Connection switching apparatus, connection switching network control system and connection switching network control method

• US 6,366,582 B1
• Filed: 09/18/1998
• Issued: 04/02/2002
• Est. Priority Date: 09/19/1997
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Miyamoto, Takanori, Nishikado, Takashi, Kawakita, Kenji
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US09/157,152
• Time in Patent Office: 1,292 Days
• Field of Search: 370/352, 370/386, 370/389, 370/395, 370/401
• US Class Current: 370/401
• CPC Class Codes: H04L 2012/5626 Network management, e.g. Intelligent nets
• CPC Class Codes: H04L 2012/563 Signalling, e.g. protocols, reference model
• CPC Class Codes: H04L 49/309 Header conversion, routing tables or routing tags
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

In a communication network including connection switching exchanges such as an ATM, a connection management means is provided in a network management unit of the communication network. A group of logical connections with a fixed group size and consecutive identifiers assigned to the connections is treated as a unit. The number of logical connections in such a group is an integer with power of 2. Logical connections in the communication network and connection identifiers assigned to the logical connections are set up and released in connection setting units each equal to a multiple of the group size in a unitary manner across the whole communication network. A priority level is assigned to each connection setting unit. When logical connections have been set for a plurality of connection setting units sharing the same connection identifiers, logical connections with the shared connection identifiers pertaining to a connection setting unit with a smallest size is considered to be valid.

Claims

1. A connection switching network control system employed in a communication network comprising a plurality of connection switching exchanges and a plurality of terminating nodes connected to each other by a plurality of communication lines wherein:

a plurality of logical communications are implemented through each of said communication lines;

said connection switching exchanges each comprise an exchange represented by an ATM (Asynchronous Transfer Mode) and a frame relay for switching said logical connections of said communication lines through substitution of connection identifiers each identifying one of said logical connections using a switching table provided in each of said connection switching exchanges to show switching relations among said logical connections;

said connection switching exchanges each serve as a relay apparatus; and

said terminating nodes each serve as a communication terminal or a gateway apparatus connected to an external network,

said connection switching network control system comprising an operation-control network composed of lines different from said communication lines and a network management unit which is provided in said communication network, connected to said communication switching exchanges in said communication network by said operation-control network and provided with grouped-connection management means as well as connection-control information for controlling said logical connections in said entire communication network, wherein said grouped-connection management means;

uses said operation-control network as operation-control communication lines for communicating with said connection switching exchanges;

puts a fixed number of said logical connections having consecutive connection identifiers within said communication network in a plurality of group units while referring to and updating said connection-control information;

controls said logical connections in said communication network in said group units;

assigns a connection identifier to logical connections passing through a plurality of connection switching exchanges; and

issues a command to set up or release logical connections in one of said group units with consecutive connection identifiers in said group unit to said connection switching exchanges by way of operation-control communication lines.

2. A connection switching network control system according to claim 1 wherein:

said network management unit is provided with stored information concerning a network configuration of said communication network and network-configuration-information setting means for setting up and updating said information concerning a network configuration through said operation-control communication line or another communication line connected to said network management unit, wherein said information on a network configuration is composed of;

connection-configuration information concerning a configuration of logical connections among said terminating nodes and said connection switching exchanges constituting said communication network;

initial connection setting specifying information used for specifying initial setting of initial logical connections; and

grouped-control specifying information comprising a group size specifying the size of a control unit and group applicable range information used for specifying a range of connection identifiers to which control in group units is to be applied;

said connection-control information used for controlling states of utilization, routes and attributes of said logical connections is stored in said network management unit by said grouped-connection management means employed in said network management unit in accordance with said grouped-control specifying information stored as said information on a network configuration for logical connections having connection identifiers specified by said group applicable range information of said grouped-control specifying information in each unit with a size specified by said group size of said grouped-control specifying information;

in initial setup processing to set up initial logical connections in accordance with said initial connection setting specifying information or in response to a request to set up a new logical connection received from an edge connection switching exchange, that is, one of said connection switching exchanges directly connected to one of said terminating nodes, by way of one of said operation-control communication lines, said grouped-connection management means;

refers to said connection-control information to assign free consecutive connection identifiers or consecutive connection identifiers specified by said initial connection setting specifying information or as specified by said request as a batch for a group of logical connections having a size determined by said group size of said grouped-control specifying information;

refers to said connection-configuration information to identify said connection switching exchanges on a route of a requested connection; and

gives a command to said identified connection switching exchanges by way of said operation-control communication lines on said route to carry out switching in a batch operation on said group of logical connections having said consecutive connection identifiers assigned above from input communication lines to output communication lines on said route for both said input communication lines and said output communication lines;

said connection switching exchanges are each provided with a control mechanism which is connected to said corresponding operation-control communication line, used for controlling said connection switching exchange and includes a connection setup/release sub-mechanism for setting up and releasing a logical connection wherein, when said command is received from said grouped-connection management means employed in said network management unit, said connection setup/release mechanism;

sets up said switching table in said connection switching exchange in a batch operation by using a specified group of connection identifiers so as to carry out switching on a specified group of connections without changing the values of connection identifiers assigned to logical connections from specified input communication lines to specified output communication lines; and

transmits a result of said switching indicating whether said switching is successful or unsuccessful to said grouped-connection management means by way of said corresponding operation-control communication line; and

said grouped-connection management means receives said result indicating whether said switching is successful or unsuccessful from said connection switching exchange for updating said connection-control information accordingly.

