KR100296076B1 - Quality of Service(QoS) based generic shortest path search method - Google Patents

Abstract

The present invention relates to a path search method for routing based on quality of service (QoS) required when transmitting multimedia information on various information communication networks. An algorithm for providing a shortest path search applied to a single layer is provided. Of the paths that have the lowest QoS among all the paths that can occur as one destination (GSPA), and when the paths as described above are distributed, it is possible to distribute the paths in a short time (DGSPA) and In this case, if the QoS value generated in all possible paths with one destination satisfies the standard QoS value, all the paths are set to the shortest path, so that only one path is set and the error is prevented. Algorithms that provide the shortest path search that is applied to the multi-level layer, and multiplexes the DGSPA algorithm and the QRDGSPA algorithm. By providing each of the algorithms (HDGSPA, QRHDGSPA) one application to apply to Bell, there are advantages to explore ways out of each path so that the user can selectively use the method that best matches your system environment.

Description

Quality of Service (QoS) based generic shortest path search method}

The present invention relates to a path search method for routing based on a quality of service (hereinafter referred to as QoS) required for transmitting multimedia information on various information communication networks.

In general, a route search method may be described. First, a distance vector algorithm is used. The distance vector algorithm is a path search algorithm that is widely used in the Internet.

A typical example using the above scheme is the Routing Information Protocol (RIP).

The simple operation of the distance vector algorithm is described below. First, the distance value of each node connected to each network is 0 in the path search table, and the distance of other nodes in the network is zero. The value is initialized to infinity.

Then, in each step to find the route, find the shortest distance from the current node to another node and register it in the router table N. The formula for finding the shortest distance is:

D (v) ← Min [D (v), D (w) + L (w, v)]

Where D (v) is the distance from the current node to the destination node, and L (w, v) is the distance from node w to node v.

The shortest distance information found above is transmitted to neighboring nodes connected to it, and this procedure is continued until information about all nodes connected to each node is collected from each node.

Then, when no path change information is generated at each node and no information is being transmitted at each connected link, the process recognizes that all path information has been collected and terminates the path information collection process. .

The biggest advantage of the distance vector algorithm described above is that it is simple. As shown in the above execution procedure, the algorithm is very simple and easy to implement.

On the other hand, the disadvantage of the distance vector algorithm is that it consumes a relatively large amount of time and network bandwidth to collect all the path information at each node. In addition, the disadvantage of the Ping-Pong problem is that in the environment where the network state changes frequently, the information transmitted from each node is transferred to the neighboring node. In other words, there is no function to select an optimal QoS at each intermediate node.

Secondly, there is a link-state algorithm. The link-state protocol is a path search algorithm, also called 'shortest path first'. It includes a distributed database model and provides the shortest path. We use the Dijkstra's Shortest Path algorithm to find out.

Referring to the simple operation of the link-state algorithm, each local node provides its current link state to other nodes (LSA: Link-State Advertisement).

The status information of each node includes the operating interface of each node, the transmission time when the information is transmitted through the corresponding interface, and information on where the interface is connected.

The state information of each node is transmitted to other nodes using a floating function, and the transmitted information is stored in each node's link-state database.

Each node uses the stored information to find the shortest distance path from each node to other nodes using the 'Dijkstra's Shortest Path' algorithm and stores it in the path search table.

Link-state algorithms include 'Open Shortest Path First (OSPF)' for Transmission Control Protocol / Internet Protocol (TCP / IP) and Private Network-to-Network Interface for Asynchronous Transfer Mode (ATM) networks. PNNI) and the like.

The disadvantage of the link-state algorithm described above is that it is more complicated to implement than the distance-vector algorithm, and wastes a lot of bandwidth by periodically providing link state information (LSA).

In addition, the link-state algorithm collects all the path search information to maintain an optimal path suitable for the initial stage. Therefore, when various multimedia services are required in different nodes, various QoS must be satisfied for each service. However, there is a point that it is not suitable as a link-state or distance vector in which paths between all nodes are already established.

Third, the Dynamic Source Routing (DSR) algorithm is an algorithm proposed by the 'MANET' group of the Internet Engineering Task Force (IETF). Path search algorithm for 'ad-hoc' network. Also, no QoS support for multimedia services is considered here.

Referring to the operation of the dynamic source path search algorithm, the source node, which wants to transmit data, sends a path search setting request to a destination node to all adjacent nodes.

Each intermediate node to which the route request is sent transmits only the route request that arrives the earliest for the same route request, and then deletes the route information that has arrived without retransmitting.

The route request arriving at the destination records the list of nodes that have passed through to the source node, and is then passed to the source node.

When the path is established, all data packets transmitted contain intermediate node list information that the packet must pass, and the packets are transmitted in this order.

Such a dynamic source algorithm has a disadvantage of operating only in a special network environment called an 'ad-hoc' wireless network, and has a disadvantage in that there is no consideration for a multimedia service because it transmits a routing packet with a short time delay unconditionally.

Disclosure of Invention The present invention aims to implement a path search algorithm supporting QoS for a multimedia service in a general wired / wireless communication network in view of the above-described conventional problems, and thus, a destination node in a source node. Including the path information passed between nodes, each node decides whether to retransmit so that the path information is not retransmitted to the node that has passed once, and transmits the path information to the adjacent node. Only route requests that are best suited for the QoS required for the request are sent to neighboring nodes, and route information that arrives thereafter is deleted or stored as needed without retransmission, thereby eliminating CPU and bandwidth waste due to retransmission. It aims to prevent.

