Systems and methods for learning MSS of services

• US 8,717,916 B2
• Filed: 03/28/2011
• Issued: 05/06/2014
• Est. Priority Date: 03/28/2011
• Status: Active Grant

• Current Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Original Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Inventors: Jagadeeswaran, Ashok Kumar, Annamalaisami, Saravana
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Belur, Deepa
• Application Number:
  US13/073,705
• Publication Number:
  US 20120250530A1
• Time in Patent Office: 1,135 Days
• Field of Search: 370/252
• US Class Current: 370/252
• CPC Class Codes: H04L 43/04 Processing captured monitoring data, e.g. for logfile generation
• CPC Class Codes: H04L 43/08 Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
• CPC Class Codes: H04L 47/36 by determining packet size, e.g. maximum transfer unit [MTU]
• CPC Class Codes: H04L 65/765 intermediate
• 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 67/1023 based on a hash applied to IP addresses or costs
• CPC Class Codes: H04L 69/166 IP fragmentation; TCP segmentation

Abstract

The virtual Server (vServer) of an intermediary device deployed between a plurality of clients and services supports parameters for setting maximum segment size (MSS) on a per vServer/service basis and for automatically learning the MSS among the back-end services. In case of vServer/service setting, all vServers will use the MSS value set through the parameter for the MSS value set in TCP SYN+ACK to clients. In the case of learning mode, the backend service MSS will be learnt through monitor probing. The vServer will monitor and learn the MSS that is being frequently used by the services. When the learning is active, the intermediary device may keep statistics of the MSS of backend services picked up during load balancing decisions and once an interval timer expires, the MSS value may be picked by a majority and set on the vServer. If there is no majority, then the highest MSS is picked up to be set on the vServer.

Claims

1. A method for determining by an intermediary a maximum segment size (MSS) for a plurality of services managed by the intermediary, the method comprising:

(a) monitoring, by a device intermediary to a plurality of clients and a plurality of services, a plurality of maximum segment sizes being used via a plurality of transport layer connections between the device and the plurality of services;

(b) establishing, by the device from the monitored maximum segment sizes, a maximum segment size (MSS) value for the plurality of services having the plurality of maximum segment sizes by establishing a single MSS value from differing MSS values identified via monitoring the plurality of maximum segment sizes; and

(c) communicating, by the device to a client responsive to the client'"'"'s request to establish a transport layer connection with a service of the plurality of services, the single MSS value as a MSS for the requested transport layer connection.

2. The method of claim 1, wherein step (a) further comprises establishing, by the device, the plurality of transport layer connections to the plurality of services executing on one or more servers.

3. The method of claim 1, wherein step (a) further comprises monitoring, by the device, the plurality of maximum segment sizes on a predetermined frequency.

4. The method of claim 1, wherein step (a) further comprises monitoring, by the device, the plurality of maximum segment sizes for a predetermined time period.

5. The method of claim 4, wherein step (b) further comprises establishing, by the device, one maximum segment size (MSS) value upon expiration of the predetermined time period.

6. The method of claim 1, wherein step (b) further comprises selecting, by the device, a largest value from a plurality of MSS values identified via monitoring as the one maximum segment size (MSS) value.

7. The method of claim 1, wherein step (b) further comprises selecting, by the device, a majority value from a plurality of MSS values identified via monitoring as the one maximum segment size (MSS) value.

8. The method of claim 1, wherein step (c) further comprises advertising, by the device, the MSS value in an acknowledgment to establish the transport layer connection.

9. The method of claim 1, wherein step (c) further comprises communicating, by the device to the client, the MSS value comprising a value different from the MSS of the service to which the client connects.

10. A system for determining by an intermediary a maximum segment size (MSS) for a plurality of services managed by the intermediary, the system comprising:

a device intermediary to a plurality of clients and a plurality of services;

a monitor of the device monitoring a plurality of maximum segment sizes being used via a plurality of transport layer connections between the device and the plurality of services;

a virtual server of the device, responsive to monitoring of the plurality of maximum segment sizes, establishing a maximum segment size (MSS) value for the plurality of services having the plurality of maximum segment sizes by establishing a single MSS value from differing MSS values identified via monitoring the plurality of maximum segment sizes; and

wherein the virtual server communicates to a client responsive to the client'"'"'s request to establish a transport layer connection with a service of the plurality of services, the single MSS value as a MSS for the requested transport layer connection.

11. The system of claim 10, wherein the device establishes the plurality of transport layer connections to the plurality of services executing on one or more servers.

12. The system of claim 10, wherein the device monitors the plurality of maximum segment sizes on a predetermined frequency.

13. The system of claim 10, wherein the device monitors the plurality of maximum segment sizes for a predetermined time period.

14. The system of claim 13, wherein the device establishes the maximum segment size (MSS) value upon expiration of the predetermined time period.

15. The system of claim 10, wherein the device selects a largest value from a plurality of MSS values identified via monitoring as the one maximum segment size (MSS) value.

16. The system of claim 10, wherein the device selects a majority value from a plurality of MSS values identified via monitoring as the one maximum segment size (MSS) value.

17. The system of claim 10, wherein the device advertises the MSS value in an acknowledgment to establish the transport layer connection.

18. The system of claim 10, wherein the device communicates to the client the MSS value comprising a value different from the MSS of the service to which the client connects.