3. A connection switching network control system according to claim 1 wherein, when said grouped-connection management means employed in said network management unit receives a request to release logical connections in a group unit by way of one of said operation-control communication lines from an edge connection switching exchange, that is, one of said connection switching exchanges directly connected to one of said terminating nodes, or when it is necessary to release a logical connection to reflect a change made to initially set up logical connections due to a change in configuration or to cope with the occurrence of a failure or an abnormality,

said grouped-connection management means identifies a connection switching exchange on a route associated with logical connections to be released by referring to said connection-control information and issues a command to said connection switching exchange on said route to release a group of logical connections of a group unit used in setting of said logical connections in a batch operation by way of one of said operation-control communication lines;

in said connection switching exchange receiving said command to release a group of logical connections, said connection setup/release mechanism;

receives said command;

releases said group of logical connections of a specified group unit in a batch operation by clearing an entry for said specified group of logical connections in said switching table in said connection switching exchange in a batch operation; and

transmits a result indicating whether or not said specified group of logical connections have been released successfully to said grouped-connection management means employed in said network management unit by way of said operation-control communication line; and

said grouped-connection management means receives said result indicating whether or not said specified group of logical connections have been released successfully from said connection switching exchange and uses said result to update said connection-control information.

4. A connection switching network control system according to claim 1 wherein:

said grouped-connection management means employed in said network management unit handles a plurality of different group sizes with one value being a multiple or a fraction of another and has individual connection-control information for each of said group sizes for controlling logical connections in said communication network in group units specified by said associated group size; and

when said grouped-connection management means gives a command to any of said connection switching exchanges in said communication network to request said connection switching exchange to set up or release a group of logical connections with a group size specified by said group size, processing to set up a group of logical connections having a smaller group size is judged to be valid by being allowed to take precedence in case another group of logical connections with connection identifiers identical with said group of logical connections to be set up or released have already been set up for the same communication lines of said connection switching exchange.

5. A connection switching network control system according to claim 1 wherein:

said information on a network configuration of said network management unit includes a plurality of pieces of group control specifying information with a group size in one of the same plurality of pieces of group control specifying information being a multiple or a fraction of a group size in another piece of group control specifying information;

for each piece of group control specifying information, said grouped-connection management means employed in said network management unit has connection-control information for controlling states of utilization, connection routes and attributes of said logical connections having connection identifiers in a range specified in accordance with said group control specifying information in units indicated by said group size of said group control specifying information;

in initial setup processing to set up initial logical connections in accordance with said initial connection setting specifying information, in response to a request to set up a new logical connection received from an edge connection switching exchange, that is, one of said connection switching exchanges directly connected to one of said terminating nodes, by way of one of said operation-control communication lines, in response to a request to release logical connections of a group unit received from an edge connection switching exchange by way of one of said operation-control communication lines or when it is necessary to release a logical connection to reflect a change made to initially set up logical connections due to a change in configuration or to cope with the occurrence of a failure or an abnormality, said grouped-connection management means;

receives a command or request to explicitly indicates which piece of group control specifying information is to be used or an implicit command or request to select which piece of group control specifying information is to be used as implicitly suggested by a relation between a specified connection identifier and a piece of group control specifying information to be used; and

gives a command to said connection switching exchanges on a route of said specified group of logical connections to set up or release said group of logical connections having consecutive connection identifiers by using a group unit specified by said group size of said group control specifying information selected in accordance with said command or request as one unit by way of said operation-control communication lines connected to said connection switching exchanges;

said connection setup/release mechanism employed in each of said connection switching exchanges receiving said command to set up or release said group of logical connections sets up or releases an entry in said switching table for switching purposes in said connection switching exchange in a batch operation in accordance with said command by using a specified group of connection identifiers so as to carry out switching on said specified group of connections to specified communication lines; and

in processing to set up logical connections of a plurality of group units having different group sizes but sharing overlapping connection identifiers for the same communication line of one of said communication switching exchanges and in processing to release logical connections of a group unit with connection identifiers assigned to logical connections already set up in a plurality of group units having different group sizes but sharing overlapping connection identifiers for the same communication line of one of said communication switching exchanges, said grouped-connection management means gives a command to said connection setup/release mechanism employed in said connection switching exchange on said connection route to set up or release said logical connections so that setting of said logical connections sharing said overlapping connection identifiers in one of said group units with a smallest group size is valid among said group units in a range of said overlapping connection identifiers.