In addition, each route information arriving at the destination may be one or more. In this case, if the destination node selects a desired route and sends a reply message back to the original node, the reply message is registered in the message. By arriving at the raw node via an intermediate node, the route is established. When all nodes on the network send a route request message to find all routes at the same time, each node does not send a reply message. It aims to shorten the path setting time by setting the path by recognizing the path setting request message transmitted from the node as a reply.

In addition, various path information arriving at the destination node can be used as a back-up path or to increase the transmission speed using multi-path depending on the purpose. An object of the present invention is to provide a path searching method.

1 is a flow chart showing a shortest path search (GSPA) process according to the present invention.

FIG. 2 is a flowchart illustrating a detailed process of the path searching process of FIG. 1.

3 is a flow chart showing a shortest path search (DGSPA) process for supporting a distributed environment according to a first embodiment of the present invention.

4 is a flowchart illustrating a detailed process of a path searching process of FIG. 3.

5 is a flowchart illustrating a shortest path search (QRDGSPA) process using a limited QoS value according to a second embodiment of the present invention.

6 is a flowchart illustrating a detailed process of the path searching process of FIG. 5.

7 is a flowchart illustrating a process of shortest path search (HDGSPA) in a two-level network according to a third embodiment of the present invention.

8 is a flowchart illustrating a detailed process of a path searching process of FIG. 7.

9 is a flowchart illustrating a process of shortest path search (QRHDGSPA) using limited QoS values in a two-level network according to a fourth embodiment of the present invention.

FIG. 10 is a flowchart illustrating a detailed process of the path searching process of FIG. 9.

Path searching method in the information communication network according to the present invention to operate as described above, all paths existing on the network to search the shortest path among the plurality of paths that can occur from a single source node to a single destination node. A first step of initializing a set and a quality of service (QoS) value indicating connection information of nodes in the network;

And a second process of performing an actual path search by designating a starting point to search for a path when the initialization is completed.

In addition, the path search method in the information communication network according to the present invention to operate as described above, to exist on the network to search the shortest path of the plurality of paths that can occur from a single source node to a single destination node. A first step of initializing a set and a quality of service (QoS) value representing connection information of nodes in all paths;

A second process of calling a route search means by designating a starting point for the route search and receiving a result message from the route search means to distribute the route search when the initialization is completed;

After performing the route search according to the call, a third process of transmitting a result message to the call target is provided, thereby reducing the route search time.

In addition, the path search method in the information communication network according to the present invention to operate as described above, to search all the paths satisfying the reference QoS value among the plurality of paths that can occur from a single source node to a single destination node. A first step of initializing an aggregation and a quality of service (QoS) value representing connection information of nodes in all paths existing on the network;

A second step of calling the route search means by specifying a starting point to search for the route and a reference QoS value to distribute the route search when the initialization is completed, and receiving a result message from the route search means;

And performing a path search according to the call, and then transmitting a result message to the call target.

In addition, the path search method in the information communication network according to the present invention to operate as described above, the shortest path among a plurality of paths that can occur from a single source node to a single destination node on a network where the network layer is multilevel. A first step of initializing a set and a quality of service (QoS) value representing connection information of nodes in layers in all paths existing on the multilevel network to search for;

A second process of calling a route search means by designating a starting point for the route search and receiving a result message from the route search means to distribute the route search when the initialization is completed;

When performing the route search according to the call, the region of the layer that has once passed through is not rerouted, and when the route search is performed, a third process of transmitting a result message to the call target.

In addition, the path search method in the information communication network according to the present invention to operate as described above, the reference QoS value of a plurality of paths that can occur from a single source node to a single destination node on a network where the network layer is multi-level A first step of initializing a set and a quality of service (QoS) value representing connection information of nodes in a layer in all paths existing on the multilevel network to search all paths satisfying the following values;

A second step of calling the route search means by specifying a starting point to search for the route and a reference QoS value to distribute the route search when the initialization is completed, and receiving a result message from the route search means;

And performing a path search according to the call, and then transmitting a result message to the call target.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the following matters should be considered to implement an optimal search algorithm for providing multimedia services in wired and wireless networks.

First, the most important problem in designing a path search algorithm for multimedia services is that in most cases there may be at least one individual optimal path for a parameter, but there is no optimal path for all parameters. to be. For example, when two parameters (bandwidth and delay) are considered in path search, in most cases the optimal path for bandwidth and the optimal path for delay will be different. As a result, a path search supporting Qos requires a decisive protocol capable of determining whether a set path is optimal for a desired QoS.

Second, mobile terminals operating in a wireless network can move from time to time. As the mobile terminal changes the network topology from time to time, and the static routing method for establishing a communication path before the path search request is inappropriate, an adaptive routing protocol should be considered.

Third, since a terminal operating in a wireless network has less storage space and less computing power than a router operating in a wired network, a path search protocol requiring complicated calculations is inappropriate, and a simple path search protocol is required. do.

Fourth, a terminal operating in a wireless network must operate a distributed path discovery protocol operable in a distributed environment. In a wireless network environment, a protocol for establishing a path search path using a central control node frequently changes data due to the fact that a wireless terminal can move from time to time. In addition, since the terminal path information for each time period for managing the changed data is required and consumes a lot of network bandwidth, it is not suitable in a wireless network environment. As a result, the wireless mobile communication requires a distributed path search protocol in which a router maintains a minimum amount of information for path search.

Hereinafter, the shortest path search algorithm implemented in the present invention will be described.

1 is a flow chart illustrating a generic shortest path algorithm according to the present invention (hereinafter referred to as GSPA), a process of initializing a set and QoS values representing connection information of nodes in all paths existing in a network. (S1);

When the initialization is completed, a step (S2) of searching for an optimal path is performed by designating a starting point to be routed to perform an actual path search.

