Connectionless ATM data services

• US 5,517,497 A
• Filed: 03/21/1995
• Issued: 05/14/1996
• Est. Priority Date: 08/21/1991
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Le Boudec, Jean-Yves, Truong, Linh
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US08/408,445
• Time in Patent Office: 420 Days
• Field of Search: 370/54, 370/58.1, 370/58.2, 370/58.3, 370/60, 370/60.1, 370/85.13, 370/85.14, 370/94.1, 370/94.2, 370/94.3
• US Class Current: 370/399
• CPC Class Codes: H04L 2012/5645 Connectionless
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 45/10 Routing in connection-oriented networks, e.g. X.25 or ATM
• CPC Class Codes: H04L 45/42 Centralised routing
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags

Abstract

In a system using the Asynchronous Transfer Mode (ATM) for data transfers, each cell is usually routed in response to VPI/VCI values identifying a previously established connection. A connectionless transfer mode is disclosed by which to each requesting user, a unique routing identifier(RI) is allocated. All RIs allocated in the whole network are kept in a table of a routing-identifier management function (RIMF). When a source user wants to send a message to a destination user, it requests the destination RI from the RIMF and inserts the received RI into each transmitted call in the VCI field. The RI may, include a switching node identifier (SI) and a port identifier (PI). In that case, each switching node has a permanent table of all SIs plus respective routing information, and a changing table of all currently allocated PIs of locally connected users plus the respective user port names.

Claims

1. A method for transferring data messages, without establishing a connection between users, in an Asynchronous Transfer Mode system otherwise using established connections for data message transfers through a given network comprising switching nodes,

the method comprising the steps of:

A) allocating a Routing Identifier RI to any user being activated at a specific network location for connectionless data transfer services;

said Routing Identifier RI indicating routing information to a location of the user, not established by a connection set-up procedure which establishes a connection between said source user and said destination user and remaining the same valve throughout the network;

B) providing in each switching node of said network at least one table including at least a portion of each allocated Routing Identifier RI and respective routing directions for correctly routing a message cell containing a Routing Identifier RI, to the respective user;

C) providing in the network a central management function including a global table with the address of each user activated for connectionless service, together with the allocated Routing Identifier RI;

D1) transmitting, by a source user desiring to send a data message in connectionless mode to another user, a signalling message with the destination user'"'"'s address to said central management function, requesting said destination user'"'"'s Routing Identifier RI;

D2) receiving, by said source user, from central management in a signalling message the respective Routing Identifier RI if existing; and

D3) sending, by the source user, a data message to said destination user by including said received Routing Identifier RI in the header of a message of said data message.

2. Method according to claim 1, for use in a system where each cell transferred through the network comprises in its header a field for a virtual path identification (VPI) and a field for a virtual circuit identification (VCI), including the step of

inserting the routing identifier RI into each cell which is to be transferred in connectionless mode, in the field provided for said virtual circuit identification (VCI).

3. The method of claim 2 further including the step of inserting an indicium into the virtual path identification (VPI) field of each ATM cell, said indicium indicating the ATM cell is being transferred in connectionless mode.

4. Apparatus for transferring data messages, without establishing a connection between users, in an Asynchronous Transfer Mode system otherwise using established connections for data message transfers through a given network comprising a plurality of switching nodes (11), a plurality of user units (15) each connected to one of the switching nodes, and a network management center (17, 19), the apparatus comprising:

A) means (43, 47,

     53) associated with the switching nodes for allocating a Routing Identifier RI to any user unit being activated at a specific network location for connectionless data transfer services,

said Routing Identifier RI indicating routing information to a location of the user, not established by a connection set-up procedure which establishes a connection between two users wanting to communicate and remaining the same value throughout the network;

B) in each switching node of said network, table means (51,

     53) including at least a portion of said Routing Identifier RI and respective routing directions for correctly routing a message cell containing the Routing Identifier RI;

C) in the network management center, means (59,

     61) for maintaining a global table including the address of each user unit activated for connectionless service, together with the allocated Routing Identifier RI, and means (55,

     59) for updating the global table each time a new Routing Identifier RI is allocated to a user unit; and

D) in each user unit;

D1) means (27,

     31) for transmitting, when the user unit desires to send a data message in connectionless mode to another user, a signalling message to said network management center requesting the destination user'"'"'s Routing Identifier RI,

D2) means (27,

     33) for receiving, from said network management center in a signalling message the respective Routing Identifier RI if existing, and

D3) means (21, 23,

     33) for sending a data message to said another user by including said received Routing Identifier RI in the header of at least one cell of said data message.

5. In an Asynchronous Transfer Mode communications network having a plurality of interconnected switching nodes, a plurality of user units connected to the switching nodes and a network management center operatively coupled to the communications network, a device for providing connectionless data transfer services comprising:

means located in a user unit for generating and transmitting a signalling message containing the address of another user unit with whom the user unit wishes to communicate and a request for a Routing Identifier RI for said another user unit;

means located in said user unit for receiving a response signalling message containing information which includes the Routing Identifier RI, not established by a connection set-up procedure which establishes a connection between the user unit and the another user unit and indicating routing information to a location of the another user unit and remaining the same value throughout the network

means in said user unit for generating and sending a data message to the another user unit, with the Routing Identifier RI included in each ATM cell of the data message and said Routing Identifier RI is used to route said each ATM cell of the data message to the another user unit.

