Have you heard about delay tolerant networking?. It is a network designed to operate effectively over extreme distances like those encountered in space communications or on an interplanetary scale. In such an atmosphere, long latency – typically measured in hours or days – is inevitable. However, similar issues also can occur over reduced distances when interference is extreme or network resources are severely overburdened.
Delay-tolerant networking involves a number of similar technologies as are utilized in a disruption-tolerant network. But there are necessary distinctions. A delay-tolerant network needs hardware that may store huge amounts of information. Such media should be able to survive extended power loss and system restarts. It should also be readily accessible at any time.
Usually, ideal technologies for this purpose include hard drives and high-volume flash memory. The information kept in these media should be organized and prioritized by software that ensures correct and reliable store-and-forward functionality.
In a delay-tolerant network, traffic will be classified in 3 ways, referred to as expedited, normal and bulk in order of decreasing priority. Expedited packets are continuously transmitted, reassembled and verified before information of the other category from a given source to a given destination. After all expedited packets are successfully assembled at their intended destination normal traffic is sent. Bulk traffic isn’t dealt with till all packets of other categories from the same source. And sure for a similar destination has been successfully transmitted and reassembled.
Have you heard about delay tolerant networking research group? It is chartered to deal with the architectural and protocol design principles arising from the requirement to provide interoperable communications with. And among performance-challenged and extreme environments where sequential end-to-end connectivity can’t be assumed.
Among the challenges to be addressed are: very large delay for transmissions resulting from either extended periods of network partitioning or physical link properties; routing capable of operating with efficiency with pre-scheduled; frequently-disconnected or opportunistic link availability, high per-link error rates creating end-to-end reliability difficult; heterogeneous underlying network technologies; and application structure; and security mechanisms capable of limiting network access prior to information transit in an atmosphere where round-trip-times may be very large.
In fact The supposed work product of the DTNRG include architectural descriptions a bundling protocol specification. And one or more network-environment-specific “profile” documents. Also these profile documents can include descriptions of ‘convergence layers’ supposed to adapt the overlying messaging architecture to be used in specialized networking environments.
The existing net protocols don’t work well for a few environments, because of some basic assumptions designed into the internet architecture:
- Between source and destination there exists an end-to-end path for the period of a communication session.
- The retransmissions based on stable and timely feedback from information receivers is an efficient means for repairing errors for reliable communication.
- The end to end loss is usually small.
- All routers and end stations supports TCP/IP protocol.
- The applications need not worry about communication performance.
- The endpoint-based security mechanisms are adequate for meeting most security issues.
- The packet switching is the most applicable abstraction for performance and interoperability.
Also selection of a single route between sender and receiver is sufficient for achieving acceptable communication performance.0