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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
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   This Internet-Draft will expire on September 1, 2010.







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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


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   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.


























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   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.










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   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.









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    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


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   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.







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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.


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   [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



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   Juan Carlos Zuniga
   InterDigital Communications, LLC
   Email: JuanCarlos.Zuniga@InterDigital.com


   Akbar Rahman
   InterDigital Communications, LLC
   Email: Akbar.Rahman@InterDigital.com









































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