UDP -> Simplex, Half-Duplex, or Full-Duplex?

[Iluvnetwork]

Is UDP simplex, half-duplex, or full-duplex? I believe UDP is simplex, but I am not sure because people around me gave me different answers. If you know the correct answer, please let me know :) 

[Flavio Miranda]

Hi @Iluvnetwork

You're right:

"11.1.3   UDP Simplex-Talk

One of the early standard examples for socket programming is simplex-talk. The client side reads lines of text from the user’s terminal and sends them over the network to the server; the server then displays them on its terminal. The server does not acknowledge anything sent to it, or in fact send any response to the client at all. “Simplex” here refers to the one-way nature of the flow; “duplex talk” is the basis for Instant Messaging, or IM."

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[yongaik]

Normally simplex, half-duplex ot full-duplex in networking term will describe those one to one (i.e. ethernet NIC to switch-port or NIC to NIC, etc). For UDP, it can be sent in both directions simultaneously so you can refer it a full-duplex if you like, the typical significant characteristic about UDP is that is it connectionless protocol that do not perform acknowledgement to receiving of packets to the sender, as compared to TCP which is connection orientated.