• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Peer-to-peer Internet telephony
 

Peer-to-peer Internet telephony

on

  • 1,515 views

Peer-to-peer Internet telephony: challenges and status

Peer-to-peer Internet telephony: challenges and status

This was presented at the VoIP conference and expo, 2010, at IIT Rice campus, IL.

Statistics

Views

Total Views
1,515
Views on SlideShare
1,515
Embed Views
0

Actions

Likes
0
Downloads
39
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

CC Attribution License

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • Peer-to-peer (P2P) systems inherently have high scalability, robustness and fault tolerance because there is no central point of failure and the network self-organizes itself. Skype is a popular and dominant example of P2P VoIP. The IETF P2P-SIP working group was formed to explore a P2P architecture for SIP-based telephony and beyond. Traversal through NATs and firewalls is a major challenge in getting end-to-end media in a distributed P2P network. Another major problem of P2P VoIP is security against malicious peers.   I will present an overview of P2P VoIP,  the challenges, status and current trend in practice. In particular you will learn the advantages and problems associated with P2P VoIP, comparison of various architectures, design decisions and implementations, and a summary of IETF effort.

Peer-to-peer Internet telephony Peer-to-peer Internet telephony Presentation Transcript

  • Peer to peer Internet telephony challenges, status and trend Kundan Singh Oct 2010
  • What will you learn?
    • What is P2P telephony?
    • How is it implemented?
    • What are the benefits and limitations?
    • What is IETF doing about it?
  • Problem with servers
    • Server-based
      • Operations cost: maintenance, configuration
      • Central points of catastrophic failures
      • Controlled infrastructure (e.g., DNS)
    • Peer-to-peer
      • Robust: no central dependency
      • Self organizing, no configuration
      • Inherently scalable
    What is P2P telephony? C C C C C S P P P P P
  • Peer-to-peer ≠ cloud computing
    • Self management
    • Free resource sharing
    • No central co-ordination
    • Self management
    • Utility computing
    • Central co-ordination
    What is P2P telephony? managed
  • A brief history
    • Napster initiated P2P file sharing
      • “ for every one of you that falls, two shall arise.”
    • Distributed hash tables
      • Chord, CAN, Pastry, Tapestry, Kademlia, …
    • Skype (re-)invented P2P-VoIP
      • Now: 13% international calls, 54 billion minutes
    • Demonstrated P2P-SIP at Columbia University
      • IETF WG formed; several more implementations
    • Adobe added P2P to Flash Player
      • Proprietary, E2E but not quite P2P
    What is P2P telephony? 1999 2001 2003 2004 2008
  • What is P2P telephony? PBX, H.320, H.324, RTMP, Asterix/IAX, B2BUA, SBC, … SIP, H.323, XMPP/Jingle, Gtalk, RTSP, RTMFP, … Skype, P2P-SIP, … signaling + media signaling media
  • What is P2P telephony? enrollment service login server varies centralized incentive driven caching, delay storage, split-and-store implementation driven (mostly) unstructured File sharing open problem proprietary software malicious nodes caching useless; bounded load overloaded super-nodes efficiency open protocols + algorithms proprietary/close needs gateway inter-operability structured DHT  efficiency guarantee Kazaa based  unstructured topology P2P-SIP Skype
  • What is a DHT?
    • Chord
      • consistent hashing
      • data replication
    What is P2P telephony? 1 8 14 21 32 38 58 47 42 node Key 42 8+32=40 32 8+16=24 21 8+8 = 16 14 8+4 = 12 14 8+2 = 10 14 8+1 = 9 10 24 30 54 38
  • How to combine SIP + P2P?
    • SIP-using-P2P
      • SIP location service
    • P2P-over-SIP
      • + implement P2P network using SIP
    How is it implemented? P2P network SIP SIP P2P Lookup SIP P2P P2P Maintenance P2P-over-SIP P2P SIP proxies SIP-using-P2P Alice 128.59.19.194 INSERT INVITE sip:alice@128.59.19.194 FIND P2P network Alice 128.59.19.194 REGISTER INVITE alice SIP overlay
  • What are super peers? How is it implemented? Use DHT among super-peers 1 10 24 30 54 38
  • Implementation examples
    • SIPpeer
    • SIPc + OpenDHT
    • Sipeerior
    • SIPDHT
    • OpenVoIP
    • 39 peers
    • SIP thor
    • P2P-over-SIP
    • SIP-using-P2P
    • Data model
    • Service model
    • Adaptor
    How is it implemented?
  • What are the challenges?
    • Bootstrap a network
    • Security of stored data and keys
    • Data vs service model
    • NAT and firewall traversal
    • Working with free loaders
    • Getting around malicious peers
    What are the benefits and limitations?
  • When to do P2P?
    • if
      • most of the peers do not trust each other,
      • AND
      • There is no incentive to help peers
    • then
      • P2P does not evolve naturally to work
    What are the benefits and limitations? See http://p2p-sip.blogspot.com/2009/10/security-in-p2p-sip.html
  • What are the benefits and limitations? * Node capacity of 10 register/s and refresh/call rates of 1/min  more than 16 million peers (super-nodes) in the network lookup = O(logN) #connections  one or two steps Call setup latency upper bound; catastrophic failure unlikely trust (most) super nodes; probabilistic maintain = O((logN) 2 ) user count  ≈ 2 {node-capacity}* uptime, churn, … Structured P2P (Chord) no guarantee server redundancy (1-(1-R) P ); catastrophic failure possible; bulk load Availability connect to trusted nodes only trust provider; boolean Security #connections  most efficient Efficiency user count  K-degree  no limit server count  ≈ {server-count} Scaling Unstructured P2P (blind-search) server-based
  • IETF P2P-SIP working group
    • Includes
      • peer protocol, client protocol, SIP usage, locating resources.
    • Excludes
      • modification to SIP, unique identities, “research”-type, search, multicast, dynamic DNS, …
    • Must
      • use existing tools from other WGs
    What is IETF doing about it?
  • Proposed architecture
    • MUST
      • Chord DHT
      • 128-bit keys
      • DTLS and TLS
    What is IETF doing about it? SIP usage Forwarding and link management TLS Topology plugin XMPP usage Message transport Storage DTLS
  • REsource LOcation And Discovery
    • Creating pages of specifications
      • draft-ietf-p2psip-base-10 (154p), plus ICE+STUN +TURN+DTLS (260p), and: draft-ietf-p2psip-sip-05, -diagnostics-04, -self-tuning-02, service-discovery-01
    • Creating unnecessary complexity
      • No compliant implementation; discourages developers/start ups; real problems are out-of-scope
    What is IETF doing about it? 2010 2009
  • Summary
    • What is P2P telephony?
      • Versus client-server, end-to-end, and cloud
    • How is it implemented?
      • P2P-over-SIP, SIP-using-P2P, data vs service, adaptor & proxy,
    • What are the benefits and limitations?
      • Scalability, availability, maintenance, lookup
    • What is IETF doing about it?
      • RELOAD, SIP usage, …
    Visit http://39peers.net for more