Choosing an L4 or L7 switch request distribution method

Influencing how requests are distributed over proxy-cache servers

The hashing function on a switch can be set up to distribute requests over appliances based on either of the following:

IP address (the most commonly used method)
URL (L7 switches only)

Typically, you want to achieve an even distribution of requests across your appliances.

IP address-based request distribution recommendations

If you want to use the switch to use IP addresses as the basis for request distribution, see the recommendations in the following table. These recommendations provide the most balanced distribution of requests across your appliances.

For a appliance running as a...	Recommended request distribution method
Forward proxy	Destination IP address (default)
Reverse proxy	Source IP address

For a appliance running as a...

Recommended request distribution method

Forward proxy

Destination IP address (default)

Reverse proxy

Source IP address

L7 URL-based request distribution recommendation

Some L7 switches allow for request distribution based on URL. The L7 switch examines the request and determines whether the object is cacheable. This capability enables you to set up your switch so that requests for obviously uncacheable objects, such as URLs for CGI, bypass the appliance. Noncacheable objects are then obtained directly from an origin server. You should use URL-based request distribution in forward proxy deployments only.