JPH01259652A - Route selection system - Google Patents

Abstract

PURPOSE:To optimize a packet flowing quantity in a network with a simple processing such as referring to a table by selecting a route to an incoming node based on the route of the incoming node and a route table in which the weighting of each node is registered. CONSTITUTION:A route selection means 3 refers to a route table 4 and decides the transmission route of the packet so that the ratio of the transmission frequency of the packet to each route may come nearest to the weighting by receiving from the subscriber of an own node to the subscriber of another node by a subscriber packet transmission and reception means 2. An intra- network packet transmission and reception means 1 adds route information to indicate the route decided by the route decision means 3 to the packet, transmits to another node and the reception packet is transmitted to another node in accordance with the route information added to the reception packet by receiving the packet to which the route information is added from another node. Thus, the packet flowing quantity in the network can be optimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a route selection method in a packet switching network.

[Conventional technology]

Conventionally, the route selection method in packet-switched networks is to prioritize the routes to be selected in advance, send packets to the highest priority route unless there is a failure, and then send packets to the next highest priority route in the event of a failure. A fixed method that sends packets along a route, a dynamic routing method that manages information on failures and abnormal traffic by exchanging control information between nodes, and always selects the optimal route; There is a minimum queuing method, etc., in which a low bias value is determined, a delay estimated from the queue length for each route is added to this value, and the packet is sent to the route estimated to have the smallest delay.

(Problems to be Solved by the Invention) However, among the conventional methods described above, in the fixed method, when traffic increases, the packet delivery delay increases over time, and it is difficult to optimize the packet flow rate within the network. I can't.

Furthermore, according to the dynamic routing method, it is possible to logically select the optimal route at that point in time, but in addition to packets, control information for routing is sent around the network, and the processing becomes extremely difficult. It becomes complicated. Furthermore, according to the minimum queuing method, it is possible to optimize the bucket flow rate within the network through relatively simple processing, but loops can occur even when there are no failure points or busy communication lines within the network. It becomes easier to do.

The purpose of the present invention is to optimize the bucket flow rate within the network through simple processing, and when there is no abnormality within the network.
An object of the present invention is to provide a route selection method that can prevent the occurrence of loops.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides the following: In a bucket switching network consisting of a plurality of nodes, each node transmits and receives packets to and from its own subscribers. A subscriber packet transmitting/receiving means for transmitting/receiving packets with other nodes, an intra-network packet transmitting/receiving means for transmitting/receiving packets with other nodes, and routes to the destination node are registered with weights given to each route for routes to the same destination node. the subscriber packet transmitting/receiving means receives a packet from a subscriber of its own node to a subscriber of another node; By doing so, the route selection means refers to the route table and determines a packet transmission route such that the ratio of the number of packet transmissions to each route is closest to the weighting, and the intra-network packet transmission/reception means The packet transmission route is determined by the route selection means, and a packet with route information indicating the determined route is sent to another node, and the received packet is received by receiving the packet with route information added from the other node. The received packet is sent to another node according to the route information added to the node.

[Operation] In the route selection means, when the subscriber packet transmitting/receiving means receives a packet from a subscriber of its own node to a subscriber of another node, it refers to a route table and determines the ratio of the number of times packets are transmitted to each route. The packet transmission route is determined so that the weighting is closest to the weighting. The intra-network packet transmitting/receiving means adds route information indicating the route determined by the route selection means to the packet, transmits it to another node, and receives the packet with route information added from the other node, thereby adding the route information to the received packet. The received packet is sent to another node according to the route information provided.

[Example] Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which the present invention is applied to a packet switching network consisting of a plurality of nodes (packet switches) A to F. Node B has intra-network packet transmitting/receiving means 1 and subscribers 6b-1 and 6b-1.
It includes a subscriber packet transmitting/receiving means 2 to which b-2 is connected, a route selection means 3, a route table 4, and a shortest route table 5. Other nodes A and CF have the same configuration as node B, and subscribers 6a and 6c to 6f are connected to nodes A and CF, respectively.

Next, the operation of this embodiment will be explained.

There are four types of packet transmission and reception:

■ Return communication between subscribers of own node (for example, from node B subscriber 6b-1 to node B subscriber 6b-2)
communication).

