Delta routing: improving the price-performance of hybrid private networks

Large enterprises connect their locations together by building a corporate network out of private communication channels, such as leased lines, frame relay and ATM links, called physical private networks or PPNs. PPNs provide good quality of service, but they are expensive. On the other hand, Internet-based virtual private networks (VPNs) can provide speedy deployment of multisite corporate networks at a small fraction of the cost of private lines. However, Internet-based VPNs do not offer the same accountability and predictability as PPNs do, since the Internet is not administrated by a single provider. In order to build a hybrid network that is both reliable and affordable, we have developed the delta routing protocol, which allows nodes on a corporate network to communicate with each other using both PPN and Internet-based VPN. The delta routing protocol works with the existing routing protocol on the PPN and allows each node to determine the best routes on the hybrid network using local information only. We have simulated and compared the delta routing protocol and the alternatives using the ns-2 simulator. The results show that the delta routing protocol outperforms the alternatives in a variety of scenarios.