Several solutions have been proposed for mobility management in IP based heterogeneous networks, working at different protocol levels, from layer 2 up to application level. In order to take the handover decision, many solutions require to monitor the performance of the heterogeneous networks to which the mobile device is connected. Measuring the physical or link level performance on a given wireless access networks does not provide a reliable indication of the perceived level of service when the application flows are handed over that wireless access network. It is therefore needed to take measurements at IP level, on the (bidirectional) path from the Mobile Host to an intermediate node handling the mobility or even to the remote Correspondent Host. Gathering such measurements in a timely, effective and efficient way is not an easy task. In this paper we show that a naïve approach using application level active measurements is highly CPU intensive. This would severely impact battery usage in Mobile Hosts and does not scale if intermediate mobility management nodes are involved. On the contrary we show that an implementation of active measurements in the Linux kernel has a very low CPU usage. In this approach an efficient use of batteries in Mobile Host can be achieved and intermediate mobility management nodes can scale up to monitoring thousands of flows towards Mobile Hosts. Finally we discuss how combining passive and active measurements could further improve the solution.

In this work we describe the demo of UPMT -Universal Perapplication Mobility management using Tunnels. UPMT is a perapplication mobility management solution highly suitable for "ABC" (Always Best Connected) mobility scenarios since it provides mechanisms to fulfill different and independent application requirements as a mobile user roams across different access network infrastructures and Service Providers. Thanks to the tunneling approach, the UPMT solution works as an overlay over current Internet and it does not require any enhancement of the networking infrastructure. With this demo we show how the Linux and Android implementations can choose the best network interface among all available ones independently for each active application, set handover policies and react to IP reconfigurations. The UPMT solution foresees a mobility management node, called Anchor Node. The Anchor Node includes a tool that perform server side monitoring of connected Mobile Hosts and tunnels and it will be shown in the demo.

Optimal interface selection is a key mobility management issue in heterogeneous wireless networks. Measuring the physical or link level performance on a given wireless access networks does not provide a reliable indication of the IP connectivity, delay and loss on the (bidirectional) paths from the Mobile Host to the node that is handling the mobility, over different heterogeneous networks. In this paper, we propose, implement and analyze mechanisms for connectivity check and performance (network delay and packet loss) monitoring over IP access networks. We evaluate the accuracy and timeliness of the performance estimates and provide guidelines for tuning up the parameters. From the implementation perspective, we show that using application level measurements is highly CPU intensive, while a kernel based implementation has comparably a very low CPU usage. The Linux kernel implementation results in an efficient use of batteries in Mobile Hosts and intermediate Mobility Management Nodes can scale up to monitoring thousands of flows. The proposed solutions have been implemented in the context of a specific mobility management solution, but the results are of general applicability. The Linux implementation is available as Open Source.Index Terms-Network monitoring, wireless networking, mobility management, vertical handover.

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