Notes - MIECT
Redes E Sistemas Autónomos
Notes - MIECT
Redes E Sistemas Autónomos
  • Redes e Sistemas Autónomos
  • Peer-to-Peer Systems and Networks
    • Content Distribution Networks
    • Peer-to-peer networks
      • Types
    • Structured vs Unstructured
    • Fully Decentralized Information System
    • FastTrack/KaZaA
    • OpenNAP/Napster
    • BitTorrent
  • InterPlanetary File System (IPFS)
    • IPFS
      • Bitswap
    • Connecting an IPFS node to the P2P network
    • Searching in DHTs (Structured)
    • File Search
    • Security
  • Ad-Hoc Networks
    • Mobile Ad-hoc networks
    • Application Scenarios
    • Routing
      • AODV - Ad Hoc On-Demand Distance Vector Routing
      • OLSR - Optimized Link State Routing Protocol
      • LAR – Location Aided Routing
      • Batman
    • IP Address Assignment
  • Self-organized systems: Data, learning and decisions
    • Use Cases and Data
    • Machine Learning
      • Supervised Learning
      • Neural Networks
      • Reinforcement Learning
      • Unsupervised Learning: K-means
    • Learning
  • Vehicular Networks
    • Vehicular Ad Hoc Networks
    • How do they work?
    • SPAT: Signal Phase And Timing
    • MAP: MAP
    • Manoeuvre Coordination Message (MCM)
    • Communication Technologies
  • QoS and Security
    • TCP- and UDP-based applications
      • TCP-Cubic
    • QUIC
    • TCP-Vegas
    • Classification of Transport protocols
    • Exploiting Buffering Capabilities
    • QoS in UDP: trade-offs
    • Transmission Quality (Batman v.3)
    • QoS-OLSR
    • Security
      • Key Management
      • RSA (Rivest-Shamir-Adleman) Key
      • Key Management in ad-hoc networks
      • Self-organized public key management (SOPKM)
      • Self-securing ad-hoc wireless networks (SSAWN)
Powered by GitBook
On this page
  • P2P file sharing
  • Strengths
  • Weaknesses
  • Gnutella
  • Hybrid Gnutella: “Ultrapeers”
  • Real Gnutella Network
  1. Peer-to-Peer Systems and Networks

Fully Decentralized Information System

PreviousStructured vs UnstructuredNextFastTrack/KaZaA

Last updated 3 months ago

P2P file sharing

  • Global scale application.

Example: Gnutella.

  • 40.000 nodes, 3 Mio files.

  • 3M nodes (Jan 2006).

Strengths

  • Good response time, scalable.

  • No infrastructure, no administration.

  • No single point of failure.

Weaknesses

  • High network traffic.

  • No structured search.

  • Free-riding.

Gnutella

Meeting Peers (Ping/Pong)

Protocol Message Types

Type
Description
Contained Information

Ping

Announce availability and probe for other servents.

None.

Pong

Response to a ping.

IP address and port# of responding servent; number and total kb of files shared.

Query

Search request

Minimum network bandwidth of responding servent; search criteria.

QueryHit

Returned by servents that have the requested file

IP address, port# and network bandwidth of responding servent; number of results and result set.

Push

File download requests for servents behind a firewall

Servent identifier; index of requested file; IP address and port to send file to.

Searching

(Query/QueryHit/GET)

Structureless

Queries are flooded to neighbors, have a TTL, and are forwarded only once.

A query may obtain several responses indicating which peers provide the requested file. Among those, it selects one and is directly contacted in order to download the file.

  • Can we search using fewer packets?

Improvements in Message Flooding

Expanding Ring.

  • Start the search with small TTL (e.g. TTL = 1).

  • If no success iteratively increases TTL (e.g. TTL = TTL +2).

k-Random Walkers.

  • Forward the query to one randomly chosen neighbor only, with large TTL.

  • Start k random walkers.

  • Random walker periodically checks with the requester whether to continue.

Hybrid Gnutella: “Ultrapeers”

Ultrapeers can be installed (KaZaA) or self-promoted (Gnutella v.2).

Real Gnutella Network

Popular open-source file-sharing network.

  • ~450,000 users as of 2003.

  • ~2,000,000 today.

Ultrapeer-based Topology.

  • Queries flooded among ultrapeers.

  • Leaf nodes are shielded from query traffic.

  • Based on multiple crawlers.