KR20190030854A - A method and apparatus for supporting mobility of host using hierarchical distributed hash table - Google Patents

Abstract

Disclosed are a method and apparatus for supporting terminal mobility using a hierarchical distributed hash table (HDHT). According to an embodiment of the present invention, a method for providing mobility comprises the steps of: registering an entry associated with a terminal at a hierarchy specified by a network access switch connected with the terminal among a plurality of hierarchies constituting an HDHT; and processing handover of the terminal using the entry, wherein the HDHT is composed of the plurality of hierarchies based on physical distance between the network access switches.

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for supporting terminal mobility using a hierarchical distributed hash table,

The following embodiments relate to a method and apparatus for supporting terminal mobility using a hierarchical distributed hash table.

As the number of small objects with computing power increases, the number of mobile terminals connected to the network is increasing greatly. Most of the devices currently connected to the Internet are low-mobility devices such as smartphones, desktops, and laptops. However, in the future, most moving objects around us, such as sensors, glasses, It is expected to be connected.

According to foreign media, the number of devices connected to the Internet by 2020 will exceed 50 billion, and more than a quarter of the world's mobile devices will be connected to the Internet. These statistics suggest that the proportion of objects with mobility will increase in the future.

As the proportion of objects with mobility connected to the network increases, mobility support and management for objects will become important in the future Internet environment. Therefore, it is necessary to design a mobility support platform for the future.

The current network operates in a centralized manner so that all user packets go through the core network. For example, 3GPP provides network-based Internet Protocol (IP) mobility using a General Packet Radio Service (GPRS) tunneling protocol.

This centralized approach has the advantage that the central anchor operates in a simple manner by rerouting the packet to the current location of the terminal. However, when the central anchor becomes inoperable, it has a single point of failure problem in which the entire system can not operate and a scalability problem that can not be accommodated when the number of users using the system increases greatly . Therefore, in the future Internet environment, it is necessary to apply the distributed method in which these problems are solved.

Embodiments can provide a technique for shortening the query time and solving the scalability problem in providing the mobility of the terminal using the hierarchical distributed hash table.

The method of providing mobility according to an exemplary embodiment of the present invention registers an entry related to the terminal in a hierarchy designated by a network access switch to which a terminal is connected among a plurality of layers constituting a hierarchical distributed hash table (HDHT) And processing the handover of the terminal using the item, wherein the hierarchical distributed hash table is composed of the plurality of layers based on a physical distance between the network access switches.

Wherein the mobility providing method further comprises generating the hierarchical distributed hash table including the plurality of layers based on a physical distance between the network access switches, Generating a plurality of lowest layers constituted by network access switches close to each other, and hierarchically creating upper layers composed of the plurality of lowest layers.

Wherein the step of registering comprises the steps of: generating a key value of an item related to the terminal; querying the hierarchical distributed hash table with the key value; And updating the item in the table.

Wherein the step of updating comprises the steps of: specifying a layer in which the item is to be stored in the item; updating a network access switch list and an IP (Internet Protocol) address of the item; And requesting registration of the item.

Wherein the step of requesting comprises the steps of: storing the item in a distributed hash table of the lowest hierarchy; and delivering the registration request sequentially from the lowest hierarchy to the highest hierarchy, when the registration request reaches a specified hierarchy, Storing the item in a hash table, storing an item in a distributed hash table node of the highest hierarchical level through a logical distance operation when the registration request reaches the highest hierarchical level, And storing the item in the distributed hash table of the specified hierarchy when the hierarchy reaches the specified hierarchy while sequentially transferring the hierarchy from the highest hierarchy to the specified hierarchy.

Each of the storing steps may include performing a logical distance operation using a key value of the item and storing the item in a network access switch having a result of the logical distance operation being the smallest value have.

Wherein the step of processing comprises: allocating a new IP (Internet Protocol) address to the terminal according to movement of the terminal; generating an item key value for the terminal and querying the hierarchical distributed hash table; And updating the item in the hierarchical distributed hash table based on the result.

The mobility providing method may further include transmitting a packet to the terminal through the hierarchical distributed hash table.

Wherein the step of transmitting comprises: generating an item key value of the terminal in a network access switch that has received the packet; determining whether an optional header is present in the packet; And forwarding the packet to a network switch to which the terminal is connected based on the value.

The forwarding step includes forwarding the packet if the option switch is not present in the packet and the network access switch that received the packet does not store the item corresponding to the item key value, If the option switch is not present in the packet and the network access switch that received the packet stores an item corresponding to the item key value, Modifying the option header by adding a new item key value to the option header, adding a new item key value to the option header, and if the option header exists in the packet and the network access switch receiving the packet stores an item corresponding to the item key value Discarding the packet if the packet does not include the packet, And if the network access switch that received the packet stores an item corresponding to the item key value, restores the destination of the packet to the terminal, removes the option header, and forwards the packet to the terminal .

The mobility providing apparatus according to an exemplary embodiment registers an entry related to the terminal in a hierarchy designated by a network access switch to which a terminal is connected among a plurality of layers constituting a hierarchical distributed hash table (HDHT) And a controller for handling a handover of the terminal using the item, wherein the hierarchical distributed hash table is configured by the plurality of layers based on a physical distance between the network access switches.

The controller includes an item register for registering an entry related to the terminal in a hierarchy designated by a network access switch to which a terminal is connected among a plurality of layers constituting a hierarchical distributed hash table (HDHT) And a handover processor for processing the handover of the terminal using the handover processor.

Wherein the controller further comprises an HDHT generator for generating the hierarchical distributed hash table including the plurality of layers based on a physical distance between the network access switches, It is possible to generate a plurality of lowest layers constituted by the nearest network access switches and to hierarchically create upper layers constituted by the plurality of lowest layers.

The item register includes a key generator for generating a key value of an item related to the terminal, a query unit for querying the key value in the hierarchical distributed hash table, And an item updater that updates the item in the table.

