Carbon-Aware Routing: Metrics and Challenges#

Sawsan El Zahr (University of Oxford)

• Why: Not a core interest for this PM, but carbon-aware routing is an emerging subfield that could eventually change link costing and TE policy the way latency-based TE did. It also connects directly to two other sessions in this program (metro optical power, AI DC power), making it part of a real trend rather than an outlier.
• What: Research on making fixed wired networks carbon-aware: which carbon-related metrics can serve as link costs in link-state routing, what realistic topologies/traffic/grid-carbon-intensity data show about their limits, and CATE, a heuristic carbon-aware traffic engineering algorithm combining grid carbon intensity with router dynamic power draw and port power-down. The honest headline: no silver bullet, but promising directions that require no new router hardware (from abstract only).
• How: Carbon-intensity signals and per-router power models feed a link cost/TE heuristic that reroutes or powers down ports to reduce emissions without equipment changes.
• Where applicable: ISP-scale fixed networks with geographically diverse paths and dynamic power features in their routers; benefits are largest where grid carbon intensity varies meaningfully across a footprint. Research-stage (Oxford), evaluated on realistic but synthetic topologies rather than a named production network.