[Click] KernelTun vs KernelTap

[Midas]

Hi,

I am a little unsure about the usage of KernelTun vs KernelTap.
Can someone please explain when to use KernelTun and when
to use KernelTap.

>From what I could make out from the documents, KernelTap
deals with Ethernet packets, while KernelTun deals with IP
packets, but it is still a little hazy and I wouldn't know when
to use which.

Another question: How do I respond to arp queries when using
KernelTun? For KernelTap the example says:

  tap0 :: KernelTap(192.0.0.1/8)
       -> fromhost_cl :: Classifier(12/0806, 12/0800);
  fromhost_cl[0] -> ARPResponder(0.0.0.0/0 1:1:1:1:1:1) -> tap0;

  fromhost_cl[1] -> ... // IP packets


Is there an analogous example to handle ARP queries with
KernelTun?

Thanks
Midas