8. A connection switching network control system according to claim 6 for controlling connection switching exchanges composing a communication network as in claim 1 wherein group units can each be set only to an integer value in power of 2 and, in initialization, said grouped-connection management means employed in said network management unit:

gives a command to said connection setup/release mechanism of each of said connection switching exchanges in said communication network by way of said operation-control communication lines to request said connection setup/release mechanisms of said connection switching exchanges to set a value obtained as a result of bit-by-bit inversion of (a group size-1) in said switching mask register employed in each of said grouped-search mechanisms to which said group size is assigned considering smaller group size is assigned to a grouped-search mechanism with higher priority if fixed priority levels are pre-assigned to said grouped-search mechanisms;

waits for responses indicating completion of said initialization coming from said connection switching exchanges; and

stores a relation between group units completing said initialization and said switching tables of said grouped-search mechanisms in said connection-control information for said group units as information associating said group units with said switching tables,

and after said initialization,

referring to said information associating said group units with said switching tables stored as part of said connection-control information at the end of said initialization, said grouped-connection management means employed in said network management unit gives a command to said connection setup/release mechanism employed in each of said connection switching exchanges to carry out processing to set up or release a group of logical connections for a group unit by specification of one of said grouped-search mechanisms with said switching table thereof to be used; and

said connection setup/release mechanism employed in said connection switching exchange updates an entry in said switching table of said specified grouped-search mechanism in said connection switching exchange in order to set up or release a specified group of logical connections in accordance with said command.

9. A connection switching network control method to be adopted in a network management unit including a grouped-connection management means according to claim 4 for controlling conventional connection switching exchanges composing a communication network wherein neither grouped-search mechanism nor priority judgment/selection mechanism are included in each of said conventional connection switching exchanges, whereby an operation to issue a command to set up or release logical connections carried out by said grouped-connection management means employed in said network management unit comprises:

a step 0 at which said grouped-connection management means employed in said network management unit, first of all, uses values of an entire connection-identifier space as a range when setting up logical connections initially in initialization and values of a group of connection identifiers of logical connections to be set up or released as a range when setting up or releasing said logical connections after said initialization, then end points of said range and start and end connection identifiers of all grouped logical connections in said range which have been set up or will be set up from now on as change points are considered as change points, and said change points are sorted in an increasing order of change-point values to form a list of change points;

step 1 at which a group size of a request to set up or release logical connections is stored as an affected group size;

step 2 at which logical connections having a connection identifier of a change point at the start side of said range are searched and, if such logical connections exist, said change point is stored as a set start point and a smallest group size among found logical connections is stored as a setting group size before going on to a step 4 but, if a logical connection having a connection identifier of a change point is not found, on the other hand, the value of a change point on said start side is stored as a set end point;

step 3 at which a next change point which follows said set end point in said change-point list and has a value different from said set end point is stored as a set start point, in the case of a request to release logical connections, a command to release a group of logical connections having connection identifiers from said set end point to said set start point is given to said connection switching exchanges on a route of said logical connections to be released and a smallest group size among logical connections having said set start point cited above in connection identifiers thereof is stored as a setting group size;

step 4 at which change points on said change-point list following said set start point are sequentially checked to search for a smallest change point where a group unit size of a logical connection having a connection identifier thereof is not greater than said setting group size, or which is an end point of a group of logical connections corresponding to said set start point;

step 5 at which said affected group size stored at step 1 is compared with a group size set previously and, in the case where an affected group size is equal to or smaller than said previously set group size and the processing is to set up logical connections, a command to set up logical connections from said set start point to said change point obtained at step 4 is issued to associated connection switching exchanges but, in the case where an affected group size is greater than said previously set group size and the processing is to release logical connections, on the other hand, a command to set up logical connections from said set start point to said change point is issued to associated connection switching exchanges; and

step 6 at which said change point obtained at step 4 is checked to find out whether or not said change point is a last change point on said change-point list and, if said point is a last change point, processing is ended but, if said change point is judged to be not a last change point, on the other hand, a logical connection having said change point in a connection identifier thereof is searched for and, if such logical connections are found, said change point is stored as a set start point and a smallest group size among found logical connections is stored as a setting group size before returning to step 4 but, if a logical connection having said change point obtained at step 4 in a connection identifier thereof is not found, on the other hand, said change point is stored as a set end point before returning to step 3.

10. A connection switching network control system according to claim 4 wherein, when switching setting of a group of logical connections with a size specified by said group size is established for a communication line of a connection switching exchange, switching setting of another group of logical connections with another group size larger than said group size is established at the same time to include connection identifiers of said group of logical connections for the same communication line of the same connection switching exchange.

11. A connection switching network control system according to claim 4 wherein a group of logical connections of a group unit linked to a communication switching exchange is distributed among a plurality of subgroups of logical connections with a subgroup size equal to a fraction of a group size of said group unit and a total number of logical connections in all said subgroups smaller than the number of logical connections in said group unit, and remaining logical connections not distributed to said subgroups are controlled as spare logical connections.

