The TCP implementation within Citrix HDX/ICA protocol used by XenDesktop and XenApp and also Citrix Netscaler is pretty Vanilla to the original TCP/IP standards and definition and the out-of-the-box configuration usually does a good job on LAN. However, for WAN scenarios particularly with higher latencies and certain kinds of data (file transfers), Citrix deployments can benefit greatly from some tuning.
Citrix HDX TCP is not optimized for many WAN scenarios but at the moment it can also be tuned manually following this advice: CTX125027 – How to Optimize HDX Bandwidth Over High Latency Connections. This is one configuration I’d love to see Citrix automate as having to tune and configure the receiver is fiddly and also not possible in organisations/scenarios where the end-points and server/network infrastructure might be provided by different teams or even companies (e.g. IaaS).
For Citrix NVIDIA GRID vGPU customers with looking at high network latency scenarios – it really is worth investigating the potential and benefits of TCP window tuning. I’d be really interested to hear feedback if you have tried this and what your experience / thoughts are too!
Norwegian, Marius Sandbu was recently awarded NGCA status by NVIDIA for his work with our community through his Netscaler, remoting protocols and experience with technologies such as UDP and TCP/IP. You can follow him on twitter @msandbu and of course do follow his excellent blog on http://msandbu.org/ !!!
In a past life I was a kernel engineer on Parasolid the numerical heart within many top CAD applications such Ansys Workbench, Dassault Solidworks, Siemens NX and Solid Edge, Bentley, Nemetscheck, Missler Top Solid; I lived, breathed and obsessed about CAD workflows, how users construct parts and use CAD applications. Now I’m in Cloud computing and VDI, I still get to work with CAD applications but am working in an industry where for many other than the customer – a CAD application is just another VDI or virtualised app or workload.
One of our really experienced experts has just done a blog on some evaluation he did on Citrix’s hot new graphics mode: http://trentent.blogspot.ca/2015/09/performance-differences-in-citrix-hdx.html. Now this guy knows what he is doing but I’m a little worried others might not fully understand what has been done or the implications for the results. Trent did some tests flipping the encoder via a registry key. We do not encourage users to play with registry keys, occasionally they can prove useful to tweak a system, but really if that is being done we should be exposing the control via properly documented policies.
Last week I had a twitter user make comment that implied the reason some of our recent thinwire enhancements have happened is because some of the HDX development and product management team are in the UK! Stefan made this comment
Citrix XenDesktop/XenApp 7.6 FP3 has introduced enhanced architecture to support both 24-bit and 32-bit advanced cursors. Historically remoting protocols have supported simpler cursors but with an increase in the use of complex and larger cursors for complex CAD and 3D applications, Citrix has introduced a new architecture to support such cursors on-going.