6. An user terminal for connecting to an Asynchronous Transfer Mode Network said user terminal including:

means located in said user terminal for transmitting, when the user terminal desires to send a data message to another user terminal in the connectionless mode, a signalling message to a network management center requesting a Routing Identifier RI, said Routing Identifier RI indicating routing information to a location of said another user terminal and is not established by a set-up procedure which establishes a connection between the user terminal and remaining the same value throughout the network and the another user terminal;

means located in said user terminal for receiving from said network management center a signalling message containing the Routing Identifier RI, if existing;

means located in said user terminal for including in each ATM cell of a data message transmitted to the another user terminal the Routing Identifier RI and an indicator which alerts nodes in the network that said ATM cell is being transmitted in the connectionless mode; and

means for transmitting each ATM cell into the ATM network.

7. In an Asynchronous Transfer Mode Network using established connections for data message transfers through the network comprising a plurality of switching nodes (11), a plurality of user units (15) connected to each one of the switching nodes, and a network management center (17, 19), apparatus for transferring data messages, without establishing a connection between users, the apparatus comprising:

A) means (43, 47,

     53) associated with each switching node for allocating a Routing Identifier RI, not established through connection set-up procedures which establish a connection between a pair of user units and identifying routing to a location of a user unit using connectionless data transfer services and remaining the same value throughout the network;

B) in each switching node of said network, table means (51,

     53) including at least a portion of each allocated Routing Identifier RI and respective routing directions for correctly routing a message cell containing the Routing Identifier RI;

C) in the network management center, means (59,

     61) for maintaining a global table including the address of each user unit activated for connectionless service together with the allocated Routing Identifier RI; and

means (55,

     59) for updating this table in response to a message received from each switching node each time a new Routing Identifier RI is allocated to an user unit by the switching node.

8. Apparatus for transferring data messages, without establishing a connection between users, in an Asynchronous Transfer Mode Network otherwise using established connections for data message transfers through the given network comprising a plurality of switching nodes (11), a plurality of user units (15) connected to each one of the switching nodes, and a network management center (17, 19), the apparatus comprising:

A) means (43, 47,

     53) associated with each switching node for allocating a Routing Identifier RI, not established through connection set-up procedures which define a connection between user units and identifying routing information to a location of an user unit activated at a specific network location, to an user unit using connectionless data transfer services and remaining the same value throughout the network

B) in each switching node of said network, table means including at least a portion of the allocated Routing Identifier RI and respective routing directions for correctly routing an ATM message cell containing the Routing Identifier RI; and

C) means in each switching node for correlating the RI in the ATM cell with a corresponding RI in the table and routing said ATM cell in accordance with the routing directions associated with said RI.

9. An apparatus for use in transferring data messages, without establishing a connection between users, in an Asynchronous Transfer Mode Network otherwise using established connections for data message transfers through the network comprising a plurality of switching nodes (11), a plurality of user units (15) connected to each one of the switching nodes, the apparatus comprising;

a cell handling means (55) for receiving and sending signalling message cells;

a network management center coupled to the cell handling means;

said network management center including a global table including an address of each user unit activated for connectionless service and Routing Identifiers RIs, each one of the Routing Identifier RI associated with the address of each user unit with said each one of the Routing Identifier RI indicating routing to a location of the user unit in the network, not established by connection set-up procedures which indicate a connection between the user units wanting to communicate and remaining the same value throughout the network; and

means for selectively updating the global table in response to a Routing Identifier RI being allocated to a user unit.

10. The apparatus of claim 9 further including means, responsive to signalling messages received from end users indicating the end user'"'"'s desire to use the connectionless service and requesting Routing Identifier RI for destination users, for interrogating the global table and returning in a signalling message to said end users the Routing Identifier RI, if existing.

11. An asynchronous transfer mode network comprising:

a plurality of switching nodes (11);

user units (15) connected to the switching nodes;

a network management center (17,

     19) coupled to the plurality of switching nodes and user units;

A) means (43, 47,

     53) associated with the switching nodes for allocating a Routing Identifier RI to any user unit being activated at a specific network location for connectionless data transfer services;

said Routing Identifier RI indicating a path to a single user unit to which message cells are to be routed, not established by a connection set-up procedure which establishes connection between user units wanting to communicate and remaining the same value throughout the network;

B) in each switching node of said network, table means (51,

     53) including a portion of each allocated Routing Identifier RI and respective routing directions for correctly routing a message cell containing a Routing Identifier RI, to the respective user unit;

C) in the network management center, means (59,

     61) for maintaining a global table including the address of each user unit activated for connectionless service, together with each allocated Routing Identifier RI, and means (55,

     59) for updating the global table each time a new Routing Identifier RI is allocated to an user unit; and

D) in each user unit;

D1) means (27,

     31) for transmitting, when the user unit desires to send a data message in connectionless mode to another user unit, a signalling message to said network management center requesting the other user unit Routing Identifier RI,

D2) means (27,

     33) for receiving, from said network management center in a signalling message the respective Routing Identifier RI if existing, and

D3) means (21, 23,

     33) for sending a data message to said another user unit by including said received Routing Identifier RI in the header of at least one cell of said data message.

12. The Asynchronous Transfer Mode Network of claim 11 further including a VPI/VCI table, in each of the switching nodes, containing information to be used in a connection-oriented virtual circuit service.

13. In an Asynchronous Transfer Mode Network having a plurality of switching nodes, a plurality of user units connected to each one of the switching nodes and a network management center, an apparatus for transferring data messages without establishing a connection between users, said apparatus comprising:

a first generator for generating an ATM cell including a first field for inserting a Routing Identifier RI, said RI identifying routing to a location of a user unit using connectionless data transfer services, not established through connection set-up procedures which establishes a connection between user units remaining the same value throughout the network;

a second generator for generating a signalling message requesting the Routing Identifier RI for a named end station;

means responsive to a response signalling message to extract the Routing Identifier RI and to insert said Routing Identifier RI in the first field of the ATM cell being transferred to the named end station; and

means for transferring/receiving the ATM cell and the signalling message.