Extending DHCPLB: The path from load balancer to server

This post details the evolution of Meta's DHCP infrastructure, moving from ISC-DHCP to ISC Kea, and finally to an extended DHCPLB acting as a server. The primary technical contribution is the replacement of the single-threaded Kea DHCP server with a multithreaded DHCPLB server implementation. This addresses the Recv-Q buffer bottleneck and improves throughput by leveraging a new Go DHCP library. The post highlights performance gains, including handling the same traffic volume with 10x fewer servers and maintaining constant latency under high QPS. It also details the development of a new DHCPLB server mode that generates responses instead of forwarding, and the use of DHCPLB for A/B testing server implementations.