Content Switching is Layer 7 Load Balancing.
Content switching can be used to distribute traffic across multiple back-end servers based on host-headers, device type, language, cookie and layer 3-4 data. This feature can be very useful for multi-tenant solutions hosting web services including SharePoint or Exchange.
A Content Switch is a virtual server that can be configured to service multiple back-end services. For example, a business with five web servers would traditionally have a public facing IP address for each server and potentially have unique firewall rules.
In this scenario, a single Content Switch would be configured to direct traffic to each of the back-end web servers based on host header, requiring just one IP address for all the sites, and one firewall rule.
I deployed Content Switching for an Australian house building customer last year (in my previous role), that had a number of web servers hosting building information for multiple brands, each with their own URLs and public IP addresses. The existing solution made use of some Microsoft TMG features but it was very complex and as they scaled out, and it was becoming increasingly hard to maintain.
I used two Content Switches on their NetScaler's to reduce their public IP’s from down to just two. Oh, and their chief security officer bought me a coffee, which believe me, he didn’t do very often! 🙂
While implementing Content Switching for this customer I spoke about the other features NetScaler provides and we soon started discussing a web application they wanted to enable on the internet that didn’t support using SSL (https). I used NetScaler to terminate SSL (SSL Offload) from the internet so this application could be securely accessed remotely. NetScaler secured the traffic over the internet, passing it internally to the application servers using http. Now users could access this business-critical information securely over the internet including while working from home.
Happy customer, very happy staff and a great example of maximisng the investment in NetScaler.
By Darren Bennett, Partner Enablement Specialist (Citrix), rhipe