NetMQ
A 100% native C# implementation of ZeroMQ for .NET
...NetMQ extends the standard socket interfaces with features traditionally provided by specialized messaging middleware products. NetMQ sockets provide an abstraction of asynchronous message queues, multiple messaging patterns, message filtering (subscriptions), seamless access to multiple transport protocols, and more. Currently, two versions are maintained Version 3 which is the stable version of NetMQ and version 4, version 4 is same as version 3 without obsolete code. You can find both versions on Nuget, for more information read the Migrating-to-v4.