JPH02206237A - Routing system and routing table revision system - Google Patents

Abstract

PURPOSE:To attain the routing not imposing unnecessary load onto links and connection device except a relevant path by storing a table recording an address of a communication terminal equipment belonging to a sub tree using its own node as a root and its accommodated link in pairs to a connection device located at each node of a tree. CONSTITUTION:All connection devices have plural links toward subsequent nodes in a tree communication network in which connection devices 9-15 are used as node and terminal accommodating equipments 101-108 and the connection devices 9-15 are interconnected by links. Then an address table is provided, in which addresses of terminal equipments belonging to a sub tree based on itself as a root and its accommodated links are stored in pairs. In the case of receiving a communication frame, the destination address is compared with the address table in its own equipment and when the relevant destination address exists in the address table, the frame is transferred to the corresponding link. When no relevant address exists and the received link is a link from a host node of a tree, the information frame is aborted or transferred to a link toward the subsequent node. ln the case of other link, the frame is transferred to a link of a host node of the tree.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a routing method and a routing table update method, and in particular to a routing method for determining a route to a destination terminal suitable for mobile communication and its routing. The present invention relates to a routing table update method for updating a routing table used in the method.

[Conventional technology]

In many conventional communication systems, the address of a terminal indicates the location of that terminal within the communication network, and therefore, by looking at the address of the destination terminal, it is possible to determine which node to connect to. .

For example, in the case of the telephone number (03) XXX-YYYY, 03 indicates Tokyo, that is, the Tokyo toll exchange, the next XXX indicates a specific subscriber exchange within Tokyo, YYYY indicates a specific link within that subscriber exchange. However, with such a location-dependent address, if the terminal moves and its connection location changes, the address must also be changed each time.

On the other hand, mobile communication is one type of communication service that can accommodate the movement of terminals. For example, in automated telephone systems and the like, identifiers that are independent of location are used as terminal addresses. The advantage of using such location-independent addresses is that there is no need to change the address even if the terminal moves, and the use of location-independent addresses will be extremely useful in systems that will enable mobile communications in the future. .

[Problem to be solved by the invention]

However, when using the above-mentioned location-independent addresses, there are actually the following problems.

In other words, when using a location-independent address, the address itself does not include any information about the accommodation location, so
In order to find the node to connect to from the address of the destination terminal, basically a conversion table (hereinafter referred to as an address table) between addresses and their accommodation locations is created for all terminals in the network.
is necessary.

Furthermore, when the terminal moves, the contents of the address table must be rewritten each time the terminal moves. The problem is where and how this address table should be maintained and updated.

One method considered as a countermeasure for this case is:
In this method, a center that maintains an address conversion table is provided in the communication system, and the sender inquires of the center about the location of the destination terminal prior to communication. However, in this case, inquiries from all terminals will be concentrated on the center for each transmission, and movement notifications will also be concentrated on each terminal movement, and in a large-scale system, the traffic load and address at the center will be concentrated. The load for table search and rewriting processing increases.

Additionally, in order to reduce the load of inquiry traffic as mentioned above, it is possible to have multiple centers, in other words, to have multiple centers that maintain the same address table, but even in that case, updating the address table will be required for all addresses. This must be done every time a terminal is moved at the center.

An object of the present invention is to solve the problem of concentration of load in the one-way center system, to use a plurality of terminal accommodating devices accommodating one or more communication terminals as end points, and to use a plurality of connecting devices as nodes, and to connect the terminal accommodating devices and the connecting devices. A routing method that does not place unnecessary loads on links and connected devices other than the route, and a routing table that can update address tables appropriately, when mobile communication is possible in a tree-like communication network in which two are connected by links. The purpose is to provide an update method.

[Means to solve the problem]

The present invention has a plurality of terminal accommodation devices accommodating one or more communication terminals as end points, and a plurality of connection devices as nodes,
A routing method in a tree-like communication network in which the terminal accommodating device and the connecting device are connected in a ring, wherein the connecting device located at each node of the tree uses the address of the communication terminal belonging to the subtree whose root is its own node. It maintains an address table in which the links it accommodates are recorded in pairs, and when a communication frame is received, its destination address is compared with the address table in its own device, and if the destination address is found in the address table. If there is no corresponding address in the address table, if the received link is from an upper node in the tree, the information frame is discarded or sent to a lower node. If the link is another link, the link is forwarded to a link to a higher node in the tree.

