ICNRG
Internet Research Task Force (IRTF)                     C. Westphal, Ed.
Internet Draft
Request for Comments: 7933                                        Huawei
Intended status:
Category: Informational                                       S. Lederer
Expires: October 26, 2016
ISSN: 2070-1721                                                 D. Posh Posch
                                                             C. Timmerer
                                       Alpen-Adria University Klagenfurt
                                                              Aytac
                                                                A. Azgin
                                                                   S.
                                                                  W. Liu
                                                                  Huawei
                                                              C. Mueller
                                                                 Bitmovin
                                                                  A.Detti
                                                                BitMovin
                                                                A. Detti
                                          University of Rome Tor Vergata
                                                               D. Corujo
                                                     University of
                                    Instituto de Telecomunicacoes Aveiro
                                                                 J. Wang
                                            City University of Hong-Kong
                                                     Marie-Jose Hong Kong
                                                            M. Montpetit
                                                             Niall
                                                                     MIT
                                                               N. Murray
                                         Athlone Institute of Technology

                                                         April 27,
                                                             August 2016

   Adaptive Video Streaming over ICN
                  draft-irtf-icnrg-videostreaming-08.txt

Status of this Memo Information-Centric Networking (ICN)

Abstract

   This Internet-Draft is submitted document considers the consequences of moving the underlying
   network architecture from the current Internet to an Information-
   Centric Networking (ICN) architecture on video distribution.  As most
   of the traffic in full conformance with future networks is expected to be video, we
   consider how to modify the
   provisions existing video streaming mechanisms.
   Several important topics related to video distribution over ICN are
   presented.  The wide range of BCP 78 scenarios covered includes the
   following: evolving Dynamic Adaptive Streaming over HTTP (DASH) to
   work over ICN and BCP 79.

   This Internet-Draft is submitted in full conformance with leverage the recent ISO/IEC Moving Picture Experts
   Group (MPEG) standard, layering encoding over ICN, introducing
   distinct requirements for video using Peer-to-Peer (P2P) mechanisms,
   adapting the
   provisions Peer-to-Peer Streaming Protocol (PPSP) for ICN, creating
   more stringent requirements over ICN because of BCP 78 delay constraints
   added by Internet Protocol Television (IPTV), and BCP 79. This document may not managing digital
   rights in ICN.  Finally, in addition to considering how existing
   mechanisms would be modified,
   and derivative works impacted by ICN, this document lists some
   research issues to design ICN-specific video streaming mechanisms.

Status of it may This Memo

   This document is not be created, and an Internet Standards Track specification; it may not be is
   published except as an Internet-Draft. for informational purposes.

   This Internet-Draft document is submitted in full conformance with a product of the Internet Research Task Force
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   provisions results of BCP 78 Internet-related research
   and BCP 79. This document may development activities.  These results might not be modified,
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   http://www.rfc-editor.org/info/rfc7933.

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Abstract

   This document considers the consequences of moving the underlying
   network architecture from the current Internet to an Information-
   Centric Network (ICN) architecture on video distribution. As most

Table of
   the traffic Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions Used in future networks is expected to be video, we consider
   how to modify the existing video streaming mechanisms. Several
   important topics related to video distribution over ICN are
   presented, covering a wide range of scenarios: we look at how to
   evolve DASH to work over ICN, and leverage the recent ISO/IEC Moving
   Picture Experts Group (MPEG) Dynamic Adaptive Streaming over HTTP
   (DASH) standard; we consider layered encoding over ICN; Peer-to-Peer
   (P2P) mechanisms introduce distinct requirements for video and we
   look at how to adapt PPSP for ICN; Internet Protocol Television
   (IPTV) adds delay constraints, and this will create more stringent
   requirements over ICN as well. As part of the discussion on video,
   we discuss Digital Rights Management (DRM) in ICN. Finally, in
   addition to considering how existing mechanisms would be impacted by
   ICN, this document lists some research issues to design ICN specific
   video streaming mechanisms.

Table of Contents
1. Introduction....................................................... This Document . . . . . . . . . . . . . .   4
2. Conventions used in this document.................................. 5
   3.  Use case scenarios Case Scenarios for ICN and Video Streaming..................... Streaming  . . . . . . .   5
   4.  Video download..................................................... 7 Download  . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Video streaming Streaming and ICN............................................ ICN . . . . . . . . . . . . . . . . . . .   7
     5.1.  Introduction to client-driven streaming Client-Driven Streaming and DASH ...............  . . . .   7
     5.2.  Layered Encoding  ..............................................  . . . . . . . . . . . . . . . . . . . .   8
     5.3.  Interactions of Video Streaming with ICN ....................... 9  . . . . . . . .   8
       5.3.1. Interaction  Interactions of DASH and with ICN ................................ 9 . . . . . . . . . . . .   8
       5.3.2.  Interaction of ICN with Layered Encoding ..................  . . . . . .  10
     5.4.  Possible Integration of Video Streaming and ICN
           Architecture  . . . . . . . . . . . . . . . . . . . . . .  11
 5.4. Possible Integration of Video streaming and ICN architecture .. 12
       5.4.1.  DASH over CCN ............................................. 12 . . . . . . . . . . . . . . . . . . . .  11
       5.4.2.  Testbed, Open Source Open-Source Tools, and Dataset ................... 14 . . . . . . .  13
   6.  P2P video distribution Video Distribution and ICN.................................... 15 ICN  . . . . . . . . . . . . . . .  14
     6.1.  Introduction to PPSP .......................................... 15  . . . . . . . . . . . . . . . . . .  14
     6.2.  PPSP over ICN: deployment concepts ............................ Deployment Concepts  . . . . . . . . . . .  16
       6.2.1.  PPSP short background ..................................... Short Background . . . . . . . . . . . . . . . .  16
       6.2.2.  From PPSP messages Messages to ICN named-data ...................... 17 Named-Data  . . . . . . . .  16
       6.2.3.  Support of PPSP interaction Interaction through a pull-based Pull-Based ICN
               API .. 18 . . . . . . . . . . . . . . . . . . . . . . . . .  17
       6.2.4.  Abstract layering Layering for PPSP over ICN ....................... . . . . . . . . .  18
       6.2.5.  PPSP interaction Interaction with the ICN routing plane ............... Routing Plane . . . . .  19
       6.2.6.  ICN deployment Deployment for PPSP ................................... 20 . . . . . . . . . . . . . . .  19
     6.3.  Impact of MPEG DASH coding schemes ............................ MPEG-DASH Coding Schemes  . . . . . . . . . . .  20
   7.  IPTV and ICN  . . . . . . . . . . . . . . . . . . . . . . . .  21
     7.1.  IPTV Challenges . . . . . . . . . . . . . . . . . . . . .  21
7. IPTV and ICN...................................................... 22
 7.1. IPTV challenges ............................................... 22
     7.2.  ICN benefits Benefits for IPTV delivery ................................ 23 Delivery  . . . . . . . . . . . . .  22
   8.  Digital Rights Managements Management in ICN................................. 25 ICN  . . . . . . . . . . . . . .  24
     8.1.  Broadcast Encryption for DRM in ICN ........................... 25 . . . . . . . . . . .  24
     8.2. AAA Based  AAA-Based DRM for ICN Networks ................................ 28  . . . . . . . . . . . . .  27
       8.2.1.  Overview .................................................. 28  . . . . . . . . . . . . . . . . . . . . . .  27
       8.2.2.  Implementation ............................................ 29  . . . . . . . . . . . . . . . . . . .  28
   9.  Future Steps for Video in ICN..................................... 30 ICN . . . . . . . . . . . . . . . .  28
     9.1. Large Scale  Large-Scale Live Events ....................................... 30 . . . . . . . . . . . . . . . . .  29
     9.2.  Video Conferencing and Real-Time Communications ............... 30 . . . . .  29
     9.3.  Store-and-Forward Optimized  Rate Adaptation ................... 30  . . . . . .  29
     9.4.  Heterogeneous  Wireless Environment Dynamics ................... 31  . . . . . .  30
     9.5.  Network Coding for Video Distribution in ICN .................. 33  . . . . . .  32
     9.6.  Synchronization Issues for Video Distribution in ICN .......... 33  . .  32
   10. Security Considerations.......................................... 34  Considerations  . . . . . . . . . . . . . . . . . .  33
   11. IANA Considerations.............................................. 34 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . .  33
   12. Conclusions...................................................... References  . . . . . . . . . . . . . . . . . . . . . . . . .  34
13. References....................................................... 35
 13.1.
     12.1.  Normative References ......................................... 35
 13.2. . . . . . . . . . . . . . . . . . .  34
     12.2.  Informative References ....................................... 35
14. . . . . . . . . . . . . . . . . .  34
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  39
   Authors' Addresses............................................... 38
15. Acknowledgements................................................. Addresses  . . . . . . . . . . . . . . . . . . . . . . .  39

1.  Introduction

   The unprecedented growth of video traffic has triggered a rethinking
   of how content is distributed, both in terms of the underlying
   Internet architecture and in terms of the streaming mechanisms to
   deliver video objects.

   In particular, the IRTF ICNRG research group has been chartered to
   study new architectures centered upon information; the main
   contributor to Internet traffic (and information dissemination) is
   video, and this is expected to stay the same in the near future.  If
   ICN is expected to become prominent, it will have to support video
   streaming efficiently.

   As such, it is necessary to discuss along going in two separate directions:

     .

      Can the current video streaming mechanisms be leveraged and
      adapted to an ICN architecture?

     .

      Can (and should) new, ICN-specific video streaming mechanisms be
      designed to fully take advantage of the new abstractions exposed
      by the ICN architecture?

   This document intends to focus focuses on the first question, question in an attempt to define
   the use cases for video streaming and some requirements.

   This document  It also
   focuses on a few scenarios, namely scenarios (namely, Netflix-like video streaming, peer-to-peer P2P
   video sharing sharing, and IPTV, IPTV) and identifies how the existing protocols
   can be adapted to an ICN architecture.  In doing so, it also
   identifies the main issues with these protocols in this ICN context.

   Some documents have started

   In addition to consider the ICN-specific
   requirements this document, other works have considered specific
   aspects of dynamic adaptive streaming [2][3][4][6]. in ICN [Lederer13b]
   [Lederer13a] [Grandl13] [Detti12].  This document is informed by
   these works, as well as others.

   In this document, we give a brief overview of the existing solutions
   for the selected scenarios.  We then consider examine the interactions of such
   existing mechanisms with the ICN architecture and list some of the
   interactions any video streaming mechanism will have to consider. We then
   Finally, we identify some areas for future research.

2.  Conventions used Used in this document This Document

   In examples, "C:" and "S:" indicate lines sent by the client and
   server
   server, respectively.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [RFC2119].

   In this document, these words will appear with that interpretation
   only when in ALL CAPS. Lower case  Lowercase uses of these words are not to be
   interpreted as carrying RFC-2119 significance. the significance described in RFC 2119.

3.  Use case scenarios Case Scenarios for ICN and Video Streaming

   For ICN specific ICN-specific descriptions, we refer to the other research group
   documents.
   documents [RFC7476].  For our purpose, we assume here that ICN means "ICN"
   refers to an architecture where content is retrieved by name and with
   no binding of content to a specific network location.

   The

   Both live and on-demand consumption of multimedia content comes along come with
   timing requirements for the delivery of the content, for both, live and on-
   demand consumption. content.  Additionally,
   real-time use cases such (such as audio-
   /video audio-video conferencing [7], [Jacobson09a],
   game streaming, etc., etc.) come along with more
   strict stricter timing requirements.  Long
   startup delays, buffering periods
   or periods, poor video quality, etc., should
   be avoided to achieve a good better Quality of Experience (QoE) to for the
   consumer of the content. (For  For a definition of QoE in the context of
   video distribution, please refer to [25]. [LeCallet13].  The working
   definition is: "Quality is as follows:

      Quality of Experience (QoE) is the degree of delight or annoyance
      of the user of an application or service.  It results from the
      fulfillment of his or her expectations with respect to the utility and / or
      and/or enjoyment of the application or service in the light of the
      user's personality and current state.") state.

   Of course, these requirements are heavily influenced by routing
   decisions and caching, which are central parts of ICN and which that have
   to be considered when streaming video in such infrastructures.

