JPH10164074A - Atm switch and atm network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a routing processing for guaranteeing service quality QOS and to effectively use a network resource by separately using weight information on a link used at the time of executing the routing processing for respective virtual hierarchies. SOLUTION: A-three hierarchies structure is given as the topology of an ATM network. A call is generated from the ATM switch node 101 of a first hierarchy to a node in the logic ATM switch node 304 of a third hierarchy, and the route is retrieved. At that time, the weight of links for the respective virtual hierarchies is generated based on the parameters of topology information of a valid band, average delay time and average fluctuation. The valid band, maximum delay fluctuation and average delay time are obtained in order in the first, second and third hierarchies in an important form. The weight is used and the route is searched. Thus, QOS is guaranteed in flexible accordance with the routing processing and the quality request of connection, and the number of the times of route search algorithms can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection setting method in an ATM network which recognizes a part of an ATM network as a logical ATM switch node and recognizes a network topology as a virtual hierarchically structured topology. In particular, the present invention relates to an ATM switch and an ATM network system in which a routing method executed when searching for a connection setting path in an ATM network is improved.

[0002]

2. Description of the Related Art ATM (Asynchronous Transfer Mode);
Asynchronous transfer mode) was created as a basic method for realizing a high-speed broadband communication network (B-ISDN) suitable for multimedia communication. That is, a communication speed of 64 for a network for digital communication services
kbps ISDN (Integrate Services Digital Network
ork (integrated service digital network) was realized, and it became possible to provide not only voice but also facsimile and data communication, but this was considered only as a system based on the digital telephone network. Therefore, the speed at which communication is performed is based on 64 kbps, which is adapted to voice communication.

[0003] However, moving images and the like are to be transmitted, and furthermore, multimedia communications aiming at providing advanced services such as video on demand have to be realized. The concept of B-ISDN has emerged as a highly reliable communication service, and ATM has emerged from the study of B-ISDN.

In recent years, a large number of network products compatible with the ATM communication system have appeared on the market. In particular, the network products have been decided by the ATM-Forum (ATM Forum) which is a group that creates ATM implementation standards. Many products having ATM switches and ATM interfaces conforming to the UNI 3.0 and UNI 3.1 standards have appeared on the market and are being put to practical use.

However, since the specification of the NNI, which is an interface between switch nodes, has not been determined, products such as the previously announced ATM switches such as the UNI3.0 and UNI3.1 have already been announced. UNI
(User Network Interface) Equipped with only an interface.
A method using the I interface specification has been adopted.

However, as such an interface between switch nodes, ATM-Forum uses PNNI (P
ribate Network Network In
Since the specification of the terface was determined in February 1996, the implementation of the PNNI system has now been started by many ATM switch vendors.

Incidentally, in the PNNI interface specification, a peer group (Peer Group) is used.
By recognizing a subnet composed of a plurality of ATM switch nodes called a logical node as one logical node, a network connecting a plurality of ATM switches is recognized as a network having a virtual hierarchical structure.

[0008] By recognizing the topology (network form) in such a virtual hierarchical structure, the PNNI system aims to reduce the topology information to be stored in each ATM switch node in the network.

FIG. 9 shows a method of recognizing a network topology in the PNNI system. In the example ATM network shown in FIG. 9, a plurality of ATM switch nodes 101, 102,.
5, 106, to 122, and these ATM switch nodes are connected by a link.

In the PNNI system, links between the ATM switch nodes and topology information of the logical ATM switch nodes are exchanged between these ATM switch nodes. In the example of the ATM network of FIG. 9, the above-mentioned 22 existing ATM switch nodes 101,
To 122 are divided into six ATM switch node groups (peer groups), and each peer group is assigned a logical AT.
They are recognized as M switch nodes 31 to 36.

Here, the existing ATM switch node 101,
A peer group consisting of 102, 103, 104 is a logical ATM switch node 31, a peer group consisting of existing ATM switch nodes 105, 106, 107 is a logical ATM switch node 32, and ATM switch nodes 108, 109, 110, 111. Is a logical ATM switch node 33, and a peer group consisting of existing ATM switch nodes 112, 113, 114 and 115 is a logical ATM switch node 34 and a peer group consisting of existing ATM switch nodes 116, 117 and 118. Are logical ATM switch nodes 35, existing ATM switch nodes 119, 120, 121, 12
The two peer groups are logical ATM switch nodes 36.

Therefore, in the PNNI, 22 real ATM switch nodes 10 shown in the lower part of FIG.
The network constituted by 1 to 122 is recognized as a virtual “lower-layer network”. Also, the logical network constituted by the six logical ATM switch nodes 31 to 36 shown in the upper part of FIG. 9 is recognized as a virtual “upper-layer network”.

Further, in an ATM network, several QOSs (Quos) are used to transfer a plurality of types of applications using the same data link protocol.
Arity of Service (quality of service) parameters are set, and these values can be requested to the network simultaneously with the connection setting request.

However, there are a plurality of types of QOS parameters (effective bandwidth, transfer delay time, transfer delay fluctuation, etc.), and it is very difficult to find a routing path that optimizes these parameters. is there.

The case where data is transmitted from the existing ATM switch node 101 to the existing ATM switch node 122 will be specifically described with reference to the drawings. In this case, the existing ATM switch node 101 on the network shown in FIG. 9, which is the calling node, behaves as follows. That is, P
In the case of the NNI system, the existing ATM switch node 101 recognizes the entire network as a topology as shown in FIG. 10 by using the above-described topology recognition system having a virtual hierarchical configuration.

FIG. 10 shows an example of the Q of the recognized network.
A case where “delay time” and “effective band” are given as OS parameters is shown. That is, in FIG. 10, for example, between the switch node 101 which is the calling node and the adjacent switch node 102, the “delay time” is “1 msec” and the “effective band” is “10 Mbp”.
s ”, and between the switch node 101 that is the calling node and the adjacent switch node 103, the“ delay time ”is“ 5 msec ”and the“ effective band ”is“ 30 Mbp ”.
s ”, and the“ delay time ”between the switch node 102 and the adjacent switch node 104 is“ 2 ms ”
"c", the "effective band" is "20 Mbps", and between the switch node 103 and the adjacent switch node 104, the "delay time" is "3 msec" and the "effective band"
Is “40 Mbps”, and the “delay time” is between the switch node 104 and the adjacent switch node 32.
Is “10 msec” and “effective band” is “50 Mbps”
From the switch node 32 to the adjacent switch node 33, the “delay time” is “10 msec”, the “effective band” is “20 Mbps”, and so on.

Here, when setting up an ATM connection from the ATM switch node 101, first, in the existing ATM switch node 101 which has generated the call, FIG.
ATM using the topology network shown in FIG.
The connection setting route is searched for, and the connection setting route on the topology shown in FIG. 10 is determined.

That is, the existing ATM switch node 101 that has generated the call is connected to the other existing ATM switch nodes 102, 103, and 10 in the peer group to which it belongs.
4 and the logical AT in the virtual upper-layer network
Logical ATM switch node 3 which is an M switch node
2, 33, 34, 35, to find one route that can finally reach the logical ATM switch node 36, and from the QOS (Quality of Service) parameter on the route, the search is performed. It is determined whether or not the route is appropriate.

As a result, if improper, another route is searched to determine whether or not the route is appropriate, and if appropriate, this is set as a candidate for a set route, and the next operation, connection setting The process proceeds to the determination process.

The process for determining whether a connection can be set is performed as follows. The existing ATM switch node 101 transmits a packet in which path information called a DTL stack is written on the set path, and sequentially determines whether a connection can be set on each link. At this time, the logical ATM switch node in FIG. 10 uses the topology of the ATM switch node of a virtual lower hierarchy in each logical switch node to independently set the connection setting path in each peer group. And transfers a packet in which path information called a DTL stack is written on the selected connection setting path, and sequentially judges whether a connection can be set on each link.

Therefore, in the logical ATM switch node 32 in the topology shown in FIG. 10, the existing ATM switch node 10 in the network shown in FIG. 9 which is an existing ATM switch node belonging to its own peer group.
5, 106, and 107, and similarly, the logical AT in the topology shown in FIG.
In the M switch node 36, the existing ATM switch nodes 119 and 12 in the network shown in FIG.
A connection setting route between 0, 121, and 122 will be determined.

Normally, in order to determine an optimal communication path for performing communication in a network, a weight (QOS parameter) is given to each link in the network, and a communication path that minimizes the sum of the weights is given. Is used, but when there are two types of weights such as “effective band” and “delay time” in the link as shown in FIG. 10, it is difficult to search for an optimal route. .

That is, when there are a plurality of weights, it is difficult to search for an optimal route. This will be described. Now, it is assumed that a route from the existing ATM switch node 101 to the logical ATM switch node 36 is searched using the "delay time" as a weight in the network of FIG.
The optimum route in this case is ““ existing ATM switch node 101 ”--->“ existing ATM switch node 102 ”--->
"Existing ATM switch node 104"--->"LogicalAT"
M switch node 32 "--->" logical ATM switch node 33 "--->" logical ATM switch node 35 "-
->"Logical ATM switch node 36"".

On the other hand, it is assumed that the search is performed using the "effective band" as a weight. In this case, "" Existing ATM switch node 101 "--->" Existing ATM switch node 103 "--->
"Existing ATM switch node 104"--->"LogicalAT"
M switch node 32 "--->" logical ATM switch node 34 "--->" logical ATM switch node 35 "-
The path "-> logical ATM switch node 36" is optimal.

From this, it can be seen that a different route is given depending on which weight element is used for the search. In such a case, it is known that it is very difficult to clarify which weight is more efficient to execute the routing.

In order to solve such a problem, the use order of QOS parameters used at the time of routing is determined at present, or a plurality of QOS parameters are merged into one parameter by some calculation formula to set a connection setting path. A search method has been proposed.

That is, when a plurality of weights are given to a link as shown in FIG. 10, first, a routing process is performed using one weight (for example, “delay time”). Then, it is checked whether a connection can be set to the route given as a result of the processing. If the connection can be set, the connection is set on the route. If the connection cannot be set, the routing process is performed again using another weight (for example, “effective bandwidth”). It is checked again whether or not a connection can be set for the route given as a result of the processing.

However, such a method has a problem that the route search algorithm must be executed many times for one connection setting. Also, in the above-described method, the connection request QO is not necessarily required.
Since a route suitable for the S parameter is not always selected, there is a problem that it is difficult to effectively use network resources, and it cannot be said that a sufficient effect is obtained.

In the above-mentioned PNNI interface specification, although the value of the QOS request must be satisfied at the time of setting the connection, and the value of the QOS parameter required from the connection is defined,
When actually setting up the connection, the required QOS
At present, there is no mention of an algorithm for executing the routing while guaranteeing the value of.

[0030]

As described above, A
In the conventional routing method in the TM network, it is difficult to guarantee a QOS parameter required at the time of setting a connection, set a connection, and effectively use network resources.

