The Internet Link protocol or IL is a connection-based transport-layer protocol designed at Bell Labs originally as part of the Plan 9 operating system and is used to carry 9P. It is assigned the Internet Protocol number of 40. It is similar to TCP but much simpler. Its main features are:
Reliable datagram service In-sequence delivery Internetworking using IP Low complexity, high performance Adaptive timeouts As of the Fourth Edition of Plan 9, 2003, IL is deprecated in favor of TCP/IP because it doesn't handle long-distance connections well.
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See also Fast Local Internet Protocol
References
Further reading Dave Presotto; Phil Winterbottom. "The IL protocol".—The original paper describing IL
