1. VIP: a Virtual Interface-based aPproach for vertical handover in single-subnet networks
Wei-Cheng Xiao1, Ling-Jyh Chen2, Shih-Hsuan Tang1, Cheng-Fu Chou1
1National Taiwan University
2Academia Sinica

2. Introduction The emerging network applications
Multi-interface/channel/radio Technologies
Human Mobility
May 22, 2007
IEEE AINA 2007

3. Handover
A seamless handover is defined as a handover scheme that maintains the connectivity of all applications on the mobile device when the handover occurs.
Challenges: maintaining application sessions (e.g., TCP)
May 22, 2007
IEEE AINA 2007

4. Question: Which one are you using? Why?
Seamless Handover
Two goals: low latencies and few packet losses
Related Work
Network Layer Approaches
MIPv4, IPv6
Upper Layer Approaches
End-to-End Approaches (e.g., Dynamic DNS)
Proxy-based Approaches (e.g., USHA)
New Session Layer Protocols (e.g., MSOCKS)
Transport Layer Protocols (e.g., TCP-MH and SCTP)
Question: Which one are you using? Why?
May 22, 2007
IEEE AINA 2007

5. Our Contribution
We propose a vertical handover solution, called VIP, for single-subnet scenarios.
We implement the proposed solution in Linux and perform a set of experiments on our testbed.
We show that VIP is a simple and practical vertical handover solution for single-subnet networks.
May 22, 2007
IEEE AINA 2007

6. VIP - Architecture VIL: a 2.5th layer solution
VI: a dummy network interface
KIS: a handover manager that determines the “best” network interface and links it to the VI
May 22, 2007
IEEE AINA 2007

7. VIP Implementation Implement on Linux platform
Invoke ARP updates dynamically to link MAC address of a newly selected interface to the VI to complete a vertical handover
May 22, 2007
IEEE AINA 2007

8. VIP – Kernel Interface Selector (KIS)
May 22, 2007
IEEE AINA 2007

9. VIP – Kernel Interface Selector (KIS)
May 22, 2007
IEEE AINA 2007

10. VIP - Evaluation Scenarios
Linux-based laptop
Debian Linux with kernel version
IEEE a: D-Link DWL-AG660
IEEE b: Intel Pro/Wireless 2200BG
Access points
IEEE a: Linksys WAP55AG router
IEEE b: Buffalo WLA2-G54C router
May 22, 2007
IEEE AINA 2007

11. VIP - Evaluation Results (L2H)
IEEE b -> IEEE a
May 22, 2007
IEEE AINA 2007

12. VIP - Evaluation Results (H2L)
IEEE a -> IEEE b
May 22, 2007
IEEE AINA 2007

13. VIP - Evaluation Results (H2L)
IEEE a -> IEEE b
freeze period
May 22, 2007
IEEE AINA 2007

14. VIP - Evaluation Results (H2L)
Solution for Freeze Period
Employ specialized TCP variant (e.g., Freeze-TCP [8])
Implement other QoS enhancement schemes (e.g., Explicit Handover Notifications [9] or ERR+EHN [5])
May 22, 2007
IEEE AINA 2007

15. Summary
We propose a vertical handover solution, called VIP, for single-subnet scenarios.
VIP is a 2.5th layer solution that combines a virtual interface and ARP update messages to achieve vertical handovers.
VIP can run stand-alone, and thus ready for immediate real-world deployment.
Using testbed experiments, we show that VIP is a simple and practical solution for vertical handover in single-subnet networks.
May 22, 2007
IEEE AINA 2007

16. Thanks! http://www.iis.sinica.edu.tw/~cclljj/
May 22, 2007
IEEE AINA 2007