Wherein the item updater specifies a layer in which the item is to be stored in the item, updates a network access switch list and an IP (Internet Protocol) address of the item, and registers in the hierarchical distributed hash table .

The item updater stores the item in a distributed hash table of the lowest hierarchical layer, sequentially transfers the registration request from the lowest hierarchical layer to the highest hierarchical layer, and when the registration request reaches the specified hierarchical layer, Storing the item and storing an item in a distributed hash table node of the highest hierarchical level through a logical distance operation when the registration request reaches the highest hierarchical level and transmitting the registration request from the highest hierarchical level to the specified hierarchical level The item can be stored in the distributed hash table of the specified hierarchy when it reaches the specified hierarchy.

The item updater may perform a logical distance operation using a key value of the item and store the item in a network access switch having a result of the logical distance operation being the smallest value.

The handover processor allocates a new IP (Internet Protocol) address to the terminal according to the movement of the terminal, generates an item key value for the terminal, queries the hierarchical distributed hash table, And update the item in the hierarchical distributed hash table.

The controller may further include a packet transmitter for transmitting a packet to the terminal through the hierarchical distributed hash table.

Wherein the packet transmitter generates an item key value of the terminal in a network access switch that has received the packet, determines whether or not an option header exists in the packet, and determines, based on the result of the determination and the item key value, And forward the packet to a network switch to which the terminal is connected.

The packet transmitter forwards the packet if the option switch is not present in the packet and the network access switch receiving the packet does not store an item corresponding to the item key value, When the network access switch storing the packet does not include the option header in the packet and stores the item corresponding to the item key value, the destination of the packet is referred to as a network to which the terminal is connected When the option header is present in the packet and the network access switch receiving the packet does not store an item corresponding to the item key value, Discards the packet, and if the option header is present in the packet and the packet If the received network access switch for storing an entry corresponding to the key item value, it is possible to restore the destination of the packet to the terminal and removes the option header to forward the packet to the terminal.

1 shows a schematic block diagram of a mobility providing apparatus according to an embodiment.
Fig. 2 shows an example of a mobility support system using the mobility providing apparatus shown in Fig.
Figure 3 shows a schematic block diagram of the controller shown in Figure 1;
Figure 4 shows a schematic block diagram of the item register shown in Figure 3;
5 shows an example of the structure of the hierarchical distributed hash table.
6 shows an example of a DHT routing table.
FIG. 7 shows an example of a pseudo code for an operation of registering an item in a hierarchical distributed hash table.
8 shows an example of a hierarchical distributed hash table entry.
9 shows an example of a pseudo code for an operation in which a network access switch updates an item associated with a terminal.
10 shows an example of a pseudo code for an operation in which a network access switch updates an item stored in a cache.
11 shows an example of the operation of the packet transmitter shown in Fig.
12 shows an example of a pseudo code for an operation of transmitting a packet.
13 shows an example of an operation of receiving a message between an OVS kernel module and a hierarchical distributed hash table.
14 shows an example of the operation of the handover processor shown in Fig.

It is to be understood that the specific structural or functional descriptions of embodiments of the present invention disclosed herein are presented for the purpose of describing embodiments only in accordance with the concepts of the present invention, May be embodied in various forms and are not limited to the embodiments described herein.

Embodiments in accordance with the concepts of the present invention are capable of various modifications and may take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. However, it is not intended to limit the embodiments according to the concepts of the present invention to the specific disclosure forms, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present invention.

The terms first, second, or the like may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example without departing from the scope of the right according to the concept of the present invention, the first element being referred to as the second element, Similarly, the second component may also be referred to as the first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Expressions that describe the relationship between components, for example, "between" and "immediately" or "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms " comprises ", or " having ", and the like, are used to specify one or more of the features, numbers, steps, operations, elements, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

1 shows a schematic block diagram of a mobility providing apparatus according to an embodiment.

Referring to FIG. 1, the Internet Engineering Task Force (IETF) summarizes the requirements of the distributed mobility management method in order to solve the persistent problems occurring in the centralized mobility providing method, And introduces mobility solutions into the data plane of a distributed mobility management environment. However, this distributed mobility management method is not actually used due to performance degradation problems such as complex tunneling method and nonoptimal path.

Recently, researches are being made on a complete dispersion method not only for the data plane but also for the control plane. When DHT (Distributed Hash Table) is used as a control surface, the number of participating nodes increases, which can increase the query time.

In order to solve the query time problem of DHT, various solutions have been suggested such as hierarchical configuration of DHT, use of One Hop DHT, simultaneous multiple queries, and consideration of physical location of DHT nodes when assigning node identifiers. However, since these methods focus on improving the DHT performance itself, the mobility of the terminal is not considered.

The mobility providing apparatus 10 can provide mobility to a terminal using a hierarchical distributed hash table (HDHT) and a network access switch that provides mobility to the terminal. The mobility providing apparatus 10 may operate the HDHT in a network access switch, store information for providing mobility of the terminal, and provide mobility to the terminal connected to the network.

The mobility providing apparatus 10 may configure the nodes participating in the lowest hierarchical distributed hash table DHT to physically close nodes such as an autonomous system and then hierarchically configure these nodes. For example, the network access switch may serve as a DHT node, and the mobility provision device 10 may configure the HDHT using network access switches.

The mobility provision device 10 can operate the HDHT separately from the network access switch.

The mobility providing apparatus 10 may store information necessary for providing the mobility of the terminal to the HDHT. When the mobility providing apparatus 10 stores an item including location information of the terminal in the HDHT, the mobility providing apparatus 10 can designate the hierarchical level at which the item is stored.

The mobility providing apparatus 10 can maintain the communication of the object by accurately transmitting the packet to the subnetwork where the terminal is located even if the terminal is fixed on the network or freely moves.