12. A connection switching network control system according to claim 1 wherein:

all apparatus in said communication network are classified into hierarchical categories wherein terminating nodes are put in a category of level-0 apparatuses, edge connection switching exchanges each directly connected to a terminating node are put in a category of level-1 apparatuses, connection switching exchanges each directly connected to a level-1 apparatus but not pertaining to said categories of level-1 apparatuses and level-0 apparatuses are put in a category of level-2 apparatuses and, by the same token, connection switching exchanges each directly connected to a level-(n−

1) apparatus but not pertaining to categories of level-(n−

1) apparatuses and numerically-lower-than-(n−

1)-level apparatuses are put in a category of level-n apparatuses, and a one-directional interterminal logical connection is set between every two level-0 apparatuses;

each one-directional interterminal logical connection has a connection identifier unique to a destination terminating node so that one-directional interterminal logical connections from terminating nodes to the same destination terminating node all have the same connection identifier, forming a so-called multipoint-to-point logical connections;

for apparatuses at all hierarchical levels i where i>

=1, one-directional interterminal logical connections from an apparatus at level i to apparatuses at level (i−

1) have consecutive connection identifiers;

for anticipated future expansion of apparatus connections, a proper number of connection identifiers are reserved for apparatuses at level i;

the total number of one-directional interterminal logical connections from an apparatus at level i to apparatuses at level (i−

1) including said reserved ones is a multiple of a group unit size and connection identifiers of logical connections toward apparatuses at level (i−

1) and reserved connection identifiers are assigned in said group unit;

a group of logical connections having connection identifiers assigned in said group unit are set in said group unit from all apparatuses at level (i+1) directly connected to said apparatus at level i to said apparatus at level i;

at a connection switching exchange at level i, a group of logical connections from apparatuses at level (i+1) to an apparatus at level i are distributed to be connected to logical connections or a group of logical connections from said apparatus at level i to apparatuses at level i−

1; and

one-directional logical connections using logical connections in group units from a high hierarchical layer to a low hierarchical layer set as described above are connected from each terminating node to form meshed interterminal connections with one-directional logical connections having group unit size equal to or greater than that of said one-directional logical connections to be connected to.

13. A connection switching network control system according to claim 12 wherein the level of each apparatus is virtually lowered by 1 layer with apparatuses at level 1 each considered to be a terminating node and one-directional logical connections stretched among edge connection switching exchanges are set up in place of said one-directional interterminal logical connections.

14. A connection switching network control system according to claim 12 wherein:

each terminating node or each edge connection switching exchange directly connected to a terminating node in said communication network is provided with IP/connection transformation information for indicating which one-directional interterminal logical connection is to be used in transmission of IP data and which apparatus or apparatuses correspond to an IP/(Internet Protocol) address or a group of IP addresses in said IP data; and

each terminating node or each edge connection switching exchange transmits IP data through a one-directional interterminal logical connection indicated by said IP/connection transformation information.

15. A connection switching network control system according to claim 12 wherein:

said network management unit is provided with IP-route information showing which terminating node or nodes a destination IP address or a group of destination IP addresses included in IP data indicate, that is, which terminating node or nodes said IP data with a destination IP address or a group of destination IP addresses should be transmitted to, or which terminating node or nodes IP data should be transmitted through;

said grouped-connection management means employed in said network management unit creates IP/connection transformation information for transforming an IP address or a group of IP addresses into connection identifiers of one-directional interterminal logical connections toward destination terminating nodes set up among terminating nodes during initialization by using said IP-route information and said connection-control information;

said grouped-connection management means employed in said network management unit transmits said IP/connection transformation information to said edge connection switching exchange directly connected to said terminating node through said operation-control communication line;

said edge connection switching exchange receives said IP/connection transformation information and stores said IP/connection transformation information;

said edge connection switching exchanges each have an IP/connection transformation mechanism as part of said control mechanism;

said IP/connection transformation mechanism is connected to said terminating nodes to which said edge connection switching exchange is linked directly by using IP logical connections having pre-configured IP connection identifiers;

any of said terminating nodes transmits IP data to said edge connection switching exchange by using said logical connections;

receiving said IP data from said terminating node, said IP/connection transformation mechanism employed in said edge connection switching exchange uses a destination IP address recorded in an IP header of said IP data received from said terminating node as a key to search said IP/connection information stored in said edge connection switching exchange for a connection identifier of a one-directional interterminal logical connection toward a destination terminating node; and

by using said one-directional interterminal logical connection, said IP data is transmitted by said edge connection switching exchange to said destination terminating node.

