While astonishingly successful, Internet is still less reliable than the phone system and supports very limited user choice and control. As many researchers observed, multipath routing is a promising paradigm to address these issues. In this thesis, we argue that multipath routing can indeed go a long way towards these goals as well as lead to a more scalable, extensible, and evolvable Internet.

We begin by describing Yet Another Multipath Routing (YAMR) protocol that provably constructs a set of paths resilient to any one interdomain link failure. YAMR uses an efficient scheme to construct the paths and a novel failure hiding technique to further reduce the control plane overhead.

Next, we describe Pathlet Routing, a protocol that departs from the path-vector paradigm. Pathlet routing allows ASes to advertise policy-compliant path segments called pathlets, and allows users to stitch them together, thus forming a complete path suitable for the user's particular needs. Pathlet routing greatly reduces the forwarding table size, can efficiently express a wide class of routing policies, and provide an exponential number of paths to the users. Finally, we investigate how pathlet routing can be a basis for an evolvable Internet architecture.