Today's BGP-based Internet offers almost no control over forwarding paths to end users. Few opportunities exist to influence paths on an application-by-application basis, e.g., the traffic class field in the IP header, but that is usually dropped when a packet reaches the first ISP. In contrast, path-aware networking (PAN) as implemented in the SCION Internet architecture offers a wealth of path choices from which applications can pick desirable subsets. However, only a few dozen applications support SCION natively today. Instead, SCION deployments connect legacy applications through SCIONIP Gateways (SIGs) that provide an overlay IP network on top of SCION. In this work, we introduce an alternative SCION to legacyIP compatibility mechanism suitable for P4-programmable hardware that can replace the SIG, called SCION-IP translation. The SCION-IP Translator addresses two issues of the SIG. First, the SIG requires fragmentation and reassembly of the underlying IP packets - a process not easily done in P4. More importantly, SIGs form an overlay network on top of SCION. Native SCION applications cannot communicate with legacy applications. Thus, the SIG hinders native application development. The main innovation of the SCION-IP Translator is that it translates headers directly without introducing another (tunneling) layer to the network stack. We prototype a SCION-IP Translator using Intel Tofino switches of the first and second generation and provide insights from deploying SCION-IP translation in a university network participating in the SCION Education, Research and Academic network (SCIERA).

Today's Internet frequently suffers from unreliable packet forwarding and security vulnerabilities, while it largely depends on the Border Gateway Protocol (BGP) that obscures routing complexities from end-hosts. Path-Aware Networking (PAN) is a novel paradigm that aims to overcome BGP's limitations by offering end-hosts control over packet routing. However, an optimal path choice based on PAN requires realtime performance data about the different path options. Programmable data planes and Software-Defined Networking (SDN) enable to add real-time telemetry data to user packets. However, existing implementations are limited to single administrative domains, lacking the security and privacy required for interdomain telemetry. This paper proposes the first hardware implementation of Inter-Domain In-band Network Telemetry (ID-INT), extending the P4-based SCION border router targeting Tofino 2. Leveraging SCION's path-aware features and robust security mechanisms, like the DRKey system for secure key derivation, our ID-INT implementation on Tofino ensures telemetry data authenticity and integrity. We demonstrate the benefits of ID-INT on Tofino by evaluating the Deadline-aware Multipath Transport Protocol (DMTP) as an example application utilizing ID-INT data to improve its responsiveness to network conditions. Our testbed experiments show that ID-INT enables DMTP to dynamically adjust the sending rate based on instantaneous queue length data, highlighting ID-INT's practical benefits in enhancing an application's performance.