Performance has been the key in everything we try to optimize and deliver from NetScaler. From many years and several releases we have been optimizing application delivery in XenApp and XenDesktop environments. ICA is the key protocol and we understand ICA well to optimize the flow. ICA works over TCP and for most of the protocols working on top of TCP, lots of value can be delivered by understanding the protocol behavior and accordingly optimizing the TCP layer.
NetScaler has the TCP optimization layer which is controlled by the TCP profiles. TCP profiles are feature rich from optimization and acceleration perspective and carries lots of value. The most exciting part about TCP profiles is the flexibility to use them with any TCP based endpoint on NetScaler. On same NetScaler we can use different TCP congestion avoidance algorithms for different endpoints like vservers, services etc. When we talk about ICA and the core XenApp/XenDesktop components, NetScaler plays important role from Load Balancing perspective and on every such endpoint, now we can use specific TCP profile to optimize and accelerate the flow.
Interestingly with NetScaler 10 GA build 69.4, we have added built-in TCP profile for XenApp/XenDesktop environment and ICA protocol based flows. This makes it very exciting that you do not need to be a TCP and ICA expert to define a profile which can provide best performance for XenApp and XenDesktop deployments. Here is a snapshot of various tuned parameters for this TCP profile.
As you can see the profile is defined keeping in mind the small packets and chatty scenarios of the VDI environments. The parameters have been set to optimal value based on our experience working with such deployments over many years. For example we want to ensure that you can send out more number of packets per MSS because ICA flow can have really small packets. In case of busy network with more drops and retransmissions you want to ensure that more number of packets can be sent per retransmission. The minimum retransmission timeout value is also reduced significantly such that there is less wait time for successive retransmissions. Window scaling and Selective Acknowledgement are enabled for this profile for better experience over long pipes. Nagle’s algorithm is also enabled considering the small packet scenario. Overall every parameter is researched and optimally set for the XenApp and XenDesktop deployments to give you the best experience.
Please refer to following blog, if you want to understand the parameters in details.
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