End-to-end bidirectional keep-alive using virtual circuits

• US 6,304,546 B1
• Filed: 12/19/1996
• Issued: 10/16/2001
• Est. Priority Date: 12/19/1996
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Fowler, Gregory A., Natarajan, Shankar
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US08/769,305
• Time in Patent Office: 1,762 Days
• Field of Search: 370/216, 370/217, 370/218, 370/229, 370/230, 370/231, 370/235, 370/236, 370/242, 370/244, 370/284, 370/389, 370/394, 370/395, 370/396, 370/397, 370/400, 370/409, 370/410, 709/220, 709/221, 709/234, 709/235, 714/1, 714/2, 714/3, 714/4
• US Class Current: 370/216
• CPC Class Codes: H04L 12/2854 Wide area networks, e.g. public data networks
• CPC Class Codes: H04L 2012/5627 Fault tolerance and recovery
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications
• CPC Class Codes: H04L 41/40 using virtualisation of network functions or resources, e.g. SDN or NFV entities
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 43/10 Active monitoring, e.g. heartbeat, ping or trace-route
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

The invention provides a method and system for sending and receiving end-to-end bidirectional keep-alive messages using virtual circuits. Nodes coupled to a network, such as a frame relay network, periodically exchange link-layer “keep-alive” messages which indicate information regarding configuration and status of the virtual circuit, as well as information regarding congestion at sending nodes. Nodes respond to received keep-alive messages, or to timed-out failure to receive keep-alive messages, with follow-on actions, such as attempting to reconnect when a virtual circuit fails. Keep-alive messages may be propagated across multiple networks of either similar or different architecture. Keep-alive messages include sent and received sequence numbers, thus providing receiving nodes with a technique for determining if any keep-alive messages have been lost. Keep-alive messages can also include information regarding configuration of the virtual circuit, status of the virtual circuit (including counts of recent keep-alive message failure or success), and congestion at the sending node.

Claims

1. A system for providing keep-alive detection between end nodes of a virtual circuit in a data network, the system comprising:

said virtual circuit including a first end node, a second end node and at least one intermediate router;

said first end node being coupled to a first router of said at least one intermediate router;

said second end node being coupled to a second router of said at least one intermediate router, said second end node further being coupled to said first end node via said virtual circuit;

said virtual circuit being represented by an associated data link connection identifier (DLCI) other than that used by a local management interface, and configured to allow transmission of data frames between said first and second end nodes;

said first end node including a first keep-alive mechanism configured to send at least one data link-layer keep-alive REQUEST message to said second end node via said virtual circuit;

said second end node including a second keep-alive mechanism configured to respond to reception of said at least one keep-alive REQUEST message by sending at least one data link-layer keep-alive REPLY message to said first end node via said virtual circuit; and

wherein said first end node is configured to take action to alter connectivity of the virtual circuit in response to a failure to receive said at least one keep-alive REPLY message within a timeout period.

2. The system of claim 1 wherein said data network is a frame relay network, and wherein first end node is configured to transmit said at least one keep-alive REQUEST message over said virtual circuit using a frame format that is compatible with data frames being transmitted over the virtual circuit represented by the selected data link connection identifier (DLCI).

3. A system as in claim 1, wherein said at least one keep-alive REQUEST message and said at least one keep-alive REPLY message comprise data link-level protocol messages.

4. A system as in claim 1, wherein said at least one keep-alive REPLY message includes information regarding configuration of said virtual circuit.

5. A system as in claim 1, wherein said at least one keep-alive REPLY message includes information regarding status of said virtual circuit.

6. A system as in claim 1, wherein said at least one keep-alive REQUEST message includes information regarding congestion in said frame relay network at said first node.

7. A system as in claim 1, wherein said at least one keep-alive REQUEST message and said at least one keep-alive REPLY message include sent and received sequence numbers.

8. A system as in claim 1, wherein said response includes attempting to reconnect said virtual circuit.

9. A system as in claim 2, wherein said second end node is coupled to said frame relay network using a second network.

10. A system as in claim 9, wherein said second network is a frame relay network.

11. A system as in claim 9, wherein said second network is other than a frame relay network.

12. A system as in claim 1, wherein said at least one keep-alive REQUEST message and said at least one keep-alive REPLY message are each configured to be transmitted as frames according to a frame relay protocol;

and

wherein said at least one keep-alive REQUEST message and said at least one keep-alive REPLY message each include a respective field having a predetermined value which may be used for identifying the frame as a keep-alive message.

13. A method for providing keep-alive detection between end nodes of a virtual circuit in a data network, the method comprising:

sending, via the virtual circuit, at least one data link-layer keep-alive REQUEST message from a first end node to a second end node of the virtual circuit, said first end node including a keep-alive mechanism for detecting a failure of communication with said second end node, said virtual circuit being identified by an associated data link connection identifier (DLCI) other than that used by a local management interface, and configured to allow transmission of data frames between said first and second end nodes;

waiting for receipt of a data link-layer keep-alive REPLY message from said second end node via said virtual circuit; and

taking action to alter connectivity of said virtual circuit in response to a failure to receive said at least one keep-alive REPLY message within a predetermined timeout period.

14. The method of claim 13 wherein said sending includes sending a plurality of keep-alive REQUEST message to said second end node at predetermined intervals.

15. The method of claim 13, further comprising:

receiving at said second end node, via said virtual circuit, said at least one keep-alive REQUEST message; and

responding to said at least one keep-alive REQUEST message by sending at least one data link-layer keep-alive REPLY message over said virtual circuit to said first end node.

