Cisco Cisco IOS Software Release 12.4(9)T

In a single-tunnel scenario, you can configure a default route through an interface to the home agent to 
help with collocated care-of address registrations. Do not use this configuration if your mobile router is 
configured for multipath support because it would defeat the purpose of multipath support.

Before you configure the Mobile Router Multipath Support feature, you should understand the following 
concepts:

The Mobile Router Multipath Support feature extends the mobile router functionality to multiple 
interfaces. Before the introduction of this feature, the mobile router received agent advertisements on 
multiple roaming interfaces. However, it would register through only one interface and set up the tunnel 
and routes based on that registration. During the routing or tunneling phase, packets arrive at the home 
agent. The home agent performs two encapsulations of the packets and tunnels them to the foreign agent. 
The foreign agent performs one de-encapsulation and forwards the packets to the mobile router, which 
performs another de-encapsulation. The mobile router then forwards the original packets to the IP 
devices on the mobile networks. See 

 for an illustration of routing within a mobile network using 

a single tunnel.