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Cisco Aironet 1200 Series Access Point Software Configuration Guide
OL-2159-05
Chapter6 Configuring Proxy M obile IP
Introduction to Mobility in IP
Issues to Consider While Deploying Proxy Mobile IP
When deploying proxy Mobile IP, consider these key issues:
•Proxy Mobile IP is currently not supported with VLANs. Do not enable VLANs if you plan to use
proxy Mobile IP.
•Enabling proxy Mobile IP on the access point requi res software release 12.01T1 or later.
•Synchronize clocks between access points, home agents, and foreign agents and use the Network
Time Protocol (NTP) rather than manually setting clocks. Registration requests may fail if the
timestamps generated by the requestor are outside the window expected by the receiver.
•Be sure to enable proxy Mobile IP on each SSID that requires it. None of the proxy Mobile IP
configuration commands take effect until proxy Mobile IP is set on the SSID.
•An access point providing proxy Mobile IP must have a default gateway assigned (statically or
through DHCP).
•A home agent or foreign agent must be running on the network’s default gateway (assuming there
are multiple routers on the subnet). If both home and foreign agents exist on a single subnet, they
must be configured on the same gateway.
•In networked environments where mobile nodes reside on multiple subnets, routers providing proxy
Mobile IP services may need to act as both a home agent (for local subnets) and a foreign agent (for
remote subnets). Commands that enable these features can be applied to the same router without
interfering with each other.
•Proxy Mobile IP does not support broadcast or multicast capabilities for the roaming client device.
Applications that rely on multicast should not be enabled as proxy Mobile IP clients.
•Verify that there is IP connectivity between all devices before attempting to troubleshoot a proxy
Mobile IP problem. Ping all devices and interfaces in the network th at perform proxy Mobile IP
functions.
•Use loopback interfaces for any function that requires an IP address but does not require a specific
interface, such as care-of address on the foreign agent.
•Make sure that UDP port 6500 is not blocked between the authoritative access point and other access
points. A blockage prevents the propagation of subnet table updates.
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 Mobile IP client
software.
•An access point with proxy Mobile IP enabled. The access po int proxies on behalf of the visiting
client device, performing all Mobile IP functions for the device. The access point uses a subnet map
to keep track of home agent information. The access point also gets updates about new home agents
from the authoritative access point.
•An authoritative access point on your network supporting proxy Mobile IP. The authoritative access
point uses a subnet map to collect and distribute home agent in formation stored in the subnet map
to all the other access points for all visiting client devices.