In particular, ATs connected by the PNNI system
In an ATM network composed of M switches, although a QOS parameter is specified, a route search algorithm that actually guarantees QOS is not shown, and the form depends on a designer who designs an ATM switch node. However, there is no way to find a reasonable and reliable method that can set up a route search and connection in a short time.

Therefore, when searching for a connection setting path in a network operated by the PNNI system, the QOS requested from the connection can be guaranteed without fail, and the time for connection setting can be shortened. There is a demand for the development of a technology that can perform routing processing that can effectively use network resources.

Therefore, the object of the present invention is that
By utilizing the fact that the NNI recognizes the network as a virtual hierarchical configuration and using the link weight information used in the routing process for each virtual hierarchy,
It is an object of the present invention to provide a routing type ATM switch and an ATM network system in which a routing process for guaranteeing QOS in a PNNI type network can be simplified and network resources can be used effectively.

[0034]

To achieve the above object, the present invention is as follows. The present invention relates to multiple ATMs.
An ATM network comprising switches and links connecting these ATM switches,
When setting up an ATM connection in the ATM network, a part of the ATM network is recognized as a logical ATM switch in a logical upper layer, so that the entire ATM network has a virtual hierarchical structure topology. It is intended for an ATM network that performs a search for a connection setting path on a network having the topology of the virtual hierarchical structure. Means for selecting a weight of a link to be used for each virtual hierarchy, and means for searching for a connection setting path on a network having a topology of the virtual hierarchical structure with reference to the weight of the link. is there.

More specifically, an ATM switch node that performs routing (the ATM switch) is a PN
Topology recognizing means for recognizing a network topology as a virtual hierarchical configuration according to the NI system, connection setting request receiving means for receiving connection setting request information requested by a call generated on the network, and a virtual recognizing means recognized by the topology recognizing means. Weight information selecting means for selecting weight information of a link corresponding to each hierarchy; topology creating means for creating a network topology to be used for routing processing based on the connection setting request information; and weight information selecting means. Weight information adding means for adding link weight information as the weight of each link of the topology created by the topology creating means; and link weight added by the weight information adding means based on the connection setting request information. The network topo Routing process executing means for searching for a connection setting route on a network, QOS request information recognizing means for recognizing QOS request information described in the connection setting request information, and performing the routing with reference to the QOS request information. Connection setting means for setting the requested connection along the connection path selected by the processing execution means.

When routing (route setting) of the destination of the generated call, the network topology of the ATM network is recognized as a virtual hierarchical structure according to the PNNI method, and the generated call is requested by the network. Connection setting request information
The link weight information corresponding to each virtual layer is selected from the topology information, and an optimum route is selected using the selected link weight information. As described above, by selecting the weight information of the link corresponding to each virtual layer from the topology information, the required QOS parameters are guaranteed on the logical topology of the network operated by the PNNI method. When executing the routing for the purpose, the number of executions of the route search algorithm can be reduced.

Second, the ATM switch sets the weight of a link used when searching for a connection setting route to the A which is recognized as the logical ATM switch.
Means are provided for selecting each part of the TM network, and means for searching for a connection setting path on the network having the topology of the virtual hierarchical structure with reference to the weight of the selected link. More specifically, the ATM switch node (the ATM switch) executing the routing includes topology recognition means for recognizing a network topology as a virtual hierarchical configuration according to the PNNI method, and connection setting request information required by a call generated on the network. Setting request receiving means for receiving the link setting request information, weight information selecting means for selecting a link weight corresponding to each part of the ATM network recognized by the topology recognizing means, and routing processing based on the connection setting request information. Topology creation means for creating a network topology used for the weight information of the link selected by the weight information selection means, weight information addition means for adding as a weight of each link of the topology created by the topology creation means,
Routing processing executing means for searching for a connection setting path on the network topology to which a link weight has been added by the weight information adding means based on the connection setting request information; and a QOS described in the connection setting request information. Q to recognize request information
OS request information recognizing means, and connection setting means for performing requested connection setting processing along the connection path selected by the routing processing executing means while referring to the QOS request information. .

In order to route the destination of the generated call, the network topology of the ATM network is recognized as a virtual hierarchical structure according to the PNNI method, and the generated call is requested by the network. Connection setting request information
The link weight information corresponding to each virtual layer is selected from the topology information by selecting the corresponding link weight for each part of the ATM network recognized by the topology recognition means. In this way, an optimal route is selected using the weight information of the selected link.

Accordingly, the number of times of executing the route search algorithm can be reduced when executing the routing for guaranteeing the required QOS parameter on the logical topology of the network operated by the PNNI system. It becomes.

Thirdly, the ATM switch has means for selecting a link weight used for executing a connection setting path search for each connection setting path search processing, and a means for selecting the weight of the selected link. Means for searching for a connection setting route on a network having the topology of the virtual hierarchical structure with reference to the network. More specifically, the ATM switch node (the ATM switch) executing the routing includes topology recognition means for recognizing a network topology as a virtual hierarchical configuration according to the PNNI method, and connection setting request information required by a call generated on the network. A connection setting request receiving means for receiving network connection information, a topology creating means for creating a network topology used for routing processing based on the connection setting request information, and a link weight used in the network topology created by the topology creating means. Weighting information selection / adding means, and connection setting processing on the network topology to which link weights have been added by the weighting information selecting / adding means based on the connection setting request information. A routing process executing unit that searches for the QOS request information described in the connection setting request information; and a QOS request information recognizing unit that recognizes the QOS request information described in the connection setting request information. Connection setting means for performing a requested connection setting process along the connection path.

When routing (routing) the destination of the generated call, the network topology of the ATM network is recognized as a virtual hierarchical structure according to the PNNI method, and the call generated on the network is requested. Connection setting request information
The link weight information corresponding to each virtual hierarchy is selected from the topology information, and based on this, the routing processing executing means searches for a connection setting route on the network topology, but the link weight is created by the topology creating means. The route search is performed using the information obtained by the weight information selecting / adding means from the obtained network topology. Then, while referring to the QOS request information described in the connection setting request information recognized by the QOS request information recognizing means, setting processing of the requested connection is performed along the connection route selected by the routing processing executing means. I did it.

Accordingly, the number of times of executing the route search algorithm can be reduced when executing the routing for guaranteeing the required QOS parameter on the logical topology of the network operated by the PNNI system.

Fourth, ATM for performing routing
The switch node includes: a topology recognizing unit that recognizes a network topology as a virtual hierarchical configuration according to the PNNI method; a connection setting request receiving unit that receives connection setting request information requested by a call generated on the network; Based on the connection setting request received in step (a), weight information selecting means for selecting a link weight corresponding to each virtual layer recognized by the topology recognizing means, and routing processing based on the connection setting request information Topology creation means for creating a network topology;
Weight information adding means for adding the weight of the selected link based on the QOS request information obtained from the connection setting request information and the topology information recognized by the topology recognition means; A routing process executing means for searching for a connection setting path on the network topology to which the weight is added, a QOS request information recognizing means for recognizing QOS request information described in the connection setting request information, A connection setting unit that performs a requested connection setting process along the connection route selected by the routing process execution unit while referring to the information.

When routing (route setting) of the destination of the generated call, the network topology of the ATM network is recognized as a virtual hierarchical structure according to the PNNI method, and the generated call is requested by the network. Connection setting request information
The weight information of the link corresponding to each virtual layer is selected from the topology information, and based on this, the routing processing executing means searches for a connection setting route on the network topology, but the link weight is determined by the connection setting request receiving means. Based on the connection setting request received in the above and the topology recognized by the topology recognition means,
The weight of the link corresponding to each virtual layer selected by the weight information selecting means is used. Then, the range of the network topology to be routed is specified from the information sent from the connection setting request reception processing means. Based on the information, the network topology creation means selects the link selected by the weight information selection means. Is added to the network topology used for the routing process to create a network topology. The network topology creating means transfers the created network topology to the routing processing executing means, and the routing processing executing means stores information of the transferred network topology. Then, the routing processing executing means determines a path for performing connection setting based on the connection setting request information sent from the connection setting request receiving processing means and the stored topology information.

Therefore, on the logical topology of the network operated by the PNNI system, the required QOS
When performing routing to guarantee parameters, a route search algorithm can be executed using topology information according to the required quality of each connection, and flexible connection setting processing must be executed according to the type of connection. Will be able to

Fifth, ATM for performing routing
The switch node includes: a topology recognizing unit that recognizes a network topology as a virtual hierarchical configuration according to the PNNI method; a connection setting request receiving unit that receives connection setting request information requested by a call generated on the network; Weight information selecting means for selecting a weight of a link corresponding to each part of the ATM network recognized by the topology recognition means based on the connection setting request received at
Topology creation means for creating a network topology used for routing processing based on the connection setting request information; weight information adding means for adding as a weight of each link of the topology created by the topology creation means; Based on the information,
Routing processing executing means for searching for a connection setting route on the network topology to which link weights have been added by the weight information adding means; and QOS request information for recognizing QOS request information described in the connection setting request information A connection setting unit configured to perform a setting process of a requested connection along a connection route selected by the routing process execution unit while referring to the QOS request information.

When routing (route setting) of the destination of the generated call, the network topology of the ATM network is recognized as a virtual hierarchical configuration according to the PNNI system, and the generated call is requested by the network. Connection setting request information
The weight information of the link corresponding to each virtual layer is selected from the topology information, and based on this, the routing processing executing means searches for a connection setting route on the network topology, but the link weight is determined by the connection setting request receiving means. Based on the connection setting request received in the above and the topology recognized by the topology recognition means,
The weight of the link corresponding to each virtual layer selected by the weight information selecting means is used. Then, the range of the network topology to be routed is specified from the information sent from the connection setting request reception processing means. Based on the information, the network topology creation means selects the link selected by the weight information selection means. Is added to the network topology used for the routing process to create a network topology. The network topology creating means transfers the created network topology to the routing processing executing means, and the routing processing executing means stores information of the transferred network topology. Then, the routing processing executing means determines a path for performing connection setting based on the connection setting request information sent from the connection setting request receiving processing means and the stored topology information. The connection setting means performs the setting processing of the requested connection along the connection route selected by the routing processing execution means while referring to the QOS request information described in the connection setting request information. As a result, when performing routing for guaranteeing a required QOS parameter on a logical topology of a network operated by the PNNI method, a route search algorithm using topology information according to a required quality of each connection. Can be executed, and flexible connection setting processing can be executed according to the type of connection.

Sixth, ATM for performing routing
The switch node includes: a topology recognizing unit that recognizes a network topology as a virtual hierarchical configuration according to the PNNI method; a connection setting request receiving unit that receives connection setting request information requested by a call generated in the network; Based on a connection setting request received by the connection setting request receiving means, selecting a link weight to be used in the network topology created by the topology generating means. Weight information selecting / adding means, and the routing processing execution means for searching for a connection setting route on the network topology to which the link weight has been added by the weight information adding means. If the QOS request information recognizer recognizes the QOS request information in the connection setting request information, with reference to the QOS request information,
Connection setting means for setting the requested connection along the connection route selected by the routing processing executing means.

