the highest priority score. The priority score is computed (105) for each gateway from a first value (102) generated for each gateway according to decay history, DH, a second value (103) generated for each gateway according to round trip time, RTT, of the gateway and a third value (104) generated for each gateway from pre-set priority, PP, data. The round trip time is preferably measured by sending ICMP packets through the available gateways (302).

Description

DYNAMIC GATEWAY SELECTION IN IP MOBILITY BY RANKING GATEWAYS ACCORDING TO A PRIORITY SCORE

Field Of Invention

The presence invention relates to a method of gateway selection in mobile IP. More 5 specifically, the disclosed invention allows the user of a mobile node or mobile router

to optimize usage of bandwidth in various available gateway through computing different scores on predetermined aspects.

Background Of The Invention

10 In network mobility, there are scenarios which a mobile node or mobile router is

provided with more than one gateway to access a telecommunication network. For example, it is likely that the mobile node carries several egress interfaces that each of these interfaces is capable of connecting the mobile node to the home agent as long the correct gateway is presented. Generally, the mobile node only binds to a specific

15 gateway selected by or assigned to the user without considering other gateway made

available for binding. Crowding a single gateway and competing for the limited bandwidth while leaving other available gateways idle is waste of network resources.

Waste of bandwidth can be further aggravated by data duplication in delivering packet data through a gateway of a layer-2 device to a layer-3 address outside the mobile

20 network. Since layer-2 devices are lack of the capability to route the data packet

accordingly to layer-3. address, all the devices will unconditionally forward the packets to the access networks, resulting in duplicated packets destined to the home agent. Apparently, such shortcoming can be effectively overcome if the mobile node chose the appropriate gateway prior to binding for data delivery. With increasing

25 computing power in the mobile node, a predefined policy can be imposed onto the

mobile node to prompt the mobile node to dynamically select the best gateway following a mechanism stated in the policy. Specifically, a process or method has to be carried out in dynamic selection of ideal gateway in the mobile node through the predefined policy. For example, International patent publication no. WO0139444

30 discloses a method and system for dynamically selecting a destination gateway to

complete a call over a path supported at least in part by an IP telephony network and a public switched network. The gateway selection promotes reliability and availability of the telephony system in the overall network. Microsoft Corporation claims another method and system facilitate gateway selection based on health status of each gateway recorded in a hash table in the United States patent publication no. 2010/0080144. Further, United States patent publication no. 201 1/0131338 provides a method and a system capable of dynamically assigned mobility gateway according to a specified policy mechanism that identifier is associated with typical service and gateway to facilitate selection of gateway.

Summary Of The Invention

One object of the present invention is to provide a method to be performed in a mobile node or mobile router to dynamically select a preferred gateway.

Another object of the present invention is to facilitate optimized use of available bandwidth for a mobile node or router. Preferably, the mobile node selects the ideal gateway according to a set of predetermined criteria or policy that each criteria carries different weight in considering the gateway selection.

Further object of the present invention is to offer an approach to minimize data duplication due to incompatibility of data receiving address.

At least one of the preceding objects is met, in whole or in part, by the present invention, in which one of the embodiments of the present invention is a method of selecting an access gateway from a plurality of detected gateways in a mobile node comprising the steps of recording all detected gateway in a list with a priority score computed for each gateway that the priority score is acquired from a first value generated for each gateway according to decay history, a second value generated for each gateway according to round trip time of the gateway and a third value generated for each gateway from pre-set priority data in the mobile node by a user; and binding to the gateway with highest priority score among the plurality of gateways. In another embodiment, the disclosed method may comprise the steps of removing the gateway with the highest priority score from the list upon unsuccessful binding; and binding to the gateway with second highest priority score. For calculation of the first value in regards with the decay history of different gateway, the mobile node initially sets the first value of the binding gateway to maximal value and deducting n from the first value of the rest of the recorded gateway unless the first value of the gateway is at minimum in each gateway handover that n is an integer. Moreover, the disclosed method continuously detects new gateway which is yet enrolled in the list followed by recording the detected new gateway in the list and assigning a minimal value as the first value of the recorded new gateway.

For computing the second value, the mobile node retrieves the round trip time of each gateway by sending Internet Control Message Protocol (ICMP) packet through each gateway at a predetermined occasion. Specifically, the second value of each gateway is computed in the mobile node through dividing total round trip time of all gateways by round trip time of the corresponding gateway.

In the embodiment where the user wish not includes any preference, the third values of all gateways are same.

In the embodiment which the user's preference are given greater weight in gateway selection, the priority score of each gateway is calculated by multiplying sum of first and second value with the third value of each gateway.

In another embodiment, the priority score of each gateway is calculated by summing the first, the second and the third value of each gateway.