   Due to this range of requirements, we find it useful to narrow the
   focus on to four scenarios (more can be included later):

   -

   o  a video download architecture similar to that of Apple iTtunes(R), iTunes,
      where the whole file is being downloaded to the client and can be
      replayed there multiple times;
   -

   o  a video streaming architecture for playing back movies; this movies, which is
      relevant for the naming and caching aspects of ICN, ICN as well as the
      interaction with the rate adaptation mechanism necessary to
      deliver the best QoE to the end-user;
   - end user;

   o  a peer-to-peer P2P architecture for sharing videos; this videos, which introduces more
      stringent routing requirements in terms of locating copies of the content,
      content as the location of the peers evolves and peers join and
      leave the swarm they use to exchange video chunks (for Peer-
     to-Peer P2P
      definitions and taxonomy, please refer to RFC5694);
   - IPTV; this RFC 5694; and

   o  IPTV, which introduces requirements for multicasting and adds
      stronger delay constraints.

   Other scenarios, such as video-conferencing video conferencing and real-time video
   communications
   communications, are not explicitly discussed in this document, while document even
   though they are in scope.  Also, events of mass-media distribution,
   such as a large crowd in at a live event, are also adding add new requirements to be
   included in later version.

   We discuss how the versions.

   The current state-of-the-art protocols in an IP context can be
   modified for the ICN architecture.  The remainder of this document is
   organized as follows. In the next section, we
   consider follows: Section 4 discusses video download. Then in download; Section 5, we 5
   briefly describe describes DASH
   [1], [ISO-DASH] and Layered Encoding (MDC, SVC). P2P is the focus of (Modification
   Detection Code (MDC), Scalable Video Coding (SVC)); Section 6,
   where we describe PPSP. 6 focuses
   on P2P and PPSP; Section 7 highlights the requirements of
   IPTV, while IPTV;
   Section 8 describes the issues of DRM. DRM; and Section 9 lists some
   research issues to be solved for ICN-specific video delivery
   mechanisms.

   Videoconferencing

   Video-conferencing and real-time video real-time-video communications will be
   detailed more
   described in further detail in future versions of this document; as well as the
   mass works.  Mass distribution of
   content at live live, large-scale events (stadium, (stadiums, concert hall, etc) halls, etc.)
   for which there is no clearly adopted existing
   protocol. protocol is another
   topic for further research.

4.  Video download Download

   Video download, namely the fetching of a video file from a server or
   a cache down to the user's local storage, is a natural application of
   ICN.  It should be supported natively without requiring any specific
   considerations.

   This is supported now by a host of protocols (say, SCP, Secure Copy (SCP),
   FTP, or over HTTP), which would need to be replaced by the new ICN-
   specific protocols to retrieve content in ICNs.

   However, current mechanisms are built atop existing transport
   protocols.  Some ICN proposals (say, CCN (Context-Centric Network (CCN) or NDN
   Named Data Networking (NDN), for instance) attempt to leverage the
   work done upon these transport protocol and it has
   been proposed protocols.  One proposal is to use mechanisms such as the
   TCP congestion window (and the associated Adaptive Increase,
   Multiplicative Decrease -
   AIMD) (AIMD)) to decide how many object requests ("interests"
   ("Interests" in CCN/NDN terminology) should be in flight at any point
   in time.

   It should be noted that ICN intrinsically supports different
   transport mechanisms, which could achieve better performance than
   TCP, as they subsume TCP into a special case.  For instance, one
   could imagine a link-by-link transport coupled with caching.  This is
   enabled by the ICN architecture, architecture and would facilitate the point-to-
   point download of video files.

5.  Video streaming Streaming and ICN

5.1.  Introduction to client-driven streaming Client-Driven Streaming and DASH

   Media streaming over the hypertext transfer protocol (HTTP) and HTTP and, in a further consequence consequence, streaming
   over the transmission control protocol
   (TCP) TCP, has become omnipresent in today's Internet.  Content
   providers such as Netflix, Hulu, and Vudu do not deploy their own
   streaming
   equipment but equipment: they use the existing Internet infrastructure as
   it is and
   they simply deploy their own services over the top Over The Top (OTT).  This
   streaming approach works surprisingly well without any particular
   support from the underlying network due to the use of efficient video
   compression, content delivery networks Content Delivery Networks (CDNs), and adaptive video
   players.  Earlier video streaming research mostly recommended
   to use of
   the user datagram protocol User Datagram Protocol (UDP) combined with the real time
   transport protocol Real-time
   Transport Protocol (RTP).  It assumed it would not be possible to
   transfer multimedia data smoothly with TCP, because of its throughput
   variations and large retransmission delays.  This point of view has
   significantly evolved today.  HTTP streaming, and especially its most
   simple form known as progressive download, has become very popular
   over the past few years because it has some major benefits compared
   to RTP streaming.  As a consequence of the consistent use of HTTP for
   this streaming method, the existing Internet
   infrastructure, infrastructure
   consisting of proxies, caches caches, and CDNs, CDNs could be used.  Originally,
   this architecture was designed to support best
   effort best-effort delivery of
   files and not real time real-time transport of multimedia data.  Nevertheless, real time
   real-time streaming based on HTTP could also take advantage of this
   architecture, in comparison to RTP, which could not leverage any of
   the aforementioned components.  Another benefit that results from the
   use of HTTP is that the media stream could easily pass firewalls or network address translation
   Network Address Translation (NAT) gateways, which was definitely a
   key for the success of HTTP streaming.  However, HTTP streaming is
   not the holy grail of streaming as it also introduces some drawbacks
   compared to RTP.  Nevertheless, in an ICN-based video streaming
   architecture these aspects also have to be considered.

   The basic concept of DASH [1] [ISO-DASH] is to use segments of media
   content, which can be encoded at different resolutions, bit rates,
   etc., as so-called representations.  These segments are served by
   conventional HTTP Web web servers and can be addressed via HTTP GET
   requests from the client.  As a consequence, the streaming system is
   pull-based and the entire streaming logic is located on the client,
   which makes it
   scalable, scalable and allows to adapt for adaptation of the media stream
   to the client's capabilities.

   In addition to this, the content can be distributed using
   conventional CDNs and their HTTP infrastructure, which also scales
   very well.  In order to specify the relationship between the
   contents' media segments and the associated bit rate, resolution, and
   timeline, the Media Presentation Description (MPD) is used, which is a
   an XML document.  The MPD refers to the available media segments
   using HTTP URLs, which can be used by the client for retrieving them.

5.2.  Layered Encoding

   Another approach for video streaming consist consists in using layered
   encoding.  Namely, scalable video coding formats the video stream
   into different layers: a base layer which that can be decoded to provide
   the lowest bit rate for the specific stream, stream and enhancement layers
   which
   that can be transmitted separately if network conditions allow.  The
   higher layers offer higher resolutions and enhancement of the video
   quality, while the layered approach allows to adapt for adaptation to the
   network conditions.  This is used in MPEG-4 scalable profile or
   H.263+.  H264SVC is available, available but not much deployed.  JPEG2000 has a
   wavelet transform approach for layered encoding, encoding but has not been
   deployed much either.  It is not clear if the layered approach is
   fine-grained enough for rate control.

5.3.  Interactions of Video Streaming with ICN

5.3.1. Interaction  Interactions of DASH and with ICN

   Video streaming, and DASH streaming (DASH in particular, have particular) has been designed with
   goals a goal
   that are is aligned with that of most ICN proposals. Namely, proposals: it is a client-based mechanism, which
   mechanism that requests items (in this case, chunks of a video
   stream) by name.

   ICN and MPEG-DASH [1] [ISO-DASH] have several elements in common:

   -

   o  the client-initiated pull approach;
   -

   o  the content being dealt with in pieces (or chunks);
   -

   o  the support of efficient replication and distribution of content
      pieces within the network;
   -

   o  the scalable, session-free nature of the exchange between the
      client and the server at the streaming layer: the client is free
      to request any chunk from any location;
   - and

   o  the support for potentially multiple source locations.

   For the last point, DASH may list multiple source URLs in a manifest,
   and ICN is agnostic to the location of a copy it is receiving.  We do
   not imply that current video streaming mechanisms attempt to draw the
   content from multiple sources concurrently.  This is a potential
   benefit of ICN, ICN but is not considered in the current approaches
   mentioned in this document.

   As ICN is a promising candidate for the Future Internet (FI)
   architecture, it is useful to investigate its suitability in
   combination with multimedia streaming standards like MPEG-DASH.  In
   this context, the purpose of this section is to present the usage of
   ICN instead of HTTP in MPEG-DASH MPEG-DASH.

   However, there are some issues that arise from using a dynamic rate
   adaptation mechanism in an ICN architecture (note that some of the
   issues are related to caching, caching and are not necessarily unique to ICN):

   o  Naming of the data in DASH does not necessarily follow the ICN
      convention of any of the ICN proposals.  Several chunks of the
      same video stream might currently go by different names that that, for
      instance
      instance, do not share a common prefix.  There is a need to
      harmonize the naming of the chunks in DASH with the naming
      conventions of the ICN.  The naming convention of using a
      filename/time/encoding format could could, for instance instance, be made
      compatible with the convention of CCN.

   o  While chunks can be retrieved from any server, the rate adaptation
      mechanism attempts to estimate the available network bandwidth so
      as to select the proper playback rate and keep its playback buffer
      at the proper level.  Therefore, there is a need to either include
      some location semantics in the data chunks so as to properly
      assess the throughput to a specific location; location or to design a
      different mechanism to evaluate the available network bandwidth.

   o  The typical issue of access control and accounting happens in this
      context, where chunks can be cached in the network outside of the
      administrative control of the content publisher.  It might be a
      requirement from the owner of the video stream that access to
      these data chunks needs to be accounted/billed/monitored.

   o  Dynamic streaming multiplies the representations of a given video
      stream, therefore diminishing the effectiveness of caching:
      namely, to get a hit for a chunk in the cache, it has to be for
      the same format and encoding values.  Alternatively, to get the
      same hit rate as for a stream using a single encoding, the cache size
      must be scaled up to include all the possible representations.

   o  Caching introduces oscillatory dynamics as it may modify the
      estimation of the available bandwidth between the end user and the
      repository where from which it is getting the chunks from. chunks.  For instance, if
      an edge cache holds a low resolution representation near the user,
      the user getting this these low resolution chunks will observe a good performance,
      performance and will then request higher resolution chunks.  If
      those are hosted on a server with poor performance, then the
      client would have to switch back to the low representation.  This
      oscillation may be detrimental to the perceived QoE of the user.

   o  The ICN transport mechanism needs to be compatible to some extent
      with DASH.  To take a CCN example, the rate at which interests are
      issued should be such that the chunks received in return arrive
      fast enough and with the proper encoding to keep the playback
      buffer above some threshold.

   o  The usage of multiple network interfaces is possible in ICN,
      enabling a seamless handover between them.  For the combination
      with DASH, an intelligent strategy which that should focus on traffic
      load balancing
      load-balancing between the available links may be necessary.  This
      would increase the effective media throughput of DASH by
      leveraging the combined available bandwidth of all links, links; however,
      it could potentially lead to high variations of the media
      throughput.

   o  DASH does not define how the MPD is retrieved; hence, this is
      compatible with CCN.  However, the current profiles defined within
      MPEG-DASH require the MPD to contain HTTP-URLs (incl. http HTTP URLs (including HTTP and
      https
      HTTPS URI schemes) to identify segments.  To enable a more
      integrated approach as described in this document, an additional
      profile for DASH over CCN has to be defined, enabling ICN/CCN-
      based URIs to identify and request the media segments.

   We describe in Section 5.4 a potential implementation of a dynamic
   adaptive video stream over ICN, based upon DASH and CCN [5].
   [Jacobson09b].

5.3.2.  Interaction of ICN with Layered Encoding

   Issues of interest to an Information-Centric network ICN architecture in the context of layered
   video streaming include:

     .

   o  Caching of the multiple layers.  The caching priority should go to
      the base layer, layer and to defining caching policy in order to decide
      when to cache enhancement layers;
     .

   o  Synchronization of multiple content streams, as the multiple
      layers may come from different sources in the network (for
      instance, the base layer might be cached locally while the
      enhancement layers may be stored in the origin server).  Video and audio video
      audio-video streams must be synchronized, and this includes both
      intra-layer synchronization (for the layers of the same video or
      audio stream) and inter-stream synchronization (see Section 9 for
      other synchronization aspects to be included in the "Future Steps
      for Video in ICN");
     . and

   o  Naming of the different layers: when the client requests an
      object, the request can be satisfied with the base layer alone,
      aggregated with enhancement layers.  Should one request be
      sufficient to provide different streams?  In a CCN architecture architecture,
      for instance, this would violate a "one Interest, one interest-one data packet Data packet"
      principle and the client would need to specify each layer it would
      like to receive.  In a Pub/Sub architecture, the
        rendezvous point Rendezvous Point
      would have to make a decision as to which layers (or which pointer
      to which layer's location) to return.

