LOGO P2P & Multimedia Streaming NPUST-MINAR Professor : Sheau-Ru Tong Student : Yi-Chen Hsu 1

Contents Introduction 1 P2P Network Streaming Architecture 2 Stream Over P2P Neteork 3 Issues In Multimedia P2P Streaming 4 2

3 1. Introduction

Introduction – A content delivery network or content distribution network (CDN) is a system of computers containing copies of data, placed at various points in a network so as to maximize bandwidth for access to the data from clients throughout the network. A client accesses a copy of the data near to the client, as opposed to all clients accessing the same central server, so as to avoid bottleneck near that server. 1. Content Delivery Net Work(CDN) Content types include web objects, download-able objects (media files, software, documents), applications, real time media streams, and other components of internet delivery (DNS, routes, and database queries). [Wikipedia] YouTube is the most familiar solution for streaming video with client-server model over Internet

Introduction –  IP-multicast-based techniques can efficiently share a single channel, but the server is only scoped at local networks.

Introduction – Streaming Proxy Server In computer networks, a proxy server is a server (a computer system or an application program) that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. [Wikipedia]

Introduction – A caching proxy server accelerates service requests by retrieving content saved from a previous request made by the same client or even other clients. Caching proxies keep local copies of frequently requested resources, allowing large organizations to significantly reduce their upstream bandwidth usage and costs, while significantly increasing performance. [Wikipedia]

Introduction – Streaming Proxy Server Suffix-Window Caching

Introduction – A peer-to-peer, commonly abbreviated to P2P, is any distributed network architecture composed of participants that make a portion of their resources (such as processing power, disk storage or network bandwidth) directly available to other network participants, without the need for central coordination instances (such as servers or stable hosts). Peers are both suppliers and consumers of resources, in contrast to the traditional client– server model where only servers supply, and clients consume. [Wikipedia] 3. What is P2P?

Introduction – The Popular P2P Applications  P2P File System: open-after-downloading BitTorrent BitComet eDonkey eMule  P2P Media Streaming System: play-while-downloading KKBOX ezPeer Skype PPStream PPLive FOXY Freenet KazaA WinMX Winny

11 BitTorrent (protocol) A user playing the role of file-provider makes a file available to the network. This first user's file is called a seed and its availability on the network allows other users, called peers, to connect and begin to download the seed file. As new peers connect to the network and request the same file, their computer receives a different piece of the data from the seed. Once multiple peers have multiple pieces of the seed, BitTorrent allows each to become a source for that portion of the file. [Wikipedia] Introduction – 3.3

12 BitTorrent (Measurements) The number of downloaders increases exponentially in a short period of time after the torrent’s birth (the flash crowd period), and then decreases exponentially, but at a slower rate. The number of seeds also increases exponentially at first, and then decreases exponentially at a slower rate. Introduction – 3.3 FROM: Measurements, Analysis, and Modeling of BitTorrent-like Systems

13 P2P IPTV (PPStream) Introduction – 3.4 FROM: A Measurement Study of PPStream

14 P2P IPTV (PPStream) Introduction – 3.4 FROM: Study of PPStream Based on Measurement

15 P2P IPTV Measurement Introduction – FIFA World Cup  PPStream seems to get the data from many peers at the same time and its peers seem to have long session duration.  PPLive seems to get the data from only a few peers at the same time but its peers have not a long session duration.  SOPcast download policy looks like PPLive policy.  TVants download policy seems to mix PPStream and SOPcast policies. FROM: P2P IPTV Measurement: A Comparison Study

16 2. P2P Network Streaming Architecture

17 Overlay Network P2P Network Streaming Architecture – 1  Overlay network is a computer network which is built on top of another network.  Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network.  For example, distributed systems such as cloud computing, peer-to-peer networks, and client- server applications are overlay networks because their nodes run on top of the Internet. [Wikipedia]

18 Challenges P2P Network Streaming Architecture – 2  Dynamic uptime Peers don’t always stay online in the system. Requesting peers need to find new supplying peers to replace the failed ones.  Limited and dynamic peer bandwidth Unlike powerful video servers, peers have limited bandwidth capacities. The available bandwidth of supplying peers might fluctuate unexpectedly. FROM: Challenges and Approaches in Large-Scale P2P Media Streaming

19 Locating supplying peers P2P Network Streaming Architecture – 3.1  Centralized directory EX: PPStream, PPLive The simplest and most commonly used method FROM: Challenges and Approaches in Large-Scale P2P Media Streaming