The mobility providing apparatus 10 can use the information stored in the HDHT to enable other access switches to appropriately perform packet forwarding (or routing) to the subnetwork where the terminal is located, even if the terminal moves.

The mobility providing apparatus 10 may store information for providing the mobility of the terminal to the HDHT and support the mobility of the terminal through the packet processing function of the network access switch.

The mobility providing apparatus 10 may generate a key value of an item used for storing information of the terminal using information derived from the terminal.

The mobility providing apparatus 10 hierarchically configures the DHT operating in the network access switches located in the subnetwork and can designate a layer in which items containing information are to be stored when information necessary for mobility of the terminal is stored. Accordingly, when the mobile station moves under the hierarchy in which the item is stored (within the range including the hierarchical level), the mobility provision apparatus 10 can complete the inquiry about the information of the terminal in a short period of time, , And can solve the scalability problem.

The mobility providing apparatus 10 can promptly query the terminal movement information when a terminal operating in a lower layer than the layer in which the item is stored is moved through the hierarchical level designating function.

The mobility providing apparatus 10 may limit the number of overlay hops required for a query by specifying a hierarchical level at which items containing host information are stored, thereby shortening the time required for the query. An overlay hop may mean an operation in which packets are transferred between nodes on the HDHT.

The mobility providing apparatus 10 can perform a packet processing function using information related to a terminal stored in the HDHT. The mobility providing apparatus 10 can deliver packets destined for the terminal to the correct location even if the terminal changes its subnetwork through the packet processing function.

The mobility providing apparatus 10 may include a controller 100. [

The controller 100 registers an entry related to the terminal in a hierarchy designated by a network access switch to which the terminal is connected among a plurality of layers constituting the HDHT and can handle the handover of the terminal using the item .

The controller 100 may be implemented within a network access switch, or may be implemented externally. For example, each network access switch that makes up the HDHT may include a controller.

Fig. 2 shows an example of a mobility support system using the mobility providing apparatus shown in Fig.

Referring to FIG. 2, the existing terminal-based mobility support method may require modification of the terminal. In the conventional scheme, when the mobile station moves, it is necessary to modify the mobile station so that the mobile station directly transmits signal information, and performance problems such as triangular routing may occur.

The mobility providing apparatus 10 can provide mobility in a network-based manner in which only the network is modified without modifying the terminal. The mobility providing apparatus 10 may provide mobility using a distributed mobility management scheme.

The distributed mobility management method may include a partial dispersion method and a full dispersion method. The partial dispersion method and the total dispersion method can be classified according to whether or not the control plane is dispersed.

The mobility providing apparatus 10 may be included in the entire decentralized system using the HDHT as a control plane.

The mobility provision apparatus 10 can configure each DHT to be a network access switch belonging to the same autonomous system so that a query generated in the DHT can be completed quickly.

The mobility providing apparatus 10 can limit the number of overlay hops required for a query by hierarchically configuring the DHT and designating the level at which items are stored. Accordingly, the mobility providing apparatus 10 can improve the problem of the query time of the existing planar DHT and the scalability problem of the existing hierarchical DHT. In addition, the mobility providing device 10 can complete a query in a DHT operating in a lower hierarchical level than an item hierarchical level in a short time.

Since the mobility providing apparatus 10 uses the HDHT as a control plane, it can support a fully distributed mobility management scheme. Therefore, the mobility providing apparatus 10 can distribute traffic concentrated on specific network equipment, thereby solving the single point failure problem and the scalability problem, which are problems of the existing centralized method.

Since the mobility providing apparatus 10 has a hierarchical structure, it can be gradually applied from the end of the existing network. Therefore, the mobility providing apparatus 10 can be compatible with existing network systems.

Network operators and network equipment operators can gradually apply the proposed system from the end of the network, thereby enhancing interoperability between network equipment. In addition, the provider can support mobility for the terminal by implementing the mobility providing device 10, thereby providing a more improved user experience to the user.

Figure 3 shows a schematic block diagram of the controller shown in Figure 1;

Referring to FIG. 3, the controller 100 may include an HDHT generator, an item register, a handover processor, and a packet transmitter.

The HDHT generator 110 may generate an HDHT including a plurality of layers based on the physical distance between the network access switches.

The HDHT generator 110 may generate a plurality of lowest hierarchical layers constituted by network access switches physically close to each other among the network access switches and may hierarchically generate upper hierarchical layers constituted by a plurality of lowest hierarchical layers.

An entry registrator 130 may register an entry related to a terminal in a layer designated by a network access switch to which the terminal is connected among a plurality of layers constituting the HDHT.

The item register 130 may register an item including information for providing the mobility of the terminal to the HDHT.

The handover processor 150 may process the handover of the terminal using the item.

The handover processor 150 can allocate a new IP (Internet Protocol) address to the terminal according to the movement of the terminal, generate an item key value for the terminal, and query the HDHT. The handover processor 150 can update the item in the HDHT based on the query result.

The packet transmitter 170 can transmit a packet to the terminal through the HDHT.

The packet transmitter 170 may generate the item key value of the terminal in the network access switch that has received the packet and determine whether an optional header exists in the packet.

The packet transmitter 170 may forward the packet to the network switch to which the terminal is connected based on the determination result and the item key value.

Packet sender 170 may forward the packet and query the HDHT for the item if the packet does not have an optional header and the network access switch that received the packet is not storing an item corresponding to the item key value .

The packet transmitter 170 modifies the destination of the packet to the network switch to which the terminal is connected when the network access switch that received the packet without the option header does not store the item corresponding to the item key value, You can add a new entry key value to the header.

Packet transmitter 170 may discard the packet if an optional header is present in the packet and the network access switch that received the packet does not store an item corresponding to the item key value.

The packet transmitter 170 restores the destination of the packet to the terminal, removes the option header, and transmits the packet to the terminal if the option header exists in the packet and the network access switch that received the packet stores an item corresponding to the item key value. Lt; / RTI >

Figure 4 shows a schematic block diagram of the item register shown in Figure 3;

4, the item register 130 may include a key generator 131, a querier 133, and an entry updater 135.

