Bandwidth Aggregation (also known as Link Balancing)also Automatic traffic failover on link or ISP failure for multiple ISPs. Additionally, it provides automatic VPN tunnel failover on most products. The products in this section all for Multi-homed ISP/WAN link failover even if your company cannot get BGP services. (If you do not know what this is, you most likely do not have BGP services from your ISPs.) Most of the products in this section work with your company's DNS service to dynamically update the IP of the service hosted on the multiple ISPs so that the end user/client always receives content.
Here is a diagram showing a typical Link Balanced environment.