Unicast Datagram Routing

When registered on a foreign network, the mobile node chooses a default router using the following rules:

• If the mobile node is registered using a foreign agent care-of address, then the mobile node chooses its default router from among the router addresses advertised in the ICMP router advertisement portion of that agent advertisement message. The mobile node can also consider the IP source address of the agent advertisement as another possible choice for the IP address of a default router.

• If the mobile node is registered directly with its home agent using a co-located care-of address, then the mobile node chooses its default router from among those advertised in any ICMP router advertisement message that it receives. The chosen default router network prefix must match the mobile nodes externally obtained care-of address. If the mobile node's externally obtained care-of address matches the IP source address of the agent advertisement under the network prefix, the mobile node can also consider that IP source address as another possible choice for the IP address of a default router.