WorldLink Communications began testing IPv6 in May 2016 and launched it in July 2019. Currently, the provider serves over one million subscribers via IPoE, with 100% IPv6 adoption and approximately 70% of traffic running over the protocol.
The company adopted a dual-stack architecture to avoid the capital expenditures associated with Carrier-Grade NAT (CGNAT), such as hardware, session management, and logging requirements. IPv6 traffic bypasses CGNAT entirely, reducing infrastructure load.
A major technical challenge arose from DHCPv6 implementation. When fiber connections were lost, customer premises equipment (CPE) attempted to renew and rebind leases. Due to varying interpretations of RFC 3315 and RFC 8415 by manufacturers, some devices sent multiple concurrent requests, leading to thousands of DHCPv6 solicitations per second.
The provider observed up to 116 solicitations per minute from a single CPE. In a network with 80,000 subscribers, this resulted in approximately 15,467 solicitations per second, overwhelming the control plane. The issue was exacerbated by the 'delete-binding-on-renegotiation' (DBOR) function, which caused session drops.
Additional network-level obstacles included multicast filtering, MLD configuration, and DHCPv6 snooping table limits on OLTs. These issues often caused valid DHCPv6 replies to be discarded. The company now recommends offloading snooping to devices with sufficient resources and carefully managing multicast settings.