5.4.  Possible Integration of Video streaming Streaming and ICN architecture Architecture

5.4.1.  DASH over CCN

   DASH is intended to enable adaptive streaming, i.e., each content
   piece can be provided in different qualities, formats, languages,
   etc., to cope with the diversity of todays' today's networks and devices.  As
   this is an important requirement for Future Internet proposals like
   CCN, the combination of those two technologies seems to be obvious.
   Since those two proposals are located at different protocol layers - --
   DASH at the application and CCN at the network layer - -- they can be
   combined very efficiently to leverage the advantages of both and
   potentially eliminate existing disadvantages.  As CCN is not based on
   classical host-to-host connections, it is possible to consume content
   from different origin nodes as well as over different network links
   in parallel, which can be seen as an intrinsic error resilience
   feature w.r.t. with respect to the network.  This is a useful feature of CCN
   for adaptive multimedia streaming within mobile environments since
   most mobile devices are equipped with multiple network links like 3G
   and WiFi. Wi-Fi.  CCN offers this functionality out of the box box, which is
   beneficial when used for DASH-based services.  In particular, it is
   possible to enable adaptive video streaming handling both bandwidth
   and network link changes.  That is, CCN handles the network link
   decision and DASH is implemented on top of CCN to adapt the video
   stream to the available bandwidth.

   In principle, there are two options to integrate DASH and CCN: a
   proxy service acting as a broker between HTTP and CCN as proposed in
   [6],
   [Detti12], and the DASH client implementing a native CCN interface.
   The former transforms an HTTP request to a corresponding interest Interest
   packet as well as a data Data packet back to an HTTP response, including
   reliable transport as offered by TCP.  This may be a good compromise
   to implement CCN in a managed network and to support legacy devices.
   Since such a proxy is already described in [6] [Detti12], this draft document
   focuses on a more integrated approach, aiming at fully exploiting the
   potential of a CCN DASH Client. client.  That is, we describe a native CCN
   interface within the DASH client, which adopts a CCN naming scheme
   (CCN URIs) to denote segments in the Media Presentation Description (MPD). MPD.  In this architecture, only
   the network access component on the client has to be modified and the
   segment URIs within MPD have to be updated according to the CCN
   naming scheme.

   Initially, the DASH client retrieves the MPD containing the CCN URIs
   of the content representations including the media segments.  The
   naming scheme of the segments may reflect intrinsic features of CCN
   like versioning and segmentation support.  Such segmentation support
   is already compulsory for multimedia streaming in CCN and, CCN; thus, it can
   also be leveraged for DASH-based streaming over CCN.  The CCN
   versioning can be adopted in a further step to signal different
   representations of the DASH-based content, which enables an implicit
   adaptation of the requested content to the clients' bandwidth
   conditions.  That is, the interest Interest packet already provides the
   desired characteristics of a segment (such as bit rate, resolution,
   etc.) within the content name (or potentially within parameters
   defined as extra types in the packet formats).  Additionally, if
   bandwidth conditions of the corresponding interfaces or routing paths
   allow so, DASH media segments could be aggregated automatically by
   the CCN nodes, which reduces the amount of interest Interest packets needed to
   request the content.  However, such approaches need further research,
   specifically in terms of additional intelligence and processing power
   needed at the CCN nodes.

   After requesting the MPD, the DASH client will start to request
   particular segments.  Therefore, CCN interest Interest packets are generated
   by the CCN access component and forwarded to the available
   interfaces.  Within the CCN, these interest Interest packets leverage the
   efficient interest aggregation for, e.g., popular content, as well as
   the implicit multicast support.  Finally, the interest Interest packets are
   satisfied by the corresponding data Data packets containing the video
   segment data, which are stored on the origin server or any CCN node,
   respectively.  With an increasing popularity of the content, it will
   be distributed across the network resulting in lower transmission
   delays and reduced bandwidth requirements for origin servers and
   content providers providers, respectively.

   With the extensive usage of in-network caching, new drawbacks are
   introduced since the streaming logic is located at the client, i.e.,
   clients are not aware of each other and the network infrastructure
   and cache states.  Furthermore, negative effects are introduced when
   multiple clients are competing for compete in a bottleneck and when caching is
   influencing influences
   this bandwidth competition.  As mentioned above, the clients request
   individual portions of the content based on available bandwidth,
   which is calculated using throughput estimations.  This uncontrolled
   distribution of the content influences the adaptation process of
   adaptive streaming clients.  The impact of this falsified throughput
   estimation could be tremendous and leads to a wrong adaptation
   decision which that may impact the
   Quality of Experience (QoE) QoE at the client, as shown in [8].
   [Mueller12].  In ICN, the client does not have the knowledge from
   which source the requested content is actually served or how many
   origin servers of the content are available, as this is transparent
   and depends on the name-based routing.  This introduces the challenge
   that the adaptation logic of the adaptive streaming client is not
   aware of the event when the ICN routing decides to switch to a
   different origin server or content is coming through a different
   link/interface.  As most algorithms implementing the adaption logic
   are using
   use bandwidth measurements and related heuristics, the adaptation
   decisions are no longer valid when changing origin servers (or links)
   links), and these decisions potentially cause playback interruptions
   and, consequently, stalling.  Additionally, ICN supports the usage of
   multiple interfaces.  A seamless handover between these interfaces
   (and different sources for the content) comes together with changes
   in performance, e.g., due to switching between fixed and wireless,
   3G/4G and WiFi Wi-Fi networks, or between different types of servers (say
   with/without SSD, with/
   without Shared Secret Data (SSD) or with/without hardware acceleration), etc.

   Considering these characteristics of ICN, adaptation algorithms
   merely based on bandwidth measurements are not appropriate anymore,
   as potentially each segment can be transferred from another ICN node
   or interface, all with different bandwidth conditions.  Thus,
   adaptation algorithms taking into account these intrinsic
   characteristics of ICN are preferred over algorithms based on mere
   bandwidth measurements.

5.4.2.  Testbed, Open Source Open-Source Tools, and Dataset

   For the evaluations of DASH over CCN, a testbed with open source open-source
   tools and datasets is provided in [9]. [ITEC-DASH].  In particular, it
   provides two client player client-player implementations, (i) a libdash extension
   for DASH over CCN and (ii) a VLC plugin implementing DASH over CCN.
   For both
   implementations implementations, the CCNx implementation has been used as a
   basis.

   The general architecture of libdash is organized in modules, modules so that
   the library implements a MPD parser and an extensible connection
   manager.  The library provides object-oriented interfaces for these
   modules to access the MPD and the downloadable segments.  These
   components are extended to support DASH over CCN and available are located in a
   separate development branch of the github GitHub project available at
   http://www.github.com/bitmovin/libdash.
   <http://www.github.com/bitmovin/libdash>. libdash comes together with
   a fully featured DASH player with a QT-based frontend, front end, demonstrating
   the usage of libdash and providing a scientific evaluation platform.
   As an alternative, patches for the DASH plugin of the VLC player are
   provided.  These patches can be applied to the latest source code
   checkout of VLC resulting in a DASH over CCN-enabled DASH-over-CCN-enabled VLC player.

   Finally, a DASH over CCN DASH-over-CCN dataset is provided in the form of a CCNx
   repository.  It includes 15 different quality representation of the
   well-known Big Buck Bunny Movie, ranging from 100 kbps up to 4500 kbps.
   The content is split into segments of two seconds, seconds and is described by
   an associated MPD using the presented naming scheme in Section 4.1. 5.1.
   This repository can be downloaded from [9], [ITEC-DASH] and is also
   provided by a public publicly accessible CCNx node.  Associated routing
   commands for the CCNx namespaces of the content are provided via
   scripts coming together with the dataset and can be used as a public
   testbed.

6.  P2P video distribution Video Distribution and ICN

   Another

   Peer-to-Peer distribution is another form of distributing content - --
   and video in particular-
   which particular -- that ICNs need to support is Peer-to-Peer distribution (P2P). support.  We see now how
   an existing protocol such as PPSP can be modified to work in an ICN
   environment.

6.1.  Introduction to PPSP

   P2P video Video Streaming (PPS) (P2PVS) is a popular approach to redistribute
   live media over the Internet.  The proposed P2PVS solutions can be
   roughly classified in two classes:

   -  Push/Tree based

   -  Pull/Mesh based

   o  Push/Tree-based

   o  Pull/Mesh-based

   The Push/Tree based Push/Tree-based solution creates an overlay network among peers Peers
   that has a tree shape [30]. [Castro03].  Using a progressive encoding (e.g.
   (e.g., Multiple Description Coding or H.264 Scalable Video Coding),
   multiple trees could be set up to support video rate adaptation.  On
   each tree tree, an enhancement stream is sent.  The higher the number of
   received streams, the higher the video quality.  A peer controls the
   video rate by either fetching or not fetching the streams delivered
   over the distribution trees.

   The Pull/Mesh based Pull/Mesh-based solution is inspired by the BitTorrent file
   sharing mechanism.  A Tracker tracker collects information about the state of
   the swarm (i.e. (i.e., the set of participating peers).  A peer forms a
   mesh overlay network with a subset of peers, peers and exchange exchanges data with
   them.  A peer announces what data items it disposes and requests
   missing data items that are announced by connected peers.  In case of
   live streaming, the involved data set includes only a recent window
   of data items published by the source.  Also  Also, in this case, the use
   of a progressive encoding can be exploited for video rate adaptation.

   Pull/Mesh based

   Pull/Mesh-based P2PVS solutions are the more promising candidate for
   the ICN deployment, since most of ICN approach provides a pull-based
   API [5][10][11][12]. [Jacobson09b] [Detti11] [Chai11] [NETINF].  In addition, Pull/Mesh based
   Pull/Mesh-based P2PVS are more robust than Push/Tree based the Push/Tree-based one [13]
   [Magharei07], and the Peer to Peer Streaming
   Protocol (PPSP) PPSP working group [14] [IETF-PPSP] is also
   proposing a Pull/Mesh
   based Pull/Mesh-based solution.

            +------------------------------------------------+
            |                                                |
            |     +--------------------------------+         |
            |     |            Tracker             |         |
            |     +--------------------------------+         |
            |        |     ^                   ^             |
            |Tracker |     | Tracker           |Tracker      |
            |Protocol|     | Protocol          |Protocol     |
            |        |     |                   |             |
            |        V     |                   |             |
            |     +---------+    Peer     +---------+        |
            |     |   Peer  |<----------->|   Peer  |        |
            |     +---------+   Protocol  +---------+        |
            |       | ^                                      |
            |       | |Peer                                  |
            |       | |Protocol                              |
            |       V |                                      |
            |     +---------------+                          |
            |     |      Peer     |                          |
            |     +---------------+                          |
            |                                                |
            +------------------------------------------------+

               Figure 1: PPSP System Architecture (source [RFC6972]) [RFC6972]

   Figure 1 reports the PPSP architecture presented in [RFC6972].  PEERs
   announce and share video chunks and a TRACKER maintains a list of
   PEERs participating in a specific audio/video audio-video channel or in the
   distribution of a streaming file.  The tracker TRACKER functionality may be
   centralized in a server or distributed over the PEERs.  PPSP
   standardize
   standardizes the Peer peer and Tracker Protocols, which can run directly
   over UDP or TCP.

   This document discusses some preliminary concepts about the
   deployment of PPSP on top of an ICN that exposes a pull-based API,
   meanwhile considering the impact of MPEG DASH MPEG-DASH streaming format.

6.2.  PPSP over ICN: deployment concepts Deployment Concepts

6.2.1.  PPSP short background

   PPSP specifies peer protocol Short Background

   The Peer-to-Peer Streaming Peer Protocol (PPSPP) [15] is defined in
   [Bakker15] and tracker protocol
   (PPSP-TP)[16]. the Peer-to-Peer Streaming Tracker Protocol (PPSP-TP)
   is defined in [RFC7846].

