Interdomain traffic engineering (TE) controls the flow of traffic between autonomous systems (ASes) to achieve performance goals under various resource constraints. Interdomain TE can be categorized into ingress TE and egress TE, which aim to control the ingress and egress traffic flow in a network, respectively. Most interdomain TE techniques are based on BGP, which was not designed to support performance based routing. Hence even though some basic interdomain TE techniques are widely deployed, their overall effectiveness and impact on interdomain traffic are not well understood. Furthermore, systematic practices for deploying these techniques have yet to be developed. In this thesis, we explore these open issues for both ingress and egress TE. We first focus on the AS-Path prepending technique in interdomain ingress TE. We design a polynomial algorithm that takes network settings as input and produces the optimal prepending at each ingress link. We also develop methods to measure the inputs of the optimal algorithm by leveraging widely available looking glass severs and evaluate the errors of such measurement. We further propose an algorithm, based on this optimal algorithm, that is robust to input errors. We then focus on Intelligent Routing Control (IRC) systems often used at multihomed networks for egress interdomain TE. To address the possible traffic oscillation problem caused by multiple IRC systems, we design a class of randomized IRC algorithms. Through simulations, we show that the proposed algorithms can effectively mitigate oscillations. We also show that IRC systems using randomized path switching algorithms perform better than those switching path deterministically, when both types of IRC systems co-exist. To further understand the performance impact of IRC systems, we next focus on the performance of applications, such as TCP connections. We study the synergistic and antagonistic interactions between IRC and TCP connections, through a simple dual-feedback model. We first examine the impact of sudden RTT and available bandwidth changes in TCP connection. We then examine the effect of IRC measurement delays on closed loop traffic. We also show the conditions under which IRC is beneficial under various path impairment models.