PPSP BAR BOF meeting74th IETF – San Francisco, CA, USA

March, 2009 P2P Streaming Protocol (PPSP) Re

quirements

Ning Zong, Huawei Technologies

Yunfei Zhang, China Mobile Communication Corporation

Victor Pascual, Tekelec

Motivation for PPSP

P2P streaming applications have become more and more P2P streaming applications have become more and more popular on Internet due to the advantages of reduced server cost popular on Internet due to the advantages of reduced server cost and better scalability of system dimensionsand better scalability of system dimensions

An open and standardized protocol for P2P streaming would An open and standardized protocol for P2P streaming would greatly benefit many applications (e.g. web services, IPTV, greatly benefit many applications (e.g. web services, IPTV, content distribution network) through re-use of a common P2P content distribution network) through re-use of a common P2P architecture and flows to share capabilities (e.g. storage, architecture and flows to share capabilities (e.g. storage, computation) with each other.computation) with each other.

More detailed motivations are described in Problem Statement of More detailed motivations are described in Problem Statement of P2P Streaming Protocol (PPSP).P2P Streaming Protocol (PPSP).

Scope of PPSP – what PPSP does

Tracker

Request “Star Wars”and return A/B/C

requestor

A

B

C

Register “Star Wars”

Chunk Description, Peer List,Peer Status, etc.

Chunk Data

Content Registration and/or Peer List Request

PPSP Signaling

PPSP Transmission

Legend

• The basic role of PPSP is to define a protocol of locating and transmitting real-time data efficiently from multiple sources with different pieces in P2P environment.

General (Architecture) Requirements PPSP MUST be able to support streaming services when the PPSP MUST be able to support streaming services when the

number of users keeps growing.number of users keeps growing.- Content is shared among peers, thus reducing the burden on - Content is shared among peers, thus reducing the burden on servers.servers.

PPSP MUST be self-adaptive to support a large number of PPSP MUST be self-adaptive to support a large number of dynamically joining and leaving users.dynamically joining and leaving users.- Peers contact more than one peer simultaneously to share - Peers contact more than one peer simultaneously to share content, thus reducing the impact of peer churn.content, thus reducing the impact of peer churn.

Data Sharing

Signaling Requirements PPSP signaling MUST support to carry chunk description of PPSP signaling MUST support to carry chunk description of

peers.peers.- To share content, peers share information on which chunks are - To share content, peers share information on which chunks are on which peers. A common chunk description called Bit Map is on which peers. A common chunk description called Bit Map is described in draft-zong-ppsp-req-00.txt.described in draft-zong-ppsp-req-00.txt.

PPSP signaling MUST support to negotiate the meaning of PPSP signaling MUST support to negotiate the meaning of chunk description, e.g. chunk is segmented based on content chunk description, e.g. chunk is segmented based on content size or length, if based on size, then the unit is KB or Byte.size or length, if based on size, then the unit is KB or Byte.- It is useful to apply such negotiation to allow for more flexible - It is useful to apply such negotiation to allow for more flexible interaction between different applications. E.g. some P2P interaction between different applications. E.g. some P2P streaming applications are based on chunks with size of KB streaming applications are based on chunks with size of KB while others are based on size of Byte.while others are based on size of Byte.

Chunk Description

Negotiate Chunk Description

Signaling Requirements (Cont.) PPSP signaling MUST support to carry additional peer list.PPSP signaling MUST support to carry additional peer list.

- Peers need to learn about other peers by sharing and - Peers need to learn about other peers by sharing and aggregating their peer lists with information from other peers.aggregating their peer lists with information from other peers.

PPSP signaling MUST support to carry peer status for content PPSP signaling MUST support to carry peer status for content sharing (e.g. peer bandwidth, workload).sharing (e.g. peer bandwidth, workload).- With this peer status information, a peer can select more - With this peer status information, a peer can select more appropriate peers for content sharing based on some content appropriate peers for content sharing based on some content sharing strategies and/or application requirements.sharing strategies and/or application requirements.

Peer Status

Additional Peer List

Transmission Requirements PPSP transmission MUST be able to support limited start-up PPSP transmission MUST be able to support limited start-up

delay and limited latency between the broadcasting time and the delay and limited latency between the broadcasting time and the audience view time.audience view time.

PPSP transmission MAY support efficient one-to-many data PPSP transmission MAY support efficient one-to-many data transport with some attempt at fairness assurance and balance transport with some attempt at fairness assurance and balance between self-constraint and aggression for network bandwidth.between self-constraint and aggression for network bandwidth.

More transmission requirements are to be studied …More transmission requirements are to be studied …

Error Handling and Security A peer MUST be able to respond with error information to peers A peer MUST be able to respond with error information to peers

sending chunk description messages when some information sending chunk description messages when some information (e.g. chunk ID) cannot be understood in the message.(e.g. chunk ID) cannot be understood in the message.

PPSP MUST be able to provide mechanisms to prevent peers PPSP MUST be able to provide mechanisms to prevent peers from distributing wrong information, such as claiming they have from distributing wrong information, such as claiming they have the chunks that they don't, or sending out false peer status the chunks that they don't, or sending out false peer status information.information.

More error handling and security requirements are to be studied More error handling and security requirements are to be studied ……

Q&A

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