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

Study of the Relationship
between Peer to Peer
Systems and IP Multicasting
學號:M9129017
姓名: 邱 秀 純
From IEEE Communication Magazine January 2003
Outline
Introduction
Feature 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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Introduction
Peer 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 Systems
Hybrid 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
power 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 Multicast
To 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 table
PIM 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)
Sequence for joining groups
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 N
A 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
tree
Leave group , a peer sends an announces it departure
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Routing protocol(5)
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Routing protocol(6)
Comparison of PIM-SM and PIM-SSM
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
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Evaluation of applying IP Multicasting to
P2P system
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Conclusion
Problem: 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 issues
Techniques : 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
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