Your network is killing your file copy performance

We’ve all been there before, rush hour traffic.

You know how it goes. You slowly increase speed to 5mph, then 10, then 15. Excitement is building because you are now going 20mph. Then, out of nowhere, you slam on the brakes and your speed immediately drops back to 0mph. We eventually start over again, 5, 10, 15mph before we slam our foot on the brakes again bringing us to a complete stop.

At this point it is OK to yell “SERENITY NOW!!!

Unfortunately, this is how packets are being sent across the LAN/WAN. This is how TCP functions via the AIMD (Additive Increments, Multiplicative Decrements) congestion control algorithm. TCP slowly increases transmission speed and then drastically falls back when a re-transmission is required due to a timeout, collision or packet loss.

This works fine on a LAN where bandwidth is high, packet loss is low and latency is low. But as latency and packet loss increases, as is common with a WAN environment, TCP is never able to get up to full speed. We are left with only partial utilization of our WAN link.

We see this all of the time when we try to copy a file. On a LAN, the speed of the file copy remains fairly constant, but on a WAN, the bandwidth utilization slowly increases before dropping back to 0, just like rush hour traffic.

Look at what Citrix did!

Adaptive Transport is able to overcome WAN latency and packet loss. It makes a simple task, like file copying, twice as fast as a traditional Windows 10 PC and 3 times as fast as a VMware Horizon desktop.

Adaptive Transport is an alternative to traditional TCP. And it is more than simply a switch to UDP. Adaptive Transport is a newly developed Citrix enlightened data transport optimized for WAN environments by overcoming high latency and packet loss resulting in faster file copying.


If the network supports the new transport, HDX will use it. If it does not, HDX falls back to TCP.

Daniel (Follow on Twitter @djfeller)
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