PPSP Group G.Lu Internet Draft JC.Zuniga Intended status: Informational A.Rahman Expires: September 1, 2010 InterDigital Communications, LLC March 1, 2010 P2P Streaming for Mobile Nodes: Scenarios and Related Issues draft-lu-ppsp-mobile-00.txt Abstract The scenarios where a Peer-to-Peer Streaming Protocol (PPSP) contains mobile nodes need special considerations. An analysis of all the scenarios that involve mobile nodes is necessary to provide the guidelines to PPSP protocol design and applicability. This document describes the major scenarios for a PPSP network with mobile nodes and identifies some of the key issues. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on September 1, 2010. Lu, et al. Expires September 1, 2010 [Page 1] Internet-Draft P2P Streaming for Mobile Nodes March 2010 Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the BSD License. Table of Contents 1. Introduction...................................................2 2. Conventions and Terminology....................................3 3. Link Layer Mobility............................................3 4. IP Mobility....................................................4 4.1. Simple IP.................................................4 4.2. Mobile IP.................................................5 4.3. Proxy Mobile IP...........................................6 5. Mobility support with RELOAD...................................6 6. Tracker Mobility...............................................7 7. Geo-Targeting Issues...........................................7 8. Mobile Node Capabilities.......................................8 8.1. Multiple Interfaces.......................................8 8.2. Uplink vs. Downlink Bandwidth.............................8 8.3. Processing Power..........................................8 9. Security Considerations........................................8 10. IANA Considerations...........................................8 11. References....................................................8 11.1. Normative References.....................................8 11.2. Informative References...................................9 12. Acknowledgments...............................................9 1. Introduction In the past P2P solutions have mostly targeted wired or fixed connections. Mobile P2P communications are expected to grow rapidly Lu, et al. Expires September 1, 2010 [Page 2] Internet-Draft P2P Streaming for Mobile Nodes March 2010 and the nature of mobile nodes and mobile environments cause specific challenges to P2P communications, specifically for streaming scenarios. This draft discusses such mobility specific issues with the illustration of different scenarios. 2. Conventions and Terminology This document uses the same terminologies as [I-D.zhang-ppsp-problem- statement]. For simplicity, this document illustrates scenarios showing a centralized Tracker architecture. However, it should be understood that all the scenarios also apply to the distributed architecture, e.g. using a Distributed Hash Table (DHT). 3. Link Layer Mobility PPSP uses a P2P based overlay network on top of the transport network. Mobility or link quality at link layers is not visible to the peers. A Peer-To-Peer streaming session quality can suffer from high error rate and low throughput due to poor link layer conditions seen in mobile networks. Frame loss, audio/video synch loss, or streaming stalls are likely to be seen and ultimately Peer-to-Peer Streaming session can be terminated abruptly as a result of changes in L2 connectivity. Such scenario is illustrated in Figure 1. Lu, et al. Expires September 1, 2010 [Page 3] Internet-Draft P2P Streaming for Mobile Nodes March 2010 P2P streaming network +---------+ ---------- >| Tracker |< ---------- | +---------+ | | | | | | | | 2)P2P streaming session | V quality is poor or terminated V +------+ +------+ |Peer 1|< ------------X------------ >|Peer 2| +------+ +------+ IP1 ^ ^ IP2 | | X 1) Peer 1 lost | | connection | v v ****** ****** * NW1 * * NW2 * * * * * ****** ****** Figure 1 P2P Streaming with Link Layer Mobility 4. IP Mobility 4.1. Simple IP Simple IP refers to the scenario where there is no mobile IP or Proxy Mobile IP, and a peer needs to obtain a new IP address through a standard method like DHCP after losing the previous IP address. As illustrated in Figure 2, when peer 1 moves from NW1 to NW1', its IP address changes from IP1 to IP1'. The P2P Streaming session between peer 1 and peer 2 may degrade or completely be lost. Lu, et al. Expires September 1, 2010 [Page 4] Internet-Draft P2P Streaming for Mobile Nodes March 2010 P2P streaming network +---------+ ---------- >| Tracker |< ---------- | +---------+ | | | | | | | | | V V +------+ +------+ |Peer 1|< ------------------------- >|Peer 2| +------+ +------+ IP1 ^ ^ IP1' ^ IP2 | | | X ------- | | | | v v v ****** ****** ****** * NW1 * * NW1' * * NW2 * * * * * * * ****** ****** ****** Figure 2 P2P Streaming with Simple IP 4.2. Mobile IP Mobile IP provides IP mobility and hides the mobile's movement from the Correspondent Node (CN). Figure 3 illustrates the case when peer 1 moves from NW1 to NW1'. Because of Mobile IP, neither the tracker nor peer 2 are aware of the change of network for peer 1. This may cause quality problems for the P2P Streaming session. For example, peer 1 may experience high latency and increased load, which adversely affects the user experience of the P2P streaming session(s) and may result in unacceptable performance. Lu, et al. Expires September 1, 2010 [Page 5] Internet-Draft P2P Streaming for Mobile Nodes March 2010 P2P streaming network +---------+ ---------- >| Tracker |< ---------- | +---------+ | | | | | | | MIP | IP1 | Client | P2P Streaming session | V performance may not be optimal V +------+ +------+ |Peer 1|< ------------------------- >|Peer 2| +------+ +------+ ^ ^ ^ IP2 | | | X ------- | | | | v v v ****** ****** ****** * NW1 * * NW1' * * NW2 * * * * * * * ****** ****** ****** Figure 3 P2P Streaming with Mobile IP 4.3. Proxy Mobile IP The use of Proxy Mobile IP causes similar issues as the ones mentioned for Mobile IP in the above section. On top of these, Proxy Mobile IP also introduces a new issue for P2P streaming sessions. Since Proxy Mobile IP is a network based solution, the mobile node (peer) is not aware of its IP mobility so it cannot inform the tracker, P2P Cache, CDNs or other peers of the IP level mobility. Therefore IP mobility is totally invisible to the P2P Streaming session entities and harder to detect and respond accordingly. 