Cisco Systems DL-2159-05 manual How Proxy Mobile IP Works, Agent Discovery

Chapter 6 Configuring Proxy Mobile IP

Introduction to Mobility in IP

•A home agent. The home agent is a router on the visiting client’s home network that serves as the anchor point for communication with the access point and the visiting client. The home agent tunnels packets from a correspondent node on the Internet to the visiting client device by way of a tunnel to a foreign agent.

•A foreign agent. The foreign agent is a router on your network that serves as the point of attachment for the visiting client device when it is on your network, delivering packets from the home agent to the visiting client.

Figure 6-4shows the five participating devices.

Figure 6-4 Participating Devices in Proxy Mobile IP

	Client device	Client device
visiting foreign
	network		at home

Access point supporting proxy Mobile IP

Internet

			Access point
	Foreign	Home	supporting proxy
	agent	agent	Mobile IP
Authoritative
access point			81653
supporting proxy
Mobile IP

How Proxy Mobile IP Works

The proxy Mobile IP process has four main phases. These sections describe each phase:

•Agent Discovery, page 6-8

•Subnet Map Exchange, page 6-9

•Registration, page 6-10

•Tunneling, page 6-10

Agent Discovery

During the agent discovery phase, the home agent and the foreign agent advertise their services on the network by using the IRDP. The access point monitors these advertisements.

The IRDP advertisements carry mobile IP extensions that specify whether an agent is a home agent, foreign agent, or both; its care-of address; the types of services it provides, such as reverse tunneling and generic routing encapsulation (GRE); and the allowed registration lifetime or roaming period for visiting

Cisco Aironet 1200 Series Access Point Software Configuration Guide

6-8 OL-2159-05