Method for detection of stale cells following route changes in a data communication

• US 6,661,773 B1
• Filed: 06/07/1999
• Issued: 12/09/2003
• Est. Priority Date: 06/07/1999
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Pelissier, Joseph E., Cameron, Donald F.
• Primary Examiner(s): Nguyen, Steven H. D
• Assistant Examiner(s): PHAN, MAN U
• Application Number:
  US09/326,573
• Time in Patent Office: 1,646 Days
• Field of Search: 370/228, 370/235, 370/236, 370/242, 370/244, 370/247, 370/395, 370/397, 370/389, 370/410, 370/216, 370/219, 370/221, 370/218, 709/232, 709/236, 709/237, 709/245
• US Class Current: 370/228
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5627 Fault tolerance and recovery
• CPC Class Codes: H04L 2012/5647 Cell loss
• CPC Class Codes: H04L 2012/5651 Priority, marking, classes
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 49/55 Prevention, detection or correction of errors

Abstract

A method for detecting and discarding stale cells following route changes in a data communication network. The data communication network comprises a transmitter, which upon detection of a failure in a route of a network, retransmits data tagged as resent data along a different route of a multi-stage switch; and a receiver, which upon detection of tagged data from the transmitter via the different route of the multi-stage switch, utilizes tagged data for data communications while discarding previously transmitted data that are not tagged to avoid data duplication.

Claims

1. A network, comprising:

a transmitter to transmit data along a route of a network and, upon detection of a failure in a route of the network, retransmit data tagged as resent data along a different route of the network;

a receiver to receive data transmitted from the transmitter and, upon detection of tagged data, utilize said tagged data for data communications, while discarding data that are not tagged to avoid data duplication; and

a switch fabric which comprises a plurality of different routes for connecting said transmitter and said receiver for data communications;

wherein said data is transmitted in groups of cells with each cell having a header utilized for tagging by said transmitter upon detection of a failure in a route of the network; and

wherein said transmitter automatically switches to a cell tagging mode to tag unique information on said data in groups of cells individually and retransmit said tagged data as resent data along a different route of the switch fabric to said receiver during a cell tagging interval.

2. A network as claimed in claim 1, wherein said cell tagging interval is set to twice a maximum delay time that a cell exists in the switch fabric before being delivered to said receiver or discarded from the switch fabric.

3. A network as claimed in claim 2, wherein said transmitter comprises a timer which terminates said cell tagging mode upon expiration of said cell tagging interval.

4. A network, comprising:

a transmitter to transmit data along a route of a network and, upon detection of a failure in a route of the network, retransmit data tagged as resent data along a different route of the network;

a receiver to receive data transmitted from the transmitter and, upon detection of tagged data, utilize said tagged data for data communications, while discarding data that are not tagged to avoid data duplication; and

a switch fabric which comprises a plurality of different routes for connecting said transmitter and said receiver for data communications;

wherein said data is transmitted in groups of cells with each cell having a header utilized for tagging by said transmitter upon detection of a failure in a route of the network; and

wherein said receiver automatically switches to a reject untagged cell mode, upon receipt of a first tagged cell of said resent data retransmitted from said transmitter, to discard all previously transmitted data that are not tagged by said transmitter to avoid data duplication for a duration that is one-half (½

) of said cell tagging interval.

5. A network as claimed in claim 4, wherein said receiver comprises a timer which terminates said reject untagged cell mode upon expiration of the duration that is one-half (½

) of said cell tagging interval.

6. A network arrangement, comprising:

a host system;

at least one remote system;

a switch fabric comprising a plurality of different switches which interconnect said host system to said remote system along different routes for data communications, and a central network manager connected to the different switches for managing network management functions, including detecting and managing link failures along different routes between said host system and said remote system;

wherein said host system, upon detection of a link failure in a route to said remote system via said switch fabric, tags data previously transmitted to said remote system and transmits tagged data as resent data along an alternate route to said remote system;

wherein said remote system, upon detection of tagged data transmitted from said host system via said switch fabric, utilizes said tagged data for data communications, while discarding previously transmitted data that are not tagged to avoid data duplication;

wherein said data is transmitted from said host system to said remote system in groups of cells with each cell having a header utilized for tagging by said host system upon detection of a link failure in the route to said remote system via said switch fabric; and

wherein said host system automatically switches to a cell tagging mode to tag unique information onto said data in groups of cells individually and transmit said tagged data as resent data along an alternate route to said remote system during a cell tagging interval.

11. A network arrangement as claimed in claim 6, wherein each switch of said switch fabric comprises:

a plurality of ports, each port connected to a link;

a receive queue and a transmit queue coupled to each port;

a forwarding database for storing cell routing information;

a relay entity coupled to the queues and the forwarding database, for obtaining cell routing information from the forwarding database and relaying the cell to the port specified by the cell routing information; and

a management entity coupled to the relay entity, for routing the cell to said remote system.

