Tuesday, December 1, 2009

Choosing a NetScaler: Hardware Appliance or Virtual Appliance

By:Jarian Gibson

With the release of the NetScaler VPX virtual appliance for Citrix XenServer and VMware ESX I can see there may be some questions on when to use a NetScaler hardware appliance and when to use a NetScaler VPX virtual appliance. In this blog post I am going to go over when to go with a NetScaler hardware appliance and when to go with a NetScaler VPX virtual appliance.




What is a NetScaler VPX virtual appliance?
A NetScaler VPX virtual appliance is a 32-bit virtual NetScaler system that is hosted on a Citrix XenServer or VMware ESX hypervisor. NetScaler VPX can distribute, optimize, and secure Layer 4 to Layer 7 network traffic. It can also perform application specific traffic analysis. NetScaler VPX has features such as:


  • Load Balancing

  • Compression

  • Secure Sockets Layer (SSL) offload

  • Application Firewall

  • Dynamic content caching


Benefits of using a NetScaler VPX are that it can be deployed on any XenServer or ESX hypervisor installation in your environment, leverage dynamic data center processes, respond automatically during high demand periods and dynamically provision more capacity for existing web applications, and has a very flexible licensing model.

NetScaler VPX has a free express version that includes a NetScaler Standard Edition license and is limited to 1 Mbps throughput. For more information on NetScaler VPX Express see my previous blog posts - NetScaler VPX Express is a must for all XenServer environments and NetScaler VPX Express is a must for all VMware environments. NetScaler VPX Express is great for smaller environments, PoC environments, and Test/Development environments.

The NetScaler VPX Express can be upgraded for more throughput and to NetScaler Enterprise or Platinum Edition - pay as you grow with NetScaler VPX. See the table below for NetScaler VPX offerings.



The NetScaler VPX does have some performance limitations that are based on the hypervisors hardware. The performance limitations are:

  • Maximum HTTP throughput - 1Gbps

  • Maximum compression - 750 Mbps

  • Maximum Application Firewall - 500 Mbps

  • Maximum SSL transactions/second - 500 Mbps

  • Maximum SSL through put - 1Gbps


For more information on the NetScaler VPX see the NetScaler VPX Release 9.1 FAQ and the NetScaler VPX Getting Started Guide - Release 9.1

What are the differences between NetScaler MPX and NetScaler VPX?

The two main difference between NetScaler MPX and NetScaler VPX are system capacity and performance. The NetScaler VPX virtual appliance doesn't include hardware specifically designed to support SSL acceleration. The NetScaler VPX virtual appliance can terminate sessions, but unlike NetScaler hardware appliances, the associated processing isn't offloaded to dedicated hardware.

When to use a NetScaler hardware appliance?

A NetScaler hardware appliance should be use when:

  • High throughput and performance is needed

  • A high volume of SSL Offload is needed

  • More than 100 concurrent SSL VPN connections are needed

  • FIPS is required

  • Physical device security is needed


When to use a NetScaler VPX virtual appliance?

A NetScaler VPX virtual appliance should be for:

  • Lab/test environments

  • Development environments

  • Datacenter in a box projects

  • Processor intensive workloads

  • Frequently moved applications

  • Fast/remote deployments


Can NetScaler MPX hardware appliances and NetScaler VPX virtual appliances be used together?

Yes they can. NetScaler MPX hardware appliances and NetScaler VPX virtual appliances can be deployed together for centrally managed web application delivery. NetScaler MPX hardware appliances can be used for deployments at the datacenter edge to handle demanding network-wide tasks. NetScaler VPX virtual appliances can be used for deployments for app-by-app basis that are optimized for application specific demands.

As you can see there are uses for NetScaler hardware appliances, NetScaler virtual appliances, or a combination of both. Every environment is different and performance of the NetScaler VPX virtual appliance can vary with the underlying hypervisor hardware. All I can say is test and see what works for you.

If you have found this article interesting or if you have any other insights, please feel free to leave comments on this article.



More information on Netscaler

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