When routing (route setting) of the destination of the generated call, the network topology of the ATM network is recognized as a virtual hierarchical structure according to the PNNI method, and the generated call is requested by the network. Connection setting request information
The weight information of the link corresponding to each virtual layer is selected from the topology information, and based on this, the routing processing executing means searches for a connection setting route on the network topology, but the link weight is determined by the connection setting request receiving means. Based on the connection setting request received in the above and the topology recognized by the topology recognition means,
The weight of the link corresponding to each virtual layer selected by the weight information selecting means is used. The weight information selecting / adding means assigns the link weight used in the network topology created by the topology creating means to the network topology used in the routing processing based on the information sent from the connection setting request receiving processing means. Add and create a network topology. The routing processing executing means determines a route for connection setting based on the information on the network topology created by the network topology creating means. The connection setting means performs the setting processing of the requested connection along the connection route selected by the routing processing execution means while referring to the QOS request information described in the connection setting request information. As a result, it is possible to reduce the number of executions of the route search algorithm when executing the routing for guaranteeing the required QOS parameter on the logical topology of the network operated by the PNNI method.

[0050]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, a virtual multi-layered topology of an ATM network, which is a basic concept for routing (route setting) employed in the present invention, will be described.

(Basic Concept of the Present Invention) As an example of the topology (network form) of an ATM network that executes the routing method of the present invention, FIG. 1 shows an ATM network having a virtual three-layer structure. . here,
The interface between the ATM switch nodes in the network uses the PNNI system defined by the ATM-Forum, and links between the ATM switch nodes and logical ATM between the ATM switch nodes.
It is assumed that topology information in the switch node is being exchanged.

Here, in the PNNI interface specification, as described above, the peer group (Peer Gr) is used.
By recognizing a subnet composed of a plurality of ATM switch nodes called “up” as one logical node, a network connecting a plurality of ATM switches is recognized as a network having a virtual hierarchical structure. . By recognizing the topology in such a virtual hierarchical structure, the PNNI scheme aims to reduce the topology information to be stored by each ATM switch node in the network.

In this specific example, the topology of the ATM network has a virtual three-layer structure including a first layer, a second layer, and a third layer. The first hierarchy is a hierarchy of existing ATM switch nodes, and the second hierarchy is a hierarchy of logical ATM switch nodes obtained by dividing the existing ATM switch nodes into groups and capturing the relationship between the groups. The third hierarchy is a hierarchy of logical ATM switch nodes, which is a large group in which the logical ATM switch nodes of the second hierarchy are further aggregated into some groups, and the relationship between the groups is taken.

The ATM network shown in FIG. 1 includes a plurality of existing ATM switch nodes 101, 102,.
, And these existing ATM switch nodes are connected by a link that is a transmission path.
These existing ATM switch nodes 101, 10
The hierarchy composed of 2, ~, 111, ~ is the "first hierarchy"
It is.

In the ATM network shown in FIG. 1, the existing ATM switch nodes 101 and 10 exist.
2, ~, 111, ~ are grouped into 15 ATM switch node groups (peer groups), and each of the peer groups is a logical ATM switch node 201, 20.
2, 215.

However, for the sake of simplicity, logical ATM is used in the drawing.
Existing ATM switch nodes 101 to 111, which are lower-level ATM switch nodes of the switch nodes 201, 202, 203, and 204, and an existing A, which is a lower-level ATM switch node of the logical ATM switch node 209.
Although only the TM switch nodes 131 to 134 are shown, naturally, the logical ATM switch nodes 205 to 215
For example, existing ATM switch nodes also exist in lower layers of other logical ATM switch nodes.

The above logical ATM switch node 20
The hierarchy composed of 1, 202, to 215 is the second hierarchy.

Further, in the ATM network shown in FIG.
215 is divided into four ATM switch node groups (peer groups), and each peer group is assigned a logical AT.
They are recognized as M switch nodes 301-304. The hierarchy composed of the logical ATM switch nodes 301 to 304 is the third hierarchy.

That is, in the ATM network of FIG. 1, the logical AT
There are M switch nodes 301 to 304, which are “3”.
01 "<->" 302 "<->" 304 "<->" 303 "<-
The logical ATM switch nodes 301 to 304 in the third level are connected to each other in the second level which is the middle level, and the logical ATM switch nodes 201 to 301 To 204, which are "201"<->"202"<->"204"<->"20
3 "<->" 201 "and" 20 "
"2" is "205" which is a logical ATM switch node of another peer group, and "204" is "209" which is a logical ATM switch node of another peer group.
Leads to.

The logical ATM switch node 302
For the logical ATM switch nodes 205 to 208
These are “205” <-> “206” <-> “20
8 "<->" 207 "<->" 205 "
"208" is connected to "213" which is a logical ATM switch node of another peer group.

The logical ATM switch node 303
For the logical ATM switch nodes 209 to 211
These are “209” <-> “210” <-> “21”
1 "<->" 209 "and" 21 "
“0” leads to “212” which is a logical ATM switch node of another peer group.

The logical ATM switch node 304
For the logical ATM switch nodes 212 to 215
These are “212” <-> “213” <-> “21
5 "<->" 214 "<->" 212 ".

Further, looking at the first hierarchy, which is the lowest hierarchy, the logical ATM switch nodes 201 to 201 in the second hierarchy
204 has logical ATM switch nodes 101 to 104 for “201”, which are “101” <->
“102” <-> “104” <-> “103” <-> “10
"102" is a logical ATM switch node of another peer group, and "105" is a logical ATM switch node of another peer group.
And "104" is the logical A of another peer group.
It is connected to the TM switch node “116”.

The logical ATM switch node 202
For the logical ATM switch nodes 105 to 107
These are “105” <-> “106” <-> “10
7 "<->" 106 "and" 10 "
"6" is connected to "109" which is a logical ATM switch node of another peer group.

The logical ATM switch node 203
For the logical ATM switch nodes 116-118
These are “116” <-> “118” <-> “11
7 "<->" 116 "and" 11 "
"8" is connected to "110" which is a logical ATM switch node of another peer group, and although not described later, a topology of a virtual hierarchical structure is configured in such a manner.

In the PNNI system for recognizing a network as such a virtual hierarchical configuration topology, in a virtual upper hierarchical logical ATM switch node, a virtual lower hierarchical logical ATM switch node group, The topology information of existing ATM switch nodes is aggregated, and the aggregated information is notified to logical ATM switch nodes in other peer groups and existing ATM switch nodes. Therefore, the AT existing in the network having the topology as shown in FIG.
The M switch node 101 can recognize the network shown in FIG. 1 as a topology as shown in FIG.

That is, the ATM switch node 101
For the first layer, existing ATM switch nodes 102, 1 in the peer group to which the self belongs in the first layer
03,104, and the existing ATM switch node 10
The portion linked from 2,104 to the outside is regarded as the second hierarchy, and is recognized as the logical ATM switches 202, 203, 204 in the second hierarchy to which the peer group to which the self belongs in the second hierarchy belongs. The part linked from the logical ATM switches 202 and 204 to the outside is regarded as the third layer, and
It is recognized as a logical ATM switch 302, 303, 304 in the third hierarchy to which the peer group to which the self belongs in the hierarchy belongs. L1, L2 to L12 in FIG. 2 are ATM
Link between switches.

In the PNNI system, as shown by a logical ATM switch node 202 in FIG. 2, the topology of a group of ATM switch nodes in a virtual lower hierarchy is usually changed to a star topology (in each exchange, Are connected to each other by different lines. In the PNNI system, each link of the star topology is called a spoke, and each spoke has topology information as a virtual link. Thus, in effect, the topology information of each logical ATM network is
The topology information of the entire network will be recognized as each is added to the link connecting to each logical ATM switch node.

Here, the logical ATM switch node 20
Since 2, 203 and 204 are second-level ATM switch nodes, the topology information of the first-level ATM switch node group is aggregated, and the logical ATM switch nodes 302, 303 and 304 are third-level ATM switch nodes. Since it is an ATM switch node, it has topology information that further aggregates the topology information of the second-layer ATM switch node group in which the topology information of the first-layer ATM switch nodes is aggregated.

Therefore, in the topology of FIG. 2, links L1, L2, L2 having topology information of only the links connecting the first hierarchical ATM switch nodes are provided.
3 and L4 will be referred to as a first layer link. Also,
Links L5, L6, L that also take into account the topology information aggregated in the second level logical ATM switch node
The links L7, L8 are second-layer links, and the links L9, L10, L11, L12, which also take into account the topology information aggregated in the third-layer ATM switch nodes, are called third-layer links. .

Here, considering the topology information, first, it is expected that the virtual lower layer peer group is constituted by relatively close ATM switch nodes, whereas the virtual upper layer peer group Are often configured to include ATM switch nodes that are spaced far apart. Therefore, it is expected that the topology information related to the delay time of the link of the virtual lower layer is a sufficiently small value compared to the topology information related to the delay time of the link of the virtual upper layer.

A link for a relay system such as a backbone network in a corporate network, which is considered as an example of a virtual upper layer link, is usually a virtual lower layer link containing terminals. A sufficiently large band is given as compared with the band which has. Therefore, in the virtual lower hierarchy, it is expected that the bandwidth-related topology information will be a more important parameter than the delay time-related topology information.

Further, when the topology information is aggregated into the logical ATM switch node of the virtual upper hierarchy, the bandwidth-related information is obtained even if the topology information is created by aggregating many hierarchies. Since they are not added, it is expected that the aggregated topology information rarely becomes extremely large as compared with the topology information of the virtual lower hierarchy.

On the other hand, when the information related to the delay time is created by aggregating a plurality of hierarchies to form the topology information, the topology information (delay time) at each hierarchy is added, and the aggregated topology information is virtual. It is expected that the value will be extremely larger than the topology information of a typical lower layer.

From the characteristics of such topology information, P
In the case of recognizing a network topology in a virtual hierarchical configuration as in the NNI system, a parameter to which topology information such as a “delay time” parameter is added increases as the virtual hierarchy moves upward. It is considered that the parameter becomes more important than the parameter using the maximum value in each virtual layer like the “effective band” parameter.

Therefore, when recognizing the network topology in a virtual hierarchical structure like the PNNI method,
Rather than performing the routing process using the same parameters in all virtual layers,
By adopting a proper parameter selection method for each layer that executes routing processing using parameters considered to be the most important in the layer, a connection setting path that satisfies the QOS (quality of service) required by the connection can be established. , Could be discovered sooner.

Therefore, the weight of the link used when searching for the connection setting route is selected for each virtual layer and the routing process is executed, so that the connection setting route satisfying the QOS required by the connection is selected. The details of a specific example of a system that can be found earlier will be described.

(First Specific Example) Hereinafter, in the network shown in FIG. 1, the ATM switch node 101 which recognizes the network topology as shown in FIG.
The details of a case where a call occurs to an ATM switch node in the switch node 304 will be described.

