Relay Agent Encapsulation for DHCPv4
Hui Qiong Deng, Ted Lemon, Lu Huang · 2010
This document describes a general mechanism whereby DHCP relay agents can encapsulate DHCP packets that they are forwarding in the direction of DHCP servers, and decapsulate packets that they they are forwarding toward DHCP clients, so that more than one relay agent can insert relay agent suboptions into the forwarding chain.