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NACK-Oriented Reliable Multicast (NORM)
The NORM protocol web site is maintained by the Naval Research Laboratory (NRL) PROTocol Engineering Advanced Networking (PROTEAN) Research Group. The purpose of this site is to provide information on NORM and provide access to the NORM reference software provided by NRL. The NORM protocol is currently under development within the Internet Engineering Task Force (IETF) Reliable Multicast Transport (RMT) working group.
This protocol is designed to provide end-to-end reliable transport of bulk data objects or streams over generic IP multicast routing and forwarding services. NORM uses a selective, negative acknowledgement (NACK) mechanism for transport reliability and offers additional protocol mechanisms to conduct reliable multicast sessions with limited "a priori" coordination among senders and receivers.
A congestion control scheme is specified to allow the NORM protocol fairly share available network bandwidth with other transport protocols such as Transmission Control Protocol (TCP). It is capable of operating with both reciprocal multicast routing among senders and receivers and with asymmetric connectivity (possibly a unicast return path) from the senders to receivers. The protocol offers a number of features to allow different types of applications or possibly other higher level transport protocols to utilize its service in different ways. The protocol leverages the use of FEC-based repair and other IETF reliable multicast transport (RMT) building blocks in its design.
The NRL NORM source code and latest releases are available on GitHub. This includes support for building a simple test application and NS-2 network simulations. In the future, example applications for various operating systems will be provided along with binary executables, software documentation, user's guides, etc.