   Some of the operations carried out by the tracker protocol Tracker Protocol are the
   followings. When
   following: when a peer wishes to join the streaming session session, it
   contacts the Tracker tracker (CONNECT message), obtains a PEER_ID and a list
   of PEER_IDs (and IP addresses) of other peers that are participating
   to the SWARM and that the tracker has singled out for the requesting
   peer (this may be a subset of the all peers of the SWARM). In SWARM); in
   addition to this join operation, a peer may contact the tracker to
   request to renew the list of participating peers (FIND message), to
   periodically update its status to the tracker (STAT_REPORT message),
   etc.
   and so on.

   Some of the operations carried out by the peer protocol are Peer Protocol include the
   following. Using
   following: using the list of peers delivered by the tracker, a peer
   establishes a session with them (HANDSHAKE message). A message); a peer
   periodically announces to neighboring peers which chunks it has
   available for download (HAVE message). Using message); using these announcements, a
   peer requests missing chunks from neighboring peers (REQUEST
   messages), which will send be sent back to them (DATA message).

6.2.2.  From PPSP messages Messages to ICN named-data Named-Data

   An ICN provides users with data items exposed by names.  The bundle
   name and data item is usually referred as named-data, named-content, "named-data", "named-
   content", etc.  To transfer PPSP messages though through an ICN ICN, the
   messages should be wrapped as named-data items, items and receivers should
   request them by name.

   A PPSP entity receives messages from peers and/or a tracker.  Some
   operations require gathering the messages generated by another
   specific host (peer or tracker).  For instance, if a peer Peer A wishes to
   gain information about video chunks available from peer Peer B, the former
   shall fetch the PPSP HAVE messages specifically generated by the later.
   latter.  We refer to these kinds of named-data as "located-named-
   data",
   data" since they should be gathered from a specific location (e.g.
   peer (e.g.,
   Peer B).

   For other PPSP operations, such as fetching a DATA message (i.e. (i.e., a
   video chunk), as long as a peer receives the requested content, it
   doesn't matter which endpoint generated the data.We data.  We refer to this
   information with the generic term "named-data".

   The naming scheme differentiates named-data and located-named-data
   items.  In the case of named-data, the naming scheme only includes a
   content identifier (e.g. (e.g., the name of the video chunk), chunk) without any
   prefix identifying who provides the content.  For instance, a DATA
   message containing the video chunk #1 "#1" may be named as
   "ccnx:/swarmID/chunk/chunkID", where swarmID is a unique identifier
   of the streaming session, "chunk" is a keyword keyword, and chunkID is the
   chunk identifier (e.g. a (e.g., an integer number).

   In case of located-named-data, the naming scheme includes a
   location-prefix, location-
   prefix, which uniquely identifies the host generating the data item.
   This prefix may be the PEER_ID in case the host was a peer or a
   tracker identifier in case the host was the tracker.  For instance, a
   HAVE message generated by a peer Peer B may be named as
   "ccnx:/swarmID/peer/PEER_ID/HAVE", where "peer" is a keyword,
   PEER_ID_B is the identifier of peer B Peer B, and HAVE is a keyword.

6.2.3.  Support of PPSP interaction Interaction through a pull-based Pull-Based ICN API

   The PPSP procedures are based both on pull and push interactions.
   For instance, the distribution of chunks availability can be
   classified as a push-based operation, operation since a peer sends an "unsolicited"
   information (HAVE message) to neighboring peers.
   Conversely  Conversely, the
   procedure used to receive video chunks can be classified as pull-based, pull-
   based since it is supported by a request/response interaction (i.e. (i.e.,
   REQUEST, DATA messages).

   As we said, we refer to an ICN architecture which that provides a pull-
   based API.  Accordingly, the mapping of PPSP pull-based procedure is
   quite simple.  For instance, using the CCN architecture [5]
   [Jacobson09b], a PPSP DATA message may be carried by a CCN Data DATA
   message and a REQUEST message can be transferred by a CCN Interest.

   Conversely, the support of push-based PPSP operations may be more
   difficult.  We need of an adaptation functionality that carries out a
   push-based operation using the underlying pull-based service
   primitives.  For instance, a possible approach is to use the
   request/response (i.e. request/
   response (i.e., Interest/Data) four ways four-way handshakes proposed in [7].
   [Jacobson09a].  Another possibility is that receivers periodically
   send out request messages of the named-data that neighbors will push
   and, when available, the sender inserts the pushed data within a
   response message.

6.2.4.  Abstract layering Layering for PPSP over ICN

                   +-----------------------------------+
                   |            Application            |
                   +-----------------------------------+
                   |           PPSP (TCP/IP)           |
                   +-----------------------------------+
                   |  ICN - PPSP Adaptation Layer (AL) |
                   +-----------------------------------+
                   |         ICN Architecture          |
                   +-----------------------------------+

                        Figure 2: Mediator approach Approach

   Figure 2 provides a possible abstract layering for PPSP over ICN.
   The Adaptation Layer acts as a mediator (proxy) between legacy PPSP
   entities based on TCP/IP and the ICN architecture.  In facts, fact, the role
   the mediator is to use ICN to transfer PPSP legacy messages.

   This approach makes it possible to merely reuse TCP/IP P2P
   applications whose software includes also PPSP functionality.  This
   "all-in-one" development approach may be rather common since the PPSP-Application PPSP
   application interface is not going to be specified.  Moreover, if the Operating
   System
   operating system will provide libraries that expose a PPSP API, these
   will be initially based on a an underlying TCP/IP API. Also  Also, in this
   case, the mediator approach would make it possible to easily reuse
   both the PPSP libraries and the Application on top of an ICN.

                  +-----------------------------------+
                  |            Application            |
                  +-----------------------------------+
                  |             ICN-PPSP              |
                  +-----------------------------------+
                  |          ICN Architecture         |
                  +-----------------------------------+

                      Figure 3: Clean-slate approach Clean-Slate Approach

   Figure 3 sketches a clean-slate layering approach in which the
   application directly includes or interacts with a PPSP version based
   on ICN. Likely  It's likely such a PPSP_ICN integration could yield a simplier
   development,
   simpler development also because it does not require implementing a
   TCP/IP to ICN translation as in the Mediator approach.  However, the clean-
   slate
   clean-slate approach requires developing the application (in case of
   embedded PPSP functionality) or the PPSP library from scratch, scratch without
   exploiting what might already exist for TCP/IP.

   Overall, the Mediator approach may be considered as the first step of a
   migration path towards ICN native ICN-native PPSP applications.

6.2.5.  PPSP interaction Interaction with the ICN routing plane Routing Plane

   Upon the ICN API API, a user (peer) requests a content and the ICN sends it
   back.  The content is gathered by the ICN from any source, which
   could be the closest peer that disposes of the named-data item, an
   in-network cache, etc.  Actually, "where" to gather the content is
   controlled by an underlying ICN routing plane, which sets up the ICN
   forwarding tables (e.g. (e.g., CCN FIB [5]). [Jacobson09b]).

   A cross-layer interaction between the ICN routing plane and the PPSP
   may be required to support a PPSP session.  Indeed, ICN shall forward
   request messages (e.g. (e.g., CCN Interest) towards the proper peer that
   can handle them.  Depending on the layering approach, this cross-
   layer interaction is controlled either by the Adaptation Layer or by
   the ICN-PPSP.  For example, if a peer Peer A receives a HAVE message
   indicating that peer Peer B disposes of the video chunk named
   "ccnx:/swarmID/chunk/chunkID", then the former should insert in its
   ICN forwarding table an entry for the prefix
   "ccnx:/swarmID/chunk/chunkID" "ccnx:/swarmID/chunk/
   chunkID" whose next hop locator (e.g. (e.g., IP address) is the network
   address of peer Peer B [17]. [Detti13].

6.2.6.  ICN deployment Deployment for PPSP

   The ICN functionality that supports a PPSP session may be "isolated"
   or "integrated" with the one of from a public ICN.

   In the isolated case, a PPSP session is supported by an instance of
   an ICN (e.g. (e.g., deployed on top of IP), an IP) whose functionalities operate
   only on the limited set of nodes participating to the swarm, i.e. i.e.,
   peers and the tracker.  This approach resembles the one followed by a
   current P2P application, which usually form forms an overlay network among
   peers of a P2P application. And application; intermediate public IP routers do not
   carry out P2P functionalities.

   In the integrated case, the nodes of a public ICN may be involved in
   the forwarding and in-network caching procedures.  In doing so, the
   swarm may benefit from the presence of in-network caches so caches, thus
   limiting uplink traffic on peers and inter-domain traffic traffic, too.
   These are distinctive advantages of using PPSP over a public ICN, ICN
   rather than over TCP/IP.  In addition, such advantages aren't likely
   manifested in the case of isolated deployment.

   However, the possible interaction between the PPSP and the routing
   layer of a public ICN may be dramatic, both in terms of explosion of
   the forwarding tables and in terms of security.  These issues
   specifically take place for those ICN architectures for which the
   name resolution (i.e. (i.e., name to next-hop) next hop) occurs en-route, en route, like the
   CCN architecture.

   For instance, using the CCN architecture, to fetch a named-data item
   offered by a peer Peer A the on-path public ICN entities have to route the
   request messages towards the peer Peer A.  This implies that the ICN
   forwarding tables of public ICN nodes may contain many entries, e.g. e.g.,
   one entry per video chunk, and these entries are difficult to be
   aggregated since peers may have available only sparse parts of a big
   content, whose names have a same prefix (e.g. (e.g., "ccnx:/swarmID").
   Another possibility is to wrap all PPSP messages into a located-
   named-data.  In this case case, the forwarding tables should contain
   "only" the PEER_ID prefixes (e.g. (e.g., "ccnx:/swarmID/peer/PEER_ID"), so
   thus scaling down the number of entries from number of chunks to
   number of peers.  However, in this case case, the ICN mechanisms recognize a
   the same video chunk offered by different peers as different contents, so vanishing content,
   thus losing caching and multicasting ICN benefits. Moreover, in  In any case case,
   routing entries should be updated either on the base basis of the
   availability of named-data items on peers or on the presence of
   peers, and these events in a P2P session is are rapidly changing so and
   possibly hampering the convergence of the routing plane.  Finally,
   since peers have an impact on the ICN forwarding table of public
   nodes, this may open obvious security issues.

6.3.  Impact of MPEG DASH coding schemes MPEG-DASH Coding Schemes

   The introduction of video rate adaptation may significantly decrease
   the effectiveness of P2P cooperation and of in-network caching,
   depending of the kind of the video coding used by the MPEG DASH MPEG-DASH
   stream.

   In case of a MPEG DASH an MPEG-DASH streaming with MPEG AVC encoding, a the same
   video chunk is independently encoded at different rates and the
   encoding output is a different file for each rate.  For instance, in
   case of a video encoded at three different rates R1,R2,R3, rates, R1, R2, and R3; for
   each segment S S, we have three distinct files: S.R1, S.R2, and S.R3.
   These files are independent of each other.  To fetch a segment coded
   at R2 kbps, a peer shall request the specific file S.R2. Receiver-driven  Receiver-
   driven algorithms, implemented by the video client, usually handle
   the estimation of the best coding rate.

   The independence among files associated to with different encoding rates
   and the heterogeneity of peer bandwidths, bandwidths may dramatically reduce the
   interaction among peers, the effectiveness of in-network caching (in
   case of integrated deployment), and consequently consequently, the ability of PPSP
   to offload the video server (i.e. (i.e., a seeder peer).  Indeed, a
   peer Peer A
   may select a coding rate (e.g. (e.g., R1) different from the one selected
   by a peer Peer B (e.g. R2) (e.g., R2), and this prevents the former to fetch from fetching
   video chunks from the later, latter since peer Peer B only has chunks available
   that are coded at a rate different from the ones needed by Peer A.
   To overcome this issue, a common distributed rate selection algorithm
   could force peers to select the same coding rate [17]; nevertheless [Detti13];
   nevertheless, this approach may be not feasible in the in case of many
   peers.

