Specifications

Mobile Computing
Packet Data Networking
6-4 68P81095E55-E August 08, 2000
The iDEN system’s interface to the Internet is the MDG. The MDG is an enterprise
level switching router that allows for truly mobile device addressing. The MDG acts
as a conduit between the MS and the Internet. Messages across the Internet are
addressed to the MDG. The MDG re-addresses the data to the specific MS. Data for
MSs that the MDG serves is accepted and the Internet Routing Information Protocol
(RIP) is removed and the data is re-assigned to the mobile IP address used by the
iDEN system. The D-VLR locates the mobile and transfers the data packet across
the MPS to the EBTS and then to the MS.
Inter-System Mobility
For truly mobile computing the iDEN system provides Packet Data remote system
usage and roaming. Roaming uses the Home Agent and a Foreign Agent. Each of
these is an MDG sub-system that serves an iDEN network. Each agent (MDG)
contains a table of the addresses of all the roaming partner/remote MDGs (a virtual
network).
Each MDG has a Home Agent that lists the packet data services and remote location
of the MS. The remote location is the care-of-address that is also the address of the
remote MDG. The local MDG (home agent) forwards data to the remote MDG
Foreign Agent) while the MS is away from home. This MS mobility binding has
contains the IP address, the foreign agent’s address (care-of-address) and time
variable. As long as the mobile does not register in another system, the data will be
forwarded to the Foreign Agent (remote MDG).
A Foreign Agent is an MDG on the visited network that coordinates the routing of
data when an MS roams. The remote system will contact the home system to verify
registration, authentication and services. If allowed, the home system will transfer
this information to the remote system. The Foreign Agent (MDG) will add the
traveling MS to a visitor list and accepts data packets for the local (home) system.
Like home system routing, the visited system will locate and route the data packet to
the roaming MS.
The home MDG will send all data to the visited MDG that in-turn, will route the
packet to the remote iDEN system. All roaming system partners are part of a virtual
network defined in both system’s MDGs.