Mobile IP and Dynamic IP Tunnels

The Mobile IP application can create dynamic point-to-point GRE and DVMRP tunnels.

The Mobile IP application is a tunneling-based solution that enhances the utility of E-series routing platforms at the edge of the network between fixed wire and wireless network domains. This tunneling-based solution enables a router on a user's home subnet to intercept and forward IP packets to users while they roam beyond traditional network boundaries.

To achieve mobility, the mobile node takes a secondary IP address that matches the new network and redirects the traffic bound to the primary or home address to the mobile node's new network. In the Mobile IP feature, the two agents that accomplish this task are the home agent and the foreign agent.

The Mobile IP application can create a dynamic IP tunnel using the attributes in a default destination profile or a customized destination profile.

When creating the dynamic IP tunnel, the Mobile IP application assigns its name using the following format:

When the Mobile IP application creates the dynamic IP tunnel, it sets a Don't Fragment bit in the packet and in the outer IP header.

The Mobile IP home agent uses the dynamic IP tunnel for routing loop detection. The home agent examines packets that are intercepted by the home agent and destined for the mobile node. If the packet is already encapsulated, and the inner destination address is the same as the outer destination address, then the system examines the outer source address. If the outer source address is the same as the tunnel destination address or the foreign agent care-of-address (CoA), the system silently discards the packet. In all other cases, the tunnel encapsulation is successful.

For more information about configuring Mobile IP using GRE or DVMRP tunnels, see Configuring the Mobile IP Home Agent .

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