16. A connection switching network control system according to claim 12 wherein:

said network management unit is provided with IP-route information showing which terminating node or nodes a destination IP address or a group of destination IP addresses included in IP data indicate, that is, which terminating node or nodes said IP data with a destination IP address or a group of destination IP addresses should be transmitted to, or which terminating node or nodes IP data should be transmitted through;

said grouped-connection management means employed in said network management unit creates IP/connection transformation information for transforming an IP address or a group of IP addresses into connection identifiers of one-directional interterminal logical connections toward destination terminating nodes set up among terminating nodes during initialization by using said IP-route information and said connection-control information;

said grouped-connection management means employed in said network management unit transmits said IP/connection transformation information to said edge connection switching exchange directly connected to said terminating node through said operation-control communication line;

said edge connection switching exchange receives said IP/connection transformation information and stores said IP/connection transformation information;

said edge connection switching exchanges each have an IP/connection transformation mechanism as part of said control mechanism;

said IP/connection transformation mechanism is connected to said terminating nodes to which said edge connection switching exchange is linked directly by using IP logical connections having different IP connection identifiers;

each of said terminating nodes is provided with an IP/connection transformation cache for storing some of said IP/connection transformation information used for transforming a destination IP address of IP data transmitted in the past into an identifier of a one-directional interterminal connection to a destination;

first of all, said terminating node searches said IP/connection transformation cache prior to transmission of IP data in order to form a judgment as to whether or not an entry corresponding to a destination IP address included in said IP data exists in said cache and if such an entry does not exist in said IP/connection transformation cache, said terminating node transmits information on said destination IP address to said IP/connection transformation mechanism employed in said edge connection switching exchange directly connected to said terminating node by using said IP logical connection in order to obtain IP/connection transformation information;

receiving said information on said destination IP address, said IP/connection transformation mechanism employed in said edge connection switching exchange searches said IP/connection transformation information stored in said edge connection switching exchange for a desired portion associated with said destination IP address, transmitting said desired portion of said IP/connection transformation information to said terminating node originating said IP address as a result of said search operation;

receiving said result, said terminating node stores said desired portion of said IP/connection transformation information received in response to said destination IP address in said IP/connection transformation cache; and

said terminating node finds a connection identifier of a one-directional interterminal logical connection corresponding to said destination IP address from said cataloged IP/connection transformation information and then transmits said IP data to said edge connection switching exchange directly connected to said terminating node by using said connection identifier of said one-directional interterminal logical connection.

17. A connection switching network control system according to claim 16 wherein:

said IP/connection transformation cache employed in said terminating node is used for storing said entire IP/connection transformation information transmitted from said edge connection switching exchange instead of storing only part of said IP/connection transformation information when said edge connection switching exchange receives said IP/connection transformation information from said grouped-connection management means employed in said network management unit and passes on said IP/connection transformation information to all said terminating nodes by using said IP connection, or when said terminating node makes a request to said edge connection switching exchange to transmit said entire IP/connection transformation information by using said IP connection; and

in transmission of IP data, said terminating node finds a connection identifier of a one-directional interterminal logical connection corresponding to a destination IP address of said IP data from said IP/connection transformation information stored entirely in said terminating node and then transmits said IP data to said edge connection switching exchange directly connected to said terminating node by using said connection identifier of said one-directional interterminal logical connection.

18. A connection switching network control system according to claim 13 wherein each of edge connection switching exchanges of said communication network is provided with:

IP/inter-edge-exchange-connection transformation information for transforming an IP address or a group of IP addresses of IP data into connection identifiers of one-directional inter-edge-exchange logical connections to be used for transmitting said IP data; and

IP/terminal-line transformation information for transforming a destination edge connection switching exchange or a destination edge connection switching exchanges corresponding respectively to an IP address or a group of IP addresses of said IP data into information indicating which communication line connected to a terminating node said IP data should be transmitted through in order to transmit said IP data to an apparatus or apparatuses indicated by said IP address or IP addresses respectively from an edge connection switching exchange,

and in said edge communication switching exchange, said IP/inter-edge-exchange-connection transformation information and IP/terminal-line transformation information are used to transmit IP data through said one-directional inter-edge-exchange logical connections.

19. A connection switching network control method adopted in a connection switching network control system according to claim 13 wherein:

said network management unit is provided with IP-route information showing which terminating node or nodes IP data with an IP address or a group of IP addresses respectively should be transmitted to and which edge connection-switching exchange or switching exchanges IP data should be transmitted through or which terminating node or nodes and which edge connection-switching exchange or switching exchanges IP data should be transmitted through;

each of said edge connection switching exchanges is provided with an IP/connection transformation mechanism and an IP/terminal-line transformation mechanism as part of said control mechanism;

an inter-edge-exchange one-directional logical connection toward a destination edge connection switching exchange set up during said initialization is connected to said IP/terminal-line transformation mechanism; and

said IP/connection transformation mechanism is connected to a source terminating node directly connected to said edge connection switching exchange by an IP transmission logical connection having an IP connection identifier and said IP/terminal-line transformation mechanism is connected to a destination terminating node directly connected to said edge connection switching exchange by an IP reception logical connection having an IP connection identifier;

said method comprising;

a step taken by said grouped-connection management means employed in said network management unit to create IP/inter-edge-exchange-connection transformation information for transforming an IP address or a group of IP addresses of IP data into connection identifiers of one-directional inter-edge-exchange logical connections toward destination edge connection switching exchanges which were set up among terminating nodes during said initialization by using said IP-route information and said connection-control information;

