To ensure that services can be delivered reliably and continuously over theInternet, it is important that both Internet routes and edge networks aresecured. However, the sophistication and distributed nature of many at-tacks that target wide-area routing and edge networks make it difficult foran individual network, user, or router to detect these attacks. Thereforecollaboration is important. Although the benefits of collaboration betweendifferent network entities have been demonstrated, many open questionsstill remain, including how to best design distributed scalable mechanismsto mitigate attacks on the network infrastructure. This thesis makes severalcontributions that aim to secure the network infrastructure against attackstargeting wide-area routing and edge networks. First, we present a characterization of a controversial large-scale routinganomaly, in which a large Telecom operator hijacked a very large numberof Internet routes belonging to other networks. We use publicly availabledata from the time of the incident to understand what can be learned aboutlarge-scale routing anomalies and what type of data should be collected inthe future to diagnose and detect such anomalies. Second, we present multiple distributed mechanisms that enable col-laboration and information sharing between different network entities thatare affected by such attacks. The proposed mechanisms are applied in thecontexts of collaborating Autonomous Systems (ASes), users, and servers,and are shown to help raise alerts for various attacks. Using a combina-tion of data-driven analysis and simulations, based on publicly availablereal network data (including traceroutes, BGP announcements, and net-work relationship data), we show that our solutions are scalable, incur lowcommunication and processing overhead, and provide attractive tradeoffsbetween attack detection and false alert rates. Finally, for a set of previously proposed routing security mechanisms,we consider the impact of regional deployment restrictions, the scale of thecollaboration, and the size of the participants deploying the solutions. Al-though regional deployment can be seen as a restriction and the participationof large networks is often desirable, we find interesting cases where regionaldeployment can yield better results compared to random global deployment,and where smaller networks can play an important role in achieving bettersecurity gains. This study offers new insights towards incremental deploy-ment of different classes of routing security mechanisms.