■ Communication from subscribers of own node to subscribers of other nodes (
For example, communication from subscriber 6b-1 of own node B to subscriber 6a of other node A); Communication from subscriber of another node to subscriber of own node (
For example, from subscriber 6C of another node C to subscriber 13 of own node B
0 communication to subscriber 6b-2) ■ Relay of communication between subscribers of other nodes First, subscriber 6b-1 of node B relays communication between subscribers of the own node. 6
An example in which a packet is sent to b-2 will be explained.

Node B subscriber 6b-1 is node B subscriber 6b-2
The packet transmitted to the node B is received by the subscriber packet transmitting/receiving means 2 within the node B. The subscriber packet transmitting/receiving means 2 transmits the received packet to the subscriber 6b-2 of its own node B.
Therefore, the received packet is transmitted to the destination subscriber 6b-2.

Next, the subscriber 6b-1 of the node B transmits the communication from the subscriber of the own node to the subscriber of the other node to the subscriber 6e of the node E.
An example will be explained in which a packet is sent to .

A packet transmitted by the subscriber 6b-1 of the node B to the subscriber 6e of the node E is received by the subscriber packet 7) transmitting/receiving means 2 in the node B. Subscriber packet transmission/reception means 2
Since the received packet is addressed to the subscriber 6e of another node E, it instructs the route selection means 3 to select a route to the node E. When the route selection means 3 receives the above instruction, it refers to the route table 4 and selects a route to the node E. FIG. 2 is a diagram showing an example of the configuration of a part of the route table 4, in which the destination node 41
, route number 42, originating node 43, and relay node 4
4-1 to 44-3, destination node 45, weighting 46, and fault information 47 are registered. In the example shown in FIG. 2, the route from node B to node E is node B → node C → node E, where route number seed 1 is given.
, the route of node B → node A → node C → node E, which is given the route number Nα2, and the route of node B → node D, which is given the route number 3, → node A → node C → node E There are three routes with the root number 1. NQ2. This shows that the weighting of each route in 3 is 40%, 35%, and 25%, respectively. Here, weighting is information that indicates at what rate packets are sent to each route when there are multiple routes from the same source node to the same destination node.
When selecting a route, it is determined based on the processing capacity of the relay node and the line capacity of the relay line so that the load on the network is evenly distributed. In addition, FIG. 2 shows destination node 4.
1 only shows the part for node E, but parts for other destination nodes have similar configurations. An example of the operation of the route selection means 3 when selecting a route will be explained in detail with reference to FIG. 2 as follows. When the route selection means 3 is instructed by the subscriber packet transmitting/receiving means 2 to select a route to the node E, it first searches the destination node 41 part of the route table 4 and checks if the route to the node E is registered. Next, the route selection means 3 reads the weighting of each route with route numbers N11l to Nα3 from the route table 4, and selects the corresponding route. Each time a packet is transmitted, the count value of the counter is increased by 1. Next, the route selection means 3 divides the count value of the counter corresponding to each route by the weighting corresponding to each route, and calculates the quotient. Find the smallest root of. Next, the route selection means 3 reads the nodes constituting the route with the smallest quotient from the route table 4, notifies the intra-network packet transmission/reception means 1 of the read nodes, and increments the count value of the corresponding counter by 1, e.g. , if the quotient of the route corresponding to route number 2 is the smallest, route selection means 3
reads the nodes (node B → node A → node C → node E) constituting the route with route number Nα2 from the route table 4, notifies it to the network packet transmitting/receiving means 1, and also sets the counter corresponding to the route with route number Nα2. Add 1 to the count value. By performing the processing described above,
The ratio of the count values of the counters corresponding to the routes of the route numbers Na1-Nα3 (the ratio of the number of times packets are transmitted to each route) can be made the closest to the weighting registered in the route table 4.

When the intra-network packet transmitting/receiving means 1 is notified of the route for transmitting the packet from the route selecting means 3, it adds route information indicating the route to the packet and transmits it to the next node according to the route information.

The next node that receives the packet transmits the received packet to the next node according to the route information added to the received packet. Similar processing is then performed at each node, and the packet reaches the destination node.

Now, for example, if the route selection means 3 instructs the packet transmission route to be from node B → node C → node E (route with route number 1), the intra-network packet transmission and reception means 1 of node B Route information instructing the transmission route to be from node B to node C to node E is added to the packet, and the packet with the route information added is transmitted to node C via the communication line. Node C
When receiving the packet from node B, it transmits the received packet to destination node E according to the route information added to the received packet. Since the received packet at destination node E is addressed to subscriber 6e of the own node,
The received packet is transmitted to subscriber 6e.

