1 / 28

Towards Efficient Simulation of Large Scale P2P Networks

Towards Efficient Simulation of Large Scale P2P Networks. Tobias Hoßfeld. ITG-Fachgruppe 5.2.1 “Cooperating and Scalable Networks” Aachen, Ericsson, J. Sachs, 04.05.2006. Cartography of P2P Architectures. user-oriented domain. decentralized. X. Gnutella. operator-centric domain. X.

miller
Download Presentation

Towards Efficient Simulation of Large Scale P2P Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Towards Efficient Simulation of Large Scale P2P Networks Tobias Hoßfeld ITG-Fachgruppe 5.2.1“Cooperating and Scalable Networks” Aachen, Ericsson, J. Sachs, 04.05.2006

  2. Cartography of P2P Architectures user-oriented domain decentralized X Gnutella operator-centricdomain X eDonkey resource mediation Client/ centralized Server X BitTorrent centralized decentralized resource access control X Chord • Two control functions in P2P systems • Resource mediationwhere are files located • Resource access controlwho may download a file and when • Mapping of P2P architectures into architectural space • pure P2P • hybrid P2P • classic client/server • Identification of control objectives PureP2P P2P Cartography hybrid P2P

  3. Peer-to-Peer Architectures Information Provider Information Seeker Index Index Unstructured P2P-Network (Gnutella) Web-Server Tracker Information Mediator Information Mediator BitTorrent Hybrid P2P-Network (eDonkey) Information Seeker Information Provider Information Mediator Structured P2P-Network (Chord)

  4. join() leave() Basic Functions of P2P Networks knowsone peer contacts bootstrapserver bootstrapserver position in the P2P network according to the structure: self-organization new node peer informs its “neighbors” and bootstrap server node failures detected by periodical updates or not answered requests: resilience

  5. insert(key,data) retrieve(key) Basic Functions of P2P Networks (contd.) x key routes to peer y which stores data y y has (key,data) structure assigns responsibility for data based on hash function: load balancing performance improved by using shortcuts according to the known structure for a given key:scalability y responsible for (key,data) peer x wants to insert (key,data); using DHTs: key = hash(data) peer x searches for key x and asks its neighbors which redirect requests y sends data to x

  6. Basic Function of P2P Content Distribution downloading peer 2 downloadingand providingpeer 1 • Main feature is multiple source download. • Peers issue several download requests for the same file to multiple providing peers in parallel. • Providing peers serve the requesting peers simultaneously. providingpeer After successfully downloading a whole chunk, it is provided to other peers. downloading peer 1 index server #2 index server #1 providingpeer providingpeer

  7. Features of P2P Systems and Their Implications • Usually a large number of participating peers • Large-scale: a lot of nodes and even higher number of resources need to be simulated • Peers may arbitrary join or leave • Highly dynamic: a lot of user created event (due to churn, i.e. peers joining and leaving arbitrarily, as key feature of P2P systems) • Cooperative working of peers and robust systems • Complexity: • one event can cause a large number of events at other peers, i.e. system events, due to cooperation among peers • additionally periodic or provisional systems event to cope with the self-organization of p2p systems Target of Workshop: Focus on large-scale P2Pnetworks in order to consider key characteristics (e.g. regarding churn for 100 peers reasonable?)

  8. Approach For Simulating Large-Scale P2P Systems • System state has to be stored at simulation machine • requires efficient data structures (e.g. calendar queue) • How to model in order to reduce the number of events? • Resource mediation might not require to model bandwidth, only signalling delay • Resource exchange might not require to model delay if large contents are exchanged; requires modelling of bandwidth • other performance influence factors: packet loss, moving users, … • appropriate abstractions & models for investigated application • Clustering of peers to user groups... • might allow parallel simulation of clusters

  9. Workshop in Würzburg • Efficient Data Structures • Andreas Binzenhöfer, Calendar Queue and Event Design Algorithms • Jens Oberender, Modelling Resource Fragmentation • Abstractions and Models • Kolja Eger, Packet-based Simulation • Gerald Kunzmann, Signaling in Voice/Video over IP Systems • Daniel Schlosser, Tobias Hoßfeld, Periodic and Market-Based Bandwidth Allocation • Parallel Simulation • Ivan Dedinski, Parallel Discrete Event Simulation

  10. Talks Today Hier könnte Ihr Name stehen !

  11. Periodic and Market-Based Bandwidth Allocation ineDonkey Networks Tobias Hoßfeld, Daniel Schlosser

  12. Measurements of eDonkey Traffic • Case-by-case measurements of eDonkey file-sharing application in public GPRS/UMTS network • Multiple source download via GPRS

  13. UMTS upload restricts throughput UMTS download restricts throughput eDonkey Data Exchange via UMTS • Max-min-fair share of available bandwidth is observed • How to model the bandwidth allocation of fair-share P2P file-sharing applications?