The concrete example shown here is an ATM network having a configuration in which a plurality of existing ATM switches which are actual ATM switches are connected, and the existing ATM switches are connected by links. When setting up a connection, the ATM
By recognizing a part of the network as a logical ATM switch in a logical upper layer, the entire ATM network is recognized as a virtual multilayer hierarchical structure topology, and the virtual multilayer hierarchical structure topology network is recognized. When the search for the connection setting path is performed above, an optimum one is selected for each of the virtual layers from among a plurality of types of weights of the links used for executing the search for the connection setting path. The details of the routing method will be described below.

[Route Search from Calling Source Switch Node 101 to Called Destination Switch Node] ATM Switch Node 10
It is assumed that the terminal accommodated in No. 1 makes a call and requests a communication with a terminal in the peer group of the logical ATM switch node 304. Then, the ATM switch node 101 accommodating the terminal that generated the call first performs a route search.

That is, the ATM switch node 101
Indicates that the connection destination ATM switch node of the generated call is the logical ATM switch node 304 in FIG.
, The ATM switch node 101
Determines the connection setting route from the own node to the logical ATM switch node 304 using some route search algorithm. Here, as an example of a route search algorithm that is usually used, a known Dijkstr
It is assumed that a route search is performed using the algorithm a.

Here, the existing ATM switch node 101
FIG. 3A shows an example of the topology information in the network stored by. FIG. 3A shows topology information of each link in the network of FIG. 1 and topology information sent from each logical ATM switch node.
There are three parameters of “effective band”, “average delay time”, and “average delay fluctuation” of each link, and these show that the specific values are as shown in the figure at present. However, it goes without saying that many other parameters are defined in the PNNI system.

In the example of FIG. 3A, at link L1,
“Effective bandwidth”, “Average delay time”, “Average delay fluctuation”
The three parameters are “50 Mbps” and “1
0 msec "and" 0.2 msec ", and that at link L2 is" 30 Mbp ".
s "," 10 msec ", and" 0.5 msec ", and that at link L5 is" 10 msec ".
0 Mbps "," 10 msec ", and" 1 msec ".
“250 Mbps”, “50 msec”, “5 msec
c ".

When such topology information is recognized, the ATM switch node 101 executing the routing method of the present embodiment, based on these three types of parameters in the topology information, performs a Create link weights. Here, as a method of giving different link weights for each virtual hierarchy, the following methods [1] and [2] can be considered.

[1] A first method is to select one appropriate parameter in each virtual layer for each virtual layer. FIG. 3B shows the existing ATM switch node 10.
As an example of the selection of the parameters for each virtual hierarchy in 1, from the topology information in the network stored by the ATM switch node 101, the above three types of links L 1, L 2, L 3 and L 4 of the first hierarchy The "effective band" information is selected from among them, and the links L5 and L
6, L7, and L8, "maximum delay fluctuation" is selected from the above three types, and links L9, L10, and L1 of the third hierarchy are selected.
1 and L12, “Average delay time” from the above three types
An example in the case of selecting is shown.

In the case of this example, if a call is generated from the existing ATM switch node 101 to a certain existing ATM switch node in the logical ATM switch node 304, the ATM switch node 101 of this specific example will
The Dijkstra algorithm is executed using the topology information in the network shown in FIG.
You will get a solution.

As can be seen from FIG. 3A, three types of topology information, namely, “effective bandwidth”, “average delay time”, and “average delay fluctuation” are mixed here as link weights. Therefore, when executing a route search algorithm such as Dijkstra algorithm, it is necessary to determine the correlation between the weights of these links.

[2] A second method is to use all parameters, and to use a scalar quantity obtained by weighting and adding all the parameters as a link weight. As an example, the topology information of each link in the network includes three kinds of parameters (hereinafter referred to as “effective bandwidth”, “average delay time”, and “average delay fluctuation” as shown in FIG. These are P1, P2, P3
), For example, in order to determine the weight of each link, a function of f = a × P1 + b × P2 + c × P3 (where a, b, and c are constants) is determined. The function f (P1, P2,
This is a method of using one scalar amount obtained by P3) as a link weight.

In this method, the function f
Constants (a, b, and) used in (P1, P2, P3)
By setting the value of c) independently, it becomes possible to execute a routing process using link weights having different characteristics for each virtual hierarchy.

Specifically, in the example of FIG. 3A, when the parameter “effective band information” = P1, the parameter “maximum delay fluctuation” = P2, and the parameter “average delay time” = P3, the above function As values of constants (a, b, c) in f (P1, P2, P3), links L1, L
2, L3, L4 are given a = 10, b = 1, c = 1,
For the links L5, L6, L7, L8 of the second hierarchy, a = 1,
b = 10, c = 1, and the link L
9, L10, L11 and L12 have a = 1, b = 1 and c =
Suppose you give 10.

With such setting, functions f ₁ , f ₂ , and f ₃ for determining link weights are defined for each virtual hierarchy, and the link weights obtained by these functions include:
After all three types of parameters of the topology information are reflected, the weight of the link of the second hierarchy is further changed in such a manner that the parameter “effective band” is emphasized for the weight of the link of the first hierarchy. The parameter “maximum delay fluctuation” is emphasized.
The weight of the link in the hierarchy is obtained in such a manner that the parameter “average delay time” is emphasized.

As described above, in the case of a method in which an appropriate function is used to determine the link weight, FIG.
The weight of the link of each virtual hierarchy as shown in (b)
It is possible to flexibly cope with routing processing and connection quality requirements as compared to a case where only one type of parameter is used for each layer. However, even in the method of [2], since three types of parameters in the topology information are mixed as link weights, Di
When executing a route search algorithm such as the jkstra algorithm, it is necessary to determine a correlation between the weights of these links.

As described above, according to either of the methods [1] and [2], a link having a good evaluation value is searched for using one optimum weight determined for each hierarchy. And the caller ATM switch node 10
1 can be used to determine the route used to connect to the called ATM switch node. This ends the selection of the route candidate. When the selection of the route candidate is completed, the process proceeds to a process of confirming the connection setting for the candidate route.

[Connection Setting Confirmation Process by ATM Switch Node 101] The connection setting confirmation process is performed as follows. The existing ATM switch node 101 accommodating the terminal that generated the call executed the Dijkstra algorithm for the network of FIG. 3B, so that "101"->"102""->" 202 "->
It is assumed that a route "204"->"303"->"304" is obtained, and this is selected as a route candidate.

Then, as a process of confirming the connection setting, the ATM switch node 101 first sets the path candidate as a selected path, and writes a connection setting request information storage stack (hereinafter, referred to as a connection setting request information writing stack) in which information on the path and the connection setting request information are written. Is called a DTL stack). The connection setting request information includes a connection setting request from the terminal that generated the call, QOS information, and the like.

Then, the packet carrying the DTL stack is transferred along the selected route, and it is confirmed whether or not a connection can be actually set on each link on the route. Become.

Here, when the packet carrying the DTL stack reaches the logical ATM switch node 202 in FIG. 2 which is the ATM switch node of the second hierarchy via the existing ATM switch node 102 of the first hierarchy, The behavior of the logical ATM switch node 202 will be described.

[Second packet of DTL stack]
Processing at Tier Reaching Stage] The existing ATM switch node at the entrance of the logical ATM switch node 202 of the second hierarchy is the existing ATM switch node 105 as described above. Then, the fact that the packet carrying the DTL stack arrives at the logical ATM switch node 202 means that "existing A"
After it is determined that a connection can be established between the TM switch node 101 and the existing ATM switch node 102 (link L1) and “between the existing ATM switch node 102 and existing ATM switch node 105 (link L5)”, DT on existing ATM switch node 105 "
This means that the packet carrying the L stack has arrived.

At this time, in the DTL stack, the path selected by the ATM switch node 101 accommodating the terminal that originated the call is indicated by ““ logical ATM switch node 2 ”.
02 "to" the logical ATM switch node 204 ".
Existence AT which received the packet carrying the DTL stack
The M switch node 105 is connected to a logical ATM switch node 204 from its own switch node.
The route selection to the M switch node 106 will be executed.

At this time, according to the routing method of this specific example, the existing ATM switch node 105
Since the connection setting route is searched using the link of the first hierarchy existing between the switch nodes 105, 106, and 107, the weight of the link assigned to the first hierarchy or the constant assigned to the first hierarchy ( a1, b
A scalar amount obtained by a function f ₁ (P1, P2, P3) using (1, C1) is used as a link weight.

[Third packet of DTL stack]
Processing at Hierarchy Arrival Stage] Next, the packet on which the DTL stack is placed is converted into the logical ATM switch node 30 in FIG.
Logical ATM switch node 303 when it reaches 3
The behavior of is described.

The third level logical ATM switch node 3
03 has arrived on the actual network in FIG.
After it is determined that a connection can be established between "between the existing ATM switch node 105 and the existing ATM switch node 106" and "between the existing ATM switch node 106 and the existing ATM switch node 131", the existing ATM is determined.
This means that the packet with the DTL stack arrived at the switch node 131.

Here, the existing ATM switch node 131
FIG. 4 shows the network topology stored by.

At this time, in the DTL stack, the path selected by the ATM switch node 101 that generated the call is “the path from the“ logical ATM switch node 204 ”to the“ logical ATM switch node 304 ”. Is written in the DT
The existing ATM switch node 131 that has received the packet carrying the L stack receives the logical A from its own switch node.
Logical ATM connected to TM switch node 304
The process of searching for a connection setting route to the switch node 210 is executed.

At this time, according to the routing method of this specific example, the existing ATM switch node 131 uses the links L21, L22, L23, L24 of the first hierarchy and the links L25, L26, L27 of the second hierarchy. Searching for connection setting path.

Therefore, as the weight of the link in the routing processing in the existing ATM switch node 131 at this time, the “effective band” information is used for the link of the first hierarchy, and the “maximum delay fluctuation” information is used for the link of the second hierarchy. Or the constants (a1, b
1, C1) function with f ₁ (P1, P2, scalar quantity determined by P3) and assigned constant second layer (a2, b2, function with C2) f ₂ (P1, P
2, P3) may be used as a weight of the link of each layer.

In the network topology shown in FIG. 4, as a result of the routing processing being performed by the existing ATM switch node 131, the path "131"->"132"->"210" is selected as the connection setting path. Suppose. Then, the ATM switch node 131 newly rewrites the DTL stack as in the case described above. Then, the packet carrying the rewritten DTL stack is transferred along the selected route.

When the packet carrying the DTL stack arrives at the logical ATM switch node 210, the route selection processing in the logical ATM switch node 210 is executed as in the case of the logical ATM switch node 202. Will be.

Such processing is sequentially performed, and finally, when a packet carrying the DTL stack arrives at the ATM switch node to which the connection is connected, it means that a connection can be set in the network.

