why the name of network interface card increased by 1?

[YCCHen]

I've just exported an existing vm , got the .ova image file, and imported it to build another vm.

my problem is this:

the name of network interface card, i.e., eth0, eth1, ..., etc just have all been changed and increased by one, i.e., eth1, eth2, eth3

I surveyed, knowing that I can adjust the file /etc/udev/rules.d/70-persistent-net.rules, and yes, I do it to active my networking

But I'm wondering WHY the problem takes place? Why the system would increase the numbering of the names?

and if possible, WHO does this?

p.s. I'm using ubuntu 12.04

appricating replies!!!

[Perryg]

It is a feature of the Linux. Any time it detects a new MAC address it increases the eth* to a higher number.