Ascertaining that a network will forward spoofed traffic usually requires an active probing vantage point in that network, effectively preventing a comprehensive view of this global Internet vulnerability. Recently, researchers have proposed using Internet Exchange Points (IXPs) as observatories to detect spoofed packets, by leveraging Autonomous System (AS) topology knowledge extracted from Border Gateway Protocol (BGP) data to infer which source addresses should legitimately appear across parts of the IXP switch fabric. We demonstrate that the existing literature does not capture several fundamental challenges to this approach, including noise in BGP data sources, heuristic AS relationship inference, and idiosyncrasies in IXP interconnectivity fabrics. We propose a novel method to navigate these challenges, leveraging customer cone semantics of AS relationships to guide precise classification of inter-domain traffic as in-cone, out-of-cone (spoofed), unverifiable, bogon, and unassigned. We apply our method to a mid-size IXP with approximately 200 members, and find an upper bound volume of out-of-cone traffic to be more than an order of magnitude less than the previous method inferred on the same data. Our work illustrates the subtleties of scientific assessments of operational Internet infrastructure, and the need for a community focus on reproducing and repeating previous methods.

Autonomous Systems (ASes) can reach hundreds of networks via Internet eXchange Points (IXPs), allowing improvements in traffic delivery performance and competitiveness. Despite the benefits, any pair of ASes needs first to agree on exchanging traffic. By surveying 100+ network operators, we discovered that most interconnection agreements are established through ad-hoc and lengthy processes heavily influenced by personal relationships and brand image. As such, ASes prefer long-term agreements at the expense of a potential mismatch between actual delivery performance and current traffic dynamics. ASes also miss interconnection opportunities due to trust reasons. To improve wide-area traffic delivery performance, we propose Dynam-IX, a framework that allows operators to build trust cooperatively and implement traffic engineering policies to exploit the rich interconnection opportunities at IXPs quickly. Dynam-IX offers a protocol to automate the interconnection process, an intent abstraction to express interconnection policies, a legal framework to digitally handle contracts, and a distributed tamper-proof ledger to create trust among ASes. We build and evaluate a Dynam-IX prototype and show that an AS can establish tens of agreements per minute with negligible overhead for ASes and IXPs.

In SDN, forwarding devices can only operate correctly while connected to a logically centralized controller. To avoid single-point-of-failure, controller architectures are usually implemented as distributed systems. In this context, recent literature identified fundamental issues, such as device isolation and controller overload, and proposed controller placement strategies to tackle them. However, current proposals have crucial limitations: (i) device-controller connectivity is modeled using single paths, yet in practice multiple concurrent connections may occur; (ii) peaks in the arrival of new flows are only handled on-demand, assuming that the network itself can sustain high request rates; and (iii) failover mechanisms require predefined information, which, in turn, has been overlooked. This paper proposes Survivor, a controller placement strategy that addresses these challenges. The strategy explicitly considers path diversity, capacity, and failover mechanisms at network design. Comparisons to the state-of-the-art on survivable controller placement show that Survivor is superior because (a) path diversity increases the survivability significantly; and (b) capacity-awareness is essential to handle overload during both normal and failover states.

The significance of BitTorrent motivated various studies focused on modeling and evaluating the protocol characteristics and its current implementations in the Internet. So far, however, no work has investigated Optimistic Disconnect (OD), an ad hoc connection management mechanism widely employed in BitTorrent agents. OD allows a peer to search for “better” neighbors in the swarm by disconnecting peers from the current neighborhood and connecting to others. This paper presents an extensive experimental evaluation to study and quantify potential benefits of OD, such as average download time and topology robustness. We evaluate different scenarios and the impact of factors such as average peer reachability and arrival pattern. We found that OD generally improves the overall performance of the swarm (in up to 30% in the evaluated scenarios), while improving the robustness of its topology.