MultiWAN features:

• auto-failover
• load balanced
• round-robin based on user-defined weights (see configuration section)

To give you an example of how multi-WAN works, imagine two 1 Mbit/s DSL lines with two users on the local network. With every new connection to a server on the Internet, the multi-WAN system alternates WAN interfaces. User A could be downloading a large file through WAN #1, while User B is making a voice-over-IP (VoIP) telephone call on WAN #2.

With some applications, the download speed for the multi-WAN system can use the full 2 Mbit/s available. For example, downloading a large file from a peer-to-peer network will use the bandwidth from both WAN connections simultaneously. This is possible since the peer-to-peer technology uses many different Internet “peers” for downloading. At the other end of the spectrum, consider the case of downloading a large file from a web site. In this case, only a single WAN connection is used — 1 Mbit/s maximum.

Bandwidth aggregation (combining multiple WAN interfaces to look like a single WAN interface) is not possible without help for your ISP since both ends of an Internet connection must be configured.

from http://www.clarkconnect.com/docs/Network_Settings_-_Multi-WAN