Scalable Overlay Network for Peer-to-Peer File Sharing

NETWORKed MEDIA LAB.

DEPT. OF INFO. & COMM., K-JIST

Scalable Overlay Network for Scalable Overlay Network for Peer-to-Peer File SharingPeer-to-Peer File Sharing

Park, Chanmo

Networked Media Lab.Kwang-Ju Institute of Science and Technology (KJIST)

KOREA

[email protected]



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ContentsContents

Overview o Peer-to-Peer Computing and Core Operations

Challenges in P2P File Sharing Structured Overlay Network Support for P2P

o Good and Bad

Existing Overlay Network Approaches Initial Thoughts on Scalable Overlay Network Conclusions



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Peer-to-Peer Computing of the Internet2Peer-to-Peer Computing of the Internet2

Collaboration

Distributed computing and

resources

Intelligent agents

Edge Services

• create and administer collaboration areas• access to the freshest data

• move data closer to the point at which it is actually consumed• act as a network caching mechanism

• help businesses with large-scale computer processing needs using idle CPU cycle and disk space

• allow computing networks to dynamically work togetherusing intelligent agents.



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Core Operations of P2PCore Operations of P2P

Identity Operationo Refers to the name and credentials that identify an entity

Discovery Operationo Find out peers, services, or resources

Authentication Operationo Verify identity (person or machine)

Authorization Operationo Allow the verified entity permission for specific actions

and/or access

Function Operationo Application specific actions



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Challenges in Scalable P2P File SharingChallenges in Scalable P2P File Sharing

Flooding & Loop Path In Discovery Operationo results in many duplicated packet.

o Increase the network traffics

Reducing large number of Discovery operations A new topology such as structured overlay network should be

considered

1

2

2

2

33

3

3

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Loop

Loop

LoopLoop

LoopLoopLoop

4Flooding



6/18Structured Overlay Network Support for P2PStructured Overlay Network Support for P2P

Good and BadGood and Bad

Goodo may reduce duplicated packetso may remove loop in message forwarding

Bado should maintain redundant link in overlay networko Network partitioning



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Existing Overlay Network ApproachesExisting Overlay Network Approaches

AMRoute. ScatterCast End System Multicast ALMI 1998 2002200120001999

2001.3ALMI

1998.8AMRoute 1999.7

Scattercast

2001.7End System Multicast

1989IP Multicast



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AMRouteAMRoute Goal : Robust IP Multicast in

mobile ad hoc network Concept

o Dynamic logical cores Selected by core resolution

algorithm creates the mesh of a

group creates the user-multicast

treeo User-multicast trees

create a bi-directional, share tree for data distribution with group members

Low scalabilityo Electing a Logical core



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ScatterCastScatterCast Goal: partitioning a heterogeneous set of session

participants into disjoint data groups Concept

o SCX(ScatterCast proXy)s organize themselves into an overlay network of

unicast connections (mesh) build data distribution tree on the top of this

overlay structure (tree)o using native IP Multicast

Client

Client

SCX

SCX

ClientClient

Client

MulticastGroup

UnicastConnection

The Internet



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End System MulticastEnd System Multicast

Goal : overlay network efficiency Concept

o construct and maintain the mesh using distributed algorithmo Improving mesh quality by probing each otherso construct tree based on distance vector, latency

Not scalable due to probing each nodes

R1 R2

A

B

C

D

1

2

251

1

R1 R2

A

B

C

D

1

2

251

1



11/18ALMI ALMI

(An Application Level Multicast Infrastructure)(An Application Level Multicast Infrastructure)

Goal: support of multicast groups of small size Concept

o Node of a session are connected via a virtual multicast treeo Tree is formed as a minimum spanning tree by session

controller

Session Controller• handle member registration• maintain multicast tree

Virtual Multicast Tree

RRT monitoring

Parent

Child



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From Existing ApproachesFrom Existing Approaches

Mesh-first Topology o AMRoute, ScatterCast, End System Multicast

o is suitable for multimedia multicast Data delivery path is constructed over mesh

o If no RPs Not scalable Not suitable for P2P File Sharing

Existing Approaches finally construct only one data delivery patho Mesh topology is proper for failure recovery

o In the case of P2P File Sharing, Network efficiency is not issue

o For Scalability, Tree-first can be considered as possible as can



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Initial Thoughts on Scalable Overlay Network for Initial Thoughts on Scalable Overlay Network for Peer-to-Peer File SharingPeer-to-Peer File Sharing

Challenges are reducing duplications and preventing loop

Node Grouping (Tree)o For reducing duplicationso Flooding Messages are forced to sent to limited scoped

nodes by grouping

Shift from Undetermined path to Determined path o For Loop Avoidanceo Tree is constructed at first and maintained



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Initial Thoughts on Scalable Overlay Network for Initial Thoughts on Scalable Overlay Network for Peer-to-Peer File Sharing(2)Peer-to-Peer File Sharing(2)

we construct tree for grouping nodes tree

o Is a scope of message floodingo Is a shared treeo Is a data path along which all message are sent

Single Data Path within a treeo Loop avoidanceo Messages are sent to parent and child nodes except of

received node.



15/18Initial Thoughts on Scalable Overlay Network for Initial Thoughts on Scalable Overlay Network for

Peer-to-Peer File Sharing(3)Peer-to-Peer File Sharing(3)

In case of Exchanging messages between treeso New connection type (such as a InterTreeConnection) is

introduced to distinguish link within a tree from link between trees

o These types of connections are determined when a new tree is created

o New tree is created when limited number of nodes is reached

o These type messages are used when a node connected to other tree sends messages.



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ConclusionConclusion

We show Problems of Unstructured P2Po Floodingo Looping

Overview the existing Overlay Network Our Initial Thoughts on Scalable Structured Overlay

Networko Grouping into a tree for reducing duplicated messageso a shared data path for loop avoidance

Future Workso Consider proper group size and Recovery mechanism from

failureo Implement our thoughts



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Thanks!

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Scalable Overlay Network for Peer-to-Peer File Sharing