Study of the Relationship between Peer to Peer Systems and IP Multicasting

From IEEE Communication Magazine January 2003

學號 :M9129017

姓名 : 邱 秀 純

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Outline

IntroductionFeature of P2P system

Problem of P2P system

Requirements for IP Multicast over P2P systems

Evaluation of applying IP Multicasting to P2P system

Conclusion

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IntroductionPeer to Peer (P2P)System?Involve a number of directly connected “ peers” exchanging various types of information among themselves The Problem?

Applications based on P2P systems generate a lot of traffic and Require not only the resources of every peer

IP Multicasting

The Style of IP Multicasting is that the multicast routers make copies of incoming data and distribute them to a multicast tree

IP Multicasting will help to reduce the load on streaming servers and network traffic because streaming servers only have to send data once

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Feature of P2P system

P2P system have two phase: Discovery phase : A peer tries to find another peer that

has what it wants Delivery phase : direct communication is performed with

the discovered peer

Two type of P2P SystemsHybrid P2P system: has a central sever with a set of indexes , and each peer asks it during the discovery phase

Pure P2P system : lack a central server

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Problem of P2P system

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Problem of P2P system

P2P systems essentially require a broadcast mechanism, and we should usually used a series of unicast or broadcast packets

Problem:Continuous unicast packets may need the CPU powe

r and bandwidth of peers and all of the network resource

Using Broadcast packers raises concerns about wasting various resources and security because all peers receive them whether or not they want to

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Solve by using IP MulticastTo reduce the number of irrelevant packets

Decrease the need to use peers’ resources

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Requirements for IP Multicast over P2P systems

Live stream service and P2P Contents sender

Opportunities to update member list

Types of traffic flow

Range of propagation

The main differences

Contents sender can join or leave dynamically

The number of contents senders is the same as the number of contents receivers

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Routing protocol(1)PIM is IP routing protocol-independent and can leverage whichever unicast routing protocols are used to populate the unicast routing tablePIM uses this unicast routing information to perform the multicast forwarding function PIM uses the unicast routing table to perform the RPF check function instead of building up a completely independent multicast routing table PIM does not send and receive routing updates between routers.

參考網頁 http://www.cisco.com/univercd/cc/td/doc/cisintwk/

intsolns/mcst_sol/mcst_ovr.htm#xtocid25

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Routing protocol(2)PIM:compose multicast trees using routing tables made by an arbitrary unicast routing

PIM-SM : the only terminals that receive multicast messages are ones that obviously belong to the multicast group because the sent “IGMP” join messages

PIM-SSM is source-specific protocol , and the contents receiver can specify the addresses of desired sources in the IGMP join message

PIM-SSM is considered a suitable protocol for one to many live streaming services

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Routing protocol(3)

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Routing protocol(4)

PIM-SM :Send IGMP message to join/leave group

PIM-SSM:There is a multicast tree originating form each content server, there are N multicast trees if the number of peers in NA peer that wants to join this group must

1) send an IGMP join message to all multicast trees with the sender’s address

2) get all other peers to send it an IGMP join message with its own address so that it can create a new multicast treeLeave group , a peer sends an announces it departure

Sequence for joining groups

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Routing protocol(5)

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Routing protocol(6)

Achieve network load balancing:

PIM-SM: distributing RPs

PIM-SSM: unicast routing protocol

The most significant difference is PIM-SSM’s complex group-joining procedure

The PIM-SM is better than PIM-SSM for P2P system

Comparison of PIM-SM and PIM-SSM

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Evaluation of applying IP Multicasting to P2P system

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ConclusionProblem: A much faster backbone network will be required

Solution: We showed that almost every application can be improved by our proposal

We discussed which routing protocol is suitable for P2P system

Other issuesTechniques : clarify the sequences for joining/leaving groups and the effect of the RP’s location on traffic characteristics

Network management : the multicast address allocation and traffic control method for the entire network