20 P2P Network Streaming Architecture – 3.2  Hierarchical overlay structure Peers are organized into a hierarchical overlay structure such as an overlay tree. The new client probes each peer in the list and finds out the most suitable peer P x. FROM: Challenges and Approaches in Large-Scale P2P Media Streaming

21 P2P Network Streaming Architecture – 3.3  DHT-based approach Each peer is assigned a peer ID by hashing its own IP address using a common known hash function. Each object is also associated with a key in the same space of peer IDs by hashing the object itself. The peer with an ID equal to the hashed key is responsible for storing the object’s location (or the actual object). FROM: Challenges and Approaches in Large-Scale P2P Media Streaming

22 EX: BitTorrent (Kademlia) Third generation peer-to-peer networks use Distributed hash tables(DHT) to look up files in the network. Kademlia uses a "distance" calculation between two nodes. This distance is computed as the exclusive or of the two node IDs, taking the result as an integer number. The node ID is typically a large random number that is chosen with the goal of being unique for a particular node (see GUID). It can and does happen that nodes from Germany and Australia are "neighbours"; they have chosen similar random node IDs.GUID A basic Kademlia network with 2 n nodes will only take n steps (in the worst case) to find that node. [Wikipedia] P2P Network Streaming Architecture – 3.3

23 P2P Network Streaming Architecture – 3.3 EX ： P2P-over-SIP Additionally, implement P2P using SIP messaging P2P-SIP overlay Alice REGISTER INVITE alice 65a1fc d13da3 d4213f d462ba d467c4 d471f1 d46a1c Route(d46a1c) Use DHT in server farm Use DHT for all clients - but some are resource limited Use DHT among super-nodes Hierarchy Dynamically adapt servers clients

24 P2P Network Streaming Architecture – 3.4  Gossip-based Depth-first search (DFS) is an algorithm for traversing or searching a tree, tree structure, or graph. One starts at the root (selecting some node as the root in the graph case) and explores as far as possible along each branch before backtracking

25 3. Stream Over P2P Network

26 1. Content delivery path maintenance Stream Over P2P Network– 1.1  Tree-based multicast

27 Stream Over P2P Network– 1.2  Tree-based multicast SplitStream: High-Bandwidth Multicast in CooperativeEnvironments

28 Stream Over P2P Network– 1.3  Tree-based multicast Topology Optimization in Multi-Tree Based P2P Streaming System

29 In PROMISE, we represent the segment goodness as a function of the loss rate and available bandwidth because these two metrics: (1) can be measured segment wise, and (2) are the most influential on the receiving rate, and hence on the quality. A segment with high available bandwidth and low loss is unlikely to introduce high jitter or long queuing delay. PROMISE: PeertoPeer Media Streaming 2. Content delivery path selection Stream Over P2P Network– 2.1

30 Stream Over P2P Network– 2.2 CoolStreaming/DONet: A Data-Driven OverlayNetwork for Efficient Live Media Streaming

31 Stream Over P2P Network– 2.3 Inbound/outboun d Local rarest first (LRF) scheduling Optimal scheduling Optimizing the Throughput of Data-Driven Peer-to-Peer Streaming

32 Stream Over P2P Network– 2.3 Optimizing the Throughput of Data-Driven Peer-to-Peer Streaming

33 Stream Over P2P Network– 2.4 On Peer-to-Peer Media Streaming Out-bound bandwidth Buffer delay Optimal media data assignment algorithm OTS p2p

34 Stream Over P2P Network– 2.4 On Peer-to-Peer Media Streaming Optimal media data assignment algorithm OTS p2p

35 Stream Over P2P Network– 2.4 On Peer-to-Peer Media Streaming Distributed differentiated admission control protocol DAC p2p Average waiting time

36 Stream Over P2P Network– 2.4 On Peer-to-Peer Media Streaming Distributed differentiated admission control protocol DAC p2p Average waiting time

37 Stream Over P2P Network– 2.4 R2: Random Push with Random Network Coding in Live Peer-to-Peer Streaming

38 4. Issues In Multimedia P2P Streaming

39 Appropriate video coding scheme Issues In Multimedia P2P Streaming – 1 Directed acyclic dependency graph representation for a typical MPEG layered-encoded video sequence (one network packet per layer, with IPBPB format). Each packet pn Packet size sn Decoding timestamp t d n Weight w n The successful decoding of one packet is contingent on the successful decoding of some other packets, called ancestors of pn.

40 Appropriate video coding scheme Issues In Multimedia P2P Streaming – 1

41 Appropriate video coding scheme Issues In Multimedia P2P Streaming – 1

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