Brief Description Of The Drawings

Figure 1 is a block diagram reflecting general flow of one embodiment of the disclosed method; Figure 2 is a block diagram showing flow of one embodiment of the present invention in computing first value according to the decay history of the plurality of gateways; Figure 3 illustrates changes in the decay history table of different gateways in sequential handovers; is a block diagram showing flow of one embodiment of the resent invention in calculating the second value in regards with the round trip time (RTT) of the gateway;

Figure 5 illustrates the calculation of RTT in between mobile node and the home agent; Figure 6 shows the flow of Internet Control Message Protocol (ICMP) delivery from the mobile node through different gateways to a home agent and receiving the same from the home agent to compute the RTT;

Fisure 7 illustrates one of the possible ways in computing the second value based on the RTT for each identified gateways;

Fisure 8 illustrates an example of different computed third value for different gateways based on mode of operation in accord with the user preference; and

Figure 9 shows one way to compute the priority scores for different gateways after acquiring various values from different established tables.

Detailed Description Of The Invention

The most preferred embodiment of the invention is now described with reference to the figures, where like reference numbers indicate identical or functionally similar elements. While specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the art will recognize that the other configurations and arrangements can be used without departing from the spirit and scope of the invention. According to the preferred embodiment, the disclosed method of selecting an access gateway from a plurality of detected gateways in a mobile node comprising the steps of recording all detected gateway in a list with a priority score computed for each gateway that the priority score (105) is acquired from a first value (102) generated for each gateway according to decay history, a second value (103) generated for each gateway according to round trip time (RTT) of the gateway and a third value (104) generated for each gateway from pre-set priority (PP) data in the mobile node by a user; and binding (107) to the gateway with highest priority score among the plurality of gateways. Preferably, the first value, second value and third value of the detected gateway in the list are stored in respective tables in the mobile node as in the examples shown in figure 3, 7 and 9. Referring to figure 1, a general flow of the disclosed method is illustrated. Prior to binding and connecting through a gateway, the mobile node starts (101 ) the disclosed method by firstly establishing and/or checking on the decay history table (102), RTT table and PP table. All these tables contain different value of the identified gateways to be used for computing and determining priority score (105) of the identified gateways. Through referencing to the priority score, the mobile node selects the ideal gateway (106) and binds the selected gateway to tunnel for delivery of data packet. Successful establishment of the binding ends the gateway selection session (109). Further, the disclosed method may include additional step to bind to other available gateway if the binding to gateway recorded with the highest priority scores was unsuccessful, particularly due to abrupt discontinuation in the service of the selected gateway or instability in the connection of the selected gateway. More specifically, the disclosed method additionally has the steps of verifying occurrence of successful or unsuccessful binding (108), removing the gateway (1 10) with the highest priority score from the list upon unsuccessful binding; and binding to the gateway with second highest priority score. Preferably, the disclosed method repeats the step of determining (105) the gateway with latest highest priority score after removal of the failed gateway (110). It is likely the disclosed method prompts the mobile node to select the gateway previously rated with second highest priority score and currently ranked first upon removal of the failed gateway. Removal of the failed gateway in the disclosed method is temporary. The removed gateway can be enrolled into the list again once the mobile node identifies it as new gateway which shall then be allocated with relatively lower priority scores.

Figure 2 shows one embodiment of the disclosed method in computing the first value for the table regarding decay history of the recorded gateways. It is important to be noted herein that all the first identified and recorded gateway share an initial value which may be, but not necessary, the lowest or minimal value for the first value. Thus, all the identified gateways have similar first value when the decay history table first established. Upon receipt of request in establishing a new connection (202), the session for updating the decay history table starts (201). Among all the gateways, the mobile node selects one as the access interface or gateway that the first value of the selected gateway is set to maximum (209) followed by updating the decay history table (210). While the rest of the non-selected gateways, the mobile node determines if first value of each individual gateway is at minimal (204) that those with the minimal first value remain unchanged (205) in the decay history table and the rest subjected to deduction of n value (206) from the remaining first value of the gateways then newly derived first value of the non-selected gateways are updated to the decay history table (210) as well. More specifically, the first value of each gateway is computed in the mobile node by setting the first value of the binding gateway to maximal value (209) and deducting n from the first value of the rest of the recorded gateway (206) unless the first value of the gateway is at minimum value (205) in each gateway handover that n is an integer. Preferably, n equals to 1. Figure 3 shows one embodiment of the disclosed method in updating the record of first value for different gateways listed. Still, in one embodiment, the disclosed method validates presence of the recorded gateways (208) prior to updating the decay history table. The gateways fail the validation may be removed from the list or the decay history table. Apart from merely updating the first value or decay history of the existing gateway, the disclosed method also have the mobile node continuously detecting new gateway yet enrolled in the list, recording new gateway in the list and assigning an initial value, preferably a minimal value, as the first value of the recorded new gateway. This embodiment ensures the available gateways in the list are substantially updated always when the mobile node moves from one area to another.

