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Conntrack: Semantics and Scale#

Open vSwitch and OVN 2026 Fall Conference digest Program Adjacent pick 2–4 November 2026

Abstract

Aaron Conole, Red Hat, LLC.

  • Why: Conntrack quietly became the L3/L4 interface of the OpenFlow pipeline, and this year's program shows it breaking things in at least three other talks (ACL ordering, ARP tracking, DPDK performance). This is the framing talk on what conntrack must guarantee across implementations and how it scales — including hardware acceleration paths.
  • What: A decade-look at conntrack in OVS and the open questions: which behaviors must be common across all conntrack implementations, how the userspace implementation scales to modern demands, and how ct() can be extended through a hardware acceleration path — with what is done, what remains unmerged, and how to contribute. (from abstract only)
  • How: Retrospective plus forward-looking work items on common semantics, userspace scaling, and hardware ct() acceleration.
  • Where applicable: All of OVS/OVN — conntrack semantics constrain every stateful feature above them. Particularly relevant to userspace/DPDK and offload users.