Overlay network (from the English Overlay Network ) is a common case of a logical network created on top of another network. Overlay network nodes can be connected either by a physical connection or by a logical connection, for which one or several corresponding routes from physical connections exist in the main network. Examples of overlays are VPNs and peer-to-peer networks that work on the basis of the Internet and are “add-ons” to classic network protocols , providing ample opportunities that were not originally envisaged by the developers of the main protocols. Dial- up Internet access is actually carried out through an overlay (for example, using the PPP protocol), which works "on top" of a regular telephone network .
Using Overlay Networks
Overlays can be used in the following cases:
- For research, development and testing of new communication protocols that are impossible in a traditional infrastructure (for example, the study of the properties of IPv6 or one-to-many communications );
- To create new network properties that are impossible in a traditional infrastructure:
- Routing with a guarantee of service quality ,
- Infrastructure more suitable for broadcasting information flows ( Akamai ),
- More flexible, efficient and reliable routing ( Resilient Overlay Networks , Chord ),
- Enhanced connection security ( Secure Overlay Services , VPN ),
- Fully distributed network infrastructure ( Tapestry ),
- Routing without determining the destination IP address ( Distributed Hash Table );
- To create and operate services impossible in a traditional infrastructure:
- Distributed storage of information, file sharing ( OceanStore ),
- Distributed computing .
The main advantage of overlay networks is that they allow you to develop and operate new large-scale distributed services without making any changes to the main network protocols. A common drawback of overlays is the increased cost of transmitting information due to the additional level of packet processing or non-optimal routes.
See also
- Frnetet
- Tor / i2p
- Perfect Dark (P2P)
- Retroshare
- Friend-to-friend
- Darknet
- VPN
- Distributed computing
Links
- A collection of links to some overlay implementations .
- Akamai EdgePlatform, a network that processes up to 15% of global Internet traffic
- Tapestry and Chimera Projects (inaccessible link)
- Distributed Hash Tables Link Collection
- OceanStore Distributed Storage Project
- Secure Overlay Services Project - Overlay to Protect Connections from DoS Attacks
- Resilient Overlay Networks project on MIT website
- Chord project on MIT website