The key generator 131 may generate a key value of an item associated with the terminal. The key generator 131 may generate a key using a hash function. For example, the key generator 131 may generate a key using the hash function of the MD5 and SHA sequences.

The key generator 131 may generate a key of an item used for storing information of the terminal using information derived from the terminal. The key generator 131 may generate an item key using the IP address of the terminal, an arbitrary string, or a plane name space. The plane namespace may contain the result of a hash function. For example, the key generator 131 may apply a hash function to the IP address of the terminal or generate a key of an item using globally unique identifiers (GUID).

Queryor 133 can query the key value in HDHT.

The process in which the inquirer 133 transmits a query for an item may be the same as when the item updater 135 registers an item.

The inquirer 133 can calculate the key value of the desired item based on the IP address of the terminal to know the location information of the inquiry. The inquirer 133 can determine a network access switch storing an item by logically calculating the node ID and the key value of the network access switches stored in the routing table. The inquirer 133 can check whether the network access switch that received the query message is storing the item.

If the item is stored, the query unit 133 may return it to the network access switch that sent the query immediately. In this case, the number of overlay hops required for the query can be expressed as 1. The inquiry unit 133 can forward the query to the root node if the network access switch that received the query does not store the item.

The root node that receives the query may also have the routing table of the upper DHT. The inquirer 133 can use this routing table to send a query to the network access switch storing items among network access switches participating in the upper DHT. This process can be repeated until the query is delivered up to the highest DHT.

When the highest DHT node receives a query, the query unit 133 may change the direction of the query message to be directed toward the lower layer. If an item is found in the middle, the corresponding network access switch can immediately return information about the item to the itemized network access switch.

The query direction always starts in the upper hierarchy direction and can be changed in the downward direction after passing through the uppermost DHT. The number of overlay hops can be increased by one each time a query is delivered. The maximum number of overlay hops that can be spent in a query can be 5, 6, or 7 when the HDHT level is 1, 2, or 3, respectively.

The item updater 135 may update the item in the HDHT based on the query result.

The item updater 135 may specify the layer in which the item is to be stored in the item, and update the network access switch list and IP (Internet Protocol) address of the item. The item updater 135 may request registration of the item in the HDHT.

The item updater 135 stores items in DHTs of the lowest hierarchical level, and sequentially transfers the registration requests from the lowest hierarchical layer to the highest hierarchical layer, and stores the items in DHTs of the specified hierarchical layer when the registration request reaches the specified hierarchical layer.

The item updater 135 may store the item in the highest hierarchical DHT node through logical distance operation when the registration request reaches the highest hierarchical level.

The item updater 135 can sequentially store the registration request from the highest layer to the specified layer, and store the item in the DHT of the specified layer when reaching the specified layer.

The item updater 135 may perform a logical distance operation using the key value of the item and store the item in the network access switch having the smallest value of the logical distance operation.

The item updater 135 may perform a logical distance operation between the key value of the item and the node identifier stored in the DHT routing table to determine the network switch having the smallest computation value as the network access switch responsible for the item and store the item. For example, the item updater 135 may use the IP of the network access switch as the node identifier.

5 shows an example of the structure of the hierarchical distributed hash table.

In the existing DHT, items can be distributed and stored among participating nodes. The nodes participating in the DHT have an arbitrary identifier, and the key value of the item can be generated using a hash function. When a node participating in the DHT sends a query about the key value of the desired item, the query can be delivered to the node responsible for (or storing) the item.

In the conventional method of providing mobility using the DHT, an arbitrary value can be allocated in the flat namespace without considering the physical distance when allocating an identifier to the nodes. Therefore, even if the logical distance calculation value is small among the identifiers, the actual physical distance may be extremely large.

For this reason, even if there are items that are physically close to each other, it can take long time to inquire, because it can be transmitted when a query is distant. If the nodes participating in the planar DHT are distributed globally, the increase in query time can be even greater.

The mobility providing apparatus 10 can construct the DHT hierarchically to shorten the query time. In addition, the mobility providing device 10 can solve the scalability problem by designating the hierarchy in which items are stored.

The HDHT of FIG. 5 shows a case where the layer is at three levels. The HDHT generator 110 may be able to adjust the layer level according to the size of the network. The HDHT generator 110 can increase the hierarchy level when the size of the network is larger and reduce the level when the size of the network becomes smaller.

When the DHT generator 110 hierarchically configures the DHT, the lowest DHT can be configured using physically close network access switches. The HDHT generator 110 configures the lowest DHT with network access switches having near physical distances so that the queryer 133 can complete the query for the lowest DHT in a very short time.

와 같이 나타낼 수 있다. 위 첨자 i는 DHT의 계층 레벨을 나타내고, 아래 첨자 j는 DHT의 식별자를 나타낼 수 있다. 도 5에서는 편의를 위해 연속된 숫자를 이용하여 식별자를 나타내었지만, 실제 DHT의 식별자는 임의의 숫자로 정의될 수 있다.As shown in FIG. 5, a plurality of DHTs participating in HDHT

As shown in Fig. The superscript i represents the hierarchical level of the DHT, and the subscript j represents the identifier of the DHT. In FIG. 5, the identifiers are shown using consecutive numbers for the sake of convenience. However, the identifier of the actual DHT can be defined as any number.

The item updater 135 may always store the item in the lowest DHT to which the network access switch belongs. The item updater 135 may determine a network access switch responsible for items within the lowest DHT to which the network switch requesting item registration is requesting, at the request of the network access switch requesting item registration.

The item updater 135 may send a registration message to the network access switch responsible for the item. The item updater 135 may store the item in the storage space of the network access switch that has received the message.

