Broadcast control system, network element, and switching node apparatus with broadcast cell routing capabilities in asynchronous transmission mode network

• US 6,385,200 B1
• Filed: 01/23/1998
• Issued: 05/07/2002
• Est. Priority Date: 08/08/1997
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ishigaki, Shinichi, Erami, Akihisa
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): NGUYEN, STEVEN H D
• Application Number:
  US09/012,503
• Time in Patent Office: 1,565 Days
• Field of Search: 370/254, 370/255, 370/248, 370/252, 370/389, 370/390, 370/394, 370/392, 370/395, 370/399, 370/397, 370/400, 370/409, 709/224, 709/223, 709/220, 709/228, 709/236
• US Class Current: 370/395.42
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/562 Routing
• CPC Class Codes: H04L 2012/5642 Multicast/broadcast/point-multipoint, e.g. VOD
• CPC Class Codes: H04L 49/201 Multicast operation; Broadcast operation
• CPC Class Codes: H04L 49/205 Quality of Service based
• CPC Class Codes: H04L 49/25 Routing or path finding in a switch fabric
• CPC Class Codes: H04L 49/501 Overload detection

Abstract

A broadcast control system and its components capable of determining unique routes to deliver broadcast cells to every destination in an ATM network, which is designed to avoid network congestion and subsequent degradation in quality of service, as well as to reduce the workloads imposed on network equipment. The ATM network is organized by a plurality of network elements and at least one service provider terminal connected to a source network element. A broadcast routing controller disposed in the source network element distributes a broadcast routing control cell over the ATM network. Each network element on the network receives this broadcast routing control cell as well as its replicas delivered through different paths, and on the basis of information contained in those control cells, it establishes its own routing data in the local storage. This routing data indicates a particular link that is connected to the shortest path between the source network element and the present network element. When relaying broadcast cells, each network element selectively accepts broadcast cells coming through a particular link registered in the routing data and redistributes them to adjacent network elements.

Claims

1. A broadcast control system for controlling broadcast message distribution in an ATM network which is organized by a plurality of network elements and at least one service provider terminal connected to a source network element among the plurality of network elements, each network element having a plurality of links that extend to other network elements, the service provider terminal being a source of a broadcast cell, the broadcast control system comprising:

broadcast routing control cell transmission means, disposed in the source network element, for distributing a broadcast routing control cell containing reception link decision data to the plurality of network elements;

control cell relaying means, disposed in each of the plurality of network elements and activated when the broadcast routing control cell is received via one of the plurality of links, for modifying the reception link decision data contained in the received broadcast routing control cell, and transmitting the broadcast routing control cell with the modified reception link decision data through the plurality of links except for the one of the plurality of links used to receive the broadcast routing control cell;

link selection &

storage means, disposed in each of the plurality of network elements and activated when a plurality of broadcast routing control cells have been received via different routes, for selecting a particular link from among the plurality of links, based on the reception link decision data contained in each broadcast routing control cell received, and storing a record of a combination of the particular link and the source network element which distributed the plurality of broadcast routing control cells; and

broadcast cell relaying means, disposed in each of the plurality of network elements, for receiving the broadcast cell through one of the plurality of links, identifying a network element that has distributed the broadcast cell, and transmitting the broadcast cell through the rest of the plurality of links if said link selection &

storage means has a record that matches with a combination of the network element identified as the sender of the broadcast cell and the one of the plurality of links that was used to receive the broadcast cell.

2. The broadcast control system according to claim 1, further comprising cell discarding means, disposed in each of the plurality of network elements in connection with said broadcast cell relaying means, for discarding the received broadcast cell if said link selection &

storage means has no record that matches with the combination of the sender network element of the broadcast cell and the one of the plurality of links used to receive the broadcast cell.

3. The broadcast control system according to claim 1, wherein

the broadcast routing control cell consists of a header section and a payload section, and

the payload section carries a cell type that shows identity as a broadcast routing control cell, a source identifier that indicates which network element has originally sent the present broadcast routing control cell, and the number of network elements through which the broadcast routing control cell has passed before reaching the present network element.

