The stable paths problem and interdomain routing

Abstract

Abstract-Dynamic routing protocols such as RIP and OSPF essentially implement distributed algorithms for solving the shortest paths problem. The border gateway protocol (BGP) is currently the only interdomain routing protocol deployed in the Internet. BGP does not solve a shortest paths problem since any interdomain protocol is required to allow policy-based metrics to override distance-based metrics and enable autonomous systems to independently define their routing policies with little or no global coordination. It is then natural to ask if BGP can be viewed as a distributed algorithm for solving some fundamental problem. We introduce the stable paths problem and show that BGP can be viewed as a distributed algorithm for solving this problem. Unlike a shortest path tree, such a solution does not represent a global optimum, but rather an equilibrium point in which each node is assigned its local optimum.We study the stable paths problem using a derived structure called a dispute wheel, representing conflicting routing policies at various nodes. We show that if no dispute wheel can be constructed, then there exists a unique solution for the stable paths problem. We define the simple path vector protocol (SPVP), a distributed algorithm for solving the stable paths problem. SPVP is intended to capture the dynamic behavior of BGP at an abstract level. If SPVP converges, then the resulting state corresponds to a stable paths solution. If there is no solution, then SPVP always diverges. In fact, SPVP can even diverge when a solution exists. We show that SPVP will converge to the unique solution of an instance of the stable paths problem if no dispute wheel exists.

How secure are secure interdomain routing protocols?

“…We first present a model of interdomain routing and routing policies, based on the standard models in [16] and the Gao-Rexford conditions [13], followed by our threat model for traffic attraction, and finally overview our experimental setup.…”

Incentive-compatible interdomain routing

“…Next-hop policies capture an essential feature of interdomain routing as it is currently done: An AS cannot control packet forwarding beyond the neighboring AS to which it initially sends the packets. For this reason, many researchers have studied next-hop policies in order to gain insight into the behavior of interdomain protocols [6,13,24]. Policy consistency, one of the three properties that together comprise our sufficient condition for welfare maximization, is a generalization of next-hop policies.…”

“…Policy consistency, one of the three properties that together comprise our sufficient condition for welfare maximization, is a generalization of next-hop policies. Note that, although next-hop policies have been a natural and fruitful topic of research, they are not sufficient for practical use; it has been shown that uncoordinated and unconstrained local configuration of next-hop policies can produce route instability [13,24]. 2.…”

Research challenges in QoS routing

“…The policy independence between autonomous systems and the opacity of routing policies outside the autonomous system lead to instabilities. Research on the inconsistencies of BGP-4 has led to the discovery of situations, where the coordinated action of the administrators of more than two routing domains is needed to restore stability in a certain subsection of the Internet [73] and [74]. A routing management overlay, which could be able to detect and avoid this kind of situations would greatly improve the quality of the IPv6 Internet.…”