I'm worry about the NIC num(eth1) in this function, hard code is always not a good way. :)
Actually, the nic num from kernel side will ascending with interface attach, so if this is not the first time to attach an interface for a running domain, the nic num may be be eth1. I encountered this bug long time ago in another project.
Of course, it's just my view, i didn't run this case in my box.