4. The broadcast control system according to claim 1, wherein

the broadcast routing control cell consists of a header section and a payload section, and

the header section carries, using a part of VCI/VPI fields thereof, a cell type that shows identity as a broadcast routing control cell, a source identifier that indicates which network element has originally sent the present broadcast routing control cell, and the number of network elements through which the broadcast routing control cell has passed before reaching the present network element.

5. The broadcast control system according to claim 1, wherein

the broadcast cell consists of a header section and a payload section, and

the payload section carries a cell type that shows identity as a broadcast cell and a source identifier that indicates which network element has distributed the present broadcast cell that originated at the service provider terminal.

6. The broadcast control system according to claim 1, wherein

the broadcast cell consists of a header section and a payload section, and

the header section carries, in a part of VCI/VPI fields thereof, a cell type that is used to identify the broadcast cell and an identifier that indicates the sender network element that has distributed the broadcast cell having originated at the service provider terminal.

7. The broadcast control system according to claim 1, wherein

the reception link decision data contained in the broadcast routing control cell indicates the number of network elements through which the broadcast routing control cell has passed before reaching the present network element, and

said link selection &

storage means stores the record containing

(a) an identifier of the source network element that distributed the plurality of broadcast routing control cells,

(b) an identifier of the particular link that was used to receive a particular broadcast routing control cell exhibiting the smallest value in the reception link decision data, and

(c) the smallest value of network elements.

8. The broadcast control system according to claim 1, wherein

the reception link decision data contained in the broadcast routing control cell is a counter value that represents the number of network elements through which the broadcast routing control cell has passed before reaching the present network element,

the modification performed by said control cell relaying means is an addition of an increment to the counter value, and

said control cell relaying means disposed in some of the plurality of network elements adds a larger increment to the counter value than the increment to be given in the rest of the plurality of network elements.

9. The broadcast control system according to claim 1, further comprising:

request cell transmission means, disposed in each of the plurality of network elements, for transmitting a request cell that requests the source network element to transmit the broadcast routing control cell; and

control cell retransmission means, disposed in each of the plurality of network elements, for directing said broadcast routing control cell transmission means to retransmit the broadcast routing control cell, upon receipt of the request cell.

10. A network element having a broadcast control function for controlling broadcast message distribution in an ATM network organized by a plurality of network elements and at least one service provider terminal connected to a source network element that is one of the plurality of network elements, each network element having a plurality of links that extend to other network elements, the service provider terminal being a source of a broadcast routing control cell and a broadcast cell, the network element comprising:

control cell relaying means for receiving the broadcast routing control cell through one of the plurality of links, modifying reception link decision data contained in the received broadcast routing control cell, and transmitting the broadcast routing control cell with the modified reception link decision data through the plurality of links except for the one of the plurality of links used to receive the broadcast routing control cell;

link selection &

storage means, activated when a plurality of broadcast routing control cells have been received via different routes in the ATM network, for selecting a particular link from among the plurality of links, based on the reception link decision data contained in each broadcast routing control cell received, and storing a record of the particular link selected in association with the service provider terminal that originally generated the broadcast routing control cell or the source network element to which the service provider terminal is connected; and

broadcast cell relaying means for receiving the broadcast cell through one of the plurality of links, identifying a service provider terminal that is the source of the broadcast cell or a network element that has originally distributed the broadcast cell, and transmitting the broadcast cell through the rest of the plurality of link if said link selection &

storage means has a record that matches with a combination of the identified service provider terminal or network element and the one of the plurality of links that was used to receive the broadcast cell.

11. The network element according to claim 10, further comprising cell discarding means for discarding the received broadcast cell if said link selection &

storage means has no record that matches with the combination of the identified service provider terminal or network element and the one of the plurality of links that was used to receive the broadcast cell.