The item updater 135 may forward the registration request to the upper DHT. The item updater 135 can store the item when reaching the specified hierarchy to store the item while transferring the registration request to the upper layer.

The item updater 135 can determine the other top DHT node to store the item through the logical distance operation when the registration request reaches the highest DHT and change the forwarding direction of the registration request downward (lower hierarchy direction).

The item updater 135 may store items when reaching a hierarchy level and a layer specified for storing items, while transferring a registration request to a lower layer. When a layer other than the specified layer is reached, the registration message can be transmitted to the lower layer.

The item updater 135 can register and update the item for the first time through the above-described process.

에서 저장할 계층 레벨을 1, 2, 3으로 지정하여 등록 요청한 경우를 나타낼 수 있다. 항목 업데이터(135)는 모든 항목을 제일 먼저 요청이 시작된

에 저장한 후 최상위 DHT로 순차적으로 전달할 수 있다.For example, items A, B, and C in FIG. 5 are

2, and 3 in the hierarchical level to be stored. The item updater 135 is responsible for initializing all items first

And then sequentially forwarded to the highest DHT.

The item updater 135 may store the item when the layer level specified in the item and the DHT layer participating in the network access switch receiving the registration request are the same in the process of being transmitted to the highest DHT. The item updater 135 performs the operation of storing items while changing the direction of the downward direction through the DHT of the highest hierarchical level and sequentially transmitting the registration request to the lowest DHT.

The item updater 135 does not store items in the highest-order DHT unless the hierarchy specified in the item is 1, so that the highest-order DHT may not store all items. In this way, the mobility providing apparatus 10 can solve the scalability problem.

The process in which the inquirer 133 queries the item may be the same as the process of registering the item. The number of overlay hops can be increased by one each time a query is delivered. As the item is stored in the upper layer, the query unit 133 can quickly support the query because the average number of overlay hops that can be spent on the query becomes smaller.

The number of overlay hops required for the query and the delay time can be greatly changed according to the location of the network access switch for querying the hierarchy in which the items are stored.

에 속한 네트워크 접근 스위치들은 자신이 속한 DHT에 항목이 있기 때문에 질의를 빠르게 마칠 수 있다. 따라서, 질의에 소요되는 시간이 매우 짧을 수 있다.For example, if you are querying on item C,

The network access switches belonging to the DHT can terminate the query quickly because there are items in their DHT. Therefore, the time required for the query can be very short.

에 참여하고 있는 네트워크 스위치가 항목 C에 관하여 질의하는 경우 질의가 최상의 DHT를 거쳐서 다른 지역의 최하위 DHT까지 전달될 수 있다. 이 경우 원하는 항목이 물리적으로 가까운 곳에 위치함에도 불구하고 질의가 최상위 DHT를 거치기 때문에 비효율적일 수 있다.But

The query can be delivered via the best DHT to the lowest DHT in the other region. In this case, the query may be inefficient because it goes through the highest DHT, even though the desired item is physically close.

에서 질의를 시작하더라도

에 항목이 저장되기 때문에 훨씬 빠른 시간 안에 원하는 항목에 관하여 질의를 완료할 수 있다.If the item updater 135 specifies the hierarchy in which the item C is to be stored as 2, the queryer 133

Even if you start a query in

It is possible to complete the inquiry about the desired item in a much shorter time.

Accordingly, when registering the item in the HDHT, the item register 130 can determine the layer in which the item is stored in consideration of the location of the network access switches that are highly likely to query the item. Using this characteristic, the time required for the mobility providing apparatus 10 to support the mobility of the terminal can be drastically reduced.

6 shows an example of a DHT routing table.

The mobility provision apparatus 10 may configure the HDHT as a one-hop DHT. In a one-hop DHT, each network switch can maintain a DHT routing table that contains information about all network access switches participating in the same DHT.

The item updater 135 can use the routing table to determine a network access switch having a desired item at a time.

The HDHT may include a root node. The root node is the first node participating in the DHT, and can perform the registration and query message transmission between the high level DHT and the low level DHT. In addition, the root node may be responsible for propagating the latest routing table for the network access switches participating in the DHT. The DHT routing table managed by the root node can be configured as shown in FIG.

The DHT routing table may include the node ID, IP address, and port number of all network access switches participating in the same DHT. For example, if the hash function results in the HDHT using a SHA-256 hash function with a length of 32 bytes, the node ID can be assigned any value of 32 bytes in length when the network access switch participates in the HDHT.

The hash function can be replaced with another hash function as needed. All network access switches participating in the same DHT can have the same DHT routing table.

To this end, when a new network access switch sends a bootstrap message to the root node when it participates in the DHT, the root node adds the node's information to the routing table and propagates it to the participating network access switches have.

Even when the network access switch participating in the DHT leaves, the root node can propagate the fact to other nodes.

The item updater 135 may use the XOR operation to determine a network access switch to store the item. For example, in a situation where the network access switch needs information of the terminal having the IP address of "10.16.0.200", a value obtained by applying the hash function to the IP address of the terminal can be used as the item key value of the HDHT .

At this time, the key generator 131 can generate the item key value by applying the SHA-256 hash function to the string " 10.16.0.200 ". For example, the result of applying the SHA-256 hash function to the IP address of the terminal may be 0x4F9F570BE4F8.

The item updater 135 can perform an XOR operation with all the node IDs stored in the routing table using the result of applying the hash function.

The result of performing the XOR operation with each node ID in FIG. 6 may be 0x0E102D5412BA, 0x03A899E92F2C, 0x178BB5DA23C3, 0x55CECFD0B6E6. Since the second result value is the smallest, the item updater 135 can store the item of the terminal in the second network access switch.

 Item Updater (135) Since the node having the smallest logical distance operation value stores the item, the registration and inquiry message can be transmitted with only a single overlay hop.

FIG. 7 shows an example of a pseudo code for an operation of registering an item in a hierarchical distributed hash table.

