What is the latest firmware that you can load on this device:
lab-cisco3750g-apt#show hardwareCisco IOS Software, C3750 Software (C3750-I9-M), Experimental Version 12.2(20050726:174023) [astrived-wrigley 285]Copyright (c) 1986-2005 by Cisco Syste...
It's distinctly possible we got this directly from Cisco (as a vendor providing them service, not as a customer) years back, so that's a possibility.
What I'm taking from your responses is - this is not a normal case. I'll head down that path.
I did specifically see the notation in the 12.2(58) documentation saying that 12.2(55) was the last version to support the WS-3750G-24PS - which is why I was very confused when neither of the 12.2(55)'s worked.
I've tried SE12 - same result as SE1. (That's what I tried first, since it was listed as the recommended version in the download portal.) When that didn't work, I rolled back to SE1 to see if that made any difference.
Original source unknown - company has had this device for years.
Here's what I see booting 12.2(55)SE1 for example:
<Dec/13 11:47 am>Base ethernet MAC Address: 00:13:5f:0c:xx:xx
<Dec/13 11:47 am>Xmodem file system is available.
<Dec/13 11:47 am>...
We just saw this issue on a 4500X as well that was already running 3.05.03.
It appears it isn't the firmware upgrade that fixes it - but rather "have to reload the switch after configuring FastEthernet1" before it will start responding.