12. A broadcast control system for controlling broadcast message distribution in an ATM network which is organized by a plurality of network elements and at least one service provider terminal connected to a source network element among the plurality of network elements, each network element having a plurality of links that extend to other network elements, the service provider terminal being a source of a broadcast cell, the broadcast control system comprising:

broadcast routing control cell transmission means, disposed in the source network element, for distributing a broadcast routing control cell to the plurality of network elements except for the source network element, the broadcast routing control cell containing a counter value that represents the number of network elements through which the broadcast routing control cell has passed;

control cell relaying means, disposed in each of the plurality of network elements, for receiving the broadcast routing control cell through one of the plurality of links, incrementing the counter value contained in the received broadcast routing control cell, and transmitting the broadcast routing control cell with the incremented counter value through the plurality of links except for the one of the plurality of links used to receive the broadcast routing control cell;

response cell transmission means, disposed in each of the plurality of network elements, for transmitting a response cell through the one of the plurality of links that was used to receive the broadcast routing control cell, the response cell containing a replica of the counter value extracted from the received broadcast routing control cell and an identifier of the present network element responding to the broadcast routing control cell;

first detection &

storage means, disposed in the source network element and activated when a plurality of response cells have been received from the same responding network element via different routes in the ATM network, for detecting a particular response cell that exhibits the smallest counter value among those extracted from the plurality of response cells received, and storing a record that contains the identifier of the responding network element and the smallest counter value extracted from the detected particular response cell;

second detection &

storage means, disposed in the source network element, for searching said first detection &

storage means to detect a particular record that exhibits the largest counter value among all the records stored therein concerning the different responding network elements, and storing the largest counter value in the particular record detected;

broadcast cell transmission means, disposed in the source network element, for receiving the broadcast cell from the service provider terminal and distributing the received broadcast cell to the plurality of network elements after transferring the largest counter value stored in said second detection &

storage means to a down-counter field disposed as part of the received broadcast cell; and

broadcast cell relaying means, disposed in each of the plurality of network elements, for receiving the broadcast cell through one of the plurality of links, decrementing the down-counter field of the received broadcast cell, and transmitting the broadcast cell through the rest of the plurality of link only when the decremented down-counter field exhibits a non-zero value.

13. A broadcast control system for controlling broadcast message distribution in an ATM network which is organized by a plurality of network elements and at least one service provider terminal connected to a source network element among the plurality of network elements, each network element having a plurality of links that extend to other network elements, the service provider terminal being a source of a broadcast cell, the broadcast control system comprising:

broadcast routing control cell transmission means, disposed in the source network element, for distributing a broadcast routing control cell to the plurality of network elements except for the source network element, the broadcast routing control cell containing a counter value that represents the number of network elements through which the broadcast routing control cell has passed;

control cell relaying means, disposed in each of the plurality of network elements, for receiving the broadcast routing control cell through one of the plurality of links, incrementing the counter value contained in the received broadcast routing control cell, and transmitting the broadcast routing control cell with the incremented counter value through the plurality of links except for the one of the plurality of links used to receive the broadcast routing control cell;

link selection &

storage means, disposed in each of the plurality of network elements and activated when a plurality of broadcast routing control cells have been received via different routes within a predetermined time period, for selecting a particular broadcast routing control cell exhibiting the smallest counter value from among the plurality of broadcast routing control cells received, identifying a link that was used to receive the particular broadcast routing control cell, and storing a record of the identified link in combination with the source network element that originally distributed the broadcast routing control cell;

response cell transmission means, disposed in each of the plurality of network elements, for transmitting a response cell through the identified link in response to the particular broadcast routing control cell selected by said link selection &

storage means, the response cell carrying an identifier of the source network element that originally distributed the broadcast routing control cell;

relaying link storage means, disposed in each of the plurality of network elements and activated when the response cell is received through one of the plurality of links, for extracting the identifier of the source network element from the received response cell, and storing a record of the one of the plurality of links that was used to receive the response cell, in association with the extracted identifier of the source network element; and

broadcast cell relaying means, disposed in each of the plurality of network elements and activated when the broadcast cell is received, for retrieving a record relevant to the source network element from said relaying link storage means and transmitting the broadcast cell through the links described in the retrieve record.