Speaker
Description
The use of the networking protocol IPv6 on the Worldwide Large Hadron Collider Computing Grid (WLCG) storage is very successful and has been presented at earlier CHEP conferences. The campaign to deploy IPv6 on CPU services and worker nodes is going well. Dual-stack IPv6/IPv4 is not, however, a viable long-term solution; the ultimate goals include allowing WLCG sites to move completely to IPv6. Several WLCG sites have stated their wish to move soon to IPv6-only. We are close to being able to allow this, with the agreement of the experiments they support. We also continue to aim for all WLCG WAN traffic to use IPv6.
This paper reports on work since CHEP2024. Firstly, we report on the deployment of IPv6 on CPU services and worker nodes. Then, we present further work to identify and correct the use of IPv4 between two dual-stack endpoints. We then describe our plans and proposed timescales for moving WLCG wide-area network links on the LHCOPN and LHCONE networks to “IPv6-only”. Since September 2025, the Tier1 centres in the USA, followed by some other Tier1 centres have successfully removed IPv4 from their LHCOPN links to CERN with no major problems observed so far. We present plans for the remaining LHCOPN links including the aim to complete work on all links by the end of 2026 in time for the WLCG 2027 data challenge (DC27). Longer term the aim is to cease use of IPv4 on WLCG data transfers over LHCONE before the start of HL-LHC Run4. We present the steps required to make this possible.