   The use of an SVC encoding (Annex G extension of the H.264/MPEG-4 AVC
   Advanced Video Coding (AVC) video compression standard) should make
   rate adaptation possible,
   meanwhile possible while neither reducing peer collaborations
   nor the in-network caching effectiveness.  For a single video chunk, a
   an SVC encoder produces different files for the different rates
   (roughly "layers"), and these files are progressively related to each
   other.  Starting from a base-layer which base layer that provides the minimum rate
   encoding, the next rates are encoded as an "enhancement layer" of the
   previous one.  For instance, in case the video is coded with three rates
   rates, R1 (base- (base layer), R2 (enhancement-layer (enhancement layer n.1), and R3 (enhancement-layer
   (enhancement layer n.2), then for each DASH segment segment, we have three files
   files: S.R1, S.R2 S.R2, and S.R3.  The file S.R1 is the segment coded at
   the minimum rate (base-layer). (base layer).  The file S.R2 enhances S.R1, so as S.R1
   and S.R2 can be combined to obtain a segment coded at rate R2.  To
   get a segment coded at rate R2, a peer shall fetch both S.R1 and
   S.R2.  This progressive dependence among files that encode a the same
   segment at different rates makes peer cooperation possible, also in
   case peers player have autonomously selected different coding rates.
   For instance, if peer Peer A has selected the rate R1, the downloaded
   files S.R1 are useful also for a peer Peer B that has selected the rate
   R2, and vice versa.

7.  IPTV and ICN

7.1.  IPTV challenges Challenges

   IPTV refers to the delivery of quality content broadcast over the
   Internet,
   Internet and is typically associated with strict quality
   requirements, i.e., with a perceived latency of less than 500 ms and
   a packet loss rate that is multiple orders lower than the current
   loss rates experienced in the most commonly used access networks (see [31]).
   [ATIS-IIF]).  We can summarize the major challenges for the delivery
   of IPTV service as follows.

   Channel change latency represents a major concern for the IPTV
   service.  Perceived latency during channel change should be less than
   500ms.
   500 ms.  To achieve this objective over the IP infrastructure, we
   have multiple choices:

   (i)   receiving

   i     receive fast unicast streams from a dedicated server (most
         effective but not resource efficient);
   (ii)  connecting

   ii    connect to other peers in the network (efficiency depends on
         peer support, effective and resource efficient, if also
         supported with a dedicated server);
   (iii) connecting and

   iii   connect to multiple multicast sessions at once (effective but
         not resource efficient, efficient and depends on the accuracy of the
         prediction model used to track user activity).

   The second major challenge is the error recovery.  Typical IPTV
   service requirements dictate the mean time between artifacts to be
   approximately 2 hours (see [31]). [ATIS-IIF]).  This suggests the perceived
   loss rate to be around or less than or equal to 10^-7.  Current IP-based
   solutions rely on the following proactive and reactive recovery
   techniques: (i) joining the FEC Forward Error Correction (FEC) multicast
   stream corresponding to the perceived packet loss rate (not efficient
   efficient, as the recovery strength is chosen based on worst-case
   loss scenarios), scenarios); (ii) making unicast recovery requests to dedicated
   servers (requires active support from the service provider), provider); (iii)
   probing peers to acquire repair packets (finding matching peers and
   enabling their cooperation is another challenge).

7.2.  ICN benefits Benefits for IPTV delivery Delivery

   ICN presents significant advantages for the delivery of IPTV traffic.
   For instance, ICN inherently supports multicast and allows for quick
   recovery from packet losses (with the help of in-network caching).
   Similarly, peer support is also provided in the shape of in-network
   caches that typically act as the middleman between two peers, enabling
   therefore enabling earlier access to IPTV content.

   However, despite these advantages, delivery of IPTV service over
   Information Centric Networks ICNs
   brings forth new challenges.  We can list some of these challenges as
   follows:

     .

   o  Messaging overhead: ICN is a pull-based architecture and relies on
      a unique balance between requests and responses.  A user needs to
      make a request for each data Data packet.  In the case of IPTV, with
      rates up to, and to (and likely to be, be) above 15Mbps, 15 Mbps, we observe
      significant traffic upstream to bring those streams.  As the
      number of streams increases (including the same session at
      different quality levels and other formats), so does the burden on
      the routers.  Even if the majority of requests are aggregated at
      the core, routers close to the edge (where we observe the biggest
      divergence in user requests) will experience a significant
      increase in overhead to process these requests.  The same is true
      at the user side, as the uplink usage multiplies in the number of
      sessions a user requests (for instance, to minimize the impact of
      bandwidth fluctuations).
     .

   o  Cache control: As the IPTV content expires at a rapid rate (with a
      likely expiry threshold of 1s), 1 s), we need solutions to effectively
      flush out such content to also prevent degradation impact on other
      cached content, with the help of intelligently chosen naming
      conventions.  However, to allow for fast recovery and optimize
      access time to sessions (from current or new users), the timing of
      such expirations needs to be adaptive to network load and user
      demand.  However, we also need to support quick access to earlier
      content, whenever needed, needed; for instance, when the user accesses the
      rewind feature (note that in-network caches will not be of
      significant help in such scenarios due to the overhead required to
      maintain such content).
     .

   o  Access accuracy: To receive the up-to-date session data, users
      need to be aware of such information at the time of their request.
      Unlike IP multicast, since the users join a session indirectly,
      session information is critical to minimize buffering delays and
      reduce the startup latency.  Without such information, and without
      any active cooperation from the intermediate routers, stale data
      can seriously undermine the efficiency of content delivery.
      Furthermore, finding a cache does not necessarily equate to
      joining a session, as the look-
        ahead look-ahead latency for the initial
      content access point may have a shorter lifetime than originally
      intended.  For instance, if the user that has initiated the
      indirect multicast leaves the session early, the requests from the
      remaining users need to experience an additional latency of one
      RTT as they travel towards the content source.  If the startup
      latency is chosen depending on the closeness to the intermediate
      router, going to the content source in-session can lead to
      undesired pauses.

   It should be noted that IPTV includes more than just multicast.  Many
   implementations include "trick plays" (fast forward, pause, rewind)
   that often transform a multicast session into multiple unicast
   sessions.  In this context, ICN is beneficial, as the caching offers
   an implicit multicast, multicast but without tight synchronization constraints
   in between two different users.  One user may rewind, rewind and start
   playing forward again, thus drawing from a nearby cache of the
   content recently viewed by another user (whereas in a strict
   multicast session, the opportunity of one user lagging off behind
   would be more difficult to implement).

8.  Digital Rights Managements Management in ICN

   This section discusses the need for Digital Rights Management (DRM) DRM functionalities for
   multimedia streaming over ICN.  It focuses on two possible
   approaches: modifying AAA Authentication, Authorization, and Accounting
   (AAA) to support DRM in ICN, ICN and using Broadcast Encryption.

   It is assumed that ICN will be used heavily for digital content
   dissemination.  It is vital to consider DRM for digital content
   distribution.  In today's Internet Internet, there are two predominant classes
   of business models for on-demand video streaming.  The first model is
   based on advertising revenues.  Non-copyright protected (usually
   user-generated content, UGC)
   User-Generated Content (UGC)) content is offered by large
   infrastructure providers like Google (YouTube) at no charge.  The
   infrastructure is financed by spliced advertisements into the
   content.  In this context context, DRM considerations may not be required,
   since producers of UGC may only strive for the maximum possible
   dissemination.  Some producers of UGC are mainly interested to share in
   sharing content with their families, friends, colleges colleges, or others and
   have no intention to make making a profit.  However, the second class of
   business models model requires DRM, because
   they these entities are primarily
   profit oriented.  For example, large on-demand streaming platforms like Netflix
   (e.g., Netflix) establish business models based on subscriptions.
   Consumers may have to pay a monthly fee in order to get access to copyright protected
   copyright-protected content like TV series, movies movies, or music.  This
   model may be ad-supported ad supported and free to the content consumer, like
   YouTube Channels or Spotify. But Spotify, but the creator of the content expects
   some remuneration for his work.  From the perspective of the service
   providers and the copyright owners, only clients that pay the fee
   (explicitly or implicitly through ad placement) should be able to
   access and consume the content.  Anyway, the challenge is to find an
   efficient and scalable way of access control to digital content,
   which is distributed in information-centric networks. ICNs.

8.1.  Broadcast Encryption for DRM in ICN

   The

   This section discusses Broadcast Encryption (BE) as a suitable basis
   for DRM functionalities in conformance to the ICN communication
   paradigm. Especially when network inherent caching is
   paradigm (network-inherent caching, considered the advantage of BE BE,
   will be highlighted. highlighted).

   In ICN, data Data packets can be cached inherently in the network network, and any
   network participant can request a copy of these packets.  This makes
   it very difficult to implement an access control for content that is
   distributed via ICN.  A naive approach is to encrypt the transmitted
   data for each consumer with a distinct key.  This prohibits everyone
   other than the intended consumers to decrypt from decrypting and consume consuming the
   data.  However, this approach is not suitable for ICN's communication
   paradigm
   paradigm, since it would reduce the benefits gained from the inherent
   network caching.  Even if multiple consumers request the same content
   content, the requested data for each consumer would differ using this
   approach.  A better better, but still insufficient insufficient, idea is to use a single
   key for all consumers.  This does not destruct the benefits of ICN's
   caching ability.  The drawback is that if one of the consumers
   illegally distributes the key, the system is broken and broken; any entity in
   the network can access the data.  Changing the key after such an
   event is useless since the provider has no possibility to identify
   the illegal distributer. Therefore distributor.  Therefore, this person cannot be stopped
   from distributing the new key again.  In addition to this issue issue,
   other challenges have to be considered.  Subscriptions expire after a
   certain time time, and then it has to be ensured that these consumers
   cannot access the content anymore.  For a provider that serves
   millions of daily consumers (e.g. Netflix) (e.g., Netflix), there could be a
   significant number of expiring subscriptions per day.  Publishing a
   new key every time a subscription expires would require an unsuitable
   amount of computational power just to re-encrypt the collection of
   audio-visual content.

   A possible approach to solve these challenges is Broadcast
   Encryption (BE) [22] BE [Fiat94] as
   proposed in [23]. [Posch13].  From this point on, this section will focus
   only on BE as an enabler for DRM functionality in the use case of ICN
   video streaming.  This subsection continues with the explanation of
   how BE works and shows how BE can be used to implement an access
   control scheme in the context of content distribution in ICN.

   BE actually carries a misleading name.  One might expect a concrete
   encryption scheme.  However, it belongs to the family of key- key
   management schemes.  These schemes (KMS). KMS are responsible for the
   generation, exchange, storage storage, and replacement of cryptographic keys.
   The most interesting characteristics of Broadcast Encryption Schemes (BES) BE schemes are:

     . A BES

   o  BE schemes typically uses use a global trusted entity called the
        licensing agent
      Licensing Agent (LA), which is responsible for spreading a set of
      pre-generated secrets among all participants.  Each participant
      gets a distinct subset of secrets assigned from the LA.
     .

   o  The participants can agree on a common session key, which is
      chosen by the LA.  The LA broadcasts an encrypted message that
      includes the key.  Participants with a valid set of secrets can
      derive the session-key session key from this message.

     .

   o  The number of participants in the system can change dynamically.
      Entities may join or leave the communication group at any time.
      If a new entity joins joins, the LA passes on a valid set of secrets to
      that entity.  If an entity leaves (or is forced to leave) the LA
      revokes the entity's subset of keys, which means that it cannot
      derive the correct session key anymore when the LA distributes a
      new key.
     .

   o  Traitors (entities that reveal their secrets) can be traced and
      excluded from ongoing communication.  The algorithms and
      preconditions to identify a traitor vary between concrete BES. BE
      schemes.

   This listing already illustrates why BE is suitable to control the
   access to data that is distributed via an information-centric
   network. ICN.  BE enables the usage
   of a single session key for confidential data transmission between a
   dynamically changing subset or network participants.  ICN caches can
   be utilized since the data is encrypted only with a single key known
   by all legitimate clients.  Furthermore, traitors can be identified
   and removed from the system.  The issue of re-encryption still exists, exists
   because the LA will eventually update the session key when a
   participant should be excluded.  However, this disadvantage can be
   relaxed in some way if the following points are considered:

     .

   o  The updates of the session key can be delayed until a set of
      compromised secrets has been gathered.  Note that secrets may
      become compromised because of two reasons. First, reasons: first, a traitor could
      have illegally revealed the secret. Second, secret; second, the subscription of an
      entity expired.  Delayed revocation temporarily enables some non-legitimate non-
      legitimate entities to consume content.  However, this should not
      be a severe problem in home entertainment scenarios.  Updating the
      session key in regular (not too short) intervals is a good tradeoff. trade-
      off.  The longer the interval last lasts, the less computational
      resources are required for content re-encryption and the better
      the cache utilization in the ICN will be.  To evict old data from
      ICN caches that has have been encrypted with the prior session key key,
      the publisher could indicate a lifetime for transmitted packets.
     .

   o  Content should be re-encrypted dynamically at request time.  This
      has the benefit that untapped content is not re-encrypted if the
      content is not requested during two session key updates
        and therefore update; therefore,
      no resources are wasted.  Furthermore, if the updates are
      triggered in non-peak times times, the maximum amount of
        resource resources
      needed at one point in time can be lowered
        effectively, effectively since in
      peak times generally more diverse content is requested.
     .

   o  Since the amount of required computational resources may vary
      strongly from time to time time, it would be beneficial for any
      streaming provider to use cloud-based services to be able to
      dynamically adapt the required resources to the current needs.
        Regarding  In
      regard to a lack of computation time or bandwidth bandwidth, the cloud
      service could be used to scale up to overcome shortages.

