P2P Streaming for Mobile Nodes: Scenarios and Related Issues

1. Akbar RahmanJuan Carlos ZúñigaGuang LuIETF 78, July 2010http://tools.ietf.org/html/draft-lu-ppsp-mobile-02 P2P Streaming for Mobile Nodes: Scenarios and Related Issues

2. Introduction • The scenarios where P2P streaming networks contain Mobile Nodes require special consideration of the mobile device capabilities: • Uplink vs. Downlink Bandwidth • Battery Power • Multiple Interfaces • Processing Power • Geo-Targeting • Etc.

3. Uplink vs. Downlink Bandwidth • Often mobile devices have asymmetrical bandwidth capabilities where typically throughput is higher on the downlink (to the mobile) than the uplink (from the mobile) • Also many mobile networks (e.g. 2G and 3G cellular) have policies to assign bandwidth in this asymmetrical manner regardless of the capabilities of the mobile node • This bandwidth asymmetry should be considered for the Peer-Peer chunk (content) transfer protocol, and may also impact the Tracker-Peer protocol (e.g. as part of Peer status parameters reported to the Tracker)

4. Battery Power • By definition, a mobile node is often disconnected from the electrical grid and runs on its own battery power • In this scenario, the user may be willing to participate in a P2P streaming video session when the user, for example, is herself watching the content • However, as soon as the user is no longer watching the video then the mobile device may need to stop participating in the P2P session (or otherwise the battery drain will be too severe) • Battery power (or battery status) of a mobile node should be considered in both the Peer-Peer and the Tracker-Peer protocol (e.g. as part of Peer status parameters reported to the Tracker and other Peers)

5. Geo-Targeting • Geo-Targeting is a technique used to determine the physical location (geo-location) of a user. The geo-location of a user may be determined by GPS, Cellular base station ID, or most commonly IP address • Depending on the location, content providers may apply different rules. For example: • Some content (e.g. TV program) can only be viewable in selected countries (i.e. white/black lists or black-outs) • However, mobility may hide the true IP location of a device. For example: • Proxy Mobile IP provides the LMA IP address to the Tracker • Corporate VPNs may provide a server IP address to the Tracker • Etc.

6. Detailed Scenario Multiple interfaces (and Peer IP mobility)

7. Multiple Interfaces (and Peer IP Mobility) Tracker Logical P2P Overlay Network … Peer 1 (Mobile Device) Peer 2

8. Multiple Interfaces (and Peer IP Mobility) Tracker Logical P2P Overlay Network … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular WiFi DSL AN1 AN2 AN3 Internet

9. Multiple Interfaces (and Peer IP Mobility) Tracker Logical P2P Overlay Network … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular WiFi DSL AN1 AN2 AN3 IP Addresses - IP1 IP2 IP3 Internet

10. Multiple Interfaces (and Peer IP Mobility) 1) Peer 1 sends “Join” to Tracker to join P2P network Tracker Logical P2P Overlay Network … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular DSL AN1 AN3 IP Addresses - IP1 IP3 Internet

11. Multiple Interfaces (and Peer IP Mobility) 2) Tracker stores IP address (IP1) as part of Peer 1 record 1) Peer 1 sends “Join” to Tracker to join P2P network Tracker Logical P2P Overlay Network … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular DSL AN1 AN3 IP Addresses - IP1 IP3 Internet

12. Multiple Interfaces (and Peer IP Mobility) Tracker Logical P2P Overlay Network 3) Peer 1 sends “GET” to fetch content from Peer 2 … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular DSL AN1 AN3 IP Addresses - IP1 IP3 Internet

13. Multiple Interfaces (and Peer IP Mobility) Tracker Logical P2P Overlay Network 4) Peer 2 stores IP address (IP1) as destination for some content chunks … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular DSL AN1 AN3 IP Addresses - IP1 IP3 Internet

14. Multiple Interfaces (and Peer IP Mobility) Tracker Logical P2P Overlay Network … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular WiFi DSL AN1 AN2 AN3 5) IP address of Peer 1 changes as a result of mobility (e.g. via DHCP update) IP Addresses - IP1 IP2 IP3 Internet

15. Multiple Interfaces (and Peer IP Mobility) Tracker Logical P2P Overlay Network 6) Peer-Peer communication should update all nodes of IP address change (or else Peer 2 will incorrectly send chunks to IP1) … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular WiFi DSL AN1 AN2 AN3 IP Addresses - IP1 IP2 IP3 Internet

16. Multiple Interfaces (and Peer IP Mobility) 7) Tracker-Peer communication should capture IP address change (or else will have corrupted Peer Lists containing incorrect IP address for Peer 1) Tracker Logical P2P Overlay Network 6) Peer-Peer communication should update all nodes of IP address change (or else Peer 2 will incorrectly send chunks to IP1) … Peer 1 (Mobile Device) Peer 2 Physical Network 3G cellular WiFi DSL AN1 AN2 AN3 IP Addresses - IP1 IP2 IP3 Internet

17. Conclusions & Next Steps (1/2) • The scenarios where P2P streaming networks contain mobile nodes require special consideration to deal with issues such as: • Uplink vs. downlink bandwidth asymmetry • Battery status • Change of Peer IP address (possibly rapidly/frequently) • Geo-Targeting • Scenarios shown with centralized Tracker architecture, but apply equally to distributed DHT type architecture

18. Conclusions & Next Steps (2/2) • The PPSP WG should consider: • Adding these mobility requirements in the “requirements” document • Developing solutions to explicitly support mobility in the design of both Tracker-Peer and Peer-Peer protocols

19. THANK YOU