Determining if you need to load balance data over multiple NICs

Sending data over one network interface can limit throughput

Typically, in a transparent deployment with a WCCP router, NetCache chooses one network interface over which to deliver data to clients. However, delivery of data over a single network interface might not be optimal for some types of transparent proxy deployments.

For example, a streaming media cache can deliver streaming data to clients very quickly over multiple network interfaces. However, if the proxy is able to deliver streaming data over only a single network interface, the proxy is likely to become limited in its network throughput by the bandwidth of this single network interface.

How to deliver data over multiple network interfaces

By using the "WCCP NetCache IP Addresses for Load Balancing" option on the WCCP Global Settings page (Setup tab > Transparency > WCCP Global Options), you can enable NetCache to deliver data over multiple network interfaces; you list the NetCache network interfaces over which you want NetCache to deliver data to clients. If you leave the list blank, NetCache sends and receives data to clients over a single interface (per router), which NetCache chooses.

Usage guidelines for sending data over multiple network interfaces

Use the following guidelines to determine which, if any, NetCache network interfaces to list in the "WCCP NetCache IP Addresses for Load Balancing" option:

You must include the interface used for the default route in your interface list. Otherwise, a traffic loop might occur.
List only IP addresses for network interfaces through which this appliance communicates with clients. You would not, for example, list a network interface through which this appliance communicates with another appliance.
Distribute traffic over multiple interfaces only when necessary. Typically, NetCache can deliver DNS, FTP, HTTP, and NNTP data over a single network interface without adversely affecting performance.