Gordon T. Wilfong

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Dynamic routing protocols such as RIP and OSPF essentially implement distributed algorithms for solving the <i>shortest paths problem.</i> 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(More)
The Border Gateway Protocol, BGP, is currently the only interdomain routing protocol employed on the Internet. As required of any interdomain protocol, BGP allows policy-based metrics to override distance-based metrics and enables each autonomous system to independently define its routing policies with little or no global coordination. Varadhan et al. [11](More)
Let G be the digraph consisting of two oppositely-directed rings on the same set of n nodes. We provide a polynomialtime algorithm which, given a list of demands-each requiring a path from a specified source node to a specified target node-routes the demands so as to minimize the largest number of paths through any of the 2n directed links of G. The(More)
An IP routing protocol is safe if it is guaranteed to converge in the absence of network topology changes. BGP, currently the only interdomain routing protocol employed on the Internet, is not safe in this sense. It may seem that the source of BGP’s potential divergence is inherent in the requirements for any interdomain routing protocol — policy-based(More)
We study the route oscillation problem [16, 19] in the Internal Border Gateway Protocol (I-BGP)[18] when route reflection is used. We propose a formal model of I-BGP and use it to show that even deciding whether an I-BGP configuration with route reflection can converge is an NP-Complete problem. We then propose a modification to I-BGP and show that route(More)
We consider the motion planning problem for a point constrained to move along a path with radius of curvature at least one. The point moves in a two-dimensional universe with polygonal obstacles. We show the decidability of the reachability question: “Given a source placement (position and direction pair) and a target placement, is there a(More)
Motion planning algorithms have generally dealt with motion in a static environment, or more recently, with motion in an environment that changes in a known manner. We consider the problem of finding collision-free motions in a changeable environment. That is, we wish to find a motion for an object where the object is permitted to move some of the(More)