First, the initialization process (S1) is described, using the repeated statement to initialize the total QoS values accumulated in node i along the shortest route from the source node 0 to node N to the value 'MAXQ'. This value means that the node at this time is a node that is not passed.

The set of nodes arranged at node i from the source along the shortest route assumed is also initialized to an empty set {@} (S11).

For reference, the algorithm and variable definitions are as follows.

struct {Qos tqos; Oset set;} node [N]; / * Node info *. /

Oset nextset [N]; / * Cleaned neighbor set of nodes * /

Qos linkqos [N, N]; / * QoS information between each node * /

typedef struct {Qos tqos; Oset set; } Route;

Main (int ss) / * source number * /

{

int i, j; Route route;

for (i = 0; i <N; i ++) {node [i] .tqos = MAXQ; node [i] .set = {@};}

Then, it initializes a set that provides connection information of the current node and the next node to be connected, which is also initialized to an empty set using a repetition statement (S12).

For reference, the algorithm is as follows.

for (i = 0; i <N; i ++) nextset [i] = {@}; / * {@}; Empty assembly * /

Subsequently, it initializes the QoS value of the link between any node i and any node j next to it. This also assigns the QoS value by using an iterative statement for the whole node. If it is determined that it is not its own node, it assigns a predetermined QoS value, and if it is its own node, it substitutes a value of '0' (S13).

For reference, the algorithm is as follows.

for (i = 0; i <N; i ++) for (j = 0; j <N; j ++) {

if (i == j) linkqos [i, j] = ZERO else linkqos [i, j] = getlinkqos ();

}

Subsequently, a set representing the information of the node to be connected next to its own node is constructed using the connection QoS value assigned above, which also establishes a set of connections using a repetitive sentence for all nodes.

That is, if the node to be connected next in the current node is not a node of its own, the node is additionally registered in the set indicating the next connected node (S14).

For reference, the algorithm is as follows.

for (i = 0; i <N; i ++) for (j = 0; j <N; j ++) {

if (linkqos [i, j]! = ZERO && linkqos [i, j]! = MAXQ) nextset [i] = nextset [i] ∪ j;

}

/ * Connected: Qos value, unconnected: MAXQ, neighbor set building, ∪: clean set * /

Then, after starting the path search from the start point after the start point is specified, the route set is initialized as the start point, and the route QoS value also starts with the value '0' so that the path search can be started (S15). .

When all the above initialization is completed, the route search algorithm Qospath (ss, route) is called to perform the route search starting from the route search start point (S2).

For reference, the algorithm is as follows.

route.set = {ss}; route.tqos = ZERO;

Qospath (ss, route);

FIG. 2 is a flowchart illustrating a process (S2) of searching for an optimal path according to a path search algorithm (Qospath (ss, route)) operating according to the call. (S21).

For reference, the algorithm and variable definitions are as follows.

Qospath (int s, Route route)

{

Qos tqos;

int i;

tqos = F (route.tqos, linkqos [E (route.set), s]);

If the total QoS value to the current node searched for the path has been calculated, there are several paths that reach the current node through the path different from the total QoS value at this time. If the precomputed value is smaller than the total QoS value, it stops the current path search and waits for another path search call (C (tqos) <C (node [s] .tqos)). (S22).

As a result of the comparison, if the total QoS value of the current route is smaller, the route is the shortest distance from the last route, and thus the route search information should be modified to this route. Check whether it is the same (E (route.set)! = S) (S23).

If it is determined that the node is not its own node, the node is additionally registered in the connection information and the next process (S25) is performed (S24).

If it is determined that the node is its own node, the process (S24) is skipped and the total route QoS value for the current path is immediately calculated. When adding the connection information, the node is duplicated when the node is added.

At this time, the total route QoS value substitutes the total QoS value calculated in step S21 into the total route QoS value, and substitutes the route path into a path set representing a node up to now (S25).

For reference, the algorithm is as follows.

if (C (tqos) <C (node [s] .tqos)) {/ * C: Cost function for a given Qos * /

if (E (route.set)! = s) route.set = route.set ∪ s;

route.tqos = tqos;

node [s] .set = route.set;

For reference, the function E () is used to get the connection Qos between the last node and this node.

When the process is completed, since the optimal path search for the called node is completed, the processes S21 to S25 are repeatedly performed using the repetition sentence for the optimal path search for the next node.

In this case, the route search algorithm is also called. In this case, the route search is started after subtracting the performed route set from the set representing the connection to the next node. This is so as not to repeat the path once passed (S26).

For reference, the algorithm is as follows.

for (each i ∈ (nextset [s] route.set)) Qospath (i, route);

On the other hand, the method described above was described as starting the path search after subtracting the route set that was performed first from the set representing the connection to the next node when the path search algorithm is called, the present invention, even if not subtracted The algorithm of selects the shortest path if the loop value is positive in the sense of the cost function.

3 is a flowchart illustrating an optimal path search algorithm according to another embodiment of the present invention, which is a distributed generic shortest path algorithm (DGSPA). The algorithm differs from the GSPA in that it does not perform path searching for all nodes present in the network, but only for itself and the node connected to it.

If only the best case is selected among the path messages arriving at the destination node in DGSPA, only one path is searched, but if all paths satisfying the required QoS are selected, multiple paths satisfying the QoS are searched.

The process of DGSPA is described below.

Initializing a set and QoS values representing connection information of any one node and nodes in a path connected to the one node (T1);

In the initializing state, the process waits until a call is received to perform an actual path search, and when the call is received, a step (T2) of searching for an optimal path is provided.

First, the initialization process T1 will be described. The total QoS value for a certain node s is initialized to a value of 'MAXQ' which means that this node is a node that is not passed, and a value having information on the arbitrary node. And a value indicating the next node to be connected to this node is initialized to an empty set (T11).

