This section describes how Mobile-IP benefits from the network configuration system.
The network configuration system, after sending the ARPSERVER packet, will transmit a MOBAGENT packet (Table 10). This packet will contain the address(es) of mobile IP agents for this Logical IP Subnet (LIS). The RN needs to determine whether it is on the same network as its home agent. Each RN will have preconfigured its home-address, routing prefix size, and one or more home agents, as described in . Thus, the RN will know whether it is at home, or requires a foreign agent. Agents will broadcast ICMP router discovery messages with IP mobility extensions, in addition to being identified by the MOBAGENT packet, as described in .
If the RN is not at home, then it will register with its Mobile-IP home agent using UDP to send a Registration Request. It will do this by first choosing a foreign agent, and sending the message to the foreign agent, which relays the message to the home agent. The home agent responds with either a successful reply or an error code. If successful, the home agent may send a gratuitous proxy [ATM]ARP on behalf of the mobile node, and will forward and encapsulate IP traffic to the foreign agent. The foreign agent will de-encapsulate the IP packets and forward them to the remote node.