V2.8 acknowledgement modes
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Interesting question about acknowledgement modes -
- the class asked for expected behavior for EVERY permutation of the possible codes for MSH-15 and MSH-16.
- They asked if MSH-15 is NE and MSH-16 is AL (Accept acknowledgement type is Never, Application acknowledgement type is Always) is this not the same as leaving both blank (Original mode, which is Application acknowledgment only).
- I had to think a moment, but I think they are correct. Are they? And if both are set to NE, that means nothing is ever acknowledged?
- V2.8 chapter 2.9 the Message Exchange table states “Responder sends response message”.
- To muddy the waters, in 2.9.b it states “Because the protocol describes an exchange of messages, it is described in terms of two entities, the initiating and responding systems. Each is both a sender and receiver of messages. The initiating system sends first and then receives, while the responding system receives and then sends.”
- From Hans:
- I don't think we can exclude NE/NE. If they are blank/blank, we have original mode. If at least one is non-blank, we have enhanced mode. And if both indicate NE then that may be a very legitimate implementation.
- As part of the LOI/LRI IG discussions we are indicating that upon initial install one may want to set this to AL/AL, and over time as the configuration becomes more stable, shift to AL/ER to ER/ER. Someone may want to go to NE/NE at some point if they really trust the connection. Why should it be prohibited? It's valid, just not practical most of the time.