Referring to figure 4, the disclosed method computes the second value starts (301 ) with sending Internet Control Message Protocol (ICMP) packet (302) from the mobile node through the available gateways and stores the RTT for the corresponding gateway (304) in a temporary table upon receipt of reply (303). Figure 5 shows the way to compute RTT for gateway. On the other hand, the mobile node may be prompted to resend the ICMP packet if no reply received through the gateway and the resending of ICMP packet through the similar gateway has yet exceeded a predetermined number of tries (312). The mobile node automatically set the RTT of the gateways failed to reply even after the try exceeds the predetermined number to a fixed figure (31 1). Preferably, the predetermined number can be 5 to 100 times though 30 times are more preferable. Likewise, the preferred fixed figure is 5 to 30 seconds and 10 seconds are more preferable. After completing one gateway, the mobile node moves on to the next gateway (305). Optionally, the disclosed method may have the mobile node validate presence of the gateway to be tested on RTT (306) before wasting times on attempts to resend the ICMP packet should the gateway is not exist. The gateway fails the validation test may be removed from the list. Figure 6 depicts ICMP packet testing on different gateways from the mobile node to home agent. Once the mobile node finishes RTT data collection from all gateway, the total RTT is calculated (307) followed by acquiring the respective second value of each gateway using the total RTT (308). It is important to be noted herein that various formulation or algorithm can be employed in the disclosed method to derive the second value for the tested gateway. In one preferred embodiment, the second value of each gateway is computed in the mobile nodule through dividing total round trip time of all gateways by round trip time of the corresponding gateway. For example, the calculation carried out in acquiring the second value is illustrated in figure 7. Then the RTT table is updated (309) using the derived second value prior to end of the session (310). The session of the mobile node to retrieve or acquire RTT data is initiated at a defined occasion to keep the information stored in the RTT table up to date. Specifically, the disclosed method prompts the mobile node to retrieve the round trip time of each gateway by sending Internet Control Message Protocol (ICMP) packet through each gateway at a predetermined occasion.

Pursuant to another embodiment, the disclosed method also permits the gateway selection to be performed manually accord with the user preference, or at least the user's preference plays significant role in the decision of gateway selection. Preferably, the user is allowed to rank the gateway or the type of gateway through an user interface provided in the mobile node that different value are assigned to the ranked gateways in view of the ranking or pre-set priority. The gateway ranked higher receives greater value in the PP table as the third value which, in turn, is used to compute the priority score. The third value for different available gateway represents predetermined preference of the user in gateway selection besides the dynamically formed factor utilized in acquiring the first and second value. For example, the user may prefer to communicate through a WiMAX based gateway that this gateway may be set as primary or default gateway for interfacing with the home agent while the secondary and third option is respectively WiFi 1 and WiFi 2. In such scenario, the WiMAX, WiFi 1 and WiFi 2 based gateway are given a third value of 10, 8 and 6 respectively. The rest of the less preferred gateways only have third value of 4 and 2 only. Nevertheless, third value for all gateways is the same or given a default value if there was no pre-set priority. The third value of all gateways is same when the mobile node is free of priority data to ensure all the gateways carrying same weight in later stage of computing the priority score. More preferably, the default value is not zero in the disclosed method.

As in setting forth, the priority score used in the disclosed method as the identifier for gateway selection can be computed using various formulation yet the first, second and third value have to be used as input to derive the priority score for individual available gateway. In one embodiment, the priority score of each gateway can be calculated by summing the first, the second and the third^". value of each gateway that the weight of each value is almost equal in this mode of computing the priority score especially when the optimal value is limited to be substantially equivalent. Another embodiment of the disclosed method emphasizes on at least one of the value. For example, the disclosed method may allo the PP weighted higher in deciding gateway selection that the priority score of each gateway is calculated by multiplying sum of first and second value with the third value of each gateway as shown in figure 9.

One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiment described above is not intended as limitations on the scope of the invention.

Claims

aims

1. A method of selecting an access gateway from a plurality of detected gateways in a mobile node comprising the steps of

recording all detected gateway in a list with a priority score computed for each gateway that the priority score is acquired from a first value generated for each gateway according to decay history, a second value generated for each gateway according to round trip time of the gateway and a third value generated for each gateway from pre-set priority data in the mobile node by a user; and

binding to the gateway with highest priority score among the plurality of gateways.

2. A method of claim 1 further comprising the steps of removing the gateway with the highest priority score from the list upon unsuccessful binding; and binding to the gateway with second highest priority score.

3. A method of claim 1, wherein the first value of each gateway is computed in the mobile node by setting the first value of the binding gateway to maximal value and deducting n from the first value of the rest of the recorded gateway unless the first value of the gateway is at minimum value in each gateway handover that n is an integer.

4. A method of claim 1 or 3 further comprising the step of detecting new gateway yet enrolled in the list, recording new gateway in the list and assigning a minimal value as the first value of the recorded new gateway.

5. A method of claim 1, wherein the mobile node retrieves the round trip time of each gateway by sending Internet Control Message Protocol (ICMP) packet through each gateway at a predetermined occasion.

6. A method of claim 1 , wherein the second value of each gateway is computed in the mobile nodule through dividing total round trip time of all gateways by round trip time of the corresponding gateway.

7. A method of claim 1 , wherein the third value of all gateways are same when the mobile node is free of priority data.

8. A method of claim 1, wherein the priority score of each gateway is calculated by multiplying sum of first and second value with the third value of each gateway.

9. A method of claim 1, wherein the priority score of each gateway is calculated by summing the first, the second and the third value of each gateway.

10. A method of claim 1 , wherein the first value, second value and third value of the detected gateway in the list are stored in respective tables in the mobile node.