Next, communication from the subscriber of another node to the subscriber of the own node is transmitted from the subscriber 6C of node C to the subscriber 6b-1 of node B.
An example of sending a packet to a server will be explained below.

Node C receives Node B subscriber 6b-1 from subscriber 6c.
When receiving a packet for a node B, as in the case of the node B described above, the node B selects a transmission route for the packet by referring to its internal route table. After selecting a transmission route for a packet, node B adds route information indicating the transmission route of the packet to the packet, and transmits it to the next node according to the route information. The next node that receives the packet from node C transmits the received packet to the next node according to the route information added to the received packet. Thereafter, similar processing is performed, and the packets transmitted from node C are transferred to the intra-network packet transmitting/receiving means 1 of node B.
received at Since the received packet is addressed to the subscriber 6b-1 of its own node B, the intra-network packet transmitting/receiving means 1 transmits the received packet to the destination subscriber 6b-1.

Next, subscriber 6C of node C relays communications between subscribers of other nodes, and subscriber 6d of node D
The following describes an example of the operation when a node B relays a packet sent to a node B.

When node C receives a packet addressed to subscriber 6d of node D from subscriber 6c, node C selects a transmission route for the packet by referring to its internal route table, as in the case of node B described above. When node C selects a transmission route for a packet, it adds route information indicating the selected route to the packet, and transmits the packet with the route information added to the next node. Now, for example, if node C → node B → node D is selected as the route to node D, node C will change the packet transmission route to node C.
→Node B→Node D A packet to which route information indicating that the route is to be added is sent to Node B. When node B receives a packet with route information indicating that the transmission route is node C → node B → node D,
The received packet is transmitted to node D according to the route information.

If the selected route is normal, the packet is transmitted as described above, but if the communication line in the selected route is busy or has a failure, the following detour processing is performed.

Now, for example, as shown in FIG. 3, when there is a failure between nodes 8 to 0, subscriber 6e of node E sends a packet to subscriber 6b-1 of node B, and subscriber 6e
Suppose that node E -> node C -> node B is selected as the transmission route for the above packet in node E, which accommodates the above packet. Note that the transmission route selection process in node E is also performed using a route table provided within node E, similar to the transmission route selection process in node B described above. When node E selects the transmission route for the above packet, the transmission route is changed from node E to node C.
→ Add route information to the packet indicating that it will become node B, and send it to node C according to the route information.

When node C receives the above packet from node E, it attempts to transmit the received packet to node B according to the route information added to the received packet, but nodes 8 to 0
Since the communication line between them is out of order and packet 7) cannot be sent to node B, an alternative node is determined by referring to the shortest route table provided therein. FIG. 4 is a diagram showing an example of the shortest route table provided in node C, in which nodes that transmit packets for each destination node are registered with priority. In this example, if the destination node is Node B, Node B has the highest priority, but since the packet cannot be sent to Node B, Node C is the next highest priority node. Let A be an alternative node.

When deciding to make node A the substitute node, node C adds a failure flag to the received packet and sends it to the substitute node A.
Send to. Therefore, a packet is transmitted from node C to alternative node A, with a failure flag added in addition to route information indicating that the transmission route is node E→node C→node B.

When node A receives the packet with the failure flag added from node C, it refers to the shortest route table provided therein and determines the node to which the packet should be transmitted. FIG. 5 is a diagram showing an example of the configuration of the shortest route table provided in notebook A. In this example, when the destination node is node B, node B has the highest priority, so the node A sends the received packet to node B. The packet from the node A is received by the intra-network packet transmitting/receiving means 1 in the node B, and the intra-network packet transmitting/receiving means 1 transmits the received packet to the subscriber 6b-1 of the own node B.
Therefore, the received packet is transmitted to the destination subscriber 6b-1.

