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Meet the Engineering Team at Citrix NetScaler - MovingPackets.net

Meet the Engineering Team at Citrix NetScaler

@mrtugs Tweet on Citrix

We had some great vendor presentations at Networking Field Day 11 and in the face of some pretty stiff competition, Citrix won my inaugural Best surprise award, which I have just invented.

Citrix NetScaler

It’s not that the Citrix NetScaler Application Delivery Controller (ADC) is a particularly unique product; after all, I could as easily implement load balancing with the open source HAProxy, and there are impressive ADC hardware vendors in the commercial space, including the ubiquitously expensive F5 Networks and disruptive challenger A10 Networks. What grabbed my interest me however were the performance statistics of the NetScaler appliances, and specifically the process through which the performance was achieved by the Citrix engineering team.

Intel DPDK

If I might side track for a moment, at Networking Field Day 10, Intel discussed their DPDK (Data Plane Development Kit) designed to optimize soft-switched packet performance on their CPUs. Intel had noted that the performance of Open vSwitch (OVS) was nowhere near the native ability of the CPU, and consequently they invested time analyzing in scary detail exactly how packets flowed in order to find out where the bottlenecks were, and to see whether those could be eliminated or optimized in some way. When you think about it, the ability to move packets rapidly through a virtual (soft) switch is a key capability for Network Functions Virtualization (NFV); the CPU can certainly do the packet processing required for the virtual functions requested of it, but that’s all pointless if the system cannot push IP packets through at high speed in the virtualized environment.

If you haven’t seen it, you might enjoy hearing just a little insight into the analysis that led to DPDK, in the video from that session. This video features Intel’s Edwin Verplank, Principal Engineer, and if you don’t want to watch the whole thing, I’ve jump to the most relevant part around 16:26:

NetScaler’s Analysis

Returning to NetScaler, what struck me as I listened to the presentation at NFD11 were the parallels between NetScaler and Intel, in particular their apparent obsession with squeezing every last drop of performance out of the CPU, and the lengths to which they are willing to go to find out what’s preventing faster processing and mitigate the issues that are found. Here’s the Citrix NetScaler product overview and architecture presentation given by Steve Shah (VP of Product Management) and Anil Shetty (VP of Engineering), both clearly hardcore nerds:

The other Citrix presentations are linked below for convenience. It was really enjoyable listening to these two guys talk and answer questions enthusiastically and in detail, and there was a minimal level of magic unicorn dust involved in those answers. I don’t want to be misunderstood; other companies I’m sure have similarly bright engineers, but getting time with Anil and Steve was a real privilege and was thoroughly enjoyable, and they gave an extremely positive impression of the product engineering teams at Citrix.


Obsession seems to have negative connotations in its wider application, but it can be a good thing – for customers at least – and I believe it speaks volumes about a positive technical culture at NetScaler. Are the resulting products good? I’m not sure I’m able to answer that yet; I haven’t used NetScaler in anger, and while I hear a mixture of comments from engineering friends, I’m not clear yet how recent their experiences are and thus how relevant to the current product. Either way, my confidence in the team behind the NetScaler products has increased, and maybe I can shake my impression of the wider Citrix organization as just being that VDI company.

Other Presentations

As promised:

Citrix Introduction and Overview with Abhishek Chauhan

Citrix NetScaler CPX Introduction and Overview

Citrix NetScaler Management and Evolution

Citrix SD-WAN Introduction and Overview



I was an invited delegate to Network Field Day 11, at which Citrix presented. Sponsors pay to present to NFD delegates, and in turn that money funds my transport, accommodation and nutritional needs while I am there. That said, I don’t get paid anything to be there, and I’m under no obligation to write so much as a single tweet about any of the presenting companies, let alone write anything nice about them. If I have written about a sponsoring company, you can rest assured that I’m saying what I want to say and I’m writing it because I want to, not because I have to.

You can read more here if you would like.

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