Switch eth0 and eth1, how?

[Fernando Cassia]

In my server I have eth0 and eth1 (previously were em16, em17, but I
hated it so I changed to the traditional approach).

Each NIC port is connected to a different ISP. However, more often
than not while moving things around I get the cables reversed so ETH0
goes to ISP2 and ETH0 goes to ISP2, or vice versa, ie the cables are
interchanged.

So... is there a way, in such situation, to manually (say, from a bash
script) bring down both eth ports, and re-arrange those? (so that eth1
becomes eth0), and do so without a reboot?.

I´d like to make eth0 and eth1 consistent regardless of mixed cabling
so every time I bring down eth0 I know what isp I´m bringing down.
What IP each port is connected to I can figure out via a query to
www.whatismyip.com, but the question remains if it´s possible to
change the naming of two ethernet ports without a reboot.

What would be the best way? ethtool?

TIA
FC