Detecting an active network node using an invalid protocol option

• US 6,304,905 B1
• Filed: 09/16/1998
• Issued: 10/16/2001
• Est. Priority Date: 09/16/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Clark, Glenwood
• Primary Examiner(s): Rinhart, Mark H.
• Assistant Examiner(s): JAROENCHONWANIT, BUNJOB
• Application Number:
  US09/154,608
• Time in Patent Office: 1,126 Days
• Field of Search: 709/224, 709/223, 709/220, 709/204, 709/203, 707/501, 340/825.29, 340/7.23, 340/5.3, 714/49, 714/39, 714/47, 370/252
• US Class Current: 709/224
• CPC Class Codes: H04L 67/51 Discovery or management thereof, e.g. service location protocol [SLP] or web services
• CPC Class Codes: H04L 67/535 Tracking the activity of the user network monitoring arrangements H04L43/00; recording of computer activity G06F11/34
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

A method and apparatus for providing notification to a client that an access server is on-line during a communication session is disclosed. The client and the access server execute an embedded protocol, such as telnet, to define the communication session. The protocol defines a negotiation-style communication session in which a client issues a request and a server must issue a mandatory acknowledgment that identifies how the request is handled. A command option is sent from the client to the access server, wherein the option is an invalid telnet option. The access server responds, indicating that the option is invalid. The access server'"'"'s response provides a positive indication to the client that the access server is on-line. The process can be repeated frequently without requiring any significant system resources. If the access server does not immediately respond, the communication session between the client and access server can thereafter be recovered or terminated, thereby maximizing system resources.

Claims

1. A method for a first network node to determine that a second network node is active during a network communication session using a network communication protocol that defines one or more request messages and one or more corresponding mandatory acknowledgment messages, the method comprising:

sending a command from the first network node to the second network node using the network communication protocol, in which the command comprises at least one parameter value that is invalid under the protocol;

receiving a substantially immediate response from the second network node in which the response indicates that the parameter value is invalid; and

determining, at the network node process, that the second network node is active.

2. The method of claim 1, further comprising:

testing for substantially immediate receipt of the response from the second network node; and

at the first computer process, immediately determining that the second network node is off-line when the response is not immediately received.

3. The method of claim 2, further comprising terminating the communication session immediately when the second network node does not immediately respond to the command.

4. The method of claim 2, further comprising implementing a recovery procedure when the second network node does not immediately respond to the command.

5. The method of claim 1, wherein the first network node is a network client and the second network node is an access server that executes the protocol in embedded fashion.

6. A method for a first network node to determine that a second network node is off-line during a network communication session using telnet as an embedded network communication protocol, the method comprising the steps of:

sending a command from said first network node to said second network node, wherein the command comprises an invalid telnet option that is included in the command intentionally to determine whether the second network node is off-line;

receiving a response from said second network node, wherein the response indicates that the command contains an invalid option; and

determining, at the first network node, that the second network node is off-line when the second network node fails to immediately respond to the command.

7. A network access apparatus, comprising:

an access network node that includes a telnet interface that is coupled to a client network node and a communications interface that is coupled to a network service of a routed computer network;

means for sending an invalid telnet command option from the client network node to the network access apparatus using the telnet interface;

means for sending a response from the access computer process to the client network node, in which the response indicates that the command option is invalid; and

means for determining, at the client network node, that the access network node is active when the response is received substantially immediately and for determining that the access network node is inactive when the response is not received substantially immediately.

8. The apparatus of claim 7, in which the access network node executes the telnet protocol in an embedded fashion.

9. The apparatus of claim 7, further comprising:

means for testing for immediate receipt of the response from the second network node; and

means, at the first computer process, for immediately determining that the second network node is off-line when the response is not immediately received.

10. The apparatus of claim 9, further comprising means for immediately terminating the communication session when the second network node does not immediately respond to the command.

11. The apparatus of claim 9, further comprising means for implementing a recovery procedure when the second network node does not immediately respond to the command.

