A Large-Scale Measurement Study of the IPv6 Flow Label

Abstract

Congestion control coupling methods rely on knowing if multiple flows between the same host-pair share the same bottleneck. However, IPv4 load balancing hash algorithms traditionally use data from the transport layer header for flow identification, making such a guarantee impossible. We propose a novel method of controlling packet path behaviour using only IPv6 network-layer header data, and perform measurement studies from vantage points stationed around the globe to verify our proposed methodology. We identify challenges with traceroute measurement studies in the face of Equal-Cost Multi-Path (ECMP) and Link Aggregation Group (LAG) load balancing. Finally, we devise and execute an extensive measurement study to investigate whether the IPv6 flow label is completely carried to its destination and whether it can influence the behaviour of load balancing algorithms using a Paris traceroute-based implementation.