after setting sys mtu to something other than 1500 on a WS-C3750G-24TS-1U it appears that this setting will stay in effect even if the startup config is erased and the switch is reloaded. My question is. Does this mean that if I need to replace the switch and I just load a saved version of the config and the vlan.dat files. Most likley if I am running a non default MTU this will not be in effect on the new switch.
if i was understood properly, you have changed the MTU size of cisco 3750 from default 1500 bytes to 1998(eg.) now even after restarting the switch, this MTU size doesn't come to the default value of 1500 bytes & also when you tried put this config & vlan.dat file you wanted to know whether this changed MTU value will be in effect. Answer is NO, bcoz config & vlan.dat doesn't contain this MTU settings. but you can again manually change the MTU size to 1500 bytes & restart the switch.
hope this helps.
rate this post if it is been clarified.