The present invention also provides tree-like communication in which a plurality of terminal accommodating devices accommodating one or more communication terminals are used as end points, a plurality of connecting devices are used as nodes, and the terminal accommodating devices and the connecting devices are connected by links. A routing table update method in a network, in which the connection device located at each node of the tree is
It maintains an address table in which the addresses of communication terminals belonging to the subtree with its own node as the root and the links they accommodate are recorded in pairs, and when each communication terminal moves the terminal accommodation device in which it is accommodated, it A movement notification frame containing an address is sent, and when each connected device receives the movement notification frame, it compares the terminal address in the movement notification frame with the address table in its own device, and if the corresponding address is already If it is in the address table, transfer the movement notification frame to the corresponding link and rewrite the corresponding link column with the link that newly received the movement notification frame, and if the address is not in the address table in the own device. For example, the pair of the address and the link that received the movement notification frame is added to the address table, and the movement notification frame is transferred to the link to the upper node of the tree.

[Effect]

In the present invention, each connecting device can determine a route to a destination terminal in a distributed manner using a partial address table within the device itself. When a terminal is moved, local movement can be accomplished by only making local changes.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an example of a communication system to which the method of the present invention can be applied.

As shown in FIG. 1, this communication system is composed of a plurality of terminal accommodation devices 101 to 108 and a plurality of connection devices 9 to 15, and the terminal accommodation devices 101 to 108 each have a predetermined communication terminal. is connected to. Each communication terminal is a mobile terminal, and in the illustrated state, terminals C, D
. It accommodates.

In addition, terminal accommodation devices 101 to 108, connection devices 9 to 15
are connected in a tree through links.

That is, in the communication system of FIG.
A tree-like communication network is constructed in which terminal accommodation devices 101 to 108 and connection devices 9 to 15 are connected by links, with terminals 01 to 108 as end points and connection devices 9 to 15 as nodes. ~15 has multiple links toward nodes lower than itself. In the figure, there are exactly two links, but it does not necessarily have to be two. Among the two-tree links pointing toward the lower node in the figure, the left link will be called the link, and the right link will be called the link 2. Furthermore, all the connecting devices 9 to 14 other than the connecting device 15, which is the root node of the tree, each have exactly one link pointing toward an upper node.

Furthermore, the connection devices 9 to 15 hold the following address table.

FIG. 2 is an example of an address table that can be used in the present invention, and shows the contents of the address tables 9A to 15A held by each of the connecting devices 9 to 15 in the case of the configuration shown in FIG. Each connection device 9
The address tables 9A to 15A owned by ~15 are
This is a table that pairs the addresses of terminals belonging to Saffree to be targeted and their accommodating links, for example, the connection device 13
, terminals A, B and C are on the link 1 side, i.e. the first
An address table 13A is provided in which terminals 1 and 2 belong to the link side on the left side in the figure, and terminals E and E belong to the link 2 side, that is, the link side on the right side.

Next, a routing method according to the present invention will be explained using FIG. 1 showing a communication network having the above-described configuration and FIG. 2 showing an address table, taking as an example a case where terminal A communicates to terminal E.

When terminal A communicates with terminal E, first, terminal A transmits to the terminal accommodating device 101 an information frame whose destination address is the address E1 of the destination terminal. In this case, since the destination terminal is not directly connected to itself, the terminal accommodation device 101 transfers the information frame to the higher-level connection device 9.

Here, the connecting device 9 compares the destination address E1 with its own address table 9A, but as shown in FIG. 2, since El is not in the address table 9A, it transfers it to the upper connecting device 13. Then, when such transfer is performed, the connecting device 13 also transfers the destination address E.

is compared with the address table 13A. In this case, as shown in FIG. 2, the address E is in the address table 13A, and the target address is on the link 2 side, that is, on the right link side in FIG. Since it is known that terminal E is present, the information frame is first transferred to the link 2 side, that is, to the connecting device 10.

When the above transfer is performed, the following transfers are sequentially executed according to comparison with each address table.

That is, since the connecting device 10 knows that the terminal E is further on the link 2 side, the information frame is transferred to the link 2 side.
ie, to the terminal accommodating device 104. and,
Further, the terminal accommodation device 104 transfers the information frame to the terminal E.

In this way, the information frame from terminal A reaches terminal E, but the information frame does not flow to unnecessary links and connecting devices other than the links and connecting devices on the route.

Therefore, it is possible to prevent unnecessary loads from being placed on links and connecting devices other than the route, and it is possible to eliminate the concentration of load in the case of the one-center type described above.