For reference, the algorithm and variable definitions are as follows.

typedef struct {Qos tqos; Oset set; } Route;

struct {Qos tqos; Oset set;} node [s];

Oset nextset [s];

Qos linkqos [s] [N];

Route route;

node [s] .tqos = MAXQ;

node [s] .set = {@};

nextset [s] = {@};

Subsequently, the QoS value of the link connected between the arbitrary node s and the arbitrary node j next to it is initialized. This also substitutes the QoS value by using a repetition sentence and determines whether the node to be initialized is its own node. If it is not its own node, it assigns a predetermined QoS value, and if it is its own node, it assigns a value of '0' (T12).

For reference, the algorithm is as follows.

for (j = 0; j <N; j ++) {

if (s == j) linkqos [s] [j] = ZERO else linkqos [s] [j] = getlinkqos ();

}

Subsequently, a set representing a node representing information of a node to be connected next to its own node is constructed using the above-described connection QoS value, which is also constructed by using a repetitive sentence for the next connected node.

That is, if the node to be connected next in the current node is not a node of its own, the node is additionally registered in the set indicating the next connecting node (T13).

For reference, the algorithm is as follows.

for (j = 0; j <N; j ++) {

if (linkqos [s] [j]! = ZERO && linkqos [s] [j]! = MAXQ) nextset [s] = nextset [s] ∪ j;

}

/ * Connected: Qos, not connected: MAXQ, 13), nextset [s]: neighbors of s * /

As described above, when all the initialization is completed, the path search algorithm is started. If the current node corresponds to the source node, the path search algorithm is determined. If the source node is the source node, the route set is initialized to the current node, and the route QoS value is also initialized to '0'. Then call to perform the route search algorithm (QoSpath (s, route)).

If it is determined that the source node is not a source node as a result of the determination, the node that has completed the path search in another node and receives the route value and the route value received as a result of the path search process for the next node path search (receive (s, route)) Wait to be. When the result is received, the route search algorithm is called (QoSpath (s, route)) (T14, T2).

For reference, the algorithm is as follows.

if (s is the source node)

{route.set = {s};

route.tqos = ZERO;

}

else

{

receive (s, Qospath (s, route));

call (Qospath (s, route));

}

FIG. 4 is a flowchart illustrating a process (S2) of searching for an optimal route according to a path search algorithm (Qospath (int s, Route route)) operating according to the call. Calculate (T21).

For reference, the algorithm and variable definitions are as follows.

Qospath (int s, Route route)

{

Qos tqos;

int i;

tqos = F (route.tqos, linkqos [E (route.set), s]);

If the total QoS value to the current node searched for the path has been calculated, there are several paths that reach the current node through the path different from the total QoS value at this time. If the previously calculated value is smaller than the total QoS value, the path search that is currently being searched is stopped and there is another path search call (T22).

As a result of the comparison, if the total QoS value of the current route is smaller, the route is the shortest distance from the last route, and thus the route search information should be modified to this route. It is checked whether or not it is the same (T23).

If it is determined that the node is not its own node, the node is additionally registered in the connection information and the next process (T25) is performed (T24).

If it is determined that the node is its own node, the process (T24) is omitted and the total QoS value for the path up to the present is immediately calculated. This is because the node is duplicated when adding the connection information.

That is, the total QoS value calculated above is substituted into the total QoS value representing the path, and the route path is substituted into the set representing the node up to now (T25).

For reference, the algorithm is as follows.

if (C (tqos) <C (node [s] .tqos)) {/ * C: Cost function for a given Qos * /

if (E (route.set)! = s) route.set = route.set ∪ s;

route.tqos = tqos;

node [s] .set = route.set;

When the process is completed, since the optimal path search for the called node is completed, a route search (send (i, route)) message is sent for the optimal path search for each neighboring node. This message is sent to the part T14 which receives the call in the initialization process T1. When the call is performed according to the transmission of the message, the above processes (T21 to T25) are repeated.

In particular, when the path search algorithm is repeatedly executed by the call, the path search is started after subtracting the performed route set from the set representing the connection to the next node. This is to avoid repeating the path once it has passed (T26).

For reference, the algorithm is as follows.

for (each i ∈ (nextset [s] route.set))

send (i, route);

FIG. 5 is a flowchart illustrating a QoS Restricted Generic Shortest Path Algorithm (hereinafter referred to as QRDGSPA) according to another embodiment of the present invention.

QRDGSPA algorithm is as follows when compared with the GSPA algorithm implemented in FIG.

The GSPA shown in FIG. 1 selects only one route belonging to the shortest distance by arriving at the same destination.

That is, in comparing the cost, the total QoS value calculated through other paths is compared with the total QoS value calculated through the current path. If the current is small, the existing path is discarded and the current path is set as the shortest path. By doing so, you get only one path.

However, the QRDGSPA algorithm sets a reference QoS value in the process of comparing the cost, and if the QoS value calculated through each path, whether the current path or the other path is less than the set reference QoS value, all of these paths are shortest paths. To set.

In other words, if a destination is determined and there are several paths to this destination, the path is selected as the shortest path when both of these paths satisfy the QoS value.

In this case, if the path is searched through only one shortest path, and an error occurs in the path, the path search cannot be prevented.

The algorithm is almost similar to that shown in FIG. 3, and the other part is a call factor added at the part of invoking the path search algorithm and receiving the result, which is the reference QoS value described above.

That is, it is changed from receive (s, route) to receive (s, route, req) (T15), and from QoSpath (s, route) to QoSpath (s, route, req) (T2).

Since other algorithms are the same, the description is omitted.

