SYSTEMS AND METHODS FOR MAINTAINING PERSISTENCE BY A BACKUP VIRTUAL SERVER

• US 20100128598A1
• Filed: 11/24/2009
• Published: 05/27/2010
• Est. Priority Date: 11/25/2008
• Status: Active Grant

• Current Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Original Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Inventors: Gandhewar, Dinesh, Muthiah, Manikam
• Granted Patent: US 8,780,718 B2
• Time in Patent Office: Days
• US Class Current: 370/217
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/1014 based on the content of a request
• CPC Class Codes: H04L 67/1025 Dynamic adaptation of the criteria on which the server selection is based
• CPC Class Codes: H04L 67/1029 using data related to the state of servers by a load balancer
• CPC Class Codes: H04L 67/1034 Reaction to server failures by a load balancer
• CPC Class Codes: H04L 67/2885 Hierarchically arranged intermediate devices, e.g. for hierarchical caching
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54
• CPC Class Codes: H04L 67/563 Data redirection of data network streams
• 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

Abstract

The present disclosure presents systems and methods for maintaining persistence of a backup virtual server on connections currently serviced by the backup virtual server. A virtual server operating on an intermediary network device and identified as a primary virtual server for a first connection may receive a request via the first connection. The intermediary device may forward the first request to a backup virtual server of the virtual server in response to identifying that the virtual server is unavailable. The intermediary device may later identify that the virtual server is available. The virtual server may establish a new connection responsive to receiving a connection request while the intermediary device may forward a second request received via the first connection to the backup virtual server instead of the virtual server responsive to identifying that the virtual server is configured not to preempt the backup virtual server from maintaining connections currently maintained by the backup virtual server.

Claims

1. A method for maintaining connection persistence by a backup virtual server, the method comprising:

(a) receiving, by a virtual server configured on an intermediary device deployed between a client and a server, a request via a first connection established between the client and the server, the virtual server identified as a primary virtual server for the first connection, the virtual server having a backup virtual server;

(b) forwarding, by the intermediary device, the request to the backup virtual server in response to identifying that the virtual server is unavailable;

(c) identifying, by the intermediary device, that the virtual server is available;

(d) establishing, by the virtual server, a second connection responsive to receiving a connection request;

(e) receiving, by the intermediary device, a second request via the first connection; and

(f) determining, by the intermediary device, to forward the second request to the backup virtual server instead of the virtual server responsive to identifying that the virtual server is configured not to preempt the backup virtual server from servicing connections currently serviced by the backup virtual server.

2. The method of claim 1, further comprising step (g) comprising forwarding, by the intermediary device, a third request received via the second connection to the virtual server while the virtual server is available.

3. The method of claim 1, wherein the step (b) further comprises identifying, by the intermediary device, that the virtual server is unavailable in response to determining that a number of connections maintained by the virtual server exceeds a predetermined threshold.

4. The method of claim 1, wherein the step (b) further comprises identifying, by the intermediary device, that the virtual server is unavailable in response to determining that one of an amount of network traffic managed by the virtual server or a bandwidth of the network traffic managed by the virtual server exceeds a predetermined threshold.

5. The method of claim 1, wherein the step (b) further comprises identifying, by the intermediary device, that the virtual server is unavailable in response to determining that the virtual server is not functional.

6. The method of claim 1, wherein the step (d) further comprises forwarding, by the intermediary device, the connection request to the virtual server in response to identifying by the intermediary device that the virtual server is available.

7. The method of claim 1, wherein the step (f) further comprises forwarding, by the intermediary device, the second request to the backup virtual server.

8. The method of claim 1, wherein the step (f) further comprises determining, by the intermediary device, to forward the second request to the backup virtual server even though the virtual server is available.

9. The method of claim 1, further comprising:

(g) receiving, by the intermediary device, a third request via the first connection; and

(h) forwarding, by the intermediary device, the third request to the backup virtual server in response to the identification of the configuration of the virtual server and identifying that both of the virtual server and the backup virtual server are available.

10. The method of claim 1, further comprising:

(g) receiving, by the intermediary device, a fourth request via the second connection; and

(h) forwarding, by the intermediary device, the fourth request to the virtual server upon identifying that the virtual server and the backup virtual server are both available.

11. A system for maintaining connection persistence by a backup virtual server, the system comprising:

a virtual server configured on an intermediary device deployed between a client and a server receiving a request via a first connection established between the client and the server, the virtual server identified as a primary virtual server for the first connection, the virtual server having a backup virtual server and establishing a second connection responsive to receiving a connection request

the intermediary device forwarding the request to the backup virtual server in response to identifying that the virtual server is unavailable, identifying that the virtual server is available, receiving a second request via the first connection and determining to forward the second request to the backup virtual server instead of the virtual server responsive to identifying that the virtual server is configured not to preempt the backup virtual server from servicing connections currently serviced by the backup virtual server.

12. The system of claim 11, wherein the intermediary device forwards a third request received via the second connection to the virtual server while the virtual server is available.

13. The system of claim 11, wherein the intermediary device identifies that the virtual server is unavailable in response to determining that a number of connections maintained by the virtual server exceeds a predetermined threshold.

14. The system of claim 11, wherein the intermediary device identifies that the virtual server is unavailable in response to determining that one of an amount of network traffic managed by the virtual server or a bandwidth of the network traffic managed by the virtual server exceeds a predetermined threshold.

15. The system of claim 11, wherein the intermediary device identifies that the virtual server is unavailable in response to determining that the virtual server is not functional.

16. The system of claim 11, wherein the intermediary device forwards the connection request to the virtual server in response to identifying by the intermediary device that the virtual server is available.

17. The system of claim 11, wherein the intermediary device forwards the second request to the backup virtual server.

18. The system of claim 11, wherein the intermediary device determines to forward the second request to the backup virtual server even though the virtual server is available.

19. The system of claim 11, wherein the intermediary device receives a third request via the first connection and forwards the third request to the backup virtual server in response to the identification of the configuration of the virtual server and identifying that both of the virtual server and the backup virtual server are available.

20. The system of claim 11, wherein the intermediary device receives a fourth request via the second connection and forwards the fourth request to the virtual server upon identifying that the virtual server and the backup virtual server are both available.