Download Peer-to-Peer Streaming

Resilient Peer-to-Peer
Streaming
Presented by: Yun Teng
Resilient Peer-to-Peer Streaming
Authors



Venkata N. Padmanabhan
Helen J. Wang
Philip A. Chou
From

Microsoft
Motivation
 Distributing
“live” streaming media content
to a potentially large and highly dynamic
population of hosts.

“Live” streaming refer to the simultaneous
distribution of the same content to all clients
Challenge
 Peer-to-peer
content distribution is
attractive because the bandwidth available
to serve content scales with demand.
 A key challenge: making content
distribution robust to peer transience.
Approach
 Introduce
redundancy, both in network
paths and in data
 Multiple diverse distribution tree: provide
redundancy in network paths
 Multiple description coding (MDC): provide
redundancy in data
CoopNet
 Makes
selective use of P2P networking,
placing minimal demands on the peers
 Goal: help a server tide over crises such
as flash crowds rather than replace the
server with a pure P2P system
Assumption

A node participates in and contributes bandwidth
for content distribution only so long as the user
is interested in the content. It stops forwarding
traffic when the user tunes out
 A node only contribute as much upstream
bandwidth as it consumes in the downstream
direction (applies to the total bandwidth in and
out of a node aggregated over all trees
 Nodes in CoopNet are inherently unreliable
Tree management
Goals
 Short
trees
 Tree diversity
 Efficiency
 Quick join and leave
 Scalability
Conflicts
 Tree
diversity versus efficiency
 Quick join and leave versus scalability
Feasibility of the Centralized
Protocol

September 11 flash crowd at MSNBC



At peak, 18,000 nodes, 1,000 arrivals and
departures per second
On average, 10,000 nodes, 180 arrivals and
departures per second
Resource requirement



Memory: 10 MB
Network bandwidth: 8 Mbps
CPU: 40 ns memory cycle, allow 390 memory
accesses per insertion
Centralized Tree Management
 Randomized
Tree Construction
 Deterministic Tree Construction
Tree Efficiency / Topology
Awareness
 Need
an efficient way to pick a proximate
parent for a node without requiring
extensive P2P network measurements
 Each node maintains its “delay
coordinates” of ping times to a small set of
landmark hosts
 Root pick the closest node for incoming
node from a set of candidate parents
Tree Repair
 Due
to node leave
 Two types


Voluntary – Notify the root
Failure – Detect failure
Multiple Description
Coding (MDC)
Overview
 Encoding
an audio and/or video signal into
M>1 separate streams, or descriptions,
such that any subset of these descriptions
can be received and decoded.
 The distortion with respect to the original
signal is commensurate with the number
of descriptions received.
Overview (cont.)

MDC incurs a modest performance penalty
relative to layered coding, which in turn incurs a
slight performance penalty relative to single
description coding.
 The audio and/or video signal is partitioned into
groups of frames (GOF), each group having
duration of T (such as 1 second). Each GOF is
independently encoded, error protected, and
packetized into M packets.
CoopNet MDC System Architecture
Configuring MDC
 GOF
duration G = 1 second
 M = 16 descriptions
 Packet size P = 1250 bytes
 T = 8 trees
Performance evaluation
Impact of Number of Distribution
Trees
Effectiveness of MDC
 Probability
distribution of descriptions
received vs. number of distribution trees
 Root out-degree = 100
 Maximum client out-degree = 4
Impact of Repair Time
Related work
Related Work
 Application-level
Multicast
 Source Coding and Path Diversity
References

V. N. Padmanabhan, H. J. Wang, and P. A. Chou.
Resilient Peer-to-Peer Streaming. Technical Report
MSR-TR-2003-11, Microsoft Research, Redmond, WA,
March 2003.

V. N. Padmanabhan, H. J. Wang, P. A. Chou, and K.
Sripanidkulchai. Distributing Streaming Media Content
Using Cooperative Networking. In Proc. NOSSDAV, May
2002.
Q&A
Thank you!