Interdomain Ingress Traffic Engineering Through Optimized AS-Path Prepending

Abstract

Abstract. In INterdomain Ingress Traffic Engineering (INITE), a "target" Autonomous System (AS) aims to control the ingress link at which the traffic of one or more upstream source networks enters that AS. In practice, ISPs often manipulate, mostly in a trial-and-error manner, the length of the AS-Path attribute of upstream routes through a simple technique known as prepending (or padding). In this paper, we focus on prepending and propose a polynomial-time algorithm (referred to as OPV) that determines the optimal padding for an advertised route at each ingress link of the target network. Specifically, given a set of "elephant" source networks and some maximum load constraints on the ingress links of the target AS, OPV determines the minimum padding at each ingress link so that the load constraints are met, when it is feasible to do so. OPV requires as input an AS-Path length estimate from each source network to each ingress link. We describe how to estimate this matrix, leveraging the BGP Looking Glass Servers. To deal with unavoidable inaccuracies in the AS-Path length estimates, and also to compensate for the generally unknown BGP tie-breaking process in upstream networks, we also develop a robust variation (RPV) of the OPV algorithm.

HIDRA: Hierarchical Inter-Domain Routing Architecture

“…An accomplishment of HIDRA is retaining as many existing network man- For a more in-depth look, this section examines the common technique of AS path pending [41,22]. BGP utilizes the AS path attribute associated with a route primarily to ensure no loops are created when routing.…”

Inter-AS Inbound Traffic Engineering via ASPP

“…In [23], the authors proposed a polynomial-time algorithm that determines the optimal prepending length vector for an advertised route at each ingress link of the target network. Specifically, given a set of elephant source networks and some maximum load constraints on the ingress links of the target AS, their algorithm determines the minimum prepending length at each ingress link so that the load constraints are met, when it is feasible to do so.…”

Joint Optimization of Intra- and Inter-Autonomous System Traffic Engineering

“…A number of outbound inter-AS TE algorithms have been proposed recently [6,16,17]. In addition, a number of inbound inter-AS TE algorithms [18,19] have been proposed very recently based on AS-path prepending [21]. This is a commonly used technique that purposely makes a route less attractive to its upstream ASes by adding several instances of its own AS-Number to the ASpath attribute so as to increase the AS-path length of that route.…”

“…We denote n and e the number of inter-AS traffic flows and the number of egress points. The NSA calculates the profit cost for each inter-AS traffic flow by evaluating each potential egress point (lines [11][12][13][14][15][16][17][18][19][20]. The most time consuming step in this block is to find a new minimum cost route by using the Dijkstra's algorithm (line 15).…”