The LoadMaster series of load balancers supports content switching, which is sometimes referred to a URL switching. This allows the LoadMaster to direct specific requests to specific Real Servers based on the contents of the requested URL
Ordinarily, LoadMaster’s main purpose is to evenly distribute traffic to a pool of real servers. However, with Content Switching, LoadMaster takes on the role of traffic director. By examining the content of each request, traffic can be assigned to a specific server based on pattern matching. Pattern matching can be performed upon either the URL requested, any HTTP header and/or body in the request or even the source IP of the client making the request. By leveraging the power of regular expressions, patterns can be as complex as needed to get the job done.
For example, if you have two groups of servers; one group to serve images and the other to serve all other content - you can create content rules to separate these two classes of request.
Any URL that includes /images in it, such as “http://url.com/images/party.jpg” or “http://url.com/images/dogs.jpg” would be directed to server 3 and 4, while anything else would be directed to server 1 and 2.
This can be very useful if you have servers that perform different functions (application servers, static content servers, mapping servers, specialized content generation servers, etc.) that must all be served from the same general hostname (e.g., www.websitename.com).
Some common applications of Content Switching are:
• URL Switching - Dedicated application pools for specific directories or file extensions can be used when application design calls for it.
• Hostname Specific Servers - If your organization has a single public IP that has multiple hostnames associated with it, the LoadMaster can split out requests to different hosts and direct them accordingly.
• Source IP Specific Sites - By opening internal sites to specific external IPs, you can allow distributors, partners or remote offices to access specific content.
• Allowing only one URL - These are just a few samples of what you can do. As of version 6.0-32, LoadMaster fully supports PCRE style regular expressions for content rules and header modifications. This allows for a tremendous amount of control over your rules, giving administrators the flexibility they need for just about any application.
For additional syntax information, please refer to our Content Rules Guide