Specifications

15-3
Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
OL-5260-01
Chapter 15 Configuring Proxy Mobile IP
Understanding Proxy Mobile IP
• An authoritative access point on your network supporting proxy Mobile IP. The authoritative access
point uses a subnet map to keep track of the home agent information for all visiting client devices.
• 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.
• 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 15-1 shows the five participating devices.
Figure 15-1 Participating Devices in 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 15-3
• Subnet Map Exchange, page 15-4
• Registration, page 15-5
• Tunneling, page 15-5
Agent Discovery
During the agent discovery phase, the home agent and the foreign agent advertise their services on the
network by using the ICMP Router Discovery Protocol (IRDP). The access point listens to these
advertisements.
Internet
Foreign
agent
Access point
supporting proxy
Mobile IP
Home
agent
Access point
supporting proxy
Mobile IP
Client device
at home
Client device
visiting foreign
network
Authoritative
access point
supporting proxy
Mobile IP
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