Vicente Gonzlez Ruiz
November 24, 2013
Contents
1 What is the P2PSP?
- The P2PSP is an application-layer protocol for the real-time streaming of
media content between (usually networked) processes (peers).
2 Basic operation
- When a peer wants to receive streaming of a selected content:
- Peer connects to the source and joins a cluster.
- Peer acquires a list of other peers in the cluster from the source.
- The source sends a different block to each peer of the cluster, using
a Round-Robing scheme.
- Each exclusive block received from the source must be transmitted
to the rest of the peers of the cluster.
3 Transport protocols
- The P2PSP must use the UDP (at least, for big clusters).
4 Architecture
- The content is provided by the source. Usually, there is only one source in
each cluster..
- The peers meet each other asking the source or other (connected) peers.
- Peers are “connected”
to rest of peers of the cluster.
5 Chunk delivery
- Peers always push all the blocks received from the source to the rest of
peers of the cluster (peers never request the blocks).
6 Freeriding prevention
- Freeriding (how to deal with peers that only download content byt never
upload) is very agressive in the P2PSP.
- If a peer is unsupportive, the rest of peers complain to the source and it
stops sending blocks to it.
7 Content integrity
- Some special peers (trusted-peers, which are controlled by the cluster
administrator) receive from the source a cryptographic hash for earch
chunk of data which can be used to check if the content has been modified
in transit.
- When a spoiling peer send a poisoned block to a trusted-peer, it will notify
the source, which will eject the poisonous peer from the cluster.
8 Clusters (channels)
- Peers can listen to multiple clusters when they desire to receive several
channels.