If the communication line in the selected route is busy or faulty, a detour route will be selected based on the shortest route table and the packet will be sent. However, depending on the route selection and the location of the fault, the route may loop. In such cases, the following processing is performed. Now, for example, as shown in FIG. 6, when there is a failure between nodes A and C, subscriber 6b-1 of node B
The packet is sent to the subscriber 6e, and the packet is sent to the subscriber 6b-
In the same manner as described above, the transmission route for the above packet is set from node B to node A.
→Node C→Node E is selected. When node B selects the transmission route for the packet, it adds route information indicating that the transmission route is node B→node A→node C→node E to the packet, and transmits it to node A according to the route information. When node A receives a packet from node B, it tries to send the received packet to node C according to the route information added to the received packet, but there is a failure between nodes A and C, so it sends the packet to node C. Therefore, an alternative node is determined by referring to the shortest route table having the configuration shown in FIG.

In Fig. 5, when the destination node of the packet is node E,
The priority order of nodes transmitting packets is nodes C, B,
D, but the packet cannot be sent to node C, which has the highest priority, because there is a failure between nodes A and C, and node B, which has the next highest priority, is the node that sent the packet. Since the packet cannot be sent due to
Node A sets node D, which has the third priority, as an alternative node. If we decide to make node D the alternative node,
Node A adds a failure flag to the received packet and transmits it to alternative node D.

When node D receives the packet with the failure flag added from node A, it refers to the shortest route table provided therein and determines the node to which the packet should be transmitted. FIG. 7 is a diagram showing an example of the configuration of the shortest route table provided at node D. In this example, when the destination node is node E, the priority to the node is highest; Since A is the node that has transmitted the packet and cannot transmit the packet, it transmits the packet to the descendant node B, which has the next highest priority. As a result, a loop of node B→node A→node D→node B is formed.

To prevent such loops from forming, Node B
When the intra-network packet transmitting/receiving means 1 detects that a packet sent from its own node B has returned to its own node B, that is, when it detects that a loop has been formed, it changes the fault information 47 of the route table 4. 0 For example, if the route information added to the received packet is set to failure (1'°) and the part corresponding to the route information added to the packet returned to the local node is set to failure (1'°), the received packet is discarded. In the case of node B→node A→node C→node E, the portion of the failure information 47 corresponding to the route with route number Nα2 is set to “1°”. Note that when route selection means 3 selects a route, it does not select a route for which the fault information 47 is ``1''.Furthermore, the fault display in the route table 4 is cleared by a timer, and the fault display is cleared upon timeout. Then, if a loop is detected again, the above operation is repeated.

〔Effect of the invention〕

As explained above, the present invention selects a route to a destination node based on a route table in which the route to the destination node and the weighting of each node are registered. This process has the effect of optimizing the repulsion of buckets within the network. Furthermore, the route table of the present invention registers the route from the originating node to the destination node, and packets are transmitted according to that route, so unless an abnormality occurs within the network, loops will not occur. do not have. Further, since the process of determining a route using a route table does not depend on the network structure, by applying the present invention, the network structure will not be restricted and free network expansion will not be difficult.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing an example of the configuration of the route table 4, FIG. 3 is a diagram for explaining the operation when a failure occurs, and FIG. 4 is a diagram of the node C. FIG. 5 is a diagram showing an example of the configuration of the shortest route table of node A. FIG. 6 is a diagram illustrating the operation when a loop is configured. 2 is a diagram showing an example of the configuration of the shortest route table of node D. FIG. In the figure, 1... intra-network packet transmission/reception means, 2...
- Subscriber packet transmission/reception means, 3... Route selection means, 4... Route table 4.5... Shortest route table, 6a, 6b-1, 6b-2, 6c, 6d, 6e, 6
f...Subscriber, A-F...Node. Note C/1 Scenic route Chiful's refinement flJΣ is shown in the T diagram.

Claims (1)

[Claims] In a packet switching network composed of a plurality of nodes, each node has subscriber packet transmitting/receiving means for transmitting and receiving packets with its own subscribers, and a means for transmitting and receiving packets with other nodes. an intra-network packet transmitting/receiving means for transmitting and receiving packets between the two; a route table in which routes to the destination node are registered with weights given to each route for routes to the same destination node; route selection means for selecting a packet transmission route, the subscriber packet transmission/reception means receiving a packet from a subscriber of its own node to a subscriber of another node;
The route selection means refers to the route table and determines a packet transmission route such that the ratio of the number of packet transmissions to each route is closest to the weighting, and the intra-network packet transmission/reception means is the route selection means. When the transmission route of the packet is determined, a packet with route information indicating the determined route is sent to another node, and by receiving a packet with route information added from the other node, the packet is added to the received packet. A route selection method characterized by transmitting received packets to other nodes according to route information.