Further, a detailed explanation will be given with reference to FIG. 3 as well.

FIG. 3 is a flowchart showing an example of the operation of the routing process in each connecting device to implement the routing method according to the present invention.

In FIG. 3, when a connecting device receives an information frame, ie, an information frame comes from any link, it compares the address of the destination terminal with an address table within the device (step 301).

If the destination address is listed in the address table, the information frame is transferred to the corresponding link (step 302). If the destination address is not in the address table, check the link that received the information frame (step 303), and if the received link is from an upper node, discard the information frame (step 304). ), otherwise the information frame is transferred to the link of the upper node (step 305).

In this way, in the routing method of this embodiment, 1
Or a plurality of terminal accommodation devices 1 accommodating a plurality of communication terminals.
In a tree-like communication network in which terminal accommodation devices 101 to 108 and connection devices 9 to 15 are connected by links, terminal accommodation devices 101 to 108 and connection devices 9 to 15 are connected by links, with end points being 01 to 108, and nodes 9 to 15 being nodes. The connection devices 9 to 15 are
It maintains an address table in which the addresses of terminals belonging to the subtree with its own node as the root and the links they accommodate are recorded in pairs, and when a communication frame is received, the destination address is compared with the address table within the own device. If the destination address is in the address table, it is forwarded to the corresponding link, and if there is no corresponding address in the address table, the received link is a link from an upper node in the tree. If so, the information frame is discarded, and if not, it is forwarded to a link to a higher node in the tree, thereby making it possible to avoid unnecessary load as described above.

In addition, in the process of step 304, a state in which the destination address of the information frame from the upper node is not in the address table cannot occur in a normal state and is considered to be an abnormal state. Therefore, in this example, it is discarded, but it may be decided not to discard it, but to transfer it to links addressed to all lower nodes.

Next, a method of changing the address table when the terminal moves, that is, a method of updating the routing table, will be explained using FIG. 4 and subsequent figures.

The address tables 9A to 15A described above constitute a routing table, and the routing table is updated as follows.

That is, a plurality of terminal accommodating devices accommodating one or a plurality of communication terminals are taken as end points, a plurality of connection devices are taken as nodes,
In a tree-like communication network in which terminal accommodating devices and connecting devices are connected by links, the connecting device located at each node of the tree pairs the address of the terminal belonging to the subtree with its own node as the root and the link it accommodates. When each terminal moves the terminal accommodation device in which it is housed, it transmits a movement notification frame containing the address of its own terminal, and when each connected device receives the movement notification frame, Compare the terminal address in the movement notification frame with the address table in the own device, and if the corresponding address is already in the address table, transfer the movement notification frame to the corresponding link and add a new column to the corresponding link. Rewrite the movement notification frame to the link that received it, and if the address does not exist in the address table within the own device, add the pair of that address and the link that received the movement notification frame to the address table, and update the movement notification frame. Forward to a link to a higher node in the tree.

For example, to give a specific example, FIG. 4 shows the terminal E moved from the terminal accommodating device 104 to the terminal accommodating device 103 in the configuration shown in FIG. That is, in the state of FIG. 1, the terminal E is connected to the terminal accommodating device 104 as described above, but in the state of FIG. 4, the terminal E moves and the terminal accommodating device 103 connects to the terminal Terminal E is also accommodated. In this way, when the terminal E moves, the address table 1 of the connection device 10 shown in FIG.
The contents of 0A are also required to be changed along with the movement. That is, the contents of the address table 10A are as follows: Before moving, the terminal E is on the right link side in FIG.
In other words, it indicates that it is on the link 2 side, but terminal E
When it moves as shown in FIG. 4, it must be changed to the link side on the left side in FIG. 4, that is, the link 1 side.

Such an update is performed as follows.

First, when terminal E moves as shown in Figure 4, after moving,
Terminal E writes its own address E1 in a movement notification frame and transmits it to terminal accommodation device 103. In this case, the terminal accommodation device 103 records that the terminal E is directly connected to itself, and sends the movement notification frame to the connecting device 103.
Forward to 0. When such a transfer takes place, the connecting device 1
0 looks at the address table 10A and finds that the terminal E is already registered, so it transfers the movement notification frame to the corresponding link 2, and also transfers the movement notification frame to the link corresponding to the terminal in the address table 10A. Received link 1
Change to The terminal accommodation device 104 receives the terminal E movement notification frame from the connection device 10 and learns that the terminal E is no longer directly connected to itself.

