We have several switches that for some reason have all the ports set to different speeds (some 10Mbps and some 100Mbps) I want to reset all ports to auto (so they should then configure to 100Mbps) What is the best way of doing this?
Your switches are probably managed type, so you have to find their ip addresses and configure them by web interface. If you don't known how to to this...read the switch's manual or publish exact model name so we can help you.
Tools like RANCID making updating large number of switches and routers simple. But you must be very careful with uplink ports and other changes that will disconnect your session.
Personal I like to login in directly to preform the work by hand. This way I can double check that I am going to only make the correct changes needed. Also Cisco has some helpful commands to make changing large number of port at once.
Changing all Copper Ethernet speed and duplex on a cisco c3750:
Changing all Copper Ethernet speed and duplex on a group of stacked Cisco 3750s:
Cisco has a long history of AutoNeg problems and issues, but the Gigi interface level you really should use AutoNeg. Details of why at Etherealmind.
Ah, mass Cisco updates...
I used a perl script to connect (I think Net::Telnet::Cisco was my module of choice), and then loop through all the interfaces issuing the appropriate command.
You could also use it to just generate the text and copy / paste that into your terminal program.