QoS in P2P Networks

1
QoS in P2P Networks
SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D

• Ouldooz Baghban Karimi
• CMPT 765 Computer Communication Networks

2
Outline

• Introduction
• QoS in Traditional Networks
• Characteristics of P2P Networks
• Multimedia Applications in P2P Networks
• QoS Requirements of P2P Networks
• Providing QoS In P2P Networks

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
3
IntroductionQoS in Traditional IP Networks

• RSVP
• interoperate with routing protocols (Resource
  should exist!)
• Receiver-initiated setup of resource reservations
• Transport Layer
• Integrated Services
• Flow Specification
• Traffic Specification
• Service Specification (Token Bucket)
• Per flow reservations by RSVP
• DiffServ
• PHB Default, AF, EF, CS PHB
• MPLS
• Prefix fixed-size packets with MPLS header
• One or more label for each packet create a label
  stack
• Switching based on label instead of IP

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
4
Characteristics of P2P Networks

• Overlay Structure
• Overlay network made on the underlying network
• Churn
• Behaviors of nodes joining and leaving the P2P
  networks
• Scalability
• P2P Communication
• Autonomy and Privacy for Users
• Sharing Resources

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
5
QoS In P2P Networks

• Multimedia Applications in P2P Networks
• Traditional QoS vs. P2P
• Routing Models in P2P Systems
• QoS Requirements in P2P Networks
• Providing QoS for P2P Networks

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
6
Multimedia Applications in P2P Networks

• Video on Demand
• Can buffer before playback
• Low QoS sensitivity
• Better performance provided with content
  distribution algorithms
• Live Streaming
• IPTV
• QoS Sensitive
• Video Conferencing
• QoS Sensitive

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
7
Traditional QoS Support vs. P2P

• Overlay structure
• Great if underlying structure support QoS but it
  is not the case now
• Different Peer resources
• Unlike client-server that we could ensure about
  our servers
• Sharing resources
• Opens new chances

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
8
Routing Models in P2P Systems

• Centralized Directory Model
• Peers connect to a central server and publish
  information about the content they offer for
  sharing
• Flooded Request Model
• No initial announcement of shared resources
• Request from a peer is flooded (broadcast) to all
  peers in the network
• Document Routing Model
• ID assigned to document
• hash of contents
• name
• A peer requests the document from the P2P system,
  the request will go to the peer with the ID most
  similar to the document ID
• Process repeated until a copy of the document is
  found
• Document is transferred back to the request
  originator
• Each peer participating the routing keep a local
  copy

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
9
QoS Requirements in P2P Networks

• Resource availability
• Unlike to client-server systems, the peer
  providing the resource may get offline during the
  action
• Bandwidth
• Delay
• VoD, Live Steaming and Video Conferencing
• Jitter
• Live Steaming and Video Conferencing

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
10
Providing QoS for P2P Networks

• QoS Enabled Multicast in Structured P2Ps
• QoS Routing
• Improving QoS with adaptation and awareness
• Increase file availability across the network
• Reduce file-acquisition time
• acquiring it from different resources

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
11
QoS Enabled Multicast in P2P

• QoS Enabled Multicast in P2P
• In Structured P2P networks
• Pastry
• Ring structure
• Each peer a unique ID (128 Bit)
• Randomly chosen in join
• Not locality aware
• Not Qos Aware
• Implementation
• Replace Pastry random ID assignment with
  QoS-aware method
• One Pastry P2P network per multicast group
• Root of multicast tree gets greatest Pastry ID
• Try to adopt it in other types of P2P

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
12
QoS Enabled Multicast in P2P Brogle, Marc ,
CCNC 2007

• Root node has highest QoS
• requirements / capabilities
• Child QoS requirement parent QoS requirement
• all paths root ? leafs monotonically decreasing
  QoS requirements / capabilities

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
13
QoS Enabled Multicast in P2PBrogle, Marc , CCNC
2007
SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
14
QoS Enabled Multicast in P2P Brogle, Marc ,
CCNC 2007
SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
15
Probabilistic QoS RoutingS. Rajasekhar et al,
AINA 2006

• Introduce a random variations of links available
  bandwidth
• Overlay!
• Probabilistic Metric Algorithm
• Hop count
• -log Pr( Capacity (link)gtx)
• Try to minimize it
• Probabilistic Path Capacity to Hop Algorithm
• PHAvailable Path Capacity to Hop Count Ratio
• Variations (-log Pr( Capacity (link)gtx))
• Find Widest-Shortest Path

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
16
Probabilistic QoS RoutingS. Rajasekhar et al,
AINA 2006
unsuccessful file requests
Efficiency of file requests
17
QoS Adaptation Awareness

• Document Availability
• Associated Problems
• Churn
• Delay
• Replication
• Replication Algorithm
• Peer Selection for Replication Distribution
• Stability
• Locality
• Content Aware replication

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
18
Locality Management

• Group nodes in P2P network based on their
  location information
• Set a super peer
• Store a list of local peers on it
• On request
• First search local peers
• Not found
• Get from other groups
• Store a copy in super peer of other nodes of the
  group
• Locality Replication
• m/n Erasure coding
• Place on local group peers

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D
19
Greedy Replacement HeuristicMurali Krishna
Ramanathan , IPDPS'04
Results using replacement heuristic
When object is not available in the local overlay
1. Object acquired form the global overlay
2. greedy heuristic for placement is executed at
the representative peer
Random replacement
20
Conclusion

• QoS over P2P discussed
• Overlay Structure
• Churn
• Different Approaches to Support QoS
• QoS Multicast
• QoS Routing
• Availability Increasing Methods

SIMON FRASER UNIVERSITY T H I N K I N G OF T
H E W O R L D