With the above operations, the modification of the address table with respect to the movement of the terminal E is completed, but in this case, the modification of the address table is performed only in the connection device 10, and the change in the address table is performed only in the connection device 10, and
has no effect on the

In this way, when the terminal moves, only local changes are required for the movement of the terminal, and in this respect as well, the burden on the transmission path and processing can be reduced.

Further, referring to FIG. 5, a detailed explanation will be given.

FIG. 5 is a flowchart showing an example of the operation of the update process in each connected device to implement the address table update method described above.

In FIG. 5, when the connecting device receives a movement notification frame, that is, when a movement notification frame arrives due to movement of the terminal, it compares the terminal address with the address table in the device (step 501).

If the address is in the address list,
The information frame is transferred to the corresponding link, and the link corresponding to the address in the address table within the own device is rewritten to the link that received the movement notification frame (step 502).

That is, for example, in the case of movement of terminal E in FIG.
The process of rewriting the contents of the link column corresponding to , from link 2 to link 1 corresponds to the rewriting process in step 502 above.

On the other hand, if the address is not in the address table, the link that received the movement notification frame is checked (step 503), and if the received link is from a lower node, the address The link pair that received the movement notification frame is added to the address table, and the movement notification frame is further forwarded to a link to a higher-order node (step 504), otherwise it is discarded (step 505).

Note that if the address in the movement notification frame received from the upper node in step 505 is not in the address table, this is considered to be an abnormal state, which can occur in a normal state.

As mentioned above, when the terminal is moved, the above-mentioned updates are performed, so from now on, the same will be applied to the terminal after the movement.
According to the routing method as explained in FIG. 2, the route to the destination terminal can be determined while minimizing unnecessary loads on links and connecting devices. In other words, by having each connected device maintain a partial and distributed address table and determining routes in a distributed manner, it is possible to maintain a routing system that does not place unnecessary loads on links other than the route and connected devices. can.

〔Effect of the invention〕

As explained above, according to the present invention, each connected device can determine the route to the destination terminal in a distributed manner using a partial address table within itself, thereby eliminating unnecessary communication and processing for determining the route. It is not necessary, and even when moving the terminal, local movement requires only local changes, so
The burden on transmission paths and processing can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a system configuration for explaining an embodiment of the present invention, Fig. 2 is a diagram showing an example of an address table applicable to the present invention, and Fig. 3 is a diagram showing an example of the routing according to the present invention. FIG. 4 is an explanatory diagram illustrating changes in the address table due to terminal movement; FIG. 5 is a flowchart showing an example of the operation of the connecting device to execute the method; FIG. It is a flowchart which shows an example of operation of a connection device. 9-15...Connection devices 9A-15A...Address tables 101-108...Terminal accommodation devices A-J...
・Terminal

Claims (2)

[Claims] (1) Routing in a tree-like communication network in which a plurality of terminal accommodating devices that accommodate one or more communication terminals are used as end points, a plurality of connecting devices are used as nodes, and the terminal accommodating devices and the connecting devices are connected by a ring. In this method, the connection device located at each node of the tree maintains an address table that records pairs of addresses of communication terminals belonging to the subtree whose root is the own node and the links they accommodate, and receives communication frames. If the destination address is found in the address table in the own device, it is forwarded to the corresponding link, and if there is no corresponding address in the address table. If the received link is from a higher node in the tree, the information frame is discarded or forwarded to a link destined for a lower node, and if it is any other link, it is sent to a link to a higher node in the tree. A routing method characterized by forwarding to. (2) Routing in a tree-like communication network in which a plurality of terminal accommodating devices that accommodate one or more communication terminals are used as end points, a plurality of connecting devices are used as nodes, and the terminal accommodating devices and the connecting devices are connected by links. In the table update method, the connection device located at each node of the tree maintains an address table in which the addresses of communication terminals belonging to the subtree with its own node as the root and the links they accommodate are recorded in pairs. When a communication terminal moves the terminal accommodation device in which it is housed, it transmits a movement notification frame in which the address of its own terminal is written, and when each connected device receives the movement notification frame, it sends a movement notification frame to the terminal in the movement notification frame. The address is compared with the address table in the own device, and if the corresponding address is already in the address table, the movement notification frame is transferred to the corresponding link, and the corresponding link column is newly updated with the movement notification frame. If the address is not found in the address table in the own device, the pair of the address and the link that received the movement notification frame is added to the address table, and the movement notification frame is added to the tree. A routing table update method characterized by forwarding to links to higher-level nodes.