   Figure 4 show shows the potential usage of BE in a multimedia delivery
   frameworks
   framework that builds upon ICN infrastructure and uses the concept of
   dynamic adaptive streaming, e.g., DASH.  BE would be implemented on
   the top to have an efficient and scalable way of access control to
   the multimedia content.

              +--------Multimedia Delivery Framework--------+
              |                                             |
              |     Technologies            Properties      |
              |  +----------------+     +----------------+  |
              |  |   Broadcast    |<--->|   Controlled   |  |
              |  |   Encryption   |     |     Access     |  |
              |  +----------------+     +----------------+  |
              |  |Dynamic Adaptive|<--->|   Multimedia   |  |
              |  |   Streaming    |     |   Adaptation   |  |
              |  +----------------+     +----------------+  |
              |  |       ICN      |<--->|    Cachable   Cacheable    |  |
              |  | Infrastructure |     |   Data Chunks  |  |
              |  +----------------+     +----------------+  |
              +---------------------------------------------+

            Figure 4: A potential multimedia framework using BE.

8.2      .                AAA Based Potential Multimedia Framework Using BE

8.2.  AAA-Based DRM for ICN Networks

8.2.1.  Overview

   Recently, a novel approach to Digital Rights Management (DRM) DRM has emerged to link DRM to usual
   network management operations, hence linking DRM to authentication, authorization, and accounting (AAA) AAA services.
   ICN provides the abstraction of an architecture where content is
   requested by name and could be served from anywhere.  In DRM, the
   content provider (the origin of the content) allows the destination
   (the end user end-user account) to use the content.  The content provider and
   content storage/cache are at two different entities in
   ICC and ITU Carrier
   Code (ICC); for traditional DRM DRM, only source and destination count
   and not the intermediate storage.  The proposed solution allows the
   provider of the caching to be involved in the DRM policies using
   well known
   well-known AAA mechanisms.  It is important to note that this
   solution is compatible with the proposes proposal of the Broadcast Encryption
   (BE) BE, proposed earlier
   in this draft. document.  The BE proposes a technology technology, as this solution is
   more operational.

8.2.2.  Implementation

   With the proposed AAA-based DRM, when content is requested by name
   from a specific destination, the request could link back to both the
   content provider and the caching provider via traditional AAA
   mechanisms,
   mechanisms and trigger the appropriate DRM policy independently from
   where the content is stored.  In this approach approach, the caching, DRM DRM, and
   AAA remain independent entities but can work together through ICN
   mechanisms.  The proposed solution enables extending the traditional
   DRM done by the content provider to jointly being done by content
   provider and network/caching provider.

   The solution is based on the concept of a "token".  The content
   provider authenticates the end user and issues an encrypted token to
   authenticate the a named content named-content ID or IDs that the user can access.
   The token will be shared with the network provider and used as the
   interface to the AAA protocols.  At this point point, all content access is
   under the control of the network provider and the ICN.  The
   controllers and switches can manage the content requests and handle
   mobility.  The content can be accessed from anywhere as long as the
   token remains valid or the content is available in the network.  In
   such a scheme scheme, the content provider does not need to be contacted
   every time a named content named-content is requested.  This reduces the load of
   the content provider network and creates a DRM mechanism that is much
   more appropriate for the distributed caching and peer-to-peer Peer-to-Peer storage
   characteristic of ICN networks.  In particular, the content requested
   by name can be served from anywhere under the only condition that the
   storage/cache can verify that the token is valid for content access.

   The solution is also fully customizable to both content and network
   provider's needs as the tokens can be issued based on user accounts,
   location
   location, and hardware (MAC address (Media Access Control (MAC) address, for
   example) linking it naturally to legacy authentication mechanisms.
   In addition, since both content and network providers are involved in
   DRM policies policies, pollution attacks and other illegal requests for the
   content can be more easily detected.  The proposed AAA-based DRM is
   currently under full development.

9.  Future Steps for Video in ICN

   The explosion of online video services, along with their increased
   consumption by mobile wireless terminals, further exacerbates the
   challenges of Video Adaptation leveraging ICN mechanisms. mechanisms that leverage Video Adaptation.  The
   following sections present a series of research items derived from
   these challenges, further introducing next steps for the subject.

9.1. Large Scale  Large-Scale Live Events

   An active area of investigation and a potential use case where ICN
   would provide significant benefits, is that of distributing

   Distributing content, and video in particular, using local
   communications in large scale large-scale events such as sports event sporting events in a
   stadium, a concert concert, or a large
   demonstration. demonstration, is an active area of
   investigation and a potential use case where ICN would provide
   significant benefits.

   Such use-case involves use cases involve locating content that is generated on the fly
   and requires discovery mechanisms in addition to sharing mechanisms.
   The scalability of the distribution becomes important as well.

9.2.  Video Conferencing and Real-Time Communications

   Current protocols for video-conferencing video conferencing have been designed, and this
   document needs to take takes input from them to identify the key research issues.
   Real-time communications add timing constraints (both in terms of
   delay and in terms of synchronization) to the scenario discussed
   above.

   AR

   An Access Router (AR) and a Virtual Router (VR), and VR (and immersive
   multimedia experiences in general) general, are clearly an area of further
   investigation, as they involve combining multiple streams of data
   from multiple users into a coherent whole.  This raises issues of multi-source multi-destination
   multisource, multidestination multimedia streams that ICN may be
   equipped to deal with in a more natural manner than IP that IP, which is
   inherently unicast.

9.3.  Store-and-Forward Optimized Rate Adaptation

   One of the benefits of ICN is to allow the network to insert caching
   in the middle of the data transfer.  This can be used to reduce the
   overall bandwidth demands over the network by caching content for
   future re-use. But reuse, but it provides more opportunities for optimizing video
   streams.

   Consider

   Consider, for instance instance, the following scenario: a client is connected
   via an ICN network to a server.  Let's say the client is connected
   wirelessly to a node that has a caching capability, which is
   connected through a WAN to the server. Assume further  Further, assume that the
   capacity of each of the links (both the wireless and the WAN logical
   links) vary varies with time.

   If the rate adaptation is provided in an end-to-end manner, as in
   current mechanisms like DASH, then the maximal rate that can be
   supported at the client is that of the minimal bandwidth on each
   link.

   For

   If, for instance, if during time period 1, Time Period 1 the wireless capacity is 1 and
   the wired capacity is 2, 2 and during time period 2, Time Period 2 the wireless
   capacity is 2 due (due to some hotspot, hotspot) and the wired capacity is 1 due (due
   to some congestion in the network, network), then the best end-to-end rate
   that can be achieved is 1 during each period.

   However, if the cache is used during time period Time Period 1 to pre-fetch 2
   units of data, then during period 2, Time Period 2 there is 1 unit of data at
   the
   cache, cache and another unit of data, which data that can be streamed from the
   server, and
   server; therefore, the rate that can be achieved is therefore 2 units of data.
   In this case, the average bandwidth rises from 1 to 1.5 over the 2 two
   periods.

   This straw man straw-man example illustrate illustrates a) the benefit of ICN for
   increasing the throughput of the network, network and b) the need for the
   special rate adaptation mechanisms to be designed so as to take advantage
   of this gain.  End-to-end rate adaptation cannot take advantage of
   the cache availability.  The authors of [Rainer16] showed that
   buffer-based adaptation mechanisms can be one approach to tackle this
   challenge.  As buffer-based adaptation does not estimate the
   available bandwidth resources (but solely considers the video buffer
   fill state), measured bandwidth fluctuations caused by cache hits are
   not existent.  Therefore, they cannot negatively impact the
   adaptation decisions (e.g., frequent representation switching).

9.4.  Heterogeneous Wireless Environment Dynamics

   With the ever-growing increase in online services being accessed by
   mobile devices, operators have been deploying different overlapping
   wireless access networking technologies.  In this way, in the same
   area, user terminals are within range of different cellular, Wi-Fi Wi-Fi,
   or even WiMAX Worldwide Interoperability for Microwave Access (WiMAX)
   networks.  Moreover, with the advent of the Internet of Things (e.g.,
   surveillance cameras feeding video footage), this list can be further
   complemented with more specific more-specific short-range technologies, such as
   Bluetooth or ZigBee.

   In order to leverage from this plethora of connectivity
   opportunities, user terminals are coming equipped with different
   wireless access interfaces, providing them with extended connectivity
   opportunities.  In this way, such devices become able to select the
   type of access which that best suits them according to different criteria,
   such as available bandwidth, battery consumption, access do to different
   link conditions according to the user profile profile, or even access to
   different content.  Ultimately, these aspects contribute to the Quality of Experience QoE
   perceived by the
   end-user, end user, which is of utmost importance when it
   comes to video content.

   However, the fact that these users are mobile and using wireless
   technologies,
   technologies also provides a very dynamic setting, setting where the current
   optimal link conditions at a specific moment might not last or be
   maintained while the user moves.  These aspects have been amply
   analyzed in recently finished projects such as FP7 MEDIEVAL [18],
   [MEDIEVAL], where link events reporting on wireless conditions and
   available alternative connection points were combined with vide video
   requirements and traffic optimization mechanisms, mechanisms towards the
   production of a joint network and mobile terminal mobility management
   decision.  Concretely, in [19] [Fu13], link information about the
   deterioration of the wireless signal was sent towards a mobility
   management controller in the network.  This input was combined with
   information about the user profile, as well as of the current video
   service requirements, and used to trigger the decrease or increase of
   scalable video layers,
   adjusting layers (adjusting the video to the ongoing link conditions.
   conditions).  Incrementally, the video could also be adjusted when a new
   new, better connectivity opportunity presents itself.

   In this way, regarding Video Adaptation, ICN mechanisms can leverage
   from their intrinsic multiple source support capability and go beyond
   the monitoring of the status of the current link, thus exploiting the
   availability of different connectivity possibilities (e.g., different
   "interfaces").  Moreover, information obtained from the mobile
   terminal's point of view of its network link, as well as information
   from the network itself (i.e., load, policies, and others), can
   generate scenarios where such information is combined in a joint
   optimization procedure allowing the content to be forward to users
   using the best available connectivity option (e.g., exploiting
   management capabilities supported by ICN intrinsic mechanisms as in [20]).
   [Corujo12]).

   In fact, ICN base mechanisms can further be exploited in enabling new
   deployment scenarios such as preparing the network for mass requests
   from users attending a large multimedia event (i.e., concert,
   sports), allowing video to be adapted according to content, user and
   network requirements requirements, and operation capabilities in a dynamic way.

   The enablement of

   Enabling such scenarios require requires further research, with the main
   points highlighted as follows:

  . Development of

   o  how to develop a generic video services (and obviously content)
      interface allowing the definition and mapping of their
      requirements (and characteristics) into the current capabilities
      of the network;

  . How

   o  how to define a scalable mechanism allowing either the video
      application at the terminal, terminal or some kind of network management
      entity, to adapt the video content in a dynamic way;

  . How
   o  how to develop the previous research items using intrinsic ICN
      mechanisms (i.e., naming and strategy layers);

  . Leverage

   o  how to leverage intelligent pre-caching of content to prevent
      stalls and poor quality phases, which lead to bad Quality of Experience of a worse QoE for the user. This includes
      user: this includes, in particular particular, the usage in mobile
      environments, which are characterized by severe bandwidth changes
      as well as connection outages, as shown in [21];

  . How [Crabtree13]; and

   o  how to take advantage of the multi-path multipath opportunities over the
      heterogeneous wireless interfaces.

9.5.  Network Coding for Video Distribution in ICN

   An interesting research area for combining heterogeneous sources is
   to use network coding [24]. [Montpetit13b].  Network coding allows to asynchronously
   combine for
   asynchronous combining of multiple sources by having each of them
   send information that is not duplicated by the other but that can be
   combined to retrieve the video stream.