<Structure of ATM Switch Node 101> Next, an example of the structure of an existing ATM switch node 101 which enables such processing will be described with reference to FIG.

As shown in FIG. 5, the ATM switch node 101 includes a data transmission / reception processing unit 701, a network topology recognition unit 702, a network topology creation unit 703, a connection setting request reception processing unit 704,
It comprises a QOS request information recognition unit 705, a routing processing execution unit 706, a connection setting processing unit 707, and a topology information creation unit 708.

Of these, the data transmission / reception processing unit 7
No. 01 performs a process of receiving a packet addressed to the own station transmitted via a line and a process of transmitting a packet to be transmitted to the line, and the data transmission / reception processing unit 701 includes: Receiving the topology information of the link of each hierarchy and the topology information sent from each logical ATM switch node that are sent periodically, and using the received topology information as a network topology recognition unit 702
It has the function of transferring to

The network topology recognition unit 702 is
It has a function of recognizing the contents of the topology information.

The network topology creation unit 70
3 selects, based on the network topology information recognized by the network topology information recognition unit 702, topology information to be used as a weight for each link of each layer, or obtains a weight of a link of each layer by an appropriate function; It has a function of creating a network topology used for routing processing. The connection setting request reception processing unit 704 is a data transmission / reception processing unit 70
1 for extracting connection setting request information from the information received by the QOS request information recognition unit 7.
Numeral 05 stores information related to QOS corresponding to the set connection.
06 receives the topology information from the network topology creation unit 703, stores the topology information, and uses the stored topology based on the connection setting request information sent from the connection setting request reception processing unit 704. A function to determine a path for performing connection setting.

When a route for setting a connection is selected by the routing process executing unit 706, the connection setting processing unit 707 determines the QOS corresponding to the selected connection stored in the QOS request information recognizing unit 705. Based on the related information, it is determined whether or not a connection that satisfies the required QOS on the selected path can be set. The topology information creation unit 708 determines the topology related to the adjacent link. It has a function of creating information and giving it to the data transmission / reception processing unit 701.

The ATM switch node 101 of this example having such a configuration recognizes the network shown in FIG. 1 as a logical topology as shown in FIG. 2 and performs the above-described routing processing. . Therefore, in the ATM switch node 101 in FIG.
First, the topology information of each hierarchical link and the topology information sent from each logical ATM switch node, which are periodically sent, are received by the data transmission / reception processing unit 701, and the received topology information is received by the ATM switch. Network topology recognition unit 70 in node 101
Transfer to 2.

Also, connection setting request information transmitted when a call is generated from a terminal accommodated in the ATM switch node 101, a packet carrying a DTL stack transmitted from an adjacent ATM switch node, and the like. The data transmission / reception processing unit 701 receives the packet and transfers the received connection setting request information and the packet with the DTL stack to the connection setting request reception processing unit 704 in the ATM switch node 101.

Then, the connection setting request reception processing unit 704 receives the received connection setting request information and DT.
The information on the connection route, such as the transmission terminal address and the reception terminal address, in the packet carrying the L stack is transferred to the routing processing execution unit 706, and the received connection setting request information and the QOS in the packet carrying the DTL stack are transferred. The related information is transferred to the QOS request information recognition unit 705.

The connection setting request processing unit 704
Notifies the network topology creation unit 703 that creates the topology used for the routing process from the information in the DTL stack, etc., about the range of the topology for which the routing process is executed.

Next, the network topology information receiving section 702, which has received the topology information from the data transmission / reception processing section 701, adds the information as topology information of the applicable link on the logical network topology shown in FIG. And update the network topology information.

This network topology recognition unit 702
As shown in FIG. 3 (a), the topology information recognized by all the types of topology information on each link of the network topology recognized by the ATM switch node 101.

Based on the network topology information recognized by the network topology information recognition unit 702, the ATM switch node of this example selects topology information to be used as a weight for each link of each layer, There is a network topology creation unit 703 that determines a link weight by an appropriate function and creates a network topology used for routing processing.

The network topology creation unit 703
Then, for example, as shown in FIG. 3B, in the links L1, L2, L3, and L4 of the first layer, the information of "effective band" is selected as the topology information used as the weight of the link, Links L5, L6, L7, L8
For example, "average delay time" is selected as topology information used as a link weight, and "maximum delay fluctuation" is selected as topology information used as a link weight for third-layer links L9, L10, L11, and L12. Or as a function for determining the weight of each link, a function of f = a * P1 + b * P2 + c * P3 +... (Where a, b, c,.
For each virtual layer, a network topology is created in which different types of topology information are used as link weights in each layer such that one scalar quantity obtained by the function f is used as the link weight.

The created network topology is transferred from the network topology creating section 703 to the routing processing executing section 706.

The routing process execution unit 706, which has received the topology information from the network topology creation unit 703 and stores the topology information, executes the processing based on the connection setting request information sent from the connection setting request reception processing unit 704. A route for performing connection setting is determined using the stored topology information.

Normally, when executing the routing process, the same parameter is used for the weight of each link of the network. However, in this specific example, as described above, since the routing process is performed using different parameters in each layer, the correlation between the weights and the function f used at the time of the first routing process at the time of call setting are determined in advance. You need to decide.

When a route for setting a connection is selected by the routing processing execution unit 706, based on the selected route and QOS-related information corresponding to the set connection stored in the QOS request information recognition unit 705. The connection setting processing unit 707 determines whether a connection that satisfies the required QOS on the selected path can be set.

At this time, it is necessary to compare and refer to all the QOS information notified by the connection setting request information with the topology information of each link. Therefore, the connection setting processing unit 707 determines whether connection setting is possible. At this time, it is necessary to refer to all network topology information stored in the network topology recognition unit 702.

If the connection setting processing unit 707 determines that a connection cannot be set, the result is notified to the network topology creation unit 703 and the routing processing execution unit 706.

The network topology creation unit 703, having received the notification that the connection cannot be set, selects a new link weight for each virtual layer, or changes a function for calculating the link weight of each virtual layer. Thus, a network topology having a new link weight is created and notified to the routing process execution unit 706.

The routing process execution unit 706 uses the notified new network topology to re-execute the routing process for the connection request for which connection setup was not possible, and as a result, the selected new route is connected. It notifies the setting processing unit 707 and checks again whether the required quality is satisfied for all the QOSs.

The ATM switch node 101 has its own ATM
Links L1 and L2 connected to switch node 101
Must be created and notified to other ATM switch nodes in the logical ATM switch node 201. Therefore, in the ATM switch node 101, there is a topology information creation unit 708 that creates topology information of the links L1 and L2 from the connection setting state in the ATM switch node, and topology information on adjacent links transmitted from the topology information creation unit 708 is The data is transmitted from the data transmission / reception processing unit 701 to an external ATM switch node.

Further, after the connection setting request or the DTL stack is processed by the connection setting processing unit 707, if it is determined that the connection can be set, the received connection setting request information or DTL
The stack is transmitted to the ATM switch node at the next stage, and if the connection cannot be set, the connection setting is notified to the terminal that generated the call that the connection could not be set. The information is transmitted from the data transmission / reception processing unit 701 to an external ATM switch node or an accommodated terminal.

By using the different topology information for each virtual hierarchy as the link weight, it is possible to accurately determine the path that guarantees the QOS required by the connection according to the current state of the network topology. A possible routing method can be provided.

As described above, this specific example is an ATM network including a plurality of ATM switches and a link connecting the ATM switches. When setting an ATM connection in the ATM network, By recognizing a part of the ATM network as a logical ATM switch in a logical upper layer, the entire ATM network is recognized as a virtual multi-layer hierarchical topology, and on the network having the virtual multi-layer hierarchical topology. When performing a search for a connection setting route, an optimum one of a plurality of types of link weights used for executing the search for a connection setting route is selected for each virtual hierarchy. The ATM switch node that executes the method is the PNNI method Therefore, topology recognition means for recognizing the network topology as a virtual hierarchical configuration, connection setting request receiving means for receiving connection setting request information requested by a call generated on the network, and for each virtual hierarchy recognized by the topology recognition means. Weight information selecting means for selecting the weight information of the link corresponding to, a topology creating means for creating a network topology to be used for routing processing based on the connection setting request information, and a link information selected by the weight information selecting means. A weight information adding unit that adds weight information as a weight of each link of the topology created by the topology creating unit; and a link weight added by the weight information adding unit based on the connection setting request information. Network topology And routing processing execution means for searching the set route of a connection in,
QOS described in the connection setting request information
QOS request information recognizing means for recognizing request information;
While referring to the OS request information, along the connection route selected by the routing process executing means,
And a connection setting means for performing a requested connection setting process.

Then, the entire ATM network is recognized as the topology of a virtual multilayered structure, and a link has a plurality of types of weights as topology information. The weight of the link to be used is set to one type according to the characteristics of the QOS information, and the path is selected by selecting the link using the weight.
As described above, the type of link weight used in each layer is set to one type according to the characteristics of the QOS information, and is used. Therefore, in the logical topology of the network operated by the PNNI method, When performing routing to guarantee the required QOS parameters,
This makes it possible to reduce the number of executions of the route search algorithm.

The connection setting confirmation is performed by transmitting a packet carrying a connection setting request and a DTL stack including the path information. On the path to the logical ATM switch node, the path information in the DTL stack and the connection setting are checked. Based on the QOS information in the request information,
Entry Existence A at the Logical ATM Switch Node
The TM switch node performs a route search by the above-described method, determines a route, and adds DTL to information of the determined route.
Since the stack contents are rewritten and transmitted, the call originating ATM switch node does not have to search and determine the route to be taken in another logical ATM switch node, and the load on the existing ATM switch node is lightened. In addition,
At the stage where the logical ATM switch node at the final stage, which is the destination of the call, is reached, it has been confirmed that the connection setting on the route that has been followed is possible. It will be possible to route by.

By the way, the AT in the first specific example described above is used.
In the M switch node, the content of the link weight information used for each virtual hierarchy is fixedly determined in the network topology creation unit 703, and there is no freedom to finely adjust the content according to the situation. However, there is a natural need to be able to fine-tune,
In addition to the method described above, it is desired that the link weight information used for each virtual layer can be finely adjusted according to the connection setting request information requested by the generated call.

For example, "high quality is required for the cell loss rate, but low quality is acceptable for delay" or conversely, "high quality is not required for the cell loss rate, but high quality is required for delay. If the required quality differs depending on the connection, such as "request", if the topology information of the link to be used can be changed for each connection, it is possible to more accurately find a path that guarantees QOS (quality of service). A possible routing method can be provided. An example for achieving this will be described as a second specific example.

(Second Specific Example) An example in which the link weight information used for each virtual layer is changed according to the connection setting request information requested by the generated call will be described. This second
In the specific example, the network topology creating unit 70 in the ATM switch node 101 of FIG.
The third function is as follows.

That is, for each connection, in addition to the function of determining the weight of the type corresponding to the QOS required by the connection for each virtual layer, a function and a constant used for the function are further provided as necessary. Provide a function to change the value. The network topology creation unit 703 acquires information on the QOS requested by the connection from the QOS request information identification unit 705.

