System and method for providing backup machines for implementing multiple IP addresses on multiple ports

• US 6,298,063 B1
• Filed: 03/15/2000
• Issued: 10/02/2001
• Est. Priority Date: 11/03/1995
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Kersey, Edward C., Coile, Brantley W., Howes, Richard A.
• Primary Examiner(s): Olms, Douglas
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US09/526,118
• Time in Patent Office: 566 Days
• Field of Search: 370/241, 370/242, 370/243, 370/244, 370/245, 370/246, 370/247, 370/252, 370/348, 370/349, 370/401, 370/402, 370/403, 370/404, 370/405, 370/389, 370/392
• US Class Current: 370/401
• CPC Class Codes: H01R 2201/04 for network, e.g. LAN connectors
• CPC Class Codes: H01R 31/005 Intermediate parts for distributing signals
• CPC Class Codes: H04L 2101/663 Transport layer addresses, e.g. aspects of transmission control protocol [TCP] or user datagram protocol [UDP] ports
• CPC Class Codes: H04L 41/00 Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/2517 using port numbers
• CPC Class Codes: H04L 61/2564 for a higher-layer protocol, e.g. for session initiation protocol [SIP]
• CPC Class Codes: H04L 63/0254 Stateful filtering
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/63 Routing a service request depending on the request content or context
• 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

Abstract

A system and method are disclosed for redirecting a connection from a first server having a first server IP address. Incoming SYN packets sent from a client are intercepted. The SYN packets have a destination IP address corresponding to the connection and the SYN packets are sent from the client for the purpose of establishing the connection, which is supported by the first server. The number of incoming SYN packets sent from the client to the first server is monitored and it is determined whether the number of unanswered SYN packets sent by the client to the first server exceeds a ditched connection threshold number of unanswered SYN packets. The destination IP address of intercepted incoming SYN packets is changed for the connection received after determining that the number of unanswered SYN requests sent by the client to the first server exceeds a ditched connection threshold number of unanswered SYN requests to the destination IP address of a second server. In this manner, the SYN packets sent from the client for the purpose of establishing the connection are sent to the second server so that the connection is established with the second server.

Claims

1. A method of redirecting a connection from a first server having a first server address comprising:

intercepting incoming SYN packets sent from a client, the SYN packets having a destination address corresponding to the connection, the SYN packets being sent from the client for the purpose of establishing the connection, and the connection being supported by the first server;

monitoring the number of incoming SYN packets sent from the client to the first server;

determining that the number of unanswered SYN packets sent by the client to the first server exceeds a ditched connection threshold number of unanswered SYN packets; and

changing the destination address of intercepted incoming SYN packets for the connection received after determining that the number of unanswered SYN requests sent by the client to the first server exceeds the ditched connection threshold number of unanswered SYN requests to the destination address of a second server,

whereby the SYN packets sent from the client for the purpose of establishing the connection are sent to the second server so that the connection is established with the second server.

2. The method recited in claim 1 further including:

monitoring the number of times that the number of unanswered SYN packets sent to the first server exceeds the ditched connection threshold number of unanswered SYN packets, each such occurrence being counted as a ditched connection by the first server; and

determining that the number of ditched connections by the first server exceeds a failure threshold number of ditched connections; and

changing the status of the first server to a failed status;

whereby connections that may have been assigned to the first server may not be assigned to the first server because of the failed status of the first server.

3. The method recited in claim 2 further including:

periodically changing the status of the first server to a test status, the test status being a status in which a limited number of test connections are assigned to the first server and in which a test failure threshold number of ditched connections is defined for changing the status of the first server back to the failed status.

4. The method recited in claim 1 wherein the ditched connection threshold number of unanswered SYN packets is three.

5. The method recited in claim 1 wherein the ditched connection threshold number of unanswered SYN packets is four.

6. The method recited in claim 1 wherein the ditched connection threshold number of unanswered SYN packets is greater than two.

