Symbol Technologies Spectrum24 AP-4131 - Manual (Page 32)

Introduction
22 AP-4131 Access Point Product Reference Guide
Mobile IP is like giving an individual a local post office forwarding address
when leaving home for an extended period. When mail arrives for the
individual home address, it is forwarded by the local post office to the
current care-of-address. Using this method, only the local post office
requires notification of the individual current address. While this example
represents the general concept of Mobile IP operation and functionality,
it does not represent the implementation of Mobile IP used.
A tunnel is the path taken by the original packet encapsulated within the
payload portion of a second packet to some destination on the network.
A Home Agent is an AP acting as a router on the MU home network.
The home agent intercepts packets sent to the MU home address and
tunnels the message to the MU at its current location. This happens as
long as the MU keeps its home agent informed of its current location on
some foreign link.
A Foreign Agent is an AP acting as a router at the MU location on a foreign
link. The foreign agent serves as the default router for packets sent out
by the MU connected on the same foreign link.
A care-of-address is the IP address used by the MU visiting a foreign link.
This address changes each time the MU moves to another foreign link.
It can also be viewed as an exit point of a tunnel between the MU home
agent and the MU itself.
The S24 Mobile IP (roaming across routers) feature enables an MU
on the Internet to move from one subnet to another while keeping its
IP address unchanged.
To configure this feature, see section 2.4: ”Configuring System Parameters”
on page 59. The Mobile IP feature is not available if either Kerberos or
EAP-TLS have been enabled as access point security measures.