To offer seamless roaming to customers, mobile operators need an always on IP connection that persists independent of location, movement, or wireless infrastructure. They also need Quality of Service (QoS) capabilities, especially the ability to forward packets at rates appropriate for each connection. For example, if a user connects to a wireless WAN and then roams to a faster 3G network, the mobile operator needs to reduce the packet-forwarding rate at the moment the new connection takes over, in order to avoid packet loss (from too high a forwarding rate) or sub-optimal performance (from too low a forwarding rate).
Part of the Cisco Mobile Exchange framework, the Cisco Mobile Wireless Home Agent is based on the Internet Engineering Task Force (IETF) Mobile IP standard (RFC 3344), which identifies a host device by a single IP address even if the device moves its physical point of attachment from one network to another. The result: subscribers with mobile devices can roam to another network without restarting applications or terminating and re-establishing a connection.
The Cisco Mobile Wireless Home Agent is deployed at the mobile operators data center. It resides on the Cisco Catalyst Series Multiprocessor WAN Application Module, which is used in the Cisco Catalyst 6500 Series and the Cisco 7600 Series platforms. All traffic sent to the subscriber's terminal is routed through the home agent, regardless of the network where the traffic originates. Likewise, traffic from the subscriber s terminal is also routed through the home agent, regardless of its ultimate destination. As a result, the subscriber retains a constant connection and remains addressable even while roaming across different access networks. That is, the Cisco Mobile Wireless Home Agent serves as an anchor point for subscribers PCs or PDAs, no matter how many times the subscriber changes link types and crosses network boundaries.