FIG. 6 is a flowchart illustrating a path search algorithm called by the QRDGSPA, which is also compared with the path search algorithm of FIG. 4, and after the total QoS value is calculated in step 'T1', the following process is added.

That is, a process of checking whether the accumulated total QoS value from the source node to the current node satisfies the QoS value set as the reference value is added. If satisfied in this process, the next path searching algorithm is executed, and if not satisfied, the process ends (S (tqos, req) == FALSE) (T27).

At the end, the route search message send (i, route, req) is transmitted to repeat the route search algorithm again (T28).

Since other algorithms are the same as in Fig. 4, description thereof is omitted.

In the meantime, the path search process is described when the network configuration corresponds to the first level, and the process of performing the path search when the network configuration is the two level hierarchical network will be described below.

If the network configuration is two levels, the address of the two-level hierarchical network is first defined as a pair of integers [n, m].

Here n denotes a higher address and m denotes a lower address.

A set of nodes having the same higher address is called a region. In particular, in a hierarchical network, an address having a different upper address or a connection address list divided into addresses may not have the same upper address.

In other words, a connection outside a certain area cannot go through the same area again.

For example, routing address lists such as [1,2] [1,4] [1,3] [3,1] [3,2] [3,3] [2,1] [2,2] are hierarchical. It is suitable as an address list for structural routing, but with [1,2] [1,4] [1,3] [3,1] [2,1] [3,2] [3,3] [2,2] The same address list is not suitable for hierarchical routing because the address groups have [3 ,.] separated by [2,1] with the same upper address (different higher address).

In other words, this connection leaves node 3 through node [3,1], passes through node [2, 1], and enters node 3 again through node [3, 2]. That's because you can't go into the same area.

Hereinafter, a path search method at two levels will be described.

FIG. 7 is a flowchart illustrating a process of shortest path search (HDGSPA) in a two-level network according to the third embodiment of the present invention, which is substantially similar to the above-described DGSPA. Is to be initialized.

A total QoS value for any node p belonging to any layer i is initialized to a value of 'MAXQ' which means that this node is a node that is not passed, and a set having information about any node belonging to any layer. In this case, the set indicating the node belonging to the next layer to be connected with this node is initialized to the empty set (P11).

For reference, the algorithm and variable definitions are as follows.

struct {Qos tqos; Oset set;} node [H, N]; / * Hierarchical address * /

Qos linkqos [[H, N], [H, N]];

Oset nextset [H, N];

struct Route {Qos tqos; Oset set; } route;

struct Node {int s; int p;};

node [i, p] .tqos = MAXQ;

node [i, p] .set = {@};

nextset [i, p] = {@};

Subsequently, the QoS value of the link connected between any node p belonging to the arbitrary layer i and any node q belonging to any layer j next to it is initialized, which is also assigned a QoS value using a repetitive statement. However, it determines whether the node of the layer to be initialized is its own node, and if it is not its own node, substitutes a preset QoS value, and if it is its own node, substitutes a value of '0' (P12).

For reference, the algorithm is as follows.

for (i = 0; i <H; i ++) for (j = 0; j <H; j ++) {

for (p = 0; p <N; p ++) for (q = 0; q <N; q ++) {

if ((i, p) == (j, q)) linkqos [[i, p], [j, q]] = ZERO;

else linkqos [[i, p], [j, q]] = getlinkqos ();

}

Subsequently, a set representing node information of a layer to be connected next to its own node is constructed using the above-described connection QoS value, which is also constructed by using a repetition sentence for nodes of a layer connected to the next.

That is, if the node of the layer to be connected next in the node of the current layer is a node connected to a path other than its own node, the node is additionally registered to the set indicating the next connecting node (P13).

For reference, the algorithm is as follows.

for (i = 0; i <H; i ++) for (j = 0; j <H; j ++) {

for (p = 0; p <N; p ++) for (q = 0; q <N; q ++) {

if (linkqos [[i, p], [j, q]]! = ZERO && linkqos [[i, p], [j, q]]! = MAXQ)

nextset [i, p] = nextset [i, p] ∪ (j, q);

}

}

/ * Connected: Qos value, not connected: MAXQ * /

As described above, when all initialization is completed, the path search algorithm is started. If the node of the current layer corresponds to the source node, the path search algorithm is determined. If the source node is the source node, the path search algorithm is initialized to the current node. It is also initialized to '0' and then called to perform the path search algorithm (QoSpath (s, route)).

If it is determined that the source node is not the source node, the node completes the route search and receives the node, which is the value transmitted as a result of the route search process, and the route value at this time for receiving the route of the next node (receive (s, route)). Wait to be. When the result is received, the route search algorithm is called (QoSpath (s, route)) (P14, P2).

For reference, the algorithm is as follows.

if (s is the source node)

{route.set = {s};

route.tqos = ZERO;

}

else

{

receive (s, Qospath (s, route));

call (Qospath (s, route));

}

8 is a flowchart illustrating a process (P2) of searching for an optimal route according to a path search algorithm (Qospath (int s, Route route)) operating according to the call. The total QoS value is calculated (P21).

For reference, the algorithm and variable definitions are as follows.

Qospath (Node s, Route route)

{

Qos tqos;

ini i;

tqos = F (route.tqos, linkqos [E (route.set), s]);

If the total QoS value to the node in the current layer, which has been traversed above, has been calculated, the node reaches the node of the current layer through a path different from the total QoS value at this time. If the pre-calculated value is smaller than the total QoS value, the path search that is currently being searched is stopped and there is another path search call (P22).

As a result of the comparison, if the total QoS value of the current route is smaller, the route is the shortest distance from the last route, and thus the route search information should be modified to this route. Check whether it is the same (P23).

If it is determined that the node is not its own node, the node in the hierarchy is additionally registered to the connection information and the next process (P25) is performed (P24).