12. The apparatus of claim 9, wherein the first network node is a client and the second network node is an access server that executes the protocol in embedded fashion.

13. The apparatus of claim 9, wherein the second network node includes a com port interface coupled to a modem interface, in which the modem interface is coupled to a remote service that provides information to the client.

14. A computer data signal embodied in a carrier wave, the computer data signal carrying one or more sequences of instructions for a first network node to determine that a second network node is active during a communication session using a protocol that defines one or more request messages and one or more corresponding mandatory acknowledgment messages, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

sending a command from the first network node to the second network node, in which the command comprises at least one parameter value that is invalid under the protocol;

sending a response from the second network node to the first network node, in which the response indicates that the parameter value is invalid; and

determining, at the first network node, that the second network node is active.

15. The computer data signal of claim 14, the steps further comprising:

testing for immediate receipt of the response from the second network node; and

at the first computer process, immediately determining that the second network node is off-line when the response is not immediately received.

16. The computer data signal of claim 15, the steps further comprising terminating the communication session immediately when the second network node does not immediately respond to the command.

17. The computer data signal of claim 15, the steps further comprising implementing a recovery procedure when the second network node does not immediately respond to the command.

18. The computer data signal of claim 15, wherein the first network node is a client and the second network node is an access server that executes the protocol in embedded fashion.

19. The computer data signal of claim 18, wherein the second network node includes a corn port interface coupled to a modem interface, in which the modem interface is coupled to a remote service that provides information to the client.

20. A method for a first network node to determine that a second network node is inactive during a communication session using an application layer network communication protocol that defines one or more request messages and a mandatory acknowledgment message for use in responding to an invalid protocol option, the method comprising:

sending a command from the first network node to the second network node, the command having a parameter value that is invalid under the protocol that is included in the command intentionally to determine whether the second network node is inactive;

waiting to receive a response directed from the second network node to the first network node;

if a response is received substantially immediately and the response indicates that the parameter value is invalid, determining that the second network node is active;

if a response is not received substantially immediately, determining immediately that the second network node is inactive.

21. A network access server that can determine that a network client node is active during a network communication session using a protocol that defines one or more request messages and one or more mandatory corresponding acknowledgment messages, the network access server comprising:

means for sending a command from the network access server to the network client node, the command having a parameter value that is invalid under the protocol;

means for waiting to receive a response directed from the network client node to the network access server;

means for determining, if a response is received substantially immediately and the response indicates that the parameter value is invalid, that the network client node is active;

means for immediately determining, if a response is not received substantially immediately, that the network client node is inactive.

22. A network access server that can determine that a network client node is active during a network communication session using a protocol that defines one or more request messages and one or more mandatory corresponding acknowledgment messages, the network access server comprising:

a processor;

a network interface that is coupled to a network that includes the network access server and the network client node, whereby the processor may send and receive information among the network means and the network client node;

one or more stored sequences of instructions which, when executed by the processor, cause the processor to carry out the steps of;

sending a command from the network access server to the network client node, the command having a parameter value that is invalid under the protocol;

waiting to receive a response directed from the network client node to the network access server;

determining, if a response is received substantially immediately and the response indicates that the parameter value is invalid, that the network client node is active;

immediately determining, if a response is not received substantially immediately, that the network client node is inactive.

23. A computer data signal embodied in a carrier wave, the computer data signal carrying one or more sequences of instructions for a first computer process to determine that a second computer process is active during a network communication session using a network communication protocol that defines one or more request messages and one or more mandatory corresponding acknowledgment messages, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

sending a command from the first computer process to the second computer process, the command having a parameter value that is invalid under the protocol;

waiting to receive a response directed from the second computer process to the first computer process;

determining, if a response is received substantially immediately and the response indicates that the parameter value is invalid, that the second computer process is active;

immediately determining, if a response is not received substantially immediately, that the second computer process is inactive.