Download Stream Over P2P Network

LOGO
P2P & Multimedia Streaming
NPUST-MINAR
Professor : Sheau-Ru Tong
Student : Yi-Chen Hsu
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Contents
1
Introduction
2
P2P Network Streaming Architecture
3
Stream Over P2P Neteork
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Issues In Multimedia P2P Streaming
1. Introduction
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Introduction – 1.1
1. Content Delivery Net Work(CDN)
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.
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
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Introduction – 1.2
IP-multicast-based techniques can efficiently share a single
channel, but the server is only scoped at local networks.
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Introduction – 2.1
2. 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]
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Introduction – 2.2
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]
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Introduction – 2.3
Streaming Proxy Server Suffix-Window Caching
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Introduction – 3.1
3. What is P2P?
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]
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Introduction – 3.2
The Popular P2P Applications
P2P File System: open-after-downloading
• FOXY
• BitTorrent
• Winny
• Freenet
• BitComet
• KazaA
• eDonkey
• WinMX
• eMule
P2P Media Streaming System: play-while-downloading
• KKBOX
• ezPeer
• Skype
• PPStream
• PPLive
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Introduction – 3.3
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]
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Introduction – 3.3
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.
FROM: Measurements, Analysis, and Modeling of BitTorrent-like Systems
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Introduction – 3.4
P2P IPTV (PPStream)
FROM: A Measurement Study of PPStream
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Introduction – 3.4
P2P IPTV (PPStream)
FROM: Study of PPStream Based on Measurement
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Introduction – 3.4
P2P IPTV Measurement
2006 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
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2. P2P Network
Streaming Architecture
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P2P Network Streaming Architecture – 1
Overlay Network
 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 clientserver applications are overlay networks because
their nodes run on top of the Internet. [Wikipedia]
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P2P Network Streaming Architecture – 2
Challenges
 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
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P2P Network Streaming Architecture – 3.1
Locating supplying peers
 Centralized directory
• EX: PPStream, PPLive
• The simplest and most commonly used method
FROM: Challenges and Approaches in Large-Scale P2P Media Streaming
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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 Px .
FROM: Challenges and Approaches in Large-Scale P2P Media Streaming
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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
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P2P Network Streaming Architecture – 3.3
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.
 A basic Kademlia network with
2n nodes will only take n steps (in the
worst case) to find that node.
[Wikipedia]
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P2P Network Streaming Architecture – 3.3
EX：P2P-over-SIP
Additionally, implement P2P using
SIP messaging
INVITE alice
P2P-SIP
overlay
1
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14 10
servers
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38
d467c4
d462ba
d4213f
21
42
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Alice
128.59.19.194
d471f1
8
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REGISTER
1
54
10
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24 30
Route(d46a1c)
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clients
Use DHT in server farm
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Use DHT for all clients - but
some are resource limited
Use DHT among super-nodes
Hierarchy Dynamically adapt
http://www.cs.columbia.edu/IRT/p2p-sip
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
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3. Stream Over P2P Network
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Stream Over P2P Network– 1.1
1. Content delivery path maintenance
 Tree-based multicast
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Stream Over P2P Network– 1.2
 Tree-based multicast
SplitStream: High-Bandwidth Multicast in CooperativeEnvironments
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Stream Over P2P Network– 1.3
 Tree-based multicast
Topology Optimization in Multi-Tree Based P2P Streaming System
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Stream Over P2P Network– 2.1
2. Content delivery path selection
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.
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PROMISE: PeertoPeer Media Streaming
Stream Over P2P Network– 2.2
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CoolStreaming/DONet: A Data-Driven OverlayNetwork for Efficient Live Media Streaming
Stream Over P2P Network– 2.3
Inbound/outboun
d
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2
4
1
Local rarest first (LRF) scheduling
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Optimal scheduling
Optimizing the Throughput of Data-Driven Peer-to-Peer Streaming
Stream Over P2P Network– 2.3
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Optimizing the Throughput of Data-Driven Peer-to-Peer Streaming
Stream Over P2P Network– 2.4
Optimal media data assignment algorithm OTSp2p
0.5
Out-bound bandwidth
0.25
0.125
0.125
Buffer delay
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On Peer-to-Peer Media Streaming
Stream Over P2P Network– 2.4
Optimal media data assignment algorithm OTSp2p
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On Peer-to-Peer Media Streaming
Stream Over P2P Network– 2.4
Distributed differentiated admission control protocol DACp2p
Average waiting time
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On Peer-to-Peer Media Streaming
Stream Over P2P Network– 2.4
Distributed differentiated admission control protocol DACp2p
Average waiting time
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On Peer-to-Peer Media Streaming
Stream Over P2P Network– 2.4
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R2: Random Push with Random Network Coding in Live Peer-to-Peer Streaming
4. Issues In Multimedia P2P Streaming
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Issues In Multimedia P2P Streaming – 1
Appropriate video coding scheme
Each packet pn
Packet size sn
Decoding timestamp tdn
Weight
wn
Directed acyclic dependency graph representation for a typical MPEG
layered-encoded video sequence (one network packet per layer, with IPBPB
format).
The successful decoding of one packet is contingent on the successful
decoding of some other packets, called ancestors of pn.
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Issues In Multimedia P2P Streaming – 1
Appropriate video coding scheme
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Issues In Multimedia P2P Streaming – 1
Appropriate video coding scheme
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LOGO
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