   However, this creates issues in ICN in terms of defining the proper
   rate adaptation for the video stream; stream, securing the encoded data; data,
   caching the encoded data; data, timeliness of the encoded data; data, overhead of
   the network coding operations both in network resources and in added
   buffering delay, etc.

   Network coding has shown promise in reducing buffering events in
   unicast, multicast multicast, and P2P setting. [26] settings.  [Medard12] considers
   strategies using network coding to enhance QoE for multimedia
   communications.  Network coding can be applied to multiple streams,
   but also within a single stream as an equivalent of a composable
   erasure code.  Clearly, there is a need for further investigation of
   network coding in ICN, potentially as a topic of activity in the
   research group.

9.6.  Synchronization Issues for Video Distribution in ICN

   ICN de-couples decouples the fetching of video chunks from the location of
   these chunks. their locations.
   This means an audio chunk may be received from one network element (cache/storage/server) while
   (cache/storage/server), a video chunk may be received from another one another,
   while yet another chunk (say, the next one, or another layer from the
   same video stream) may come from a third element.  This introduces
   disparity in the retrieval times and locations of the different
   elements of a video stream that need to be played at the same (or
   almost same) time.  Synchronization of such delivery and playback may
   require specific synchronization tools for video delivery in ICN.

   Other synchronization aspects involve:

   - synchronizing involve synchronizing:

   o  within a single stream, for instance instance, the consecutive chunks of a
      single stream, stream or the multiple layers of a layered
     scheme, scheme when
      sources and transport layers may be different. Re-
     ordering

   o  re-ordering the packets of a stream distributed over multiple
      sources at the video client, or ensuring that multiple chunks
      coming from multiple sources arrive within an acceptable time
      window;
   - synchronizing

   o  multiple streams, such as the audio and video components of a
      video stream, which can be received from independent sources;
   - synchronizing and

   o  multiple streams from multiple sources to multiple destinations,
      such as mass distribution of live events.  For instance, for live
      video streams or video-conferencing, video conferencing, some level of synchronization
      is required so that people watching the stream view the same
      events at the same time.

   Some of these issues were addressed in [27] [Montpetit13a] in the context
   of social video consumption.  Network coding, with traffic
   engineering, is considered as a potential solution for
   synchronization issues.  Other approaches could be considered that
   are specific for to ICN as well.

   Traffic engineering in ICN [28,29] [Su14] [Chanda13] may be required to
   provide proper synchronization of multiple streams.

10.  Security Considerations

   This is informational.  There are no specific security considerations
   outside of those mentioned in the text.

11. IANA Considerations

   This document does not require any IANA action.

 12.  Conclusions

   This draft proposed document proposes adaptive video streaming for ICN, identified
   potential problems problems, and presented presents the combination of CCN with DASH as
   a solution.  As both concepts, DASH and CCN, maintain several
   elements in common, like, e.g., the content in different versions
   being dealt with in segments, combination of both technologies seems
   useful.  Thus, adaptive streaming over CCN can leverage advantages
   such as, e.g., efficient caching and intrinsic multicast support of
   CCN, routing based on named data named-data URIs, intrinsic multi-link multilink and
   multi-source
   multisource support, etc.

   In this context, the usage of CCN with DASH in mobile environments
   comes together with advantages compared to today's solutions,
   especially for devices equipped with multiple network interfaces.
   The retrieval of data over multiple links in parallel is a useful
   feature, specifically for adaptive multimedia streaming, streaming since it
   offers the possibility to dynamically switch between the available
   links depending on their bandwidth capabilities, which are
   transparent to the actual DASH client.

 13.

12.  References

13.1.

12.1.  Normative References

   [RFC6972] Y. Zhang, N. Zong, "Problem Statement and Requirements of
             the Peer-to-Peer Streaming Protocol (PPSP)", RFC6972, July
             2013

13.2. Informative References

   [1]   ISO/IEC DIS 23009-1.2, Information technology - Dynamic
         adaptive streaming over HTTP (DASH) - Part 1: Media
         presentation description and segment formats

   [2]   Lederer, S., Mueller, C.,

   [Rainer16]
              Rainer, B., Timmerer, C., Posch, D., and H. Hellwagner, H., "An Experimental Analysis "Investigating
              the Performance of Pull-based Dynamic Adaptive Streaming over HTTP in Content Centric Networks",
              in
         Proceedings of the NDN", IEEE International Conference Journal on Multimedia
         and Expo 2013, San Jose, USA, July, 2013

   [3]   Liu, Y., Geurts, J., Point, J., Lederer, S., Rainer, B.,
         Mueller, C., Timmerer, C., Hellwagner, H., "Dynamic Adaptive
         Streaming over CCN: A Caching and Overhead Analysis", Selected Areas in
         Proceedings of the IEEE international Conference Communications
              (J-SAC): Special Issue on
         Communication (ICC) 2013 - Next-Generation Networking
         Symposium, Budapest, Hungary, June, 2013

   [4]   Grandl, R., Su, K., Westphal, C., "On the Interaction of
         Adaptive Video Streaming with Content-Centric Networks",
         eprint arXiv:1307.0794, July 2013.

   [5]   V. Jacobson, D. Smetters, J. Thornton, M. Plass, N. Briggs and
         R. Braynard, "Networking named content", Distribution over Future
              Internet, Volume 34, Number 8,
              DOI 10.1109/JSAC.2016.2577365, August 2016.

   [RFC2119]  Bradner, S., "Key words for use in Proc. of the 5th
         int. Conf. on Emerging Networking Experiments RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC6972]  Zhang, Y. and Technologies
         (CoNEXT '09). ACM, New York, NY, USA, 2009, pp. 1-12.

   [6]   A. Detti, M. Pomposini, N. Blefari-Melazzi, S. Salsano Zong, "Problem Statement and A.
         Bragagnini, "Offloading cellular networks with Information-
         Centric Networking: The case of video streaming", In Proc. Requirements
              of the Int. Symp. on a World of Wireless, Mobile Peer-to-Peer Streaming Protocol (PPSP)", RFC 6972,
              DOI 10.17487/RFC6972, July 2013,
              <http://www.rfc-editor.org/info/rfc6972>.

12.2.  Informative References

   [ATIS-IIF]
              "ATIS: IIF, IPTV Interoperability Forum", 2015,
              <http://www.atis.org/iif/deliv.asp>.

   [Bakker15]
              Bakker, A., Petrocco, R., and Multimedia
         Networks (WoWMoM '12), IEEE, San Francisco, CA, USA, 1-3,
         2012.

   [7] V. Jacobson, D. K. Smetters, N. H. Briggs, M. F. Plass, P.
         Stewart, J. D. Thornton, Grishchenko, "Peer-to-
              Peer Streaming Peer Protocol (PPSPP)", RFC 7574,
              DOI 10.17487/RFC7574, July 2015,
              <http://www.rfc-editor.org/info/rfc7574>.

   [Castro03]
              Castro, M., Druschel, P., Kermarrec, A., Nandi, A., and R. L. Braynard, "VoCCN: Voice
         over content-centric networks," A.
              Rowstron, "SplitStream: High-Bandwidth Multicast in ACM ReArch Workshop, 2009

   [8]   Christopher Mueller, Stefan Lederer and Christian Timmerer, A
         proxy effect analysis and fair adaptation algorithm for
         multiple competing dynamic adaptive streaming over HTTP
         clients, In
              Cooperative Environments", Proceedings of the Conference on Visual
         Communications and Image Processing (VCIP) 2012, San Diego,
         USA, November 27-30, 2012.

   [9]   DASH Research at the Institute of Information Technology,
         Multimedia Communication Group, Alpen-Adria Universitaet
         Klagenfurt, URL: http://dash.itec.aau.at

   [10] A. Detti, N. Blefari-Melazzi, S. Salsano, and M. Pomposini
        CONET: A content centric inter-networking architecture," in 19th ACM
        Workshop
              Symposium on Information-Centric Networking (ICN), 2011.

   [11] W. K. Operating Systems Principles (SOSP '03),
              DOI 10.1145/945445.945474, October 2003.

   [Chai11]   Chai, N. W., Wang, I. N., Psaras, G. I., Pavlou, C. G., Wang, G. C. C., de
              Blas, F. G., Ramon-Salguero, L. F., Liang, S. L., Spirou, A. S.,
              Blefari-Melazzi, N., Beben, A., and E. Hadjioannou,
              "CURLING: Content-ubiquitous resolution Content-Ubiquitous Resolution and
        delivery infrastructure Delivery
              Infrastructure for next-generation services," Next Generation Services", IEEE
              Communications Magazine, vol. Volume 49, no. Issue 3, pp. 112-120,
              DOI 10.1109/MCOM.2011.5723808, March
        2011

   [12] NetInf project Website http://www.netinf.org

   [13] N. Magharei, R. Rejaie, Yang Guo, "Mesh or Multiple-Tree: A
        Comparative Study of Live P2P Streaming Approaches," INFOCOM
        2007. 26th IEEE International Conference on Computer
        Communications. IEEE , vol., no., pp.1424,1432, 6-12 May 2007

   [14] PPSP WG Website https://datatracker.ietf.org/wg/ppsp/
   [15] A. Bakker, R. Petrocco, V. Grishchenko, "Peer-to-Peer Streaming
        Peer Protocol (PPSPP)", draft-ietf-ppsp-peer-protocol-08

   [16] Rui S. Cruz, Mario S. Nunes, Yingjie Gu, Jinwei Xia, Joao P.
        Taveira, Deng Lingli, "PPSP Tracker Protocol-Base Protocol
        (PPSP-TP/1.0)", draft-ietf-ppsp-base-tracker-protocol-02

   [17] A.Detti, B. Ricci, N. Blefari-Melazzi,"Peer-To-Peer Live
         Adaptive Video Streaming for Information Centric Cellular
         Networks", IEEE PIMRC 2013,London, UK, 8-11 September 2013

   [18] http://www.ict-medieval.eu

   [19] B. Fu, G. Kunzmann, M. Wetterwald, 2011.

   [Chanda13]
              Chanda, A., Westphal, C., and D. Corujo, R. Costa, "QoE-
        aware Raychaudhuri, "Content
              Based Traffic Management for Mobile Video Delivery", Proc. Engineering in Software Defined Information
              Centric Networks", 2013 IEEE  ICC,  Workshop Conference on  Immersive  &  Interactive  Multimedia Computer
              Communications  over  the  Future  Internet  (IIMC),  Budapest,
        Hungary, Jun Workshops (INFOCOM WKSHPS),
              DOI 10.1109/INFCOMW.2013.6970717, April 2013.

   [20] Corujo

   [Corujo12]
              Corujo, D., Vidal Vidal, I., Garcia-Reinoso Garcia-Reinoso, J., Aguiar R., and R. Aguiar,
              "A Named Data Networking Flexible Framework for Management
              Communications", IEEE Communications Magazine, Vol. Volume 50, no.
              Issue 12,
        pp. 36-43, Dec 2012

   [21] Crabtree DOI 10.1109/MCOM.2012.6384449, December 2012.

   [Crabtree13]
              Crabtree, B., Stevens Stevens, T., Allan Allan, B., Lederer Lederer, S., Posch Posch,
              D.,
        Mueller C., Timmerer Mueller, C., Video and C. Timmerer, "Video Adaptation in Limited or Zero
              Limited/Zero Network Coverage, CCNxConn 2013,PARC, Coverage", CCNxCon 2013, Palo Alto, pp. 1-2, 2013

   [22] Fiat Alto
              Research Center (PARC), September 2013.

   [Detti11]  Detti, A., Blefari-Melazzi, N., Salsano, S., and M.
              Pomposini, "CONET: A Content Centric Inter-Networking
              Architecture", Proceedings of the ACM SIGCOMM Workshop on
              Information-Centric Networking,
              DOI 10.1145/2018584.2018598, August 2011.

   [Detti12]  Detti, A., Naor Pomposini, M., Blefari-Melazzi, N., Salsano,
              S., and A. Bragagnini, "Offloading cellular networks with
              Information-Centric Networking: the case of video
              streaming", 2013 IEEE 14th International Symposium on A
              World of Wireless, Mobile and Multimedia Networks
              (WoWMoM), DOI 10.1109/WoWMoM.2012.6263734, June 2012.

