PPPoECliet PPPoEDInitiation(PADI) PPPoEDOffer(PADO) PPPoEDRequest(PADR) PPPoED Session-Confirmation(PADS) PPP LCP Configuration Request PPP LCP Configuration ACK PPP LCP Configuration Request PPP LCP Configuration ACK PPP CHAP Challenge PPP CHAP Response PPP CHAP Success PPP IPCP Configuration Request PPP IPCP Configuration ACK PPP IPCP Configuration Request PPP IPCP Configuration NAK PPP IPCP Configuration Request PPP IPCP Configuration ACK PPP LCP Echo Request PPP LCP EchoReply PPP LCP Echo Request PPP LCP EchoReply PPP LCP Termination Request PPP LCP TerminationACK PPPoEDTermination(PADT) PPPoE Server 发现阶段 PPP链路建立 认证阶段 网络参数设置PPP链路维护 PPP LCP Termination Request PPP LCP TerminationACK PPPoEDTermination(PADT) PPP链路终止