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An overlay network is a computer network which is built on top of another network. A computer network is a group of interconnected Computers. Networks may be classified according to a wide variety of characteristics Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network. A node ( Latin nodus, ‘knot’ is a critical element of any Computer network. For example, many peer-to-peer networks are overlay networks because they run on top of the Internet. For other uses of the term see Peer-to-peer (disambiguation For peer-to-peer networks used for file sharing see File sharing The Internet is a global system of interconnected Computer networks Dial-up Internet is an overlay upon the telephone network. Dial-up Internet Access is a form of Internet access via Telephone lines The user's computer or Router uses an attached Modem connected to a The public switched telephone network ( PSTN) is the network of the world's public circuit-switched Telephone networks in much the same way that the

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Uses of overlay networks

Overlay networks can be constructed in order to permit routing messages to destinations not specified by an IP address. Routing is the process of selecting paths in a network along which to send network traffic An Internet Protocol ( IP) address is a numerical identification ( Logical address) that is assigned to devices participating in a Computer network For example, distributed hash tables can be used to route messages to a node having specific logical address, whose IP address is not known in advance. Distributed hash tables ( DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a Hash table: ( name, In Data Networks In computer networks a logical address refers to a Network layer address such as an IP 192

Overlay networks have also been proposed as a way to improve Internet routing, such as through quality of service guarantees to achieve higher-quality streaming media. Routing is the process of selecting paths in a network along which to send network traffic Streaming multimedia is Multimedia that is constantly received by and normally presented to an end-user while it is being delivered by a streaming provider (the Previous proposals such as IntServ, DiffServ, and IP Multicast have not seen wide acceptance largely because they require modification of all routers in the network. In Computer networking, IntServ or integrated services is an architecture that specifies the elements to guarantee Quality of service (QoS on networks This article is on differentiated services within communication networks IP Multicast is a method of forwarding IP Datagrams to a group of interested receivers A router ('rautər in the USA 'rutər in the UK and Ireland, or either pronunciation in Australia and Canada is a Computer whose software and hardware are usually On the other hand, an overlay network can be incrementally deployed on end-hosts running the overlay protocol software, without cooperation from ISPs. An Internet service provider ( ISP, also called Internet access provider or IAP) is a company which primarily offers their customers access to the Internet The overlay has no control over how packets are routed in the underlying network between two overlay nodes, but it can control, for example, the sequence of overlay nodes a message traverses before reaching its destination.

For example, Akamai Technologies manages an overlay network which provides reliable, efficient content delivery (a kind of multicast). Akamai Technologies Inc ( is a company that provides a distributed computing platform for global Internet content and application delivery, headquartered in Multicast is a network addressing method for the delivery of Information to a group of destinations simultaneously using the most efficient strategy Academic research includes End System Multicast and Overcast for multicast; RON (Resilient Overlay Network) for resilient routing; and OverQoS for quality of service guarantees, among others.

List of overlay network protocols

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External links

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