In today’s date various types of networks have been defined keeping in view the needs of the telecommunication and networking world. Overlay networks are just one of the types of various computer networks. In this article we discuss about this type of network as well as its characteristics.
About Overlay Network
– A network that is built up on another network is termed as an overlay network.
– This network also consists of nodes but the way these nodes are linked, differs from the way of linking in other types of networks.
– The nodes here are linked to each other via logical or virtual links which is completely contrary to the other types of networks that use cabling or wiring etc. i.e., the physical linkage media.
– Each of these virtual or logical link points to a path that might follow a number of physical links belonging to the underlying network.
– Some famous examples of overlay networks include cloud computing (i.e., the distributed systems), client – server applications and peer – to – peer networks etc.
– These are all overlay networks since they have their nodes running on the top of the ultimate network i.e., the Internet.
– Originally, Internet was also an overlay network since it was built up on the telephone network via advent of VoIP but today the things are upside down. Currently, telephone network is being turned in to an overlay network by building it up on the internet.
– Overlay networks are widely in use in telecommunications because they turn out to be feasible than other options because of the availability of the optical fiber and digital circuit switching equipment.
– The broader internet is a combination of the IP networks and the telecommunication transport networks.
– Both these types of networks are overlaid with at least the following 3 layers if it is the case of PSTN:
1. An optical layer
2. A transport layer
3. An IP or circuit layer
– The networks first to be overlaid on the telecommunication networks are the enterprise private networks like asynchronous transfer mode packet switching and frame relay infrastructures.
– Another characteristic feature of overlay networks is that they tend to be very complex from a physical point of view.
– This happens so because while building an overlay network so many logical layers have to be combined.
– Various entities such as universities, government and business organizations own and operate these networks.
– Another thing about overlay networks is that they allow the separation of concerns which have permitted the laying up of a set of services over the time that otherwise would not have been possible for a single telecommunication operator.
– Nowadays, overlay networks are using the internet as a basis for their construction so that the messages can be routed to the destinations that are not specified through IP addresses.
– Internet routing has improved because of the overlay networks.
– On the contrary side, the deployment of an overlay network can be done on end–hosts that run the protocol software for overlay networks.
– No cooperation from ISPs is required.
– The way of routing the packets in the underlying networks extending between any two nodes of overlay network is not in the control of the overlay network.
– However, it does controls the traversal path of the nodes.
– Below given is a list of overlay network protocols based up on TCP/ IP:
2. DHTs or distributed hash tables like KAD
4. Solipsis: This was developed for a virtual world based up on massive sharing.
5. HyPar View: This had a high degree of robustness but was much unstructured.
6. Peer – to – peer protocols such as utorrent, shareaza, tribler, limewire and so on.