MsgSeqNum too low on Logon

1

If an acceptor receives a Logon request with MsgSeqNum too low, the connection should be closed.
However, it’s recommended to send a Logout (5) as a response
Questions:

  1. what MsgSeqNum (34) should the Logout have if there were no previous session?
  2. should the acceptor increment nextMsgSeqNumIn?
2

I don’t have the spec handy at the moment, but IMHO every outgoing or incoming message needs to consume a sequence number (apart from PossDup of course). And if it is the first message, it should be seqnum 1.

Cheers
Chris

3

Hi Joachim,

It’s been a very long time since I have to deal with session layer. In your case, if I receive from you a Logon with a MsgSeqNum lower than I expected I would initiate a Logout and terminate the session. My Logout will have whatever is my next seq num. After that I would call the other side and do a manual seq num reset to 1 to ensure clean restart.