Netscaler Knowledgebase

What do you mean by performance of your application, are you sure that it is due to TCP? not HTTP?

In the past I have done extensive optimizations to sites solely on HTTP. Just once have had to change netscaler's TCP parameters.

Daniel

I do not know your scenario, but HTTP optimization can be quite complex...
On the TCP part:
When I did that TCP optimization was because the site suffered from huge spikes of traffic, so the backend servers needed protection. So a lot of optimization in surge queue, some, rate limiting was done also. The MTU was changed to a better value for that specific load. Thats all I can think of right now. Some TCP parameters were tweaked to according to the vendor for that specific server type/model/load.

The site in question handled concert tickets,

Daniel

compression and caching are both HTTP features.
Surge queue, Burst limiting, Window scaling, Window size, tcp buffer size are TCP paramets that can be tweaked on the NS.
Of this only surge queue and burst limit will have a direct impact on the backend. Window Size is possible to get an impact on the backend, but it is mainly affecting users, you should experiment on the values that provide de appliance, If I remember correctly there are only 3 possible values there. Buffer size will only limit the capacity of the netscaler and has no direct impact on the users or backend. There must be a very good reason to change the value.

My point, you should rarely look at the TCP parameters on the netscaler to gain any significant optimization, you must have detected a specific issue to change a parameter on the TCP level.

If you have problems, 90% of the times will be on the application itself or the platform on which it runs. If you have speed problems, maybe you can gain some speed with some HTTP tricks here and there, but of the application takes 1 full second to answer a query, the netscaler will not decrease that speed much.

Here are a couple KBs that should help with this -
http://support.citrix.com/article/CTX113656   for NS 8.0 to 9.0
http://support.citrix.com/article/CTX130962   for NS 9.2 and 9.3 (including VPX)

Of note, before 9.2 the TCP settings were global.  Now you can in fact create TCP profiles and possibly do exactly what you are looking to do.

http://support.citrix.com/servlet/KbServlet/download/27517-102-664714/NS-Admin-Guide.pdf   <--search for nstcp

For Client side optimizations, apply the profile to the Virtual Server, but if you want different profile settings to the back end, you have to set that on a per service basis.  So if you have ten servers hosting your app, you have to apply the server side TCP profile ten times. 

In a leading competitor, you specify client and server tcp profiles once within the virtual server.

HTH,

Carl B

mkalle,
   According to this http://support.citrix.com/proddocs/topic/netscaler-load-balancing-93/ns-lb-largescale-configsvcgrps-modify-tsk.html it does not look like you can define a TCP profile at the service group level, so you would have to apply this to each service group member.
   That would have been nice should it be available, but instead you have to apply it to n number of servers behind your virtual server.

CarlB

At Synergy a guy from AOL spoke a lot about The TCP Profiles and the ubergeeky work that they did to help their sites perform much better.  The slides and profiles should be available on Monday.

Additionally despite what the page I pulled up on Edocs states, apparently you can apply tcpprofiles to service Groups.

CarlB