a step taken by said grouped-connection management means employed in said network management unit to create IP/terminal-line transformation information used for transforming information on a destination edge connection switching exchange included in IP data into information indicating which terminating node and which communication line IP data should be transmitted to and transmitted through by using said IP-route information and said connection-configuration information for an IP address or a group of IP addresses of said IP data;

a step taken by said grouped-connection management means employed in said network management unit to transmit said IP/inter-edge-exchange-connection transformation information and said IP/terminal-line transformation information to said edge connection switching exchanges directly connected to said terminating nodes through said operation-control communication lines;

a step taken by said edge connection switching exchanges to receive said IP/inter-edge-exchange-connection transformation information and said IP/terminal-line transformation information and store said IP/inter-edge-exchange-connection transformation information and said IP/terminal-line transformation information;

a step taken by a terminating node to transmit IP data to an edge connection switching exchange by using said IP transmission logical connection;

a step taken by said IP/connection transformation mechanism employed in said edge connection switching exchange receiving said IP data from said terminating node to use a destination IP address recorded in an IP header of said IP data received from said terminating node as a key to search said IP/inter-edge-exchange connection transformation information stored in said edge connection switching exchange for a connection identifier of a one-directional inter-edge-exchange logical connection toward a destination edge connection switching exchange to transmit said IP data to said destination edge connection switching exchange by using said one-directional inter-edge-exchange logical connection; and

a step taken by said IP/terminal-line transformation mechanism employed in said destination edge connection switching exchange to receive said IP data transmitted by said source edge connection switching exchange through said one-directional inter-edge-exchange logical connection and, by referring to said IP/terminal-line transformation information, to pass on said IP data to said terminating node connected to said communication line for said IP data through said IP reception logical connection.

20. A connection switching network control method adopted in a connection switching network control system according to claim 1 wherein said connection setup/release mechanism employed in each edge connection switching exchange directly connected to one of said terminating nodes serves as a buffer for requests to set up a logical connection made by said terminating node, makes the requests into setting of a group of logical connections in a new connection setting unit which is a multiple of a group size, and, for each group of logical connections dynamically set, said connection setup/release mechanism has terminal-connection-control information on said group of logical connections and on the status of assignment of the logical connections to said terminating nodes, said method comprising:

a step taken by said terminating node to issue a request to set up a new logical connection to an edge connection switching exchange through a signaling logical connection;

a step taken by said connection setup/release mechanism of said edge connection switching exchange receiving said request to check pieces of said terminal-connection-control information in order to search for terminal-connection-control information with destination and attribute conditions satisfying said request;

a step taken by said connection setup/release mechanism of said edge connection switching exchange to request said grouped-connection management means employed in said network management unit to set up a group of logical connections in said new connection setting unit size from said edge connection switching exchange to a destination apparatus with requested attributes specified in said request by using a method adopted by said connection switching network control system according to claim 1, and catalog said group of logical connections obtained from said grouped-connection management means in said terminal-connection-control information as unassigned logical connections if terminal-connection-control information meeting said conditions is not found;

a step taken by said connection setup/release mechanism of said edge connection switching exchange to select as many logical connections as requested from said found terminal-connection-control information or terminal-connection-control information cataloged at said above step by using said terminal-connection-control information and to update said terminal-connection-control information if terminal-connection-control information meeting said conditions is found;

a step taken by said connection setup/release mechanism of said edge connection switching exchange to set up said switching table to link said logical connection selected at said above step starting from said edge connection switching exchange and ending at said destination to said terminating node, which made said request, by using said same connection identifier as said logical connection; and

a step taken by said connection setup/release mechanism to report said set connection identifier to said terminating node which made said request.

21. A connection switching network control method according to claim 20 wherein said terminal-connection-control information includes time-out information used for releasing a group of logical connections, said method composed of:

a sequence of steps to release a logical connection comprising;

a step taken by a terminating node to issue a request to release a logical connection to an edge connection switching exchange directly connected to said terminating node through a signaling logical connection;

a step taken by said connection setup/release mechanism of said edge connection switching exchange receiving said request to search for terminal-connection-control information for said logical connection being released by using a connection identifier specified in said request;

a step taken by said connection setup/release mechanism to update said terminal-connection-control information found at said above step by changing status of assignment of said logical connection being released connected to terminating nodes into an unassigned one;

a step taken by said connection setup/release mechanism to invalidate an entry in said switching table in said edge connection switching exchange corresponding to said logical connection being released; and

a step taken by said connection setup/release mechanism to set said time-out information in said found terminal-connection-control information for releasing all logical connections in a group with a size equal to the size of said new connection setting unit associated with said terminal-connection-control information in case status of assignments of all said logical connections is unassigned status, and

a sequence of steps executed by said connection setup/release mechanism to periodically check said time-out information of said terminal-connection-control information with a group of logical connections associated with said terminal-connection-control information having unassigned status, said sequence comprising the steps of;

requesting said grouped-connection management means employed in said network control means through an operation-control communication line to release a group of unassigned logical connections associated with said terminal-connection-control information with a group size equal to the size of said new logical connection unit if said time-out information of said terminal-connection-control information set at said above step indicates that said unassigned status of a group of logical connections associated with said terminal-connection-control information has been continuing for more than a predetermined period of time; and

deleting said terminal-connection-control information.