The network topology creation unit 703 sends Q
Based on the QOS request information acquired by the OS request information identification unit 705, the weight of the type corresponding to the QOS required for the connection is determined for each layer, and a function and a constant used for the function are determined as necessary. Change the value.

Some connections require a high quality for the cell loss rate, but some connections allow a low quality for the delay, and others have a low quality for the cell loss rate, but a high quality for the delay. There are also connections that require

Therefore, for example, in the case where a connection has been made to the network having topology information as shown in FIG. In the network topology creating unit 703, “effective bandwidth” information is selected as the topology information used for the weights of the first and second hierarchical links, and “average delay time” is used as the topology information used for the weight of the third hierarchical links. Or the first level and the second level
In the functions f ₁ and f ₂ for determining the weight of the link in the hierarchy, a large value is given to a1 and a2 which are the coefficients of the parameter “effective band”, and in the function f ₃ for determining the weight of the link in the third hierarchy, A method of giving a large value to b3 which is a coefficient of the “average delay time” is conceivable.

Conversely, when a connection occurs in which “the cell loss rate is low quality and the delay is high quality”, the network topology creation unit 703 uses the topology information used for the weight of the first layer link. only select "effective bandwidth" information, or using the "average delay" as topology information used for weighting the link in the second layer and the third layer, the function f ₁ for determining the weight of a link of the first hierarchy b2 gives a large value for a1 is the coefficient parameter "effective band", second, the function f _2, f ₃ for determining the weight of the links in the third layer are the coefficients of the parameters "average delay" A method of giving a large value to b3 can be considered.

By changing the topology information of the link to be used in accordance with the required QOS of each connection for each connection, it is possible to provide a routing method that can more accurately obtain a path guaranteeing the QOS. Become.

Hereinafter, in the network shown in FIG. 1, the ATM switch node 101 which recognizes the network topology as shown in FIG.
Taking a case where a call is made to the ATM switch node 04 in the example as an example, the second details regarding the routing method will be described.

In this specific example, in an ATM network for searching for a connection setting path on a network having a virtual hierarchical structure, the weight of a link used for executing a search for a connection setting path is determined by the logical ATM switch. Is selected for each part of the ATM network recognized as: In addition, topology information used as a link weight used when searching for the connection setting path is selected based on a required quality of a call generated in the ATM network.

In the following, similar to the case of the routing method described in the first specific example, the Dijkstra algorithm is used when setting the connection from the ATM switch node 101 to the logical ATM switch node 304. Similarly, the stored topology information has three parameters of “effective band”, “average delay time”, and “average delay fluctuation” of each link.

When such topology information is recognized, the ATM switch node 101 executing the routing method in the second specific example, based on these three types of topology information, sets each logical ATM. A link weight is created for each switch node (Peer Group). As a method of assigning different link weights to each virtual layer, the following two methods can be considered as in the routing method in the first specific example.

[I] First, there is a method of selecting one piece of topology information for each logical ATM switch node. At this time, as a result of referring to the QOS information in the transmitted connection setting request information, “effective band” information is selected for the links L1, L2, L3, and L4 in the logical ATM switch node 201, and the logical "Maximum delay fluctuation" is selected for the links L5, L6, L7 and L8 in the ATM switch node 301, and the logical ATM switch node 3 is selected.
Links L9, L1 between 01, 302, 303, 304
Assuming that “average delay time” is selected for 0, L11, and L12, the weight of each link obtained as a result is as shown in FIG.
It becomes the same as (b). However, in the case of this method, the types of link weights used in the logical ATM switch nodes 202, 203, and 204 may be different. Different routes may be selected. Also,
Even in this method, the existing ATM switch node 101 is configured as shown in FIG.
Since the Dijkstra algorithm is executed on the network shown in (b), it is necessary to determine the correlation between the weights of these three types of links.

[Ii] Second, in order to determine the link weight using the parameters (P1, P2, P3) of each link, f = a × P1 + b × P2 + c × P3
(Where a, b, and c are constants)
Function f _PG (P1, P
2, P3) is used as a link weight. In this method, each logical A
For each TM switch node (each peer group), the function f _PG
Constants (a _PG , b) used in (P1, P2, P3)
_PG , c _PG ) is set independently and each time a connection setting request is received.
Routing processing using link weights having different characteristics for each TM switch node can be executed.

If such an appropriate function is used to determine the link weight, the link weight in each logical ATM switch node described above can be calculated as follows.
It is possible to flexibly cope with routing processing and connection quality requirements as compared with a case where one type of parameter different for each layer is used. However,
Even in this method, three types of topology information are mixed as link weights. Therefore, when a route search algorithm such as Dijkstra algorithm is executed, it is necessary to determine a correlation between the weights of these links.

As in the previous case, when the Dijkstra algorithm is executed on the network shown in FIG. 3B, as the connection setting path, "" existing ATM switch node 101 "->" existing ATM switch node 1 "
02 "->" Logical ATM switch node 202 "->
"Logical ATM switch node 204"->"Logical A
FIG. 2 is a diagram showing a packet on the second hierarchy in which a route “TM switch node 303 ″ —>“ logical ATM switch node 304 ”” is selected, and a DTL stack on which route information that is information of the selected route is written. The behavior of the logical ATM switch node 202 when it reaches the logical ATM switch node 202 in 2 will be described.

ATM switch node 101 that originated the call
The path selected by “logical ATM switch node 202” is changed from “logical ATM switch node 202” to “logical ATM switch node 20”.
Since the path toward 4 ”is written in the DTL stack, the ATM switch node 105 that has received the packet carrying the DTL stack is connected from its own switch node to the logical ATM switch node 204. The route selection to the ATM switch node 106 is executed.

At this time, according to the routing method of this embodiment, the existing ATM switch node 105
Since the connection setting path is searched using the link in the switch node 202, the ATM switch node 105 determines the weight of the link to be assigned to the logical ATM switch node 202 or the constant assigned to the logical ATM switch node 202. (A ₂₀₂ , b ₂₀₂ , c
₂₀₂ ) in the connection setting request information
It is determined by referring to the OS information, and as a result, the obtained link weight assigned to the logical ATM switch node 202 or a constant (a ₂₀₂ , b ₂₀₂ , c ₂₀₂ ) assigned to the logical ATM switch node Function f using
_The scalar amount obtained by ₂₀₂ (P1, P2, P3) is used as the link weight.

The behavior of the logical ATM switch node 303 when the packet carrying the DTL stack reaches the logical ATM switch node 303 in FIG. 2 will be described. The initial connection route is “101”-> “10”
2 "->" 202 "->" 204 "->" 303 "->
Since it is “304”, the final call destination written in the DTL stack is the existing ATM switch node of the logical ATM switch node 304 of the third hierarchy, and the remaining ATM switch nodes viewed from the logical ATM switch node 303 The path is a logical ATM switch node 304 including in its peer group the ATM switch node that is the final destination.
It is.

The existing ATM switch node 131
The network topology stored in the existing ATM switch node 131 is as shown in FIG.
Performs a process of searching for a connection setting path from the own switch node to the logical ATM switch node 210, which is the only node that can be linked to the logical ATM switch node 304.

At this time, according to the routing method of this specific example, the existing ATM switch node 131 connects the link L2 in the logical ATM switch 209, which is a logical ATM switch in the second hierarchy of the peer group to which it belongs.
, L22, L23, L24 and the logical A in the third hierarchy of the peer group to which the logical ATM switch 209 belongs.
The connection setting path is searched using the links L25, L26 and L27 in the logical ATM switch node 303 which is the TM switch node.

Accordingly, as a result of referring to the QOS information in the received connection setting request information in the routing processing in the existing ATM switch node 131 at this time, the weight of the link to be used is as follows.
"The weight of the link assigned to the logical ATM switch node 209 in the second hierarchy and the logical AT in the third hierarchy
Method "and using each weight of the link assigned to M switch node 303," assigned constant logical ATM switch node 209 at the second hierarchical (a _{20 9,} b
₂₀₉ , c ₂₀₉ ), and a function f ₂₀₉ (P1, P2, P
3) and the function f ₃₀₃ (P ₃₀₃ ) using the constants (a ₃₀₃ , b ₃₀₃ , c ₃₀₃ ) assigned to the logical ATM switch node 303 in the third hierarchy.
1, P2, P3) as the weight of the link of each layer.

The existing ATM switch node 131
Is the same as the case of the routing method in the first specific example,
After executing the routing process (route selection process), a DTL stack in which the route information is rewritten along the selected route obtained as a result is created, and a packet carrying the rewritten DTL stack is transferred.

When the packet carrying the DTL stack arrives at the logical ATM switch node 210, the existing AT in the logical ATM switch node 210
The M switch node similarly executes a route selection process, creates a DTL stack in which the route information is rewritten along the selected route obtained by the process, and transfers a packet on which the rewritten DTL stack is loaded.

In this way, every time a packet carrying a DTL stack passes from an existing ATM switch node which is a node of the first hierarchy to a logical ATM switch node which is a node of the second hierarchy, that packet is transferred to the logical ATM switch node which is a second layer. An existing ATM switch node belonging to the logical ATM switch node, which is a two-layer node, serving as an entry, executes a route selection process, and rewrites the DTL stack along the obtained selected route information along the selected route. When a process of creating and transferring a packet on which the rewritten DTL stack is carried out is performed, finally, the DT reaches the ATM switch node to which the connection is connected.
When the packet carrying the L stack arrives, the connection from the existing ATM switch node at the call source to the logical ATM switch node at the call destination can be set.

As described above, the second example recognizes the entire ATM network as a virtual multilayer hierarchical structure topology, and searches for a connection setting path on a network having the virtual multilayer hierarchical structure topology. In a routing method in which the weight of a link used in performing the search of the set route is selected and used for each of the virtual layers from among a plurality of types, the link weight information used for each virtual layer is The change is made in accordance with the connection setting request information required by the generated call, whereby the topology information of the link to be used is changed for each connection and the quality of service (QOS) is changed.
Is obtained, so that the route that guarantees the route can be more accurately obtained and routed. Therefore, a communication service satisfying the required quality can be promptly provided.

(Third Specific Example) Next, when searching for a connection setting path on an ATM network having a virtual hierarchical structure, the weight of a link used when searching for a connection setting path is determined by the logical value. A third specific example will be described in which a selection is made for each part of the ATM network recognized as an ATM switch and the selection is made based on the required quality of the call.

FIG. 5 shows the configuration of the internal function of the ATM switch node 101 to which the third specific example is applied. The ATM switch node 101 of this specific example also basically recognizes the network shown in FIG. 1 as a logical topology as shown in FIG. 2 and performs the above-described routing processing. 5, in the ATM switch node 101, as in the case of the routing method described in the first specific example, the data transmission / reception processing unit 7
01, network topology recognition section 702, network topology creation section, connection setting request processing section 7
04, a QOS request information recognition unit 705, a routing processing execution unit 706, a connection setting processing unit 707, and a topology information creation unit 708.