If it is determined that the node is its own node, the process (P24) is omitted and the total QoS value for the path up to the present is immediately calculated. When adding the connection information, the node is duplicated when the node is added.

That is, the total QoS value calculated above is substituted for the total QoS value representing the path, and the node path in the layer is substituted into the set representing the node up to now (P25).

For reference, the algorithm is as follows.

if (C (tqos) <C (node [s] .tqos)) {/ * C: Cost function for a given Qos * /

if (E (route.set)! = s) route.set = route.set ∪ s;

route.tqos = tqos;

node [s] .set = route.set;

When the process is completed, since the optimal path search for the called node is completed, the optimal path search message is sent to each neighboring node. This message is sent to part T14 which receives the call in the initialization process P14. When the call is performed according to the message transmission, the above processes (P21 to P25) are repeated.

In particular, when the path search algorithm is repeatedly performed by the call, the path search is started after subtracting the performed route set from the set representing the connection to the node in the next layer. This is to ensure that paths in the hierarchy that have been traversed are not repeated again.

For example, {(s, p), (w, r), (f, g), (h, k)}-{(c, p), (w, r), (f, v), (h, r)} = {(s, p), (h, k)} This means that the hierarchical layer does not go through the hierarchical path, and the w and f hierarchies have already gone through, so it does not go through again. (T26).

For reference, the algorithm is as follows.

for (each i ∈ (nextset [s] route.set))

send (i, route);

FIG. 9 is a flowchart illustrating a process of Shortest Path Search Algorithm (QRHDGSPA) using a limited QoS value in a two-level network according to a fourth embodiment of the present invention, which is almost similar to the QRGSPA described above. If you do this, you have to initialize both levels.

Compared to the QRDGSPA algorithm implemented in FIG. 5, the QRHDGSPA algorithm arrives at the same destination from all nodes including the layer. The QRHDGSPA algorithm selects all nodes satisfying the reference QoS as the optimal path.

The path search process is almost similar to that shown in FIG. 7, and in the other part, one call factor is added at the part of invoking the path search algorithm and receiving the result, which is the reference QoS value described above.

That is, it is changed from receive (s, route) to receive (s, route, req) (P15), and from QoSpath (s, route) to QoSpath (s, route, req) (P2).

Other algorithms are the same as in Fig. 7, so description thereof is omitted.

FIG. 10 is a flowchart illustrating a path search algorithm called by QRHDGSPA, which is also almost similar to the path search algorithm QRDGSPA of FIG. 6, and the other part performs hierarchical search during path search. When performing a recursive search for the next route search, the area that has once passed through is not passed through again.

The searching process is almost similar to that shown in FIG. 8, and the other part is added with the following process after calculating the total QoS value in process 'P21'.

That is, a process of checking whether the accumulated total QoS value from the source node to the node in the current layer satisfies the QoS value set as the reference value is added. If satisfied in this process, the next path searching algorithm is executed, and if not satisfied, the process ends (S (tqos, req) == FALSE) (P27).

When the route search algorithm is called to repeat the route search algorithm at the last time, a route search message (send (i, route, req)) is transmitted as in FIG. 8 (P28).

Other algorithms are the same as in Fig. 8, so description thereof is omitted.

In addition, when the comparison target becomes a delay value that receives a reception value for message transmission, and the number of intermediate nodes existing between the destination node and the destination node, the occurrence of the current path occurs. It is good if the value is smaller than the value generated in the existing path, and when comparing the bandwidth value, the value generated in the current path should be larger than the value generated in the existing path.

These conditions can be selectively used according to the users who use the respective path searching methods. Also, the HDGSPA and QRHDGSPA algorithms in the second level layer can be used for the sake of explanation. For example, the level of the network can be configured as many levels as possible, and accordingly, the present invention can also be applied to multiple levels because the set is increased according to the level.

As described in detail above, the present invention is an algorithm for providing a shortest path search applied to a single layer to provide QoS-based path searching required for transmitting multimedia information on various information communication networks. Among the paths that can occur, the method of searching for the path with the lowest QoS among all paths (GSPA), and the method of distributing the paths by searching the paths as described above (DGSPA), and If the QoS value generated in all possible paths to the destination satisfies the standard QoS value, all the paths are set to the shortest path, so that only one path is set and there is a way to prevent the error from occurring (QRDGSPA). Algorithm that provides the shortest path search that is applied to the multilevel layer, and performs the DGSPA and QRDGSPA algorithms. By providing each of the algorithms (HDGSPA, QRHDGSPA) the application to work with the level, has the advantage that in each of the path search algorithm so that the user can optionally use the algorithm to know for their system environment.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications and modifications belong to the following claims You will have to look.

Claims (20)