5. Mobility support with RELOAD It has already been identified in the proposed WG charter that any PPSP developed protocol should be analyzed for interactions with the RELOAD protocol [I-D.ietf-p2psip-base]. The RELOAD protocol provides Lu, et al. Expires September 1, 2010 [Page 6] Internet-Draft P2P Streaming for Mobile Nodes March 2010 a signaling and routing mechanism for P2P overlay networks over the general Internet. The latest RELOAD draft (http://tools.ietf.org/html/draft-ietf-p2psip-base-07) also has a future consideration section for support of HIP (section 5.6.1.1). HIP is an experimental mobility protocol with good security properties. In addition to HIP, the following mobility protocols should also be considered for PPSP-RELOAD interactions: . Mobile IP . Proxy Mobile IP 6. Tracker Mobility Normally trackers are assumed to be fixed nodes. However, in a mobile environment mobile nodes can also become trackers. In this sense, similar considerations to the ones described above for mobile peers should be applied to mobile trackers. 7. Geo-Targeting Issues Geo-targeting is a technique used to determine the physical location (i.e. geo-location) of a user. The geo-location is based on geographical and other personal information provided by the requester peer or a third party. Techniques to determine geo-location of a user can rely on civic location, GPS geographical coordinates or most commonly IP address. The primary source for IP address geographical data is the regional Internet registries. Depending on the location, different regulations and rules may apply. For instance, some content may not be distributed on certain locations or can only be distributed on some other locations. Current content distribution policies can apply certain rules to P2P Streaming clients. However, IP mobility can hide a peer or a tracker moving from one region to another where possibly different content distribution rules may apply hence rendering the set forth policies un-enforceable. Lu, et al. Expires September 1, 2010 [Page 7] Internet-Draft P2P Streaming for Mobile Nodes March 2010 8. Mobile Node Capabilities Mobile nodes are constrained by nature due to their limited battery, screen size, computational capability and they operate in variable and unpredictable environments. These attributes bring about the problems mentioned above that may adversely affect the P2P Streaming sessions. 8.1. Multiple Interfaces A mobile node can switch between different radio access technologies such as 3G or Wi-Fi occasionally or frequently, which may cause the P2P Streaming session quality to degrade due to latency introduced or P2P Streaming session totally terminated. 8.2. Uplink vs. Downlink Bandwidth Often mobile devices have asymmetrical bandwidth capabilities. For instance, most mobile devices are capable of handling higher bit rates in the downlink than in the uplink. Since peer-to-peer streaming sessions can be either generated or terminated on a mobile device, these mobile node capabilities should be taken into account. 8.3. Processing Power Some devices are more capable than others in terms of computational performance or processing power. Similarly, devices can have different performance for generating a session (e.g. video recording) or terminating it (e.g. video display). Taking these differences into account is important for maintaining a good quality of the P2P streaming session. 9. Security Considerations This draft does not introduce new threats to security. 10. IANA Considerations This document makes no request of IANA. 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Lu, et al. Expires September 1, 2010 [Page 8] Internet-Draft P2P Streaming for Mobile Nodes March 2010 [RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and Demon Internet Ltd., November 1997. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in Ipv6", RFC 3775, June 2004. 11.2. Informative References [I-D.zhang-ppsp-problem-statement] Zhang, Y., Zong, N., Camarillo, G., Seng, J., and R. Yang, "Problem Statement of P2P Streaming Protocol (PPSP)", draft-zhang-ppsp-problem-statement-05 (Work in progress), October 20, 2009. [I-D.zong-ppsp-reqs] Zong, N., Zhang, Y., Pascual, V., and C. Williams, "P2P Streaming Protocol (PPSP) Requirements", draft-zong-ppsp- reqs-02 (Work in progress), October 22, 2009. [I-D.gu-ppsp-survey] Gu, Y., Zong, N., Zhang, Hui., Zhang, Y., Camarillo, G., and Y. Liu, "Survey of P2P Streaming Applications", draft- gu-ppsp-survey-01 (Work in progress), October 22, 2009. [I-D.ietf-p2psip-base] Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and H. Schulzrinne, "REsource LOcation And Discovery (RELOAD)Base Protocol", draft-ietf-p2psip-base-07 (Work in progress), February 17, 2010. 12. Acknowledgments The authors would like to thank Serhad Doken for his thorough review and valuable inputs to this draft. This document was prepared using 2-Word-v2.0.template.dot. Authors' Addresses Guang Lu InterDigital Communications, LLC Email: Guang.Lu@InterDigital.com Lu, et al. Expires September 1, 2010 [Page 9] Internet-Draft P2P Streaming for Mobile Nodes March 2010 Juan Carlos Zuniga InterDigital Communications, LLC Email: JuanCarlos.Zuniga@InterDigital.com Akbar Rahman InterDigital Communications, LLC Email: Akbar.Rahman@InterDigital.com Lu, et al. Expires September 1, 2010 [Page 10]