Basically, these functional elements are the same as those of the first specific example, but there is a change in the function of the network topology creating unit 703. That is, in this specific example, the processing inside the network topology creation unit 703 in each of the above processing functions executes processing different from the routing method described in the first specific example. Details are shown below.

As shown in FIG. 3A, the topology information recognized by the network topology recognition unit 702 includes all types of topology information in each link of the network topology recognized by the ATM switch node 101. Contains. The ATM switch node of this specific example has the network topology information recognizing unit 7
02, based on the network topology information recognized at step 02, topology information to be used as a link weight for each logical ATM switch node,
There is a network topology creation unit 703 that finds a link weight for each M switch node using an appropriate function and creates a network topology used for routing processing.

The network topology creation unit 703
Then, for example, as described above, the effective band information is selected for the links L1, L2, L3, and L4 in the logical ATM switch node 201, and the links L5, L6, L7, and L8 in the logical ATM switch node 301 are selected. Selects the "maximum delay fluctuation" and outputs the logical ATM switch nodes 301 and 3
Links L9, L10, L1 between 02, 303, 304
A function f = a × P1 + b × 1 for selecting “average delay time” for L1, L12 and determining link weights using topology information (P1, P2, P3) of each link.
P2 + c × P3 (where a, b, and c are constants) are determined in advance, and this function f is set for each logical ATM switch node.
By using one scalar quantity obtained by (P1, P2, P3) as a link weight, a network topology is created in which different types of topology information are used as link weights for each logical ATM switch node.

The created network topology is transferred from the network topology creating section 703 to the routing processing executing section 704.

Thus, the third specific example is a logical ATM
The link weight is determined by using different topology information for each switch node. In this way, the path for guaranteeing the QOS required by the connection can be accurately determined according to the current state of the network topology. Can be provided.

Further, as in the case of the routing method described in the second specific example, the network topology creation unit 7
It is also conceivable that the value of the topology information created in 03 is changed according to the connection setting request information requested by the generated call. By changing the topology information of the link used for each connection, Q
It is possible to provide a routing method that can more accurately obtain a path that guarantees the OS.

(Fourth Specific Example) Next, the virtual hierarchical structure A
In performing the search for the connection setting path on the TM network, the weight of the link used for executing the search for the connection setting path is selected for each of the connection setting path search processes. An example of selection based on the required quality of a call generated in the ATM network will be described as a fourth specific example.

The network shown in FIG. 1 uses a case where a call is made from the ATM switch node 101 which recognizes the topology as shown in FIG. 2 to the ATM switch node in the logical ATM switch node 304 by using the routing method. Will be described in detail.

In the routing method of this specific example,
The weight of the link of the network topology for executing the routing process for each of the first routing process in the existing ATM switch node that has accepted the call and each routing process in each logical ATM switch node during the connection setting. To determine.

The network topology information stored in the ATM switch node 101 is as shown in FIG. 2, and the topology information of each link is shown in FIG.
Suppose that it was as shown in (a).

At this time, the ATM switch node 101 of this specific example executes a process of searching for a connection setting route on the network of FIG.
Must determine the topology information to be used as the link weight.

As a method of determining the link weight in the ATM switch node 101, the following method can be considered.

[A] First, topology information corresponding to each virtual hierarchy is allocated in advance, and when the routing processing is executed, for example, when the topology information as shown in FIG. Is a method of setting the weight of a link by using topology information assigned to a link of a virtually highest hierarchy among the links included in the topology of FIG. 6A. Specifically, as in the previous case, “effective bandwidth” is allocated as topology information corresponding to the first-layer link, and an average delay time is allocated as topology information corresponding to the second-layer link. Assuming that “maximum delay fluctuation” is assigned as the topology information corresponding to the link in the third hierarchy, the ATM switch node 101 of the present specific example, when the topology information as shown in FIG. The "maximum delay fluctuation" assigned as the topology information corresponding to this link is used as the link weight. FIG. 6B shows a network topology used when executing the routing process when the maximum delay fluctuation is used as the link weight.

[B] Secondly, a function ff = a × P1 + b × P2 + c × P3 (where a, b) for determining the weight of the link using the parameters (P1, P2, P3) of each link , C are constants), and constants (a1, b1, C1), (a2, b2, C2), (a1, b1, C1) used for the functions f ₁ , f ₂ , f ₃ corresponding to each virtual hierarchy are determined.
This is a method of assigning the value of (a3, b3, C3). In this way, when performing the routing process,
For example, when the topology information as shown in FIG. 6 is recognized, the constant (a) assigned to the link of the virtually highest hierarchical layer among the links included in the topology of FIG.
3, b3, C3) function f ₃ using (P1, P2, P
The scalar amount obtained by 3) is used as the link weight.

The routing processing in the fourth specific example,
That is, as a method for determining the weight of the link to be used for each network that executes the routing process, various methods can be considered in addition to such an example. If these methods are used, it means that "the weight of the link used when executing the routing process is one type of parameter". Therefore, a route search algorithm such as Dijkstra algorithm can be executed using the weight of the link as it is.

Also in this case, as the connection setting path, “101”-> “102” —> “202” —> “2”
Assuming that the route "04"->"303"->"304" is selected, the existing ATM switch node 101
A DTL stack in which the selected path and the connection setting request information are written is created, and a packet carrying the DTL stack is transferred along the selected path, and a connection can be actually set to each link on the selected path. I will check if it is.

Here, when the packet carrying the DTL stack reaches the logical ATM switch node 202 in FIG. 2 which is the logical ATM switch node of the second hierarchy,
The routing process in the logical ATM switch node 202 will be described.

Second Level Logical ATM Switch Node 2
02, the real ATM contained therein
Since only the connection setting route between the switch nodes 105, 106, and 107 is searched, only the link of the first hierarchy exists in the network topology used for this routing process.

Therefore, the existing ATM switch node 105
As the weight of each link used in the routing processing in the above, "effective band" which is topology information corresponding to the link of the first layer and "constants (a1, b1, c1) assigned to the first layer" are used. Function f ₁ (P1,
P2, P3) will be used.

The routing processing at the logical ATM switch node 303 when the packet carrying the DTL stack reaches the logical ATM switch node 303 in FIG. 2 which is the third hierarchy will be described.

In this state, the packet arrives at the existing ATM switch node 131 which is an existing ATM switch node located at the entrance of the peer group belonging to the logical ATM switch node 303 of the third hierarchy.
FIG. 7 shows the network topology stored in the existing ATM switch node 131 at this stage.

Also in this example, the path selected by the existing ATM switch node 101 that generated the call is transferred from the second-layer logical ATM switch node 204 to the third-layer logical ATM switch node 304 in the DTL stack. It is written that it is a route to
The first that received the packet carrying the DTL stack
The existing ATM switch node 131 in the hierarchy is shifted from its own switch node to the logical ATM switch node 30 in the third hierarchy.
In other words, only the connection setting route to the logical ATM switch node 210 of the second hierarchy connected to the fourth node is searched.

At this time, the network topology used for the routing process includes first-level links L21,
L22, L23, and L24, and a link L25,
Only L26 and L27 exist.

Therefore, according to this specific example, the existing ATM switch node 131 uses the “average delay time”, which is the topology information associated with the second hierarchy, and the “constant (a2, function f using b2, C2)
_{2 The} routing process is performed using the "scalar amount given by (P1, P2, P3)" as the weight of each link in the network.

Therefore, also in this case, it is not necessary to determine the correlation between the parameters, so that the routing process can be easily executed.

Also in this specific example, the above-described processing is sequentially performed, and finally, when a packet carrying a DTL stack arrives at the ATM switch node to which the connection is to be made, the connection can be set. Will be.

Next, FIG. 8 shows an example of a configuration diagram of internal functions of the ATM switch node 101 using the routing method. The ATM switch node 101 in the fourth specific example includes a data transmission / reception processing unit 1001, a network topology recognition unit 1002, a connection setting request reception processing unit 1004, and a QOS request information recognition unit 100.
5, a routing processing execution unit 1006, a connection setting processing unit 1007, a topology information creation unit 1008, a weight information selection unit 1013, and a network topology creation unit 1014.

Among these, the data transmission / reception processing unit 1
001 is for receiving the packet sent to the own ATM switch node 101 sent via the line and for sending the packet to be transmitted to the line. The reception processing unit 1001
It has a function of receiving the topology information of the link of each layer and the topology information sent from each logical ATM switch node, and transferring the received topology information to the network topology recognition unit 1002.

Network topology recognition section 1002
Has a function of recognizing the content of the topology information.

The network topology creation unit 10
14 is a network topology information recognition unit 100
Based on the network topology information recognized in step 2,
It has a function of selecting topology information to be used as a weight for each link of each layer, obtaining a link weight of each layer by an appropriate function, and creating a network topology to be used for routing processing.

Connection setting request reception processing unit 1004
Performs a process of extracting connection setting request information from information received by the data transmission / reception processing unit 1001, and the QOS request information recognition unit 1005 stores QOS-related information corresponding to the set connection. The routing processing execution unit 1006 receives the topology information from the network topology creation unit 1014, stores the topology information, and based on the connection setting request information sent from the connection setting request reception processing unit 1004. Has a function of determining a path for performing connection setting using the stored topology.

When a route for setting a connection is selected by the routing process execution unit 1006, the connection setting processing unit 1007 checks the selected route and the QOS corresponding to the set connection stored in the QOS request information recognizing unit 1005. Based on the related information, it is determined whether or not a connection that satisfies the required QOS on the selected path can be set up.
The topology information creating unit 1008 creates topology information related to the adjacent link and sends the data to the data transmission / reception processing unit 10.
01.

The weight information selecting unit 1013 selects topology information to be assigned to each virtual layer from the topology information stored in the network topology information recognizing unit 1002, and a function f for calculating the weight of a link to be assigned to each virtual layer. It has a function of selecting values of constants (a, b, c) used in (P1, P2, P3).

The ATM switch node 101 in the fourth specific example recognizes the network topology shown in FIG. 1 as a logical topology as shown in FIG. 2 as in the previous case, but uses it at the time of routing. The topology information is selected for each network topology to be routed.

For this reason, in the existing ATM switch node 101 of the fourth specific example shown in FIG. 8, first, the topology information of the transmitted link of each hierarchy and each logical AT
The topology information sent from the M switch node is
After being received by the data transmission / reception processing unit 1001, it is transferred to the network topology recognition unit 1002,
The information is updated as applicable link information on the logical network topology shown in FIG.

Also, connection setting request information transmitted from a terminal accommodated in the ATM switch node 101 when a call is generated, and a packet carrying a DTL stack transmitted from an adjacent ATM switch node. Are received by the data transmission / reception processing unit 1001 and transferred to the connection setting request reception processing unit 1004.