22. A connection switching network control method adopted in a connection switching network control system according to claim 1 for handling a failure occurring in said communication network wherein:

a plurality of different group sizes are used;

a group of detour logical connections are provided in advance for a group of normal-route logical connections;

the size of said group of detour logical connections is larger than the size of said group of normal-route logical connections; and

connection identifiers used in said group of normal-route logical connections are used as connection identifiers in said group of detour logical connections,

said method comprising the steps taken by said grouped-connection management means employed in said network management unit to;

identify a failing group of logical connections and a failing route affected by said failure by referring to said connection-control information and said connection-configuration information stored in said network management unit;

examine whether or not a group of detour logical connections for said failing group of logical connections with a group size greater than the group size of said failing group of logical connections have already been set up by referring to said connection-control information;

give a command to said connection switching exchanges on said failing route through said operation-control communication lines to invalidate connection switching for said failing group of logical connections if such a group of detour logical connections have already been set up; and

update said connection-control information to reflect said invalidated connection switching.

23. A connection switching network control method adopted in a connection switching network control system according to claim 1 for handling a failure occurring in said communication network, said method comprising the steps taken by said grouped-connection management means employed in said network management unit to:

identify a failing group of logical connections and a failing route affected by said failure by referring to said connection-control information and said connection-configuration information stored in said network management unit; and

examine whether or not a group of detour logical connections for said failing group of logical connections with a group size greater than the group size of said failing group of logical connections have already been set up by referring to said connection-control information and if a result of examination indicates that a group of detour logical connections have not been set up then;

determine a detour route by referring to said connection-control information and said connection-configuration information;

form a judgment based on consideration of conditions such as a band as to whether said connection identifiers of said failing group of logical connections are to be used as they are as connection identifiers of a group of detour logical connections or other connection identifiers are to be assigned to said group of detour logical connections and, if necessary, assign new connection identifiers to said group of detour logical connections;

give a command to connection switching exchanges at locations on said detour route determined at said above step by way of said operation-control communication lines to carry out connection switching on said group of logical connections having said detour connection identifiers with a group size equal to that of said failing group of logical connections;

give a command to a connection switching exchange or a terminating node at an end on the source side of said detour route to carry out connection switching to link a group of a logical connections connected to said failing group of logical connections to said group of detour logical connections switched by said connection switching exchanges at locations on said detour route with a group size equal to that of said failing group of logical connections with any one of the ends of said detour route regarded as a source in the case of a failing group of logical connections composed of bi-directional logical connections after completion of said above step to switch a group of detour logical connections for said connection switching exchanges at locations on said detour route;

give a command to a connection switching exchange or a terminating node at an end on the destination side of said detour route to carry out connection switching to link a group of a logical connections connected to said failing group of logical connections to said group of detour logical connections switched by said connection switching exchanges at locations on said detour route with a group size equal to that of said failing group of logical connections after completion of said above step to switch logical connections in said connection switching exchange or said terminating node at said end on said source side of said detour route; and

update said connection-control information to reflect said setting of said detour route.

24. A connection switching network control method adopted in a connection switching network control system according to claim 1 wherein:

said network management unit is connected by communication lines using operation-control logical connections each having a connection identifier directly to said communication network including connection switching exchanges serving as relay apparatuses in the same way as said terminating nodes and said connection switching exchanges are connected to said communication network; and

said communication lines using said operation-control logical connections are each used as an operation-control communication line of said communication network.

25. A connection switching network control system wherein:

a connection setup/release mechanism serving as a control mechanism according to claim 2, an IP/connection transformation mechanism according to claim 15 and an IP/terminal-line transformation mechanism according to claim 19 are provided for each of said communication lines in each of said connection switching exchanges; and

there is provided a logical connection distribution mechanism for controlling distribution of logical connections to sub-mechanisms in said control mechanism for handling only data packets of logical connections toward said control mechanism.

26. A connection switching network control system according to 1 wherein:

the plurality of network management units are provided in said communication network;

connection-control information according to claim 1 subjected to unitary control across said entire communication network is provided in each of said network management units by adopting the same technique as a distributed data base in a cache subjected to control of consistency among said network management units; and

processing is distributed among the same plurality of network management units according to ranges of distribution of connection identifiers and ranges of distribution of connection switching exchanges.

