SKYPE AS OVERLAY NETWORK

INTRODUCTIONSkype is an application that provides video chat and

voice call services.Skype is available for Microsoft Windows, Macintosh, or

Linux, as well as Android, Blackberry, and both Apple and Windows smartphones and tablets.

Skype allows users to communicate over the Internet by voice using a microphone, by video by using a webcam, as well as with instant messaging.

Skype-to-Skype calls to other users are free of charge

SKYPE ARCHITECTURE Skype is an overlay peer-to-peer network.There are two types of nodes in this overlay network,

ordinary hosts and super nodes (SN).An ordinary host is a Skype application that can be used

to place voice calls and send text messages.A super node is an ordinary host’s end-point on the Skype

network. Any node with a public IP address having sufficient CPU, memory, and network bandwidth is a candidate to become a super node.

An ordinary host must connect to a super node and must register itself with the Skype login server for a successful login.

The Skype login server is an important entity in the Skype network. User names and passwords are stored at the login server.

User authentication at login is also done at this server.

This server also ensures that Skype login names are unique across the Skype name space.

PROTOCOLSkype uses a proprietary Internet telephony (VoIP) network

called the Skype protocol.The protocol has not been made publicly available by Skype,

and official applications using the protocol are closed-source.The protocol has not been made publicly available by Skype,

and official applications using the protocol are closed-source.The main difference between Skype and standard VoIP clients

is that Skype operates on a peer-to-peer model , rather than the more usual client–server model.

HISTORY OF SKYPESkype was founded in 2003 by Niklas Zennström, from

Sweden, and Janus Friis, from Denmark.The Skype software was created by Estonians Ahti Heinla,

Priit Kasesalu, and Jaan Tallinn.The first public beta version was released on 29 August

2003.In June 2005, Skype entered into an agreement with the

Polish web portal Onet.pl for an integrated offering on the Polish market.

FEATURES OF SKYPERegistered users of Skype are identified by a unique Skype Name and

may be listed in the Skype directory.Skype allows these registered users to communicate through both

instant messaging and voice chat.Voice chat allows telephone calls between pairs of users and

conference calling and uses a proprietary audio codec.Skype's text chat client allows group chats, emoticons, storing chat

history, and editing of previous messages.Skype supports conference calls, video chats, and screen sharing

between 25 people at a time for free.

SKYPE FUNCTIONSi. Startupii. Loginiii. User searchiv. Call establishment and tear downv. Media transfervi. Presence messages

SECURITY & PRIVACY

Skype uses secure algorithms and standards to protect users from hackers and phishing.Skype will not sell, rent, trade or otherwise transfer any personal and/or traffic data or communication

content outside of Microsoft.

ADVANTAGES OF SKYPE

Need internet accessThe quality of voice is sometime too unclear to hear clearlyInternational calls cost moneyRequirements to use it keep people from using it (Laptops

headphones , webcam)Requires Wi-Fi or 3G service to run

Video chat with friends and familyApp can be downloaded onto iPhones and Android phonesCompatible with Mac and PCBasic version is freeBusinesses can use this program to save money

DISADVANTAGES OF SKYPE

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