Peer-to-Peer Based Multimedia Distribution Service

Zhe Xiang, Qian Zhang, Wenwu Zhu, Zhensheng Zhang, and Ya-Qin Zhang

IEEE TRANSACTIONS ON MULTIMEDIA, April, 2004

Outline

Introduction P2p based multimedia distribution service

architecture Design of the system

Topology-aware overlay Replication strategies

Simulation results Conclusion

Characteristics of multimedia distribution service in p2p system

A peer shares data with other peers A peer searches data from other peers Dedicated server is not needed Replica is allowed

P2p based multimedia distribution service architecture

How does a new node join

Content Delivery

Node A of group G requests for content C If C is in group G: transfer directly If C is not in group G: transfer C to G first

Replication G may make a replication for delay concern

(inter-group replication strategy) A may make a replication for robust concern

(intra-group replication strategy)

Inter-group replication strategy

Peer pj in group Gr requests content ci

Find nearest group Gp that contains ci

Calculate avg. distance d between neighbors If d(Gp,Gr)<d: end If (free space>size of ci): replicate ci in local stor

age, end Else: remove stored contents according to avail

ability (or maybe LRU, LFU,…etc.) Replicate content ci into local storage

Problem formulation

Seed replication matrix X={xij}: xij=1 if Gj holds seed for content ci

xij=0 otherwise

Access matrix Y={yij} yij=k: k≠j, d(Gj,Gk)=min{d(Gj,Gs), xis=1}

Inter-group replication:

M

i

N

jyji jiGGdr

1 1

)),((,

subject to

M

ijijji NjxSx

1,, .,...,2,1},1,0{,)(

minimize

Theoretical analysis

Only consider total capacity:

M

i

N

jji SS

1 1

Avg. distance between neighbors:

2

12

)(

ii

i LL

cd

2

1

)()(

iii Lcdcd

Popularity factor

Assume popularity follows a Zipf distribution Suppose M contents are ordered in a desce

nding order of popularity ri:

Normally, skew factor(α) is chosen as 0.271 The authors vary skew factor from 0.1 to 0.5

)1(

)1(

i

iri

Intra-group replication strategy

Peer pj requests content cr within its group Calculate A(cr) Calculate A’(ci) for any content ci in pj’s storage Create list {c1,c2…ck} in a descending order of A’(ci) If (FreeStorage+total size of contents in list)<sr: end Find j in list such that

Delete contents c1,…cj

Replicate content cr

Problem formulation

N

jjiji xcA

1, )1(1)(

Replica replication matrix X{xij} xij=1 if per pj holds a replica of content ci

Xij=0 otherwise

Availability A(ci) of content ci:

Simulation methodology

Edge longitude = 300 ms Group number: 200 Latency:

Small if in the same group According to distance if in different group

# of hops increases linearly to distance Bandwidth ranges from 800 kbps to 1.4 Mbps 10000 video chips, each is encoded in 1.28 Mbps

bit rate length of video clips: 3~5 min

Simulation results

Simulation results (cont’)

Simulation results (cont’)

Simulation results (cont’)

Conclusion

Proposed a framework for multimedia distribution based on p2p network Hosts are self-organized into groups Proposed heuristic method to make replica in

the system