7. The method recited in claim 2 wherein the failure threshold number of ditched connections is three.

8. The method recited in claim 2 wherein the failure threshold number of ditched connections is four.

9. The method recited in claim 2 wherein the failure threshold number of ditched connections is greater than two.

10. The method recited in claim 3 wherein the limited number of test connections is one.

11. The method recited in claim 3 wherein the limited number of test connections is less than three.

12. The method recited in claim 3 wherein the test failure threshold number of ditched connections is less than three.

13. The method recited in claim 3 wherein the test failure threshold number of ditched connections is one.

14. The method recited in claim 2 further including:

assigning a backup server to replace the first server so long as the status of the first server is the failed status.

15. A connection management system for redirecting a connection from a first server having a first server address comprising:

a client interface to an external network, the client interface being operative to intercept incoming SYN packets sent from a client, the SYN packets having a destination IP address corresponding to the connection, the SYN packets being sent from the client for the purpose of establishing the connection, and the connection being supported by the first server;

a connection status monitor, the connection status monitor being operative to monitor the number of incoming SYN packets sent from the client to the first server and determine whether the number of unanswered SYN packets sent by the client to the first server exceeds a ditched connection threshold number of unanswered SYN packets; and

a packet translator monitor, the packet translator monitor being operative to change the destination address of intercepted incoming SYN packets for the connection received after determining that the number of unanswered SYN requests sent by the client to the first server exceeds the ditched connection threshold number of unanswered SYN requests to the destination address of a second server,

wherein the connection management system redirects SYN packets sent from the client for the purpose of establishing the connection from the first server to the second server so that the connection is established with the second server.

16. The connection management system described in claim 15 further including:

a ditched connection monitor, the ditched connection monitor being operative to monitor the number of times that the number of unanswered SYN packets sent to the first server exceeds the ditched connection threshold number of unanswered SYN packets, each such occurrence being counted as a ditched connection by the first server and to determine whether the number of ditched connections by the first server exceeds a failure threshold number of ditched connections; and

a failure status indicator, the failure status indicator being operative to indicate the failed status of the first server;

whereby the failure status indicator indicates that connections that may have been assigned to the first server should not be assigned to the first server because of the failed status of the first server.

17. The system recited in claim 16 further including:

a failed machine tester, the failed machine tester being operative to periodically change the status of the first server to a test status, the test status being a status in which a limited number of test connections are assigned to the first server and in which a test failure threshold number of ditched connections is defined for changing the status of the first server back to the failed status.

18. The system recited in claim 15 wherein the ditched connection threshold number of unanswered SYN packets is three.

19. The system recited in claim 15 wherein the ditched connection threshold number of unanswered SYN packets is four.

20. The system recited in claim 15 wherein the ditched connection threshold number of unanswered SYN packets is greater than two.

21. The system recited in claim 16 wherein the failure threshold number of ditched connections is three.

22. The system recited in claim 16 wherein the failure threshold number of ditched connections is four.

23. The system recited in claim 16 wherein the failure threshold number of ditched connections is greater than two.

24. The system recited in claim 17 wherein the limited number of test connections is one.

25. The system recited in claim 17 wherein the limited number of test connections is less than three.

26. The system recited in claim 17 wherein the test failure threshold number of ditched connections is one.

27. The system recited in claim 17 wherein the test failure threshold number of ditched connections is less than three.

28. The system recited in claim 16 further including a backup server designator, said backup server designator being operative to designate a backup server to replace the first server so long as the status of the first server is the failed status.

29. A method of redirecting packets from a first server having a first server address comprising:

intercepting incoming initialization packets sent from a client, the packets having a destination address corresponding to a communication protocol supported by the first server, the incoming initialization packets being sent from the client for the purpose of establishing a communication, the communication being supported by the first server;

monitoring the number of incoming packets sent from the client to the first server;

determining that the number of unanswered initialization packets sent by the client to the first server exceeds a failed communication threshold number of unanswered initialization packets; and

changing the destination address of intercepted incoming initialization packets for a communication received after determining that the number of unanswered initialization requests sent by the client to the first server exceeds the failed communication threshold number of unanswered initialization packets to the destination address of a second server;

wherein the initialization packets sent from the client for the purpose of establishing the communication are sent to the second server so that the communication is established with the second server.