Dynamic Routing for Multi-Homed Enterprise Gateways

Small and medium sized businesses often operate local area networks that connect via service providers to the Internet. If multiple connections are required, there are two options available: A gateway router that operates the border gateway protocol or a simpler gateway appliance that mostly uses load balancing and often network address translation. However, there is no simple way to multi-home small networks, when access links have diverse performance parameters, capacities or costs. Dynamic overflow routing addresses this issue in a straightforward way. This paper discusses dynamic routing and details, how bandwidth resources can be managed. It gives a simple estimate that helps to forecast resources for routing decisions and it underlines the need for a bidirectional gateway routing mechanism, accounting simultaneously for upstream as well as downstream traffic.