The IPv6 routing infrastructure is an important part of the modern Internet, and the collection of its interface addresses is greatly significant in network security, performance optimization, and measurement analysis. However, existing methods suffer from two major problems: the lack of flexibility in budget allocation across probing rounds and the absence of a dynamic hop limit adjustment mechanism based on feedback. These problems lead to the low hit rate and inefficiency of existing methods for discovering router interfaces, which seriously hinders the comprehensive knowledge of IPv6 routing infrastructure.To this end, we propose Helixir, a feedback-based, high hit-rate, and efficient IPv6 router interface discovery system. Helixir’s core design includes a dynamic budget allocation mechanism across probing rounds, an inter-prefix budget allocation strategy that adequately trades off exploration and exploitation, and a hop limit selection method based on Thompson sampling. Real-world experiments show that with a 100M budget, Helixir achieves a hit rate 3.64× that of state-of-the-art methods on the BGP prefixes dataset, and Helixir successfully discovers over 31 million IPv6 router interface addresses in total within half an hour. In addition, a systematic security analysis of the discovered router interfaces shows that many devices open sensitive ports and expose hundreds of potential CVE vulnerabilities, highlighting the security risks in the IPv6 network.

The vastness of the IPv6 address space has led to the common practice of allocating prefixes to end users rather than individual addresses. Users can assign these prefixes as a single subnet or divide them into multiple subnets for different purposes. Allocation strategies vary significantly in terms of prefix granularity, and identifying the actual granularity of subnet assignments is crucial for improving measurement efficiency, accuracy, and for better IPv6 network management. However, no existing method can discover IPv6 subnets at an Internet-Wide scale.To this end, we propose SubRecon, an Internet-Wide IPv6 subnet discovery system. SubRecon consists of two key phases: subnet delimitation and target expansion. In the subnet delimitation phase, we perform a systematic scan across the entire IPv6 address space without relying on any existing seed dataset. This phase adopts a top-down approach, probing prefixes from the shortest to the longest in a hierarchical manner. At each level, we recursively refine prefixes and discard sub-prefixes that do not meet the convergence condition. This pruning strategy eliminates redundant probes in unallocated regions, significantly reducing the search space and improving probing efficiency. To further improve coverage, the target expansion phase leverages the active address dataset as an auxiliary input. It identifies active addresses not covered by previously discovered subnets, expands them into new candidate target prefixes, and performs another round of subnet delimitation. This helps enhance the completeness and coverage of the final discovered subnet set. Experimental results show that SubRecon discovers 8,381,974 IPv6 subnets across 14,147 autonomous systems, and the resulting subnet list can serve as high-quality input for topology discovery. Additionally, during the subnet discovery process, SubRecon identifies a large number of last-hop router interfaces, discovering approximately 10 million more than the current state-of-the-art methods.

The performance of collective communication schedules is crucial for the efficiency of machine learning jobs and GPU cluster utilization. Existing open-source collective communication libraries (such as NCCL and RCCL) rely on fixed schedules and cannot adjust to varying topology and model requirements. State-of-the-art collective schedule synthesizers (such as TECCL and TACCL) utilize Mixed Integer Linear Program for modeling but encounter search space explosion and scalability challenges. In this paper, we propose SyCCL, a scalable collective schedule synthesizer that aims to synthesize near-optimal schedules in tens of minutes for production-scale machine-learning jobs. SyCCL leverages collective and topology symmetries to decompose the original collective communication demand into smaller sub-demands within smaller topology subsets. SyCCL proposes efficient search strategies to quickly explore potential sub-demands, synthesizes corresponding sub-schedules, and integrates these sub-schedules into complete schedules. Our 32-A100 testbed and production-scale simulation experiments show that SyCCL improves collective performance by up to 127% while reducing synthesis time by 2 to 4 orders of magnitude compared to state-of-the-art efforts.

As online cloud services expand rapidly, layer-7 load balancing has become indispensable for maintaining service availability and performance. The emergence of programmable switches with both high performance and a certain degree of flexibility has made it possible to apply programmable switches to load balancing. Nevertheless, the limited memory capacity and the relatively sluggish speed of table entry insertion and deletion of programmable switches have severely constrained their performance.

Programmable switches have revolutionized network operations by enabling the flexible customization of packet processing logic using language like P4. However, changing the programs running on the switch requires disturbing traffic and suspending other unrelated programs. In this paper, we present P4runpro, enabling runtime data plane updates with dynamic resource allocation. The P4runpro data plane abstracts hardware resources and defines dynamically reconfigurable atomic operations that form packet processing logic. P4runpro provides runtime programming interfaces called P4runpro primitives for the operator to write high-level programs. We have designed the P4runpro compiler to automatically and consistently link the P4runpro programs to the running data plane. We implement our prototype on a Tofino switch. We implement 15 example runtime programs using P4runpro to demonstrate its generality and expressiveness. Our evaluation results show that compared to the state-of-the-art, P4runpro can respond within hundreds of milliseconds, achieve an average of 60% to 80% dynamic resource utilization, concurrently run ≈0.6K to ≈2.8K programs, and introduce lower overhead. Our case studies illustrate the benefit of runtime programming and prove the same functionality between P4runpro and conventional P4 programs.