7. A network arrangement, comprising:

a host system;

at least one remote system;

a switch fabric comprising a plurality of different switches which interconnect said host system to said remote system along different routes for data communications, and a central network manager connected to the different switches for managing network management functions, including detecting and managing link failures along different routes between said host system and said remote system;

wherein said host system, upon detection of a link failure in a route to said remote system via said switch fabric, tags data previously transmitted to said remote system and transmits tagged data as resent data along an alternate route to said remote system;

wherein said remote system, upon detection of tagged data transmitted from said host system via said switch fabric, utilizes said tagged data for data communications, while discarding previously transmitted data that are not tagged to avoid data duplication;

wherein said data is transmitted from said host system to said remote system in groups of cells with each cell having a header utilized for tagging by said host system upon detection of a link failure in the route to said remote system via said switch fabric; and

wherein said cell tagging interval is set to twice a maximum delay time that a cell exists in said switch fabric before being delivered to said remote system or discarded from said switch fabric.

8. A network arrangement as claimed in claim 7, wherein said host system comprises a timer which terminates said cell tagging mode upon expiration of said cell tagging interval.

9. A network arrangement, comprising:

a host system;

at least one remote system;

a switch fabric comprising a plurality of different switches which interconnect said host system to said remote system along different routes for data communications, and a central network manager connected to the different switches for managing network management functions, including detecting and managing link failures along different routes between said host system and said remote system;

wherein said host system, upon detection of a link failure in a route to said remote system via said switch fabric, tags data previously transmitted to said remote system and transmits tagged data as resent data along an alternate route to said remote system;

wherein said remote system, upon detection of tagged data transmitted from said host system via said switch fabric, utilizes said tagged data for data communications, while discarding previously transmitted data that are not tagged to avoid data duplication;

wherein said data is transmitted from said host system to said remote system in groups of cells with each cell having a header utilized for tagging by said host system upon detection of a link failure in the route to said remote system via said switch fabric; and

wherein said remote system automatically switches to a reject untagged cell mode, upon receipt of a first tagged cell of said resent data transmitted from said host system via said switch fabric, to discard all previously transmitted data that are not tagged by said host system to avoid data duplication for a duration that is one-half (½

) of said cell tagging interval.

10. A network arrangement as claimed in claim 9, wherein said remote system comprises a timer which terminates said reject untagged cell mode upon expiration of the duration that is one-half (½

) of said cell tagging interval.

12. A method for detecting and discarding stale cells following route changes in a data communication network comprising at least a source node, a destination node, and a multi-stage switch comprised of a plurality of different routes connecting said source node to said destination node, said method comprising:

transmitting, at said source node, data in groups of cells to said destination node alone a route of said multi-stage switch;

detecting a link failure along the route of said multi-stage switch between said source node and said destination node;

upon detection, at said source node, of said link failure along the route of said multi-stage switch between said source node and said destination node, tagging unique tagging code onto a header of each cell of previously transmitted data for a cell tagging interval, and transmitting tagged cells as resent data to said destination node along an alternate route of said multi-stage switch; and

upon detection, at said destination node, of a first of tagged cells transmitted as resent data from said source node via said multi-stage switch, discarding all untagged cells for a reject untagged cell interval and utilizing said tagged cells for data communications;

wherein said cell tagging interval, corresponds to twice a maximum delay time that a cell exists in said multi-stage switch before being either delivered to said destination node or discarded from said multi-stage switch, and said reject untagged cell interval corresponds to one-half (½

) of said cell tagging interval.

13. A network comprising:

a source node to transmit data;

a destination node to receive and acknowledge data transmitted from the source node; and

a switch fabric including a plurality of switches to establish connection links between the source node and the destination along different routes for data communications;

wherein the source node is configured to detect a link failure along a route to the destination node, to tag data that was not acknowledged from the destination node during a data tagging mode, and to transmit tagged data along an alternate route to the destination node;

wherein the destination node is configured to discard, upon receipt of the tagged data transmitted from the source node, data that are not tagged during a untagged data reject mode; and

wherein the source node remains in the data tagging mode to tag data that was not acknowledged from the destination node for a tagging period greater than twice a lifetime of the switch fabric indicating a maximum delay time that data packets exist in the switch fabric before being delivered to the destination node or discarded from the switch fabric.

14. A network as claimed in claim 13, wherein the destination node remains in the untagged data reject mode for one-half (½

) of the tagging period used by the source node to tag data for transmission along the alternate route.

15. A network as claimed in claim 13, wherein the data is tagged by prepending a special code to a header of each individual data packet during the data tagging mode prior to transmission to the destination node along the alternate route.

16. A method for detecting and discarding stale data packets following route changes in a data communication network comprising at least a source node, a destination node, and a switch fabric comprised of a plurality of switches to establish connection links between the source node and the destination along different routes for data communications, said method comprising:

transmitting, at the source node, data in groups of packets along a route to the destination node;

detecting a link failure along the route between the source node and the destination node;

upon detection, at the source node, of the link failure along the route between the source node and the destination, tagging a unique code onto each data packet of previously transmitted data for a data tagging period, and transmitting tagged data packets to the destination node along an alternate route; and

upon detection, at the destination node, of a first of tagged data packets transmitted from the source node, discarding all untagged data packets for an untagged data reject period and utilizing said tagged data packets for data communications;

wherein the data tagging period is greater than twice a lifetime of the switch fabric indicating a maximum delay time that data packets exist in the switch fabric before being delivered to the destination node or discarded from the switch fabric.

17. A method as claimed in claim 16, wherein the untagged data reject period is one-half (½

) the data tagging period used by the source node to tag data packets for transmission along the alternate route.

18. A method as claimed in claim 16, wherein the source node contains a timer configured to terminate the tagging of individual data packets, upon expiration of the data tagging period.