Then, the connection setting request reception processing section 1004 receives the received connection setting request information and DT
In the L stack, information about the connection route, such as the transmission terminal address and the reception terminal address, is transferred to the routing processing execution unit 1006, and the QOS-related information is
The request is transferred to the S request information recognition unit 1005.

In the ATM switch node 101 of this specific example, as described above, from among the topology information stored in the network topology information recognition unit 1002,
Select topology information to be assigned to each virtual tier,
Function f for calculating link weights assigned to each virtual hierarchy
(P1, P2, P3) used constants (a,
There is a weight information selection unit 1013 that selects the value of b, c).

The connection setting request reception processing unit 1
Since the range of the network topology for performing the routing process is specified from the information sent from the 004, the weight of the link selected by the weight information selection unit 1013 is added to the network topology used for the routing process based on the information. A network topology creating unit 1014 exists.

Then, the network topology creating section 1
014 transfers the created network topology to the routing process execution unit 1006.

Upon receiving the topology information from the network topology creation unit 1014, the routing processing execution unit 1006 stores the topology information.
Then, based on the connection setting request information sent from the connection setting request reception processing unit 1004 and the stored topology information, the routing processing execution unit 1006 determines the path for performing the connection setting.

[0208] By the routing processing execution unit 1006,
When a connection setting path is selected, the connection setting processing unit 1007 uses the selected path and the QOS-related information recognized by the QOS request information recognition unit 1005 based on the selected path.
It is determined whether or not a connection can be set up on the selected path under a condition satisfying the required QOS.

However, at this time, it is necessary to refer to the topology information of each link for all the QOS information notified by the connection setting request information.

Therefore, connection setting processing section 1007
In order to determine whether connection setting is possible or not, the network topology information stored in the network topology recognition unit 1002 must be referred to. Also, the existing ATM switch node 101 has a topology information creation unit 1008 that creates topology information of the links L1 and L2 from the connection setting state in the ATM switch node 101 as in the above specific example, and sends out the topology information creation unit 1008 therefrom. Topology information about the neighboring link
The data is transmitted from the data transmission / reception processing unit 1001 to an external ATM switch node. Further, the above-mentioned connection setting availability information is transmitted from the data transmission / reception processing unit 1001 to an external ATM switch node or a terminal accommodated therein.

The above existing ATM switch node 1
01 shows a case where the weight information selection unit 1013 fixedly determines the weight information of the link selected for each virtual hierarchy. However, the routing method according to the present invention is not limited to such a method, and may also change the type of topology information selected for each virtual layer according to the connection setting request information requested by the generated call.

For example, for a network having topology information as shown in FIG. 6, “high quality is required for the cell loss rate, but low quality is acceptable for delay”.
When such a connection occurs, the weight information selection unit 1013 selects effective bandwidth information as topology information used for the weights of the first and second hierarchical links, and the topology information used for the weight of the third hierarchical links. In the functions f ₁ and f ₂ for determining the weights of the links of the first and second layers, a large value is given to the coefficients a1 and a2 of the effective band, and can be considered methods such as giving a large value to b3 are coefficients of the average delay time in the function f ₃ for determining the weight.

On the other hand, when a connection such as “the cell loss rate does not require high quality but delay requires high quality” occurs, the weight information selection unit 1
In 013, “effective bandwidth” information is selected only for the topology information used for the weight of the link of the first layer, and “average delay time” is used as the topology information used for the weight of the link of the second and third layers. 1 in the function f ₁ determines the weight of the hierarchy of links have a significant value in a1 is the coefficient of "effective band", second, the function f _2, f ₃ for determining the weight of the links in the third layer A method of giving a large value to b2 and b3, which are coefficients of the "average delay time", can be considered.

By changing the topology information of the link used for each connection, it can be expected that a routing method capable of more accurately obtaining a path for guaranteeing QOS can be provided.

The present invention is not limited to the specific examples described above, but can be implemented with various modifications.

[0216]

As described above, when the routing method according to the present invention is used, when searching for a connection setting route in a network operated by the PNNI method, the QOS requested from the connection is reliably guaranteed. At the same time, it is possible to shorten the time for setting up a connection, and to execute a routing process that can effectively use network resources.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the present invention, showing an example of a network topology that executes the routing method of the present invention.

FIG. 2 is a diagram showing an example of topology information used by a PNNI routing method.

FIG. 3 is a diagram for explaining the present invention, showing an example of a method for creating topology information in the routing method of the present invention.

FIG. 4 is a diagram for explaining the present invention, and is a diagram showing another example of a topology recognition system in the routing system of the present invention.

FIG. 5 is a diagram for explaining the present invention, and is a block diagram showing an example of an internal configuration of an ATM switch node that executes the routing method of the present invention.

FIG. 6 is a diagram for explaining the present invention, showing another example of a method for creating topology information in the routing method of the present invention.

FIG. 7 is a diagram for explaining the present invention, and is a diagram showing another example of a topology recognition method in the routing method of the present invention.

FIG. 8 is a diagram for explaining the present invention, and is a block diagram showing another example of the internal configuration of the ATM switch node that executes the routing method of the present invention.

FIG. 9 is a diagram showing the concept of a network topology recognition method in PNNI.

FIG. 10 is a diagram showing an example of topology information used in a conventional routing method.

[Explanation of symbols]

 101 ATM switch node 701, 1001 Data transmission / reception processing unit 702, 1002 Network topology recognition unit 703, 1014 Network topology creation unit 704, 1004 Connection setting request reception processing unit 705, 1005 QOS request information recognition unit 706, 1006 ... Routing processing execution unit 707, 1007 ... Connection setting processing unit 708, 1008 ... Topology information creation unit 1013 ... Weight information selection unit.

Claims (13)

[Claims] An ATM switch comprising a plurality of ATM switches.
An ATM network for connecting between TM switches by a link, wherein when setting up an ATM connection in the ATM network, a part of the ATM network is recognized as a logical ATM switch in a logical upper layer. In a switch used in an ATM network for recognizing the entire ATM network as a virtual hierarchical structure topology and searching for a connection setting path on the network having the virtual hierarchical structure topology, a search for a connection setting path is performed. An ATM switch comprising means for selecting a link weight to be used for execution for each virtual hierarchy. 2. An ATM switch comprising a plurality of ATM switches.
An ATM network for connecting between TM switches by a link, wherein when setting up an ATM connection in the ATM network, a part of the ATM network is recognized as a logical ATM switch in a logical upper layer. In a switch used in an ATM network for recognizing the entire ATM network as a virtual hierarchical structure topology and searching for a connection setting path on the network having the virtual hierarchical structure topology, a search for a connection setting path is performed. Means for selecting a link weight used for execution for each virtual hierarchy, means for searching for a connection setting route on the network of the virtual hierarchical structure with reference to the weight of the selected link, An ATM switch comprising: 3. An ATM switch comprising a plurality of ATM switches.
An ATM network for connecting between TM switches by a link, wherein when setting up an ATM connection in the ATM network, a part of the ATM network is recognized as a logical ATM switch in a logical upper layer. In a switch used in an ATM network for recognizing the entire ATM network as a virtual hierarchical structure topology and searching for a connection setting path on the network having the virtual hierarchical structure topology, a search for a connection setting path is performed. Means for selecting a link weight to be used for execution for each part of the ATM network recognized as the logical ATM switch; and referring to the selected link weight, the topology network of the virtual hierarchical structure. Connection setting ATM switch, characterized in that the and means for performing a search. 4. An ATM switch comprising a plurality of ATM switches.
An ATM network for connecting between TM switches by a link, wherein when setting up an ATM connection in the ATM network, a part of the ATM network is recognized as a logical ATM switch in a logical upper layer. In a switch used in an ATM network for recognizing the entire ATM network as a virtual hierarchical structure topology and searching for a connection setting path on the network having the virtual hierarchical structure topology, a search for a connection setting path is performed. Means for selecting a link weight to be used for each execution of the connection setting path search processing; and searching for a connection setting path on the network of the virtual hierarchical structure topology with reference to the selected link weight. Means for performing ATM switch according to claim. 5. The ATM network system according to claim 1, wherein the topology information used as a link weight used when executing the search for the connection setting route is the AT.
An ATM switch for selecting based on a required quality of a call generated in an M network. 6. The ATM switch according to claim 3, wherein the topology information used as a link weight used when performing the search for the connection setting path is the AT.
An ATM switch for selecting based on a required quality of a call generated in an M network. 7. The ATM switch according to claim 4, wherein the topology information used as a link weight used when searching for the connection setting path is the AT.
An ATM switch for selecting based on a required quality of a call generated in an M network. 8. An ATM switch comprising a plurality of ATM switches.
AT constituted by links connecting M switches
An M network, wherein A in the ATM network
When setting up the TM connection, the selected ATM
Recognize a part of the network as a logical ATM switch in a logical upper layer, whereby the ATM
In an ATM network that recognizes the entire network as a virtual hierarchical structure topology and searches for a connection setting path on the network having the virtual hierarchical structure topology, the ATM switch executes a connection setting path search. Means for selecting a link weight to be used for each virtual hierarchy, and means for searching for a connection setting path on a network having a topology of the virtual hierarchical structure with reference to the link weight. An ATM network system, characterized in that: 9. An ATM switch comprising a plurality of ATM switches.
AT constituted by links connecting M switches
An M network, wherein A in the ATM network
When setting up a TM connection, a part of the ATM network is replaced with a logical AT in a logical upper layer.
An ATM switch which recognizes the entire ATM network as a topology having a virtual hierarchical structure and searches for a connection setting path on the network having the topology having the virtual hierarchical structure. Means for selecting, for each part of the ATM network that is recognized as the logical ATM switch, the weight of a link to be used in executing a search for a connection setting path, and referring to the weight of the selected link. Means for searching for a connection setting path on the network having the topology of the virtual hierarchical structure.
TM network system. 10. An ATM switch comprising a plurality of ATM switches.
A composed of links connecting the TM switches
When setting up an ATM connection in the ATM network, a part of the ATM network is connected to a logical A in a logical upper layer.
An ATM network which recognizes the ATM switch as a TM switch, thereby recognizing the entire ATM network as a topology of a virtual hierarchical structure, and searches for a connection setting path on the network of the topology of the virtual hierarchical structure. Means for selecting a link weight to be used when executing a connection setting path search for each connection setting path search process; and referring to the selected link weight to determine the topology of the virtual hierarchical structure. Means for searching for a connection setting path on a network. 11. The ATM network system according to claim 8, wherein the topology information used as a link weight used when performing the search for the connection setting path is transmitted to the ATM network system.
An ATM network system wherein selection is made based on a required quality of a call generated in an M network. 12. The ATM network system according to claim 9, wherein the topology information used as a link weight used when executing the search for the connection setting path is the AT.
An ATM network system wherein selection is made based on a required quality of a call generated in an M network. 13. The ATM network system according to claim 10, wherein the topology information used as a link weight used when searching for the connection setting route is the AT.
An ATM network system wherein selection is made based on a required quality of a call generated in an M network.