  14. Simulation of Fair-Share Bandwidth Allocation • Events which influence the bandwidth allocation are that a peer… • starts the download of a file • finishs a download • goes offline while downloading • continues downloading a file after joining the network again • We consider eDonkey-like file-sharing networks • Aim: Modeling of bandwidth allocation in fair-share networks Events t Dt Dt Dt Dt Dt Dt Dt Dt Dt Dt Dt Computation of allocated bandwidth t

  15. Stream-based or packet-based approach? • TCP can be neglected if conditions are fulfilled (540 kB blocks) • Signaling vs. data exchange: RTT vs. bandwidth

  16. What means fair-share? Peer 2 3 kbps Peer 3 11 kbps uploading Peer 1 40 kbps Peer 4 20 kbps Peer 5 40 kbps • All peers get the same bandwidth • If a peer cannot consume completely the allocated bandwidth, the surplus is distributed among the remaining peers 11 kbps 3 kbps 13 kbps 13 kbps

  17. Periodic Bandwidth Allocation Peer 3 Peer 2 Peer 4 Peer 5 • For each Dt, for each peer: compute bandwidth allocation Allocated bandwidth can be overbooked or underbooked Peer 1

  18. Market-Based Bandwidth Allocation • For each event, consider affected, i.e. connected, peers • All affected peers make a bid • Strategy • If there are no other bids, propose x = not allocated bandwidth / #peers • If minimal bid y of all affected peers is smaller than x, then keep bid y and compute x‘ • If all bids are larger than x, then bid x on these connections • Finish: If lower bid of a connection is the minimal bid of a peer and is repeated

  19. Market-Based Bandwidth Allocation Downloading network links Uploading network links 20 NL3: 40kbps 15 3.333 NL4: 30kbps NL0: 10kbps 10 NL1: 10kbps 5 NL5: 10kbps 5 NL2: 80kbps NL6: 10kbps 20 10 NL7: 10kbps Initial bid: x = BW / #peers 40 NL8: 40kbps

  20. MBBA Example Downloading network links Uploading network links 20 NL3: 40kbps 3.333 15 NL4: 30kbps 3.333 NL0: 10kbps 26.667 10 NL1: 10kbps 5 NL5: 10kbps 5 25 3.333 NL2: 80kbps 5 NL6: 10kbps 25 6.667 25 20 10 NL7: 10kbps If minimal bid y of all connected peers holds y<x, then set bid y and compute x‘ x = BW / #peers. If all y<x, keep x. 40 NL8: 40kbps

  21. MBBA Example Downloading network links Uploading network links 20 NL3: 40kbps 3.333 NL4: 30kbps 3.333 NL0: 10kbps 26.667 10 NL1: 10kbps 5 NL5: 10kbps 25 3.333 NL2: 80kbps 5 NL6: 10kbps 25 6.667 25 10 NL7: 10kbps Finish: If lower bid of a connection is the minimal of a peer and is repeated 40 NL8: 40kbps

  22. MBBA Example 25 5 25 25 Downloading network links Uploading network links NL3: 40kbps 3.333 NL4: 30kbps NL0: 10kbps 5 26.667 NL1: 10kbps NL5: 10kbps 24.444 NL2: 80kbps NL6: 10kbps 6.667 6.667 24.444 24.444 10 NL7: 10kbps Finish: If lower bid of a connection is the minimal of a peer and is repeated Minimal bid y<x, set y and compute x‘ 40 NL8: 40kbps

  23. MBBA Example Downloading network links Uploading network links NL3: 40kbps 3.333 NL4: 30kbps NL0: 10kbps 5 26.667 NL1: 10kbps NL5: 10kbps 24.444 31.667 6.667 NL2: 80kbps NL6: 10kbps 10 24.444 31.667 24.444 10 NL7: 10kbps Finish: If lower bid of a connection is the minimal of a peer and is repeated If all y<x, keep x. 40 NL8: 40kbps

  24. MBBA Example Downloading network links Uploading network links NL3: 40kbps 3.333 NL4: 30kbps NL0: 10kbps 5 26.667 NL1: 10kbps NL5: 10kbps 6.667 NL2: 80kbps NL6: 10kbps 31.667 36.666 10 NL7: 10kbps Finish: If lower bid of a connection is the minimal of a peer and is repeated 40 NL8: 40kbps

  25. MBBA Example Downloading network links Uploading network links NL3: 40kbps 3.333 NL4: 30kbps NL0: 10kbps 5 26.667 NL1: 10kbps NL5: 10kbps 6.667 NL2: 80kbps NL6: 10kbps 10 NL7: 10kbps 36.666 NL8: 40kbps

  26. Comparison PBA vs. MBBA • Exchange of small files

  27. Comparison PBA vs. MBBA • Exchange of large files MBBA: computes and allocates immediately fair-share bandwidth -> in real systems this requires some time PBA: bandwidth overbooked or underbooked for Δt -> in next step bandwidth is adapted

  28. Conclusion • For P2P content distribution networks, like eDonkey, resource access control is crucial point • Fair-share bandwidth allocation has to be modeled • We have proposed two stream-based approaches which are valid in the considered scenarios • Periodic bandwidth allocation PBA • Market-based bandwidth allocation MBBA • Depending on the number of events influencing the resource access control PBA or MBBA has to be preferred

More Related