Detecting an active network node using a login attempt

• US 6,347,339 B1
• Filed: 12/01/1998
• Issued: 02/12/2002
• Est. Priority Date: 12/01/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Morris, Herbert C., Calabrese, John S.
• Primary Examiner(s): Winder, Patrice L.
• Application Number:
  US09/203,546
• Time in Patent Office: 1,169 Days
• Field of Search: 709/225, 709/227, 709/229, 709/224, 709/237, 709/223, 714/4, 714/25, 714/39, 714/6, 713/200, 713/201
• US Class Current: 709/237
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications
• CPC Class Codes: H04L 43/0811 by checking connectivity

Abstract

A method and apparatus for notifying a first network node that a second network node has gone off-line during a communication session is disclosed. The first network node may be a client and the second network node may be a server. The client and the server communicate using an embedded protocol, such as telnet. The protocol defines a login process that must be used by the client to establish a logical connection to the server. The protocol also specifies that the server must immediately issue a response to a login attempt, by either establishing a connection or issuing an error message. The first network node determines that no communications have been received from the second server in a pre-determined period of time. The first network node generates invalid login information, such as a randomly generated invalid user id and an invalid password. A login command is sent from the first network node to the second network node. The login command includes the previously generated invalid login information. The second network node responds, indicating that the login information is invalid or that login is refused. The response provides a positive indication to the first network node that the second network node is on-line. The process can be repeated frequently without requiring any significant system resources. If the second network node does not immediately respond, the communication session can be recovered or terminated, thereby maximizing system resources.

Claims

1. A method of determining from a first node in a network whether a second node is active, wherein the first node has previously established a logical connection to the second node, comprising the computer-implemented steps of:

communicating network messages between the first node and the second node;

after a pre-determined period of inactivity in communicating the network messages;

generating login information that is invalid at the second node;

sending an invalid login command that contains the invalid login information to the second node; and

determining that the second node is active when the second node responds to the login command by refusing to execute a login of the first node.

2. The method recited in claim 1, further including:

determining that the second node is inactive when the second node fails to respond to the invalid login command after a predetermined time period.

3. The method recited in claim 1, wherein generating login information comprises generating a randomly-selected invalid user identifier and generating a randomly-selected invalid password that is associated with the user identifier.

4. The method recited in claim 3, wherein sending a login command comprises sending a Telnet login command, with the invalid user identifier and user password as parameters, to the second node.

5. The method recited in claim 1, wherein sending a login command comprises sending a Telnet protocol login command, containing the invalid user information as a parameter, from the first node to the second node.

6. In a network system comprising a first node and a second node that communicate over a network using Telnet protocol, a method of determining from the first node whether the second node is operational, the method comprising:

after a predetermined period of inactivity in communicating network messages;

generating login information that is invalid at the second node;

sending an invalid login command that contains the invalid login information to the second node;

determining that the second node is active only if the second node immediately responds to the login command by refusing to execute a login of the first node; and

determining that the second node is inactive only if the second node fails to immediately respond to the invalid login command.

7. A method of determining whether an access server is active, from a client that is coupled through a network to the access server, and wherein a fixed pre-determined number of connections are permitted between the client and the access server, comprising:

communicating network messages between the client and access server;

after a pre-determined period of inactivity in communicating the network messages;

generating invalid login information at the client;

sending an invalid login command that contains the invalid login information from the client to the access server; and

determining that the access server is active only if access server immediately responds to the login command by refusing to execute a login of the client.

8. The method recited in claim 7, further including:

determining that the access server is inactive only when the access server fails to respond to the client after a predetermined time period.

9. The method recited in claim 7, wherein generating invalid login information comprises generating, at the client, a randomly-selected user identifier and generating a randomly-selected user password, wherein the user identifier and user password are invalid at the access server.

10. The method recited in claim 7, wherein sending a login command comprises sending a Telnet login command, containing the invalid user information as a parameter, from the client to the access server.

11. A network node, comprising:

a network interface coupled through a network to a second node whereby the network node is logically connected to the second node;

one or more processors; and

a memory comprising one or more sequences of instructions which, when executed by the one or more processors, cause the network node to carry out the steps of;

communicating network messages between the first node and the second node;

after a pre-determined period of inactivity in communicating the network messages;

generating login information that is invalid at the second node;

sending a login command, including the login information, from the first node to the second node; and

determining that the second node is active only if the second node immediately responds to the login command by refusing to execute a login of the first node.

12. The network node recited in claim 11, the memory further including sequences of instructions that cause the network node to carry out the steps of:

determining that the second node is inactive only when the second node fails to respond to the first node after a predetermined time period.

13. The network node recited in claim 11, wherein generating login information comprises generating a randomly-selected user identifier and generating a randomly-selected user password.

14. The network node recited in claim 13, wherein sending a login command comprise sending a Telnet login command, with the user identifier and user password as parameters, to the second node.

15. The network node recited in claim 11, wherein sending a login command comprises sending a Telnet protocol login command, containing the user information as a parameter, from the first node to the second node.

16. A computer-readable medium comprising one or more sequences of instructions, which when executed by one or more processors, cause the one or more processors to carry out the steps of:

communicating network messages between a first node and a second node;

after a pre-determined period of inactivity in communicating the network messages;

generating login information that is invalid at the second node;

sending an invalid login command, including the invalid login information, from the first node to the second node; and

determining that the second node is active only if the second node immediately responds to the login command by refusing to execute a login of the first node.

17. The computer-readable medium recited in claim 16, wherein generating login information comprises generating a randomly-selected user identifier and generating a randomly-selected user password.

18. The computer-readable medium recited in claim 16, and wherein sending a login command comprises sending a Telnet login command, including the user identifier and the user password as parameters, to the second server.

19. An apparatus for determining from a first node in a network whether a second node is active, wherein the first node has previously established a logical connection to the second node, comprising:

means for communicating network messages between the first node and the second node;

means for generating, after a pre-determined period of inactivity in communicating the network messages, login information that is invalid at the second node, for sending an invalid login command that contains the invalid login information to the second node, and for determining that the second node is active when the second node responds to the login command by refusing to execute a login of the first node.

20. The apparatus recited in claim 19, further including means for determining that the second node is inactive when the second node fails to respond to the invalid login command after a predetermined time period.

21. The apparatus recited in claim 19, wherein the means for generating login information comprises means for generating a randomly-selected invalid user identifier and generating a randomly-selected invalid password that is associated with the user identifier.

22. The apparatus recited in claim 21, wherein the means for sending a login command comprises means for sending a Telnet login command, with the invalid user identifier and user password as parameters, to the second node.

23. The apparatus recited in claim 19, wherein the means for sending a login command comprises means for sending a Telnet protocol login command, containing the invalid user information as a parameter, from the first node to the second node.

24. A method of determining from a first node in a network whether a second node is active, wherein the first node has previously established a logical connection to the second node, comprising the computer-implemented steps of:

communicating network messages between the first node and the second node;

after a pre-determined period of inactivity in communicating the network messages;

at the second node, generating login information that is known to be invalid;

sending an invalid login command that contains the invalid login information to the second node; and

automatically determining that the second node is active when the second node responds to the login command by refusing to execute a login of the first node.