170 likes | 194 Views
Discover the differences and similarities between Skype and SIP in the realm of VoIP communication. Learn about P2P systems, hybrid models, security protocols, and more. Uncover the strengths and weaknesses of each approach for your telecommunications needs.
E N D
VoIP, P2P and SIP A review of the current VoIP systems Helsinki University of Technology TKK Octavi Miró
Summary • Introduction • VoIP • P2P Systems • Skype • SIP • Skype - SIP Similarities and Differences • Conclusion
VoIP • Voice over Internet Protocol. • Two or more people can speak with each other over internet using their computers. • Skype is the first peer-to-peer based IP telephony. • Normally there are three basic functions: • Resource location • Session establishment and management • Presence status
P2P Systems • P2P are dynamic, reliable and scalable networks. • Resources are shared between the peers (file-sharing). • Resources can be accessed directly from other peers. • There are different kinds of P2P networks: • Structured • Unstructured • Centralized • Pure • Hybrid
P2P Systems - Hybrid P2P • Pro’s • No single point of failure • Can provide anonymity • Reduces the signaling load without reducing the reliability • Con’s • Still signaling traffic • Overlay topology not optimal • Super nodes have to bear a significantly higher load
Skype (I) • Most VoIP system used. • Privative. • Architecture: • Host nodes • Super nodes • Login node • Skype uses a central authentication server to authenticate users.
Skype (II) LOGIN • A skype client authenticates its username and password with login server. • Advertises its presence to other peers and buddies. • Determines the type of NAT and firewall it is behind. NAT TRANSVERSAL AND FIREWALL • A variation of the STUN and TURN protocols to determine the type of NAT and firewall it is behind.
Skype (III) SECURITY • Username and password for authentication. • Uses the Advanced Encryption Standard (AES) for the calls.
SIP (I) • The Session Initiation Protocol is a signaling protocol, used for setting up and tearing down multimedia communication sessions. • One of its applications is in VoIP (P2PSIP). • SIP entities • User Agents (Uas) • SIP Proxy • SIP Registar • SIP Redirect Server
SIP (II) LOGGING IN • By registration Server. The SIP registration server also stores the IP address and port used to connect to each SIP client. NAT TRANSVERSAL AND FIREWALL • Uses STUN to translate Information inside IP packets for NAT and firewall traversal
SIP (III) SECURITY • SIP authenticates by Digest Authentication. • Communication by extension (TLS). Example:
SIP - Skype Main Similarities • No differences in the main architecture. • Hybrid P2P. • Supernode in Skype, SIP Proxy and Redirect server in SIP. • Login process is the same in SIP and Skype • Register before direct transmission. • Login Server in Skype and Registar Server in SIP. • Similar NAT and firewall transversal protocol (STUN).
SIP-Skype Main Differences • SIP is open and Skype uses a proprietary protocol. • Skype encrypts communications. SIP don’t (just by extension). • SIP just a little part of the whole protocol (more flexible). • SIP is a standard (compatibility and reuse). Skype just an application.
Conclusion • SIP and Skype are two different approaches to VoIP communication. • SIP has the strength of flexibility, Skype is easy to install, use and has transparent network access; both offer excellent sound quality. • Nobody knows, whether Skype is a backdoor and really secure. • Skype uses the own “clients” –supernodes- of servers. Less cost more escalability. • SIP-P2P has still work to do for VoIP communications (security, performance…).
Questions? Thank you!