6. A connection switching network control system for controlling connection switching exchanges comprising an ATM and a frame relay for switching a plurality of communication lines wherein:

each of said connection switching exchanges has a function to set up a plurality of logical connections in each of said communication lines for connecting said connection switching exchange to directly connected apparatuses, such as other connection switching exchanges, a communication terminal or a gateway apparatus for communication with another network, as well as a function to switch two of said logical connections set up in two or less communication lines connecting said connection switching exchange to said directly connected apparatuses;

for each of said communication lines or each of said connection switching exchanges, there is provided individually a switching table used for showing a relation of communication-line information on a communication line used by a logical connection on an input side of a pair of logical connections to be switched and a connection identifier assigned to said logical connection on said input side versus communication-line information on a communication line used by a logical connection on an output side of said pair of logical connections to be switched and a connection identifier assigned to said logical connection on said output side and used for showing optional attribute information on attributes of said logical connections; and

each of said connection switching exchanges comprises;

a switching-table search mechanism for carrying out a search operation to search said switching table for a switching-table entry by using information on a connection identifier recorded in a header of a data packet received through one of said communication lines on said input side and said communication-line information on said communication line and for outputting search-result valid/invalid information indicating whether a result of said search operation is valid or invalid and said switching-table entry found in said search operation in the case of a valid result;

for said communication lines connected to said connection switching exchange, a connection-identifier transformation mechanism for replacing said connection identifier recorded in said header of said input data packet in the case of search-result valid/invalid information indicating a valid result of said search operation carried out by said switching-table search mechanism with a connection identifier assigned to a logical connection on said output side toward a switching destination by referring to said search-result valid/invalid information output by said switching-table search mechanism;

a switch mechanism for switching said data packet from said communication line on said input side to said communication line on said output side of said switching destination by using said result of said search operation;

a control mechanism connected to said switch mechanism by a special signal line wherein, as part of said control mechanism, a connection setup/release mechanism is provided for setting up said switching table through a signal line during initialization to switch to a signaling logical connection having a special connection identifier and for setting up a new logical connection or releasing an existing logical connection by updating said switching table in response to a request received through said signaling logical connection;

a switching mask register associated with said switching table allowing a value received from said connection setup/release mechanism through a signal line to be set therein;

a mask mechanism for generating a logical product (an AND value) of said connection identifier recorded in said header of said input data packet and contents of said switching mask register and supplying said logical product to said switching-table search mechanism for use in said search operation to search said switching table instead of directly supplying said connection identifier recorded in said header of said input data packet to said switching-table search mechanism; and

switching-information transformation mechanism for computing a logical product of said connection identifier of said input data packet and a value resulting from bit-by-bit inversion of contents of said switching-mask register and generating a logical sum (an OR value) of said logical product and an output connection identifier included in said switching-table entry obtained as a result of said search operation carried out by said switching-table search mechanism,

wherein said logical sum output by said switching-information transformation mechanism is used as a new search result supplied to said connection-identifier transformation mechanism and, if said search-result valid/invalid information indicates a valid search result, said connection identifier included in said input data packet is replaced in said connection-identifier transformation mechanism, and said switch mechanism carries out switching on said input data packet completing processing in said connection-identifier transformation mechanism from said communication line on said input side to said communication line on said output side of a switching destination by using information on an output communication line of said search result.

7. A connection switching network control system according to claim 6 wherein:

each of said connection switching exchanges has;

a plurality of grouped-search mechanisms each comprising said switching table, said switching mask register, said mask mechanism and said switching-information transformation mechanism wherein said switching tables are searched at the same time and search results are supplied to said switching-information transformation mechanisms to be subjected to transformations; and

a priority judgment/selection mechanism receiving switching-table entries of said search results obtained from said transformations carried out by said switching-information transformation mechanisms employed in said grouped-search mechanisms and pieces of search-result valid/invalid information from said switching-table search mechanisms employed in said grouped-search mechanisms each associated with one of said switching-table entries, wherein said switching-table entries each indicated to be a valid search result by said associated search-result valid/invalid information are subjected to a priority judgment wherein fixed different priority levels are assigned in advance to said grouped-search mechanisms or a priority judgment comprising the steps of;

inputting contents of said switching mask registers employed in said grouped-search mechanisms;

treating each of said values as an unsigned integer;

judging one of said switching-table entries of said search results associated with a greatest one among said unsigned integers to be a switching-table entry output by one of said grouped-search mechanisms with a highest priority level; and

selecting said switching-table entry with said highest priority level among said switching-table entries output by the same plurality of said grouped-search mechanisms each indicated to be a valid search result by said associated search-result valid/invalid information, and outputting said selected switching-table entry as a final search result along with final search-result valid/invalid information obtained as a logical sum (an OR value) of all said pieces of search-result valid/invalid information for indicating whether said final search result is valid or invalid;

said final search result and said final search-result valid/invalid information output by said priority judgment/selection mechanism are supplied to said connection-identifier transformation mechanism as a new search result and new search-result valid/invalid information in which said connection identifier included in said input data packet is replaced provided that said new search-result valid/invalid information indicates that said new search result is valid and said switch mechanism carries out switching of said input data packet completing processing in said connection-identifier transformation mechanism from said communication line on said input side to said communication line on said output side for said switching destination by using information on an output communication line recorded in said switching-table entry of said new search result.