In the path search method on an information communication network, In order to search the shortest path among a plurality of paths that can occur from a single source node to a single destination node, an initializing set and quality of service (QoS) value indicating connection information of nodes in all paths existing in the network are initialized. 1 course; And a second process of performing a real path search by designating a starting point to search for a path when the initialization is completed. The first step includes: initializing total QoS values accumulated in any node along the shortest route from the source from node 0 to node N; A second step of initializing a set of nodes which have been passed from a source to an arbitrary node along an arbitrary shortest path; A third step of initializing a set providing connection information of a current node and a node to be connected next; A fourth step of initializing a QoS value of a link connected between any node and any node next to it; A fifth step of constructing a set representing information of a node to be connected next to its own node using the QoS value initialized in the fourth step; A sixth process of initializing a route search to start a route search by initializing a route set to the starting point and performing a route search starting from a value 0 of a route QoS; Path searching method supporting quality of service (QoS), characterized in that for repeating each process from node 0 to node N. The method of claim 2, In the fifth process, when a set representing information about a node to be connected next to the node is constructed, the next node is connected if the node to be connected next to the current node is not a node of its own. Path searching method supporting quality of service (QoS), characterized in that the registration in addition to. The method of claim 1, The second process includes: a first process of calculating a total QoS value up to a node of which a path has been searched so far; When the total QoS value is calculated, if the calculated value is smaller than the total QoS value previously reached and reached to the current node through a path different from the total QoS value at this time, the search for the current path is stopped and the other path is stopped. A second process of waiting for a search call; A third step of determining whether or not the last node of the route arriving at the current route is the same as its own node in order to modify the route search information if the total QoS value of the currently arrived route is smaller as a result of the comparison; A fourth step of additionally registering the node in the connection information if the node is not its own node and omitting the additional registration if the node is its own node; A fifth step of substituting the total QoS value calculated in the first step into the total route QoS value for the path up to now and registering the route path in a set representing the node up to now; After completion of each process, in order to search for a path to a next node of the called node, a sixth process may be repeated after subtracting the performed route set from a set representing a connection to the next node. Path search method for supporting a quality of service (QoS) characterized in that it comprises. In the path search method on an information communication network, In order to search the shortest path among a plurality of paths that can occur from a single source node to a single destination node, an initializing set and quality of service (QoS) value indicating connection information of nodes in all paths existing in the network are initialized. 1 course; A second process of calling a route search means by designating a starting point for the route search and receiving a result message from the route search means to distribute the route search when the initialization is completed; And performing a path search according to the call, and then transmitting a result message to the call target, thereby shortening the path search time. The method of claim 5, The first step of initializing total QoS values accumulated in any node along the shortest route from the source from node 0 to node N; A second step of initializing a value having information about the arbitrary node and a value indicating a next node to be connected with the node; A third step of initializing a QoS value of a link connected between the any node and any node next to it; A fourth step of constructing a set representing information of a node to be connected next to the own node by using the QoS value initialized in the third step; A fifth process of determining whether a current node corresponds to a source node when the initialization is completed; A sixth step of initializing a set representing a path to a current node if the source node is the source node, initializing a QoS value of the set to '0', and then calling a path searching unit; And a seventh process of calling the route search means by using a set and a value representing a value corresponding to this node and a route corresponding to the node if the source node is not a source node. Navigation method. The method of claim 6, In the fourth step, when a set representing information about a node to be connected next to the node is constructed, the next node is connected if the node to be connected next to the current node is not a node of its own. Path searching method supporting quality of service (QoS), characterized in that the registration in addition to. The method of claim 5, The second step includes a first step of calculating a total QoS value up to a node of the path searched to date; When the total QoS value is calculated, if the calculated value is smaller than the total QoS value previously reached and reached to the current node through a path different from the total QoS value at this time, the search for the current path is stopped and the other path is stopped. A second process of waiting for a search call; A third step of determining whether or not the last node of the route arriving at the current route is the same as its own node in order to modify the route search information if the total QoS value of the currently arrived route is smaller as a result of the comparison; A fourth step of additionally registering the node in the connection information if the node is not its own node and omitting the additional registration if the node is its own node; A fifth step of substituting the total QoS value calculated in the first step into the total route QoS value for the path up to now and registering the route path in a set representing the node up to now; After each process is completed, the route set is subtracted from the set representing the connection to the next node for the route search to the next node of the called node. And a sixth process of transmitting to a place, wherein the route search method supports quality of service. In the path search method on an information communication network, Aggregation and Quality of Service (QoS) indicating the connection information of nodes in all paths existing in the network to search all paths satisfying the baseline QoS value among the multiple paths that can occur from a single source node to a single destination node. A first step of initializing a value; A second step of calling the route search means by specifying a starting point to search for the route and a reference QoS value to distribute the route search when the initialization is completed, and receiving a result message from the route search means; And performing a route search according to the call, and then transmitting a result message to the call target. The method of claim 9, The first step of initializing total QoS values accumulated in any node along the shortest route from the source from node 0 to node N; A second step of initializing a value having information about the arbitrary node and a value indicating a next node to be connected with the node; A third step of initializing a QoS value of a link connected between the any node and any node next to it; A fourth step of constructing a set representing information of a node to be connected next to the own node by using the QoS value initialized in the third step; A fifth process of determining whether a current node corresponds to a source node when the initialization is completed; A sixth step of initializing a set representing a path to a current node if the source node is the source node, initializing a QoS value of the set to '0', and then calling a path searching unit; And a seventh process of calling a route search means using a value corresponding to this node, a reference QoS value, and a set and a value representing a route at this time, if it is not the source node. ) Is a path navigation method. The method of claim 10, In the fourth step, when a set representing information about a node to be connected next to the node is constructed, the next node is connected if the node to be connected next to the current node is not a node of its own. Path searching method supporting quality of service (QoS), characterized in that the registration in addition to. The method of claim 9, The second step includes a first step of calculating a total QoS value up to a node of the path searched to date; Determining whether the accumulated total QoS value from the source node to the current node satisfies the reference QoS value, and if not satisfied, terminates the path search; If the reference QoS value is satisfied, if the previously calculated value