Referring to FIG. 7, the item updater 135 can always store items in the lowest DHT to which the network access switch requesting registration is belonging. The item updater 135 determines a network access switch for storing this item using the routing table of the lowest DHT belonging to the network access switch requesting registration of the item and sends a message to register the item to the corresponding network access switch (2).

The network access switch that receives the message can register the item in its own storage (③). The item updater 135 may further transmit a message to the root node requesting that the item is forwarded to the upper DHT (4). Information about the root node can be maintained from when the network access switch participates in the DHT. Since the root node also has the routing table of the upper DHT, it can forward the request to the upper DHT (⑤).

The item updater 135 can continue to forward the registration request to the upper DHT (⑥) and store the item when it passes through the designated hierarchy (⑦).

When the registration request message reaches the top DHT, the item updater 135 can determine the other top DHT node to store the item by logical distance calculation and change the forwarding direction to downward direction (8).

The item updater 135 can store an item when the DHT layer level participating in the network access switch receiving the item registration message changed in the forwarding direction is the same as the specified layer level (9). If the layer level is different, the item updater 135 can transmit the registration message to the lower layer (10).

If the item updater 135 updates the contents of the item, the item updater 135 may also transmit the item update message in the same manner as the registration process.

8 shows an example of a hierarchical distributed hash table entry.

Referring to FIG. 8, a typical Access Router (AR) can assign an IP address to hosts connected to it and perform a default gateway so that communication can be performed. In addition, when the terminal requests a network connection to itself, it can assign an IP address through authentication. The mobility providing apparatus 10 can maintain the IP address of the terminal through Dynamic Host Configuration Protocol (DHCP) even if the terminal moves to another subnetwork.

The key generator 131 may generate the key value of the item by completing the authentication procedure and applying a hash function to the IP address assigned to the host. The inquirer 133 can confirm whether the terminal information is stored in the HDHT by sending a query to the HDHT as a key value. If there is an entry, it means that the host has already connected to this network. In this case, the item updater 135 can update the mobility information of the terminal to the item.

If there is no stored item, since the host first accesses the network, the item updater 135 can newly create and insert an HDHT item containing the location information of the terminal. For example, the content of the item may be composed of a key value of an item, a current IP address of the terminal, an IP address of a network access switch to which a destination node is currently connected, and a list of network access switches caching the item, have.

Figure 9 shows an example of a pseudo code for an operation in which a network access switch updates an entry associated with a terminal, and Figure 10 shows an example of a pseudo code for an operation in which a network access switch updates an item stored in the cache.

Referring to FIG. 9, the item updater 131 can newly register or update the location information of the terminal held by the network access switch. The item updater 131 can generate a key value of an item based on the IP address of the terminal (1). A query is sent by using the key value of the item updater 131 item to check whether the item has been registered (2).

If there is no corresponding item, the item updater 131 may generate a new item, and then record the IP address of the terminal currently connected to the terminal IP item and specify the level at which the item is stored (3). The default value of the hierarchy level at which the item updater 131 stores items is 3, which may be later modified.

The item updater 131 may replace the network access switch IP item with the network access switch IP address to which the terminal is connected (step 4). The item updater 131 can add itself to the network access switch list (5). The item updater 131 may request registration of the created or modified item information in the HDHT (6). At this time, the item updater 131 must specify the level of the hierarchy in which the item is inserted. Each node may know its hierarchical level when participating in a DHT.

In the example of the pseudocode of Fig. 9, the item updater 131 may update the item as it is at the existing hierarchical level. After storing the item updater 131 item information in the cache of the network switch to which the terminal is connected (7), the message can be sent to the network switches that have been caching the item (8).

Network switches that receive the cache update message will check their cache for an entry matching that key. The item updater 131 can update the cache item if there is an item to be matched. The operation of initiating the cache entry may be represented as an example of the pseudo code of FIG.

Referring to FIG. 10, the item updater 131 stores the location information in the HDHT each time the terminal moves through the two functions A_new_MN_is_associated () and Cache_Update_Arrived (), and updates the items of the network access switches caching the location information .

11 shows an example of the operation of the packet transmitter shown in Fig.

Referring to FIG. 11, the packet transmitter 170 may perform a packet processing function using information stored in the HDHT to support mobility of the terminal. The packet transmitter 170 can generate a key value of the item when the packet arrives to the network access switch and check whether there is a cached item.

Packet sender 170 may check if the packet has an optional header added by another network access switch. If there is no option header added by another network access switch, the packet transmitter 170 can forward the packet immediately and query the HDHT if there is no cached item.

The packet transmitter 170 may forward the packet after correcting the destination IP address of the packet to the IP address of the network access switch to which the terminal is connected and adding the key value of the item to the option header when there is a cached item .

Conversely, if the network access switch receives a packet with an optional header added by another network access switch, the packet transmitter 170 may discard the packet immediately if there is no cached entry.

Option header indicates that there is no cached entry, the packet transmitter 170 may determine that there is no terminal to transmit the packet and discard the packet because the terminal may not have accessed the network access switch.

The packet transmitter 170 may restore the destination IP address of the packet to the IP address of the terminal and remove the option header of the packet and forward the packet if there is a cached item. In this case, the packet can be normally transmitted to the terminal.

The packet transmitter 170 can transmit the packet whose destination is the IP address of the terminal to the newly connected location even if the terminal moves to another sub network.

In the example of FIG. 11, the mobile terminal may be connected to the network access switch A and the other terminal may be connected to the network access switch C. When the counterpart terminal sends a packet to the mobile terminal, the packet transmitter 170 can check whether the mobile terminal information is stored in the cache entry of the network access switch C.

If there is information of the mobile terminal in the cache, the packet transmitter 170 may modify the destination IP address of the packet to the IP address of the network access switch A and insert the key value of the item in the option header.

