Richard
I am not sure that I have seen quite what you describe. Here are some thoughts:
- are you SURE that there are no open sessions? probably the most common cause of the symptom that you describe is that all of the VTYs have sessions hanging and there is nothing to accept new sessions.
- is there any possibility that there has been some config change? is there perhaps an access-class (or permit list) which is restricting access? is it possible that transport input (or output) has changed and no longer includes telnet? (moving toward SSH)
- is it possible that someone has configured "no exec" on the vty? I have seen this when someone was trying to configure "no exec-timeout" and thought they were using a valid abbreviation when they typed "no exec". The result would be to reject any telnet attempt.
If none of these seem to explain it, then perhaps you could post that part of the running config.
HTH
Rick
HTH
Rick