   [Detti13]  Detti, A., Ricci, B., and N. Blefari-Melazzi, "Peer-To-
              Peer Live Adaptive Video Streaming for Information Centric
              Cellular Networks", 2013 IEEE 24th Annual International
              Symposium on Personal, Indoor, and Mobile Radio
              Communications (PIMRC), DOI 10.1109/PIMRC.2013.6666771,
              September 2013.

   [Fiat94]   Fiat, A. and M. Naor, "Broadcast Encryption", in Advances in
              Cryptology (Crypto'93), volume 773 of - CRYPTO '93 Proceedings, Lecture Notes in
              Computer Science, pages 480-491. Springer Berlin / Heidelberg, Volume 773, pp. 480-491, 1994.

   [23]  Posch

   [Fu13]     Fu, B., Kunzmann, G., Wetterwald, M., Corujo, D.,  Hellwagner  H.,  Schartner  P.,  "On-Demand and R.
              Costa, "QoE-aware traffic management for mobile video
              delivery", 2013 IEEE International Conference on
              Communications Workshops (ICC),
              DOI 10.1109/ICCW.2013.6649314, June 2013.

   [Grandl13]
              Grandl, R., Su, K., and C. Westphal, "On the Interaction
              of Adaptive Video Streaming based with Content-Centric
              Networks", 2013 IEEE International Conference on
              Multimedia and Expo (ICME), DOI 10.1109/ICME.2013.6607500,
              July 2013.

   [IETF-PPSP]
              IETF, "Peer to Peer Streaming Protocol (ppsp)",
              <https://datatracker.ietf.org/wg/ppsp/>.

   [ISO-DASH]
              ISO, "Information technology -- Dynamic adaptive streaming
              over HTTP (DASH) -- Part 1: Media presentation description
              and segment formats", ISO/IEC 23009-1:2014, May 2014.

   [ITEC-DASH]
              "ITEC - Dynamic Adaptive Encrypted Content Chunks",                                        th             in Proceedings of Streaming over HTTP", DASH
              Research at the 8  International Workshop on Secure
        Network  Protocols  (NPSec'13),  Los  Alamitos,  IEEE  Computer
        Society Press, October, 2013.

   [24]  Montpetit M.J., Westphal C., Trossen Institute of Information
              Technology, Multimedia Communication Group, Alpen-Adria
              Universitaet Klagenfurt, <http://dash.itec.aau.at>.

   [Jacobson09a]
              Jacobson, V., Smetters, D., Briggs, N., Plass, M.,
              Stewart, P., Thornton, J., and R. Braynard, "VoCCN: Voice-
              over Content-Centric Networks", Proceedings of the 2009
              Workshop on Re-architecting the Internet,
              DOI 10.1145/1658978.1658980, December 2009.

   [Jacobson09b]
              Jacobson, V., Smetters, D., "Network Coding Meets
        Information Centric Networks," in Thornton, J., Plass, M.,
              Briggs, N., and R. Braynard, "Networking Named Content",
              Proceedings of the workshop 5th International Conference on Name-Oriented Mobility (NOM), jointly with ACM MobiHoc 2013,
        Hilton Head, SC, June 2013.

   [25]
              Emerging Networking Experiments and Technologies (CoNEXT),
              DOI 10.1145/1658939.1658941, December 2009.

   [LeCallet13]
              Le Callet Callet, P., Moeller S. Moeller, S., and  Perkis A. (eds.),  Qualinet Perkis, "Qualinet White
              Paper on Definitions of Quality of  Experience
        (2012). Experience", European
              Network on Quality of Experience in Multimedia Systems and   Services  (COST
              Services, COST Action IC  1003),  Lausanne,
        Switzerland, 1003, Version 1.2, March 2013.

   [26] Medard

   [Lederer13a]
              Lederer, S., Liu, Y., Geurts, J., Point, J., Lederer, S.,
              Mueller, C., Rainer, B., Timmerer, C., and H. Hellwagner,
              "Dynamic Adaptive Streaming over CCN: A Caching and
              Overhead Analysis", 2013 IEEE International Conference on
              Communication (ICC), DOI 10.1109/ICC.2013.6655116, June
              2013.

   [Lederer13b]
              Lederer, S., Mueller, C., Rainer, B., Timmerer, C., and H.
              Hellwagner, "An Experimental Analysis of Dynamic Adaptive
              Streaming over HTTP in Content Centric Networks", 2013
              IEEE International Conference on Multimedia and Expo
              (ICME), DOI 10.1109/ICME.2013.6607500, July 2013.

   [Magharei07]
              Magharei, N., Rejaie, R., and Y. Guo, "Mesh or Multiple-
              Tree: A Comparative Study of Live P2P Streaming
              Approaches", IEEE INFOCOM 2007 - 26th IEEE International
              Conference on Computer Communications,
              DOI 10.1109/INFCOM.2007.168, May 2007.

   [Medard12]
              Medard, M., Kim Kim, M., ParandehGheibi Parandeh-Gheibi, M., Zeng Zeng, W., Montpetit M.J.,
        Quality and M.
              Montpetit, "Quality of Experience for Multimedia
              Communications: Network
        Coding Strategies, Technical Report, MIT, 2012/3

   [27] Montpetit M.J., Holtzman H., Chakrabarti Coding Strategies", Laboratory of
              Electronics, Massachusetts Institute of Technology, March
              2012.

   [MEDIEVAL]
              "MEDIEVAL: MultiMEDia transport for mobIlE Video
              AppLications", 2010, <http://www.ict-medieval.eu>.

   [Montpetit13a]
              Montpetit, M., Holtzman, H., Chakrabarti, K., and M.
              Matijasevic, "Social video consumption: Synchronized
              viewing experiences across devices and networks", 2013
              IEEE International Conference on Communications Workshops
              (ICC), pp. 286-290, DOI 10.1109/ICCW.2013.6649245, 2013.

   [Montpetit13b]
              Montpetit, M., Westphal, C., and D. Trossen, "Network
              Coding Meets Information-Centric Networking: An
              Architectural Case for Information Dispersion Through
              Native Network Coding", Proceedings of the 1st ACM
              Workshop on Emerging Name-Oriented Mobile Networking
              Design-Architecture, Algorithms, and Applications,
              DOI 10.1145/2248361.2248370, June 2013.

   [Mueller12]
              Mueller, C., Lederer, S., and C. Timmerer, "A Proxy Effect
              Analysis and Fair Adaptation Algorithm for Multiple
              Competing Dynamic Adaptive Streaming over HTTP Clients",
              2012 IEEE Visual Communications and Image Processing
              (VCIP), DOI 10.1109/VCIP.2012.6410799, November 2012.

   [NETINF]   "NetInf: Network of Information", <http://www.netinf.org>.

   [Posch13]  Posch, D., Hellwagner, H., and P. Schartner, "On-Demand
              Video Streaming based on Dynamic Adaptive Encrypted
              Content Chunks", Proceedings of the 8th International
              Workshop on Secure Network Protocols (NPSec '13),
              DOI 10.1109/ICNP.2013.6733673, October 2013.

   [RFC7476]  Pentikousis, K., Matijasevic Ed., Ohlman, B., Corujo, D., Boggia, G.,
              Tyson, G., Davies, E., Molinaro, A., and S. Eum,
              "Information-Centric Networking: Baseline Scenarios",
              RFC 7476, DOI 10.17487/RFC7476, March 2015,
              <http://www.rfc-editor.org/info/rfc7476>.

   [RFC7846]  Cruz, R., Nunes, M.,
        Social  video  consumption:  Synchronized  viewing  experiences
        across devices Xia, J., Huang, R., Ed., Taveira, J.,
              and networks, IEEE International Conference on
        Communications Workshops (ICC), 2013, 286-290

   [28] Su K., Westphal C., On D. Lingli, "Peer-to-Peer Streaming Tracker Protocol
              (PPSTP)", RFC 7846, DOI 10.17487/RFC7846, May 2016,
              <http://www.rfc-editor.org/info/rfc7846>.

   [Su14]     Su, K. and C. Westphal, "On the Benefit of Information
              Centric Networks for Traffic Engineering, IEEE ICC Conference, June Engineering", 2014

   [29] Chanda A., Westphal C., Raychaudhuri D., Content Based Traffic
        Engineering in Software Defined Information Centric Networks,
        in IEEE INFOCOM Workshop NOMEN'13, April, 2013

   [30] Castro M., Druschel P., Kermarrec A.-M., Nandi A., Rowstron A.,
        Singh A. SplitStream: Highbandwidth multicast in cooperative
        environments. In Proceedings of ACM SOSP (2003).

   [31] ATIS     IPTV     Interoperability     Forum,     ATIS     IFF,
        http://www.atis.org/iif/deliv.asp

 14. Authors' Addresses

   Stefan Lederer, Christian Timmerer, Daniel Posch
   Alpen-Adria University Klagenfurt
   Universitaetsstrasse 65-67, 9020 Klagenfurt, Austria

   Email: {firstname.lastname}@itec.aau.at

   Cedric Westphal, Aytac Azgin. Shucheng (Will) Liu
   Huawei
   2330 Central Expressway, Santa Clara, CA95050, USA

   Email: {cedric.westphal,aytac.azgin,liushucheng}@huawei.com
   Christopher Mueller
   bitmovin GmbH
   Lakeside B01, 9020 Klagenfurt, Austria

   Email: christopher.mueller@bitmovin.net

   Andrea Detti
   Electronic Engineering Dept.
   University of Rome Tor Vergata
   Via del Politecnico 1, Rome, Italy

   Email: andrea.detti@uniroma2.it

   Daniel Corujo,
   Advanced Telecommunications and Networks Group
   Instituto de Telecomunicacoes
   Campus Universitario de Santiago
   P-3810-193 Aveiro, Portugal

   Email: dcorujo@av.it.pt

   Jianping Wang
   City University of Hong Kong
   Hong Kong, China

   Email: jianwang@cityu.edu.hk

   Marie-Jose Montpetit

   Email: marie@mjmontpetit.com

   Niall Murray
   Dept. of Electronic, Computer and Software Engineering
   Athlone Institute of Technology
   Dublin Rd., Athlone, Ireland

   Email: nmurray@research.ait.ie

 15. Acknowledgements
              International Conference on Communications (ICC),
              DOI 10.1109/ICC.2014.6883810, June 2014.

Acknowledgments

   This work was supported in part by the EC European Community in the
   context of the SocialSensor (FP7-ICT-287975) project and partly
   performed in the Lakeside Labs research cluster at AAU.  SocialSensor
   receives research funding from the European Community's Seventh
   Framework Programme.  The work for this document was also partially
   performed in the context of the FP7/NICT EU-JAPAN GreenICN project,
   http://www.greenicn.org.
   <http://www.greenicn.org>.  Apart from this, the European Commission
   has no responsibility for the content of this draft. document.  The
   information in this document is provided as is and no guarantee or
   warranty is given that the information is fit for any particular
   purpose.  The
   user thereof user, thereof, uses the information at its sole risk
   and liability.

   The authors would like to thank Shucheng (Will) Will (Shucheng) Liu from Huawei for
   supporting Dr. Wang's research and Marie-Jose Montpetit of MIT for
   her help in writing the section regarding AAA for DRM section. DRM.

Authors' Addresses

   Cedric Westphal (editor)
   Huawei

   Email: Cedric.Westphal@huawei.com

   Stefan Lederer
   Alpen-Adria University Klagenfurt

   Email: stefan.lederer@itec.aau.at

   Daniel Posch
   Alpen-Adria University Klagenfurt

   Email: daniel.posch@itec.aau.at

   Christian Timmerer
   Alpen-Adria University Klagenfurt

   Email: christian.timmerer@itec.aau.at
   Aytac Azgin
   Huawei

   Email: aytac.azgin@huawei.com

   Will (Shucheng) Liu
   Huawei

   Email: liushucheng@huawei.com

   Christopher Mueller
   BitMovin

   Email: christopher.mueller@bitmovin.net

   Andrea Detti
   University of Rome Tor Vergata

   Email: andrea.detti@uniroma2.it

   Daniel Corujo
   Instituto de Telecomunicacoes Aveiro

   Email: dcorujo@av.it.pt

   Jianping Wang
   City University of Hong Kong

   Email: jianwang@cityu.edu.hk

   Marie-Jose Montpetit
   MIT

   Email: marie@mjmontpetit.com

   Niall Murray
   Athlone Institute of Technology

   Email: nmurray@research.ait.ie