Overlay networks

Overlay network means in general:• Overlay: means put something on top of

something else.• A network is defined as a system for connecting

computers using a single transmission technology. The computers can communicate with each other in a network. They can send and receive data from each other when they are in a network.

Overlay network means a computer network that is on top of another network.

Overview:• During the last six years, overlay networks have

become one of the most conspicuous tools for Internet research and development. • While overlays are at least as old as the Internet,

they weren’t generally regarded as an area of research on their own until the late 1990s.

Purpose:•The main purpose of the overlay network is to add missing functionality without a complete network redesign.

Benefits•They avoid burdening the underlying network with features better performed at higher layers. For example, content routing requires that the content routers.

Short Comings: • Overlay Network highly decentralized.• Security and privacy issues.• Miss-communications between overlay and underlay

networks

Examples of overlay networks:

•Peer to Peer Networks (P2P)•Virtual Private Networks

Peer to Peer Overlay Network:

• PEER-TO-PEER (P2P) overlay networks are distributed systems in nature, without any hierarchical organization or centralized control. Peers form self-organizing overlay networks that are overlayed on the Internet Protocol (IP)

Virtual Private Network• VPNs are networks deployed on a public network

infrastructure that utilize the same security , management, and quality of service policies that are applied in a private network. VPNs provide an alternative to building a private network for site-to site communication over a public network or the Internet.

Conclusion:

• Overlay networks are better to improve functionality of another underlay network but they are also creating some problems because they don’t have complete control of physical networks.