16. The method of claim 13 wherein the data network is a frame relay network.

17. A method for providing keep-alive detection between end nodes of a virtual circuit in a data network, the method comprising:

receiving at a keep-alive mechanism of a second end node, a plurality of data link-layer keep-alive REQUEST messages, at least one of said keep-alive REQUEST messages being sent from a first end node via said virtual circuit, said at least one keep-alive REQUEST message being used by the first node to detect a failure of communication with the second end node, said virtual circuit being identified by an associated data link connection identifier (DLCI) other than that used by a local management interface, and configured to allow transmission of data frames between said first and second end nodes; and

responding to each received keep-alive REQUEST message by sending a respective data link-layer keep-alive REPLY message to said first end node over said virtual circuit.

18. The method of claim 17, further comprising:

sending, via said virtual circuit, each of said plurality of said at least one keep-alive REQUEST messages from a first keep-alive mechanism at said first node;

waiting for said at least one keep-alive REPLY messages at said first keep-alive mechanism; and

taking action to alter connectivity of said virtual circuit in response to a failure to receive a keep-alive REPLY message within a selected timeout period.

19. The method of claim 17 wherein said data network is a frame relay network.

20. A computer program product for providing keep-alive detection between end nodes of a virtual circuit in a data network, the computer program product comprising:

a computer readable medium comprising;

computer code for sending, via the virtual circuit, at least one data link-layer keep-alive REQUEST message from a first end node to a second end node of the virtual circuit, said first end node including a keep-alive mechanism for detecting a failure of communication with said second end node, said virtual circuit being identified by an associated data link connection identifier (DLCI) other than that used by a local management interface, and configured to allow transmission of data frames between said first and second end nodes;

computer code for waiting for receipt of a data link-layer keep-alive REPLY message from said second end node via said virtual circuit; and

computer code for taking action to alter connectivity of said virtual circuit in response to a failure to receive said at least one keep-alive REPLY message within a predetermined timeout period.

21. The computer program product of claim 20 wherein said sending code includes computer code for sending a plurality of keep-alive REQUEST message to said second end node at predetermined intervals.

22. The computer program product of claim 20, further comprising:

computer code for receiving at said second end node, via said virtual circuit, said at least one keep-alive REQUEST message; and

computer code for responding to said at least one keep-alive REQUEST message by sending at least one data link-layer keep-alive REPLY message over said virtual circuit to said first end node.

23. The computer program product of claim 20 wherein the data network is a frame relay network.

24. A system for providing keep-alive detection between end nodes of a virtual circuit in a data network, the system comprising:

means for sending, via the virtual circuit, at least one data link-layer keep-alive REQUEST message from a first end node to a second end node of the virtual circuit, said first end node including a keep-alive mechanism for detecting a failure of communication with said second end node, said virtual circuit being identified by an associated data link connection identifier (DLCI) other than that used by a local management interface, and configured to allow transmission of data frames between said first and second end nodes;

means for waiting for receipt of a data link-layer keep-alive REPLY message from said second end node via said virtual circuit; and

means for taking action to alter connectivity of said virtual circuit in response to a failure to receive said at least one keep-alive REPLY message within a predetermined timeout period.

25. A method for providing keep-alive detection between end nodes of a virtual circuit in a data network, the method comprising:

sending, via said virtual circuit, a data link-layer keep-alive REQUEST message from a first keep-alive mechanism disposed at a first end node of the virtual circuit, said at least one keep-alive REQUEST message being addressed to a second end node of the virtual circuit, said virtual circuit being identified by an associated data link connection identifier (DLCI) other than that used by a local management interface, and configured to allow transmission of data frames between said first and second end nodes;

receiving said at least one keep-alive REQUEST message at a second keep-alive mechanism disposed at said second end node;

responding to said at least one keep-alive REQUEST message by sending at least one data link-layer keep-alive REPLY message to said first end node via said virtual circuit;

waiting for said at least one keep-alive REPLY message at said first end node; and

taking action to alter connectivity of said virtual circuit in response to a failure to receive said at least one keep-alive REPLY message within a timeout period.

26. A method as in claim 25, wherein said taking action includes attempting to reconnect said virtual circuit.

27. An end node coupled to one or more routers which are part of a virtual circuit of a frame relay network, said end node including:

a keep-alive mechanism including;

a send mechanism configured to send at least one data link-layer keep-alive REQUEST message over the virtual circuit, said virtual circuit being represented by an associated data link connection identifier (DLCI) other than that used by a local management interface, and configured to allow transmission of data frames between end nodes of the virtual circuit;

a reply receive mechanism configured to receive, via said virtual circuit, a data link-layer keep-alive REPLY message, responsive to said at least one keep-alive REQUEST message; and

a timeout mechanism configured to initiate at least one action in response to a failure to receive said at least one keep-alive REPLY message at the reply receive mechanism within a timeout period.

28. The node of claim 27, wherein the virtual circuit connects the end node to a second end node, said second end node including:

a keep-alive receive mechanism in communication with said send mechanism via said virtual circuit, said at least one keep-alive receive mechanism including;

a request receive mechanism configured to receive said at least one keep-alive REQUEST message from the first end node; and

a send reply mechanism configured to send said at least one keep-alive REPLY message responsive to the request receive mechanism.

29. The node of claim 28, wherein said second end node includes a second keep-alive mechanism.

30. The node of claim 27, wherein said at least one keep-alive mechanism further comprises a receive mechanism in communication with a second keep-alive mechanism of a second end node via a second virtual circuit represented by a second DLCI, said receive mechanism including:

a request receive mechanism configured to receive said at least one keep-alive REQUEST message from said second node; and

a send reply mechanism configured to send said at least one keep-alive REPLY message to the request receive mechanism in response to receiving said at least one keep-alive REQUEST message.

31. The node of claim 27, wherein said at least one keep-alive REQUEST message and said at least one keep-alive REPLY message comprise link-level protocol messages.