The growing energy consumption of Information and Communication Technology (ICT) has raised concerns about its environmental impact. However, the carbon efficiency of data transmission over the Internet has so far received little attention. This carbon efficiency can be enhanced effectively by sending traffic over carbon-efficient inter-domain paths. However, challenges in estimating and disseminating carbon intensity of inter-domain paths have prevented carbon-aware path selection from becoming a reality. In this paper, we take advantage of path-aware network architectures to overcome these challenges. In particular, we design CIRo, a system for forecasting the carbon intensity of inter-domain paths and disseminating them across the Internet. We implement a proof of concept for CIRo on the codebase of the SCION path-aware Internet architecture and test it on the SCIONLab global research testbed. Further, we demonstrate the potential of CIRo for reducing the carbon footprint of endpoints and end domains through large-scale simulations. We show that CIRo can reduce the carbon intensity of communications by at least 47% for half of the domain pairs and the carbon footprint of Internet usage by at least 50% for 87% of end domains.

翻译：信息与通信技术领域的能源消耗持续增长，引发了对环境影响的广泛担忧。然而，互联网数据传输的碳效率迄今未得到充分关注。通过选择低碳域间路径传输流量，可有效提升碳效率。但域间路径碳强度的估算与传播挑战，阻碍了碳感知路径选择成为现实。本文利用路径感知网络架构解决上述挑战，设计并实现CIRo系统——该系统可预测域间路径的碳强度，并通过互联网传播这些信息。我们在SCION路径感知互联网架构代码基础上构建CIRo概念验证系统，并在SCIONLab全球研究测试平台上完成验证。进一步通过大规模仿真，证明了CIRo在降低端点和终端域碳足迹方面的潜力。结果表明：对半数域对而言，CIRo可使通信碳强度降低至少47%；对87%的终端域而言，互联网使用碳足迹可减少至少50%。