Chapter 7. Metro Mobility: Cisco Mobile Networks
As the name suggests, Cisco Mobile Networks allows entire networks to be mobile while maintaining IP connectivity. In a nutshell, a router is used as a Mobile Node to enable mobility for all its attached networks. The advantage of Mobile Networks is that because the router is the Mobile Node, all the devices attached to the mobile network inherit the mobility without having to be Mobile IP aware. A good example of network mobility is an airplane outfitted with a mobile router, allowing the passengers to stay connected to the Internet as they fly to their destination. Just imagine being able to surf the Internet, trade stocks, or even connect to your corporate virtual private network (VPN) while flying in the sky! Now, that would take the world of business travel to a new level! Or, imagine being the chief of police and having complete intranet access to criminal records and database information as you drive in your police vehicle outfitted with a mobile router.
Typically, the nodes that reside on the mobile network are not even aware that IP mobility is transpiring right under their noses. The nodes need not have any Mobile IP client software, although they could. In essence, the mobile router shields mobility and roaming from the nodes; as far as the nodes are concerned, they are directly attached to a fixed network. As shown in Figure 7-1, a mobile network comprises the three main Mobile IP entities: Home Agent, Foreign Agent (FA), and mobile router (the Mobile Node in this case is a router).
Figure 7-1. Key Components of a Cisco Mobile Networks Solution
Cisco Mobile Networks is standard Mobile IP with a few additions to enable network mobility. Most of the information presented in previous chapters applies to a mobile router just as it would to any other Mobile Node, with a few exceptions. Before we get into the details, lets look at a few questions we need to address:
As we answer each of these questions in this chapter, you will see that a mobile router is primarily a standard Mobile IP Mobile Node. As with a Mobile Node, it follows the Mobile IP phases as outlined in Chapter 2, "Understanding Mobile IP," namely, move detection and agent discovery, Mobile IP handover, registration, and deregistration. However, because the mobile router has mobile networks attached to it, additional features are designed to ensure that traffic is properly delivered to nodes on the mobile networks. To this end, a key feature of Cisco Mobile Networks is dual Mobile IP tunnelsinside the tunnel from the Home Agent to the CoA is another tunnel from the Home Agent to the mobile router, as depicted in Figure 7-2.
Figure 7-2. Key Feature of Cisco Mobile Networks (Dual Tunnels)
In the first part of the chapter, we examine the three Mobile IP entities, the Mobile Node (Router), Home Agent, and FA and see the behavior and additional features involved with Cisco Mobile Networks. We introduce the IOS configuration for the different features. In the latter part of the chapter, we look at IOS enhancements to support Cisco Mobile Networks that arose from the type of environments in which a mobile router is typically deployed. Specifically, we examine how the mobile router operates in fault-tolerant mode, with asymmetric links, and in Colocated Care-of Address (CCoA) mode. Finally, we consider the integration of Cisco Mobile Networks with quality-of-service mechanisms and IP Security (IPSec).