is smaller than the total QoS value that has been reached and reached to the current node through a path different from the total QoS value, the path search that is currently being searched is stopped and another path search call is made. A third process of waiting for it to be present; A fourth step of determining whether or not the last node of the route arriving at the current route is the same as its own node in order to modify the route search information if the total QoS value of the currently arrived route is smaller as a result of the comparison; A fifth step of additionally registering the node in the connection information if the node is not its own node and omitting the additional registration if the node is its own node; A sixth step of substituting the total QoS value calculated in the first step into the total route QoS value for the path up to now and registering the route path in a set representing the node up to now; After each process is completed, in order to search for a path to the next node of the called node, after subtracting the performed route set from the set representing the connection to the next node, this value and the reference QoS value are used as the result message. And a seventh process of transmitting the route search means to the place where the route search means is called. In the path search method on an information communication network, Connection information of nodes in layers in all paths existing on the multilevel network to search the shortest path among a plurality of paths that can occur from a single source node to a single destination node on a network where the network layer is multilevel. A first step of initializing a set and a quality of service (QoS) value indicating a value; A second process of calling a route search means by designating a starting point for the route search and receiving a result message from the route search means to distribute the route search when the initialization is completed; When the route search is performed according to the call, the layer of the layer that has once passed through is not rerouted, and when the route search is performed, a third process of transmitting a result message to the call target is provided. Supported route navigation methods. The method of claim 13, The first step of initializing total QoS values accumulated in nodes in an arbitrary layer along the shortest route from the source from node 0 to node N; A second step of initializing a value having information about a node in the arbitrary hierarchy and a value indicating a next node to be connected with the node in the hierarchy; A third step of initializing a QoS value of a link connected between the node in any layer and any node next to it; A fourth step of constructing a set representing information of a node to be connected next to the own node by using the QoS value initialized in the third step; A fifth step of determining whether a node in the current layer corresponds to a source node when the initialization is completed; A sixth step of initializing a set representing a path to a node in a current layer if the source node is a source node, initializing a QoS value of the set to '0', and then calling a path searching unit; And a seventh process of calling a route search means using a value corresponding to a node in this hierarchy, a set and a value representing a route at this time, if it is not a source node. How to navigate the route. The method of claim 13, In the fourth step, when a set representing information about a node to be connected after the node is constructed, if the node in the layer to be connected next is a node in which the path is connected without being a node of the node in the current layer, the next connection node. Path searching method supporting quality of service (QoS), characterized in that the additional registration to the set indicating. The method of claim 13, The second step includes a first step of calculating a total QoS value up to any node in the layer that has been traversed so far; When the total QoS value is calculated, if the calculated value is smaller than the total QoS value previously reached and reached to the current node through a path different from the total QoS value at this time, the search for the current path is stopped and the other path is stopped. A second process of waiting for a search call; A third step of determining whether or not the last node of the route arriving at the current route is the same as its own node in order to modify the route search information if the total QoS value of the currently arrived route is smaller as a result of the comparison; A fourth step of additionally registering a node in the hierarchy to the connection information if the node is not its own node and omitting the additional registration if the node is its own node; A fifth step of substituting the total QoS value calculated in the first step into the total route QoS value for the path up to now and registering the route path in a set representing nodes in the hierarchy up to now; ; After each process is completed, the route set means is subtracted from the set representing the connection to the next node for the route search for the next node of the node in the called hierarchy. And a sixth process of transmitting to the place where the call is made. In the path search method on an information communication network, Layers on all paths existing on the multilevel network to search for all paths satisfying the reference QoS value among a plurality of paths that may occur from a single source node to a single destination node on a network where the network layer is multilevel. A first step of initializing a set representing a connection information of the nodes and a quality of service (QoS) value; A second step of calling the route search means by specifying a starting point to search for the route and a reference QoS value to distribute the route search when the initialization is completed, and receiving a result message from the route search means; And performing a route search according to the call, and then transmitting a result message to the call target. The method of claim 17, The first step of initializing total QoS values accumulated in nodes in an arbitrary layer along the shortest route from the source from node 0 to node N; A second step of initializing a value having information about a node in the arbitrary hierarchy and a value indicating a next node to be connected with the node in the hierarchy; A third step of initializing a QoS value of a link connected between the node in any layer and any node next to it; A fourth step of constructing a set representing information of a node to be connected next to the own node by using the QoS value initialized in the third step; A fifth step of determining whether a node in the current layer corresponds to a source node when the initialization is completed; A sixth step of initializing a set representing a path to a node in a current layer if the source node is a source node, initializing a QoS value of the set to '0', and then calling a path searching unit; And a seventh process of invoking a route searching means using a value corresponding to a node in this layer, a reference QoS value, and a set and a value representing a route at this time, if the determination result is not a source node. Path discovery method with support for QoS. The method of claim 17, In the fourth step, when a set representing information about a node to be connected after the node is constructed, if the node in the layer to be connected next is a node in which the path is connected without being a node of the node in the current layer, the next connection node. Path searching method supporting quality of service (QoS), characterized in that the additional registration to the set indicating. The method of claim 17, The second process includes a first process of calculating a total QoS value to nodes in the hierarchy of paths searched to date; A second step of determining whether the accumulated total QoS value from the source node to the node in the current layer satisfies the reference QoS value, and terminates path searching if not satisfied; When the reference QoS value is satisfied, if the previously calculated value is smaller than the total QoS value previously reached by reaching the node of the current layer through a path different from the total QoS value, the search for the current path is stopped and the other path is stopped. A third process of waiting for a search call; A fourth step of determining whether or not the last node of the route arriving at the current route is the same as its own node in order to modify the route search information if the total QoS value of the currently arrived route is smaller as a result of the comparison; A fifth step of additionally registering a node in the hierarchy to the connection information if the node is not its own node and omitting the additional registration if the node is its own node; A sixth step of substituting the total QoS value calculated in the first step into the total route QoS value for the path up to now and registering the route path in a set representing nodes in the hierarchy up to now; ; After each process is completed, this value and the reference QoS value are subtracted from the set representing the connection to the next node for the path search for the next node of the node in the called layer. And a seventh process of transmitting the route search means to the place where the route search means is called.