When this packet arrives at the network access switch A, the packet transmitter 170 can restore the destination IP address to the IP address of the mobile terminal, remove the option header, and deliver the packet to the mobile terminal.

12 shows an example of a pseudo code for an operation of transmitting a packet.

Referring to FIG. 12, the packet transmitter 170 can generate a key value by applying a hash function to an IP address of a destination node when a packet arrives to a network access switch, and check whether a cached item exists in the network access switch , ②). The packet transmitter 170 can check whether the packet includes an optional header added by another network access switch (3). If there is no option header added by another network access switch, the packet transmitter 170 may perform steps 4 and 5.

The packet transmitter 170 immediately forwards the packet if there is no cached item, and can send a query to the HDHT (4). If the location information of the destination node is cached, the packet transmitter 170 corrects the destination IP address of the packet to the IP address of the network access switch to which the destination node is connected, adds the key value of the item to the option header, Can export (⑤).

If the packet transmitter 170 receives a packet having an optional header added by another network access switch, the packet transmitter 170 may drop the packet if there is no cached item (6). The packet transmitter 170 may restore the destination IP address of the packet to the IP address of the terminal if the cached item exists, and forward the packet after removing the option header of the packet (7). In this case, the packet can be normally transmitted to the terminal.

Since the packet transmitter 170 performs the Packet_Processing () function through the network access switch, even if the terminal moves to another network access switch, packets with the destination IP address of the terminal can be delivered to the newly connected network access switch .

The packet transmitter 170 can restore the destination IP address to the IP address of the terminal when the packets arrive at the network access switch to which the terminal is connected, thereby allowing the packets to normally arrive at the terminal.

For example, as shown in FIG. 11, a mobile terminal may be connected to a network access switch A and a counterpart terminal may be connected to a network access switch C. When the counterpart terminal sends a packet to the mobile terminal, the packet transmitter 170 can check whether the mobile terminal information is stored in the cache entry of the network access switch C. If there is information of the mobile terminal in the cache, the packet transmitter 170 may modify the destination IP address of the packet to the IP address of the network access switch A and insert the key value of the item in the option header.

When this packet arrives at the network access switch A, the packet transmitter 170 can restore the destination IP address to the IP address of the mobile terminal, remove the option header, and deliver the packet to the mobile terminal.

13 shows an example of an operation of receiving a message between an OVS kernel module and a hierarchical distributed hash table.

Referring to FIG. 13, the network access switch may be implemented by modifying an ES (Edge Switch) operating in a MoE (Mobility of Everything). MoE 's ES is implemented by modifying the source code of the OVS (Open vSwitch) kernel module, and OVS can work with Flat DHT to register or find the location information of the terminal. The mobility provision device 10 can provide a network access switch that is interlocked with the HDHT based on the ES and can specify the HDHT level of the item. Registration and query messages between the OVS kernel module and the HDHT can be passed through the socket IPC.

14 shows an example of the operation of the handover processor shown in Fig.

Referring to FIG. 14, the handover processor 150 can support handover when a mobile terminal establishes a connection with a new network access switch.

The handover processor 150 can establish a L2 association with a newly connected network access switch. The handover processor 150 may allocate an IP address to the mobile terminal through Dynamic Host Configuration Protocol (DHCP).

The handover processor 150 may generate a key value of the item for the mobile terminal and query the item. The handover processor 150 updates the existing entry if it exists, and registers the new entry if it does not exist.

When the item is updated, the handover processor 150 may send a cache update message to the network access switches caching the item. The network access switches receiving the cache update message can update their cache entries.

The handover processor 150 can recover the communication of the mobile terminal when the packets are transferred to the new location of the mobile terminal after the items of the network access switches that have been caching items for the mobile terminal are updated.

The query time of a query that occurs to support the mobility of the terminal can be greatly changed according to the hierarchical level of the item. When a mobile terminal that is in communication with a counterpart terminal performs a handover, the handover processor 150 fetches a list of network switches caching location information of the mobile terminal from the HDHT when the mobile terminal is connected to the network access switch, Can be transmitted.

The cache update operation must be performed before the packets with the mobile terminal as the destination can be correctly transferred to the new location of the mobile terminal. Therefore, the HDHT query time can greatly affect the handover delay time.

In order to reduce the query time, the item register 130 can determine the hierarchical level at which items are stored in consideration of the moving range of the mobile terminal. If the hierarchical level at which the item is stored is set to match the movement range of the mobile terminal, most queries generated when the mobile terminal moves can be made in a short time. Accordingly, the time required for handover of the mobile terminal can be greatly reduced.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, controller, arithmetic logic unit (ALU), digital signal processor, microcomputer, field programmable gate array (FPGA) , A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing apparatus may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (21)

