Specifications

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Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
OL-5260-01
Chapter 15 Configuring Proxy Mobile IP
Understanding Proxy Mobile IP
Understanding Proxy Mobile IP
These sections explain how access points conduct proxy Mobile IP:
• Overview, page 15-2
• Components of a Proxy Mobile IP Network, page 15-2
• How Proxy Mobile IP Works, page 15-3
• Proxy Mobile IP Security, page 15-6
Overview
The access point’s proxy Mobile IP feature works in conjunction with the Mobile IP feature in Cisco IOS
software. When you enable proxy Mobile IP on your access point and on your wired network, the access
point helps client devices from other networks remain connected to their home networks. The visiting
client devices do not need special software; the access point provides proxy Mobile IP services on their
behalf. Any wireless client can participate.
Mobile IP provides users the freedom to roam beyond their home subnets while maintaining their home
IP addresses. This enables transparent routing of IP datagrams to mobile users during their movement,
so that data sessions can be initiated to them while they roam. For example, a client device with an IP
address of 192.95.5.2 could associate to an access point on a network whose IP addresses are in the
209.165.200.x range. The guest client device keeps its 192.95.5.2 IP address, and the access point
forwards its packets through a Mobile IP enabled router across the Internet to a router on the client’s
home network.
Access points with proxy Mobile IP enabled attempt to provide proxy service for any client device that
associates and does not perform the following:
• Does not issue a DHCP request to get a new IP address.
• Does not support a Mobile IP stack. If a device supports a Mobile IP stack, the access point assumes
that the device will perform its own Mobile IP functions.
You enable proxy Mobile IP for specific SSIDs on the access point, providing support only for clients
that use those SSIDs. Proxy Mobile IP does not support VLANs. You can pause proxy Mobile IP support
without losing your proxy Mobile IP configuration.
Proxy Mobile IP is disabled by default.
Note Guest client devices do not receive broadcast and multicast packets.
Components of a Proxy Mobile IP Network
Five devices participate in proxy Mobile IP:
• A visiting client device. The visiting client device is any device such as a personal digital assistant
or a laptop that can associate to a wireless access point. It does not need any special proxy Mobile
IP software.
• An access point with proxy Mobile IP enabled. The access point proxies on behalf of the visiting
client device, performing all Mobile IP services for the device.