PMPATH: A Policy Routing System for Multihomed End-Hosts

Abstract

To achieve profits derived from multihoming, policy routing is supposed to be necessary. For routers' policy routing, some systems and implementations already exist. In addition to routers' operating systems with policy routing functions, IP Filter and iproute2 are useful for policy routing on routers. But they don't suit for policy routing on multihomed end-hosts because of differences on network environments between routers and end-hosts. In contrast with routers' network environments, there are some dynamic changes of network environments with some types of end-hosts, for example, laptop computers. Therefore, another policy routing system is needed for end-hosts' policy routing, which adapts to dynamic changes of network environment. PMPATH (Policy based MultiPATH routing system) is a policy routing system and designed especially for end-hosts uses. PMPATH uses source address selection as network selection, PMPATH can adapt to dynamic changes of network environment. PMPATH's policies for source address selection are defined in form of address block. PMPATH also provides outgoing interface selection. We implemented PMPATH on NetBSD 2.99.15 and tested its performance on multihomed end-hosts. PMPATH implementation works well even if there are changes of network environment. In this result, it is shown that PMPATH is useful for multihomed end-hosts' policy routing.