Path-aware networking (PAN) enables endpoints to locally select end-to-end network paths based on path properties. This approach contrasts with the traditional Internet architecture, where routers determine the next hop towards the destination based on the routing information provided by the Border Gateway Protocol (BGP). By providing this additional transparency and control, PAN opens up opportunities to optimize path selection, with the potential to enhance network performance and user experience metrics. In this paper, we evaluate the potential benefits of PAN for enhancing end-to-end performance. We design Polaris, a concrete feedback-driven path optimization mechanism for PAN, and study its impact on Quality of Service (QoS) as compared to current Internet mechanisms. Our extensive simulation results show the viability and effectiveness of Polaris, revealing that it outperforms the current Internet mechanisms by an average of${4 2 \%}$improvement in receiving rate and${8 1 \%}$reduction in median loss, in the presence of background traffic.

The SCION Next-Generation Network (NGN) architecture has expanded steadily since 2017, with today 20+ ISPs offering SCION connectivity. In production, IP-to-SCION-to-IP translation by SCION-IP-Gateways (SIGs) is used, such that applications are unaware of the NGN communication. To accelerate innovation and deployments, our aim is to increase the number of native SCION use cases, where the application is fully SCION-aware and optimizes communication across all path choices offered by the network. We set out to achieve two core objectives: (1) facilitating simple native connectivity for applications, and (2) enhancing the scalability of SCION deployment at academic sites.

The question at which layer network functionality is presented or abstracted remains a research challenge. Traditionally, network functionality was either placed into the core network, middleboxes, or into the operating system - but recent developments have expanded the design space to directly introduce functionality into the application (and in particular into the browser) as a way to expose it to the user.

Network testbeds have empowered networking re-search and facilitated scientific progress. However, current testbeds focus mainly on experiments involving the current Inter-net. In this paper, we propose SCIONLAB, a novel global network testbed that enables exciting research opportunities and experimentation with the SCION next-generation Internet architecture. New users can join SCIONLAB as a full-fledged autonomous system with minimal effort and administrative overhead, and directly gain unfettered access to its inter-domain routing system. Based on a well-connected network topology consisting of globally distributed nodes, SCIONLAB enables new experiments, such as inter-domain multipath communication, path-aware networking, exploration of novel routing policies, and new approaches for DDoS defense. SCIONLAB has been operational since 2016 and has supported diverse research projects. We describe the design and implementation of SCIONLAB, and present use cases that illustrate exciting research opportunities.