Registering an entry related to the terminal in a layer designated by a network access switch to which a terminal is connected among a plurality of layers constituting a hierarchical distributed hash table (HDHT); And
Processing the handover of the terminal using the item
Lt; / RTI >
Wherein the hierarchical distributed hash table comprises a plurality of layers based on a physical distance between the network access switches
A method for providing mobility.
The method according to claim 1,
Generating the hierarchical distributed hash table including the plurality of layers based on a physical distance between the network access switches;
Further comprising:
Wherein the generating comprises:
Creating a plurality of lowest layers comprising network access switches physically close to the network access switches; And
Hierarchically creating upper layers comprised of the plurality of lowest layers
Lt; / RTI >
The method according to claim 1,
Wherein the registering step comprises:
Generating a key value of an item associated with the terminal;
Querying the hierarchical distributed hash table for the key value; And
And updating the item in the hierarchical distributed hash table based on the query result
Lt; / RTI >
The method of claim 3,
Wherein the updating comprises:
Specifying a layer in which the item is to be stored in the item;
Updating a network access switch list and an IP (Internet Protocol) address of the item; And
Requesting registration of the item in the hierarchical distributed hash table
Lt; / RTI >
5. The method of claim 4,
Wherein the requesting step comprises:
Storing the item in a distributed hash table of the lowest layer;
Storing the item in a distributed hash table of the specified hierarchy when the registration request reaches the specified hierarchy while sequentially transmitting the registration request from the lowest hierarchical layer to the highest hierarchical layer;
Storing an item in a distributed hash table node of the highest hierarchical layer through a logical distance operation when the registration request reaches the highest hierarchical layer; And
Storing the item in the distributed hash table of the specified hierarchy when the specified request arrives at the specified hierarchy while sequentially transmitting the registration request from the highest layer to the specified layer
Lt; / RTI >
6. The method of claim 5,
Wherein each of the storing steps comprises:
Performing a logical distance operation using a key value of the item; And
Storing the item in a network access switch having a result of the logical distance operation being the smallest value
Lt; / RTI >
The method according to claim 1,
Wherein the processing comprises:
Assigning a new IP (Internet Protocol) address to the terminal according to movement of the terminal;
Generating an item key value for the terminal and querying the hierarchical distributed hash table; And
And updating the item in the hierarchical distributed hash table based on the query result
Lt; / RTI >
The method according to claim 1,
And transmitting a packet to the terminal through the hierarchical distributed hash table
Further comprising the steps of:
9. The method of claim 8,
Wherein the transmitting comprises:
Generating an item key value of the terminal in a network access switch that receives the packet;
Determining whether an optional header exists in the packet; And
Forwarding the packet to a network switch to which the terminal is connected based on the result of the determination and the item key value
Lt; / RTI >
10. The method of claim 9,
Wherein the forwarding comprises:
If the network access switch that received the packet without the option header does not store an item corresponding to the item key value, forwarding the packet and querying the hierarchical distributed hash table about the item ;
Modifying the destination of the packet to a network switch to which the terminal is connected if the network access switch that received the packet without storing the option header does not store the item corresponding to the item key value, Adding a new item key value to the header;
Discarding the packet if the option header exists in the packet and the network access switch receiving the packet does not store an item corresponding to the item key value; And
If the option header exists in the packet and the network access switch that received the packet stores an item corresponding to the item key value, restores the destination of the packet to the terminal, removes the option header, Forwarding the packet to
Lt; / RTI >
An entry related to the terminal is registered in a hierarchy designated by a network access switch to which a terminal is connected among a plurality of layers constituting a hierarchical distributed hash table (HDHT), and the entry Controller that handles over
Lt; / RTI >
Wherein the hierarchical distributed hash table comprises a plurality of layers based on a physical distance between the network access switches
A device for providing mobility.
12. The method of claim 11,
The controller comprising:
An item register for registering an entry related to the terminal in a hierarchy designated by a network access switch to which a terminal is connected among a plurality of layers constituting a hierarchical distributed hash table (HDHT); And
A handover processor for handling the handover of the terminal using the item,
Wherein the mobility providing device includes:
13. The method of claim 12,
The controller comprising:
An HDHT generator for generating the hierarchical distributed hash table including the plurality of layers based on a physical distance between the network access switches;
Further comprising:
The HDHT generator comprises:
A plurality of lowest layers constituted by network access switches physically close to each other among the network access switches, and hierarchically forming upper layers constituted by the plurality of lowest layers
Mobility providing device.
13. The method of claim 12,
Wherein the item register comprises:
A key generator for generating a key value of an item related to the terminal;
A query unit for querying the hierarchical distributed hash table with the key value; And
An item updater for updating the item in the hierarchical distributed hash table based on the query result;
And a mobile device.
15. The method of claim 14,
The item updater,
Specifies a layer in which the item is to be stored in the item, updates a network access switch list and an IP (Internet Protocol) address of the item, and requests registration of the item in the hierarchical distributed hash table
Mobility providing device.
16. The method of claim 15,
The item updater,
Stores the item in a distributed hash table of the lowest layer,
Storing the item in the distributed hash table of the specified hierarchy when the registration request reaches the specified hierarchy while sequentially transmitting the registration request from the lowest hierarchical layer to the highest hierarchical layer,
Storing an item in the distributed hierarchical hash table node of the highest hierarchical layer through a logical distance operation when the registration request reaches the highest hierarchical layer,
And sequentially transmits the registration request from the highest layer to the specified layer and stores the item in the distributed hash table of the specified layer when reaching the specified layer
Mobility providing device.
17. The method of claim 16,
The item updater,
Performing a logical distance operation using the key value of the item, and storing the item in a network access switch having a result of the logical distance operation being the smallest value
Mobility providing device.
13. The method of claim 12,
The handover processor includes:
Allocates a new IP (Internet Protocol) address to the terminal according to the movement of the terminal, generates an item key value for the terminal, queries the hierarchical distributed hash table, Updating the item
Mobility providing device.
13. The method of claim 12,
The controller comprising:
A packet transmitter for transmitting a packet to the terminal through the hierarchical distributed hash table,
Further comprising:
20. The method of claim 19,
The packet transmitter includes:
The method comprising: generating an item key value of the terminal in a network access switch that receives the packet; determining whether an option header exists in the packet; determining, based on a result of the determination and the item key value, Lt; RTI ID = 0.0 >
Mobility providing device.
21. The method of claim 20,
The packet transmitter includes:
If the network access switch that received the packet without the option header does not store an item corresponding to the item key value, forwarding the packet and querying the hierarchical distributed hash table about the item and,
Modifying the destination of the packet to a network switch to which the terminal is connected if the network access switch that received the packet without storing the option header does not store the item corresponding to the item key value, Add a new entry key value to the header,
Discarding the packet if the option header exists in the packet and the network access switch receiving the packet does not store an item corresponding to the item key value,
If the option header exists in the packet and the network access switch that received the packet stores an item corresponding to the item key value, restores the destination of the packet to the terminal, removes the option header, Lt; RTI ID = 0.0 >
Mobility providing device.

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