[Xorp-hackers] Netlink ethertap [Re: Fwd: Interface Management]

[Pavlin Radoslavov]

> Can someone please explain in detail, how XORP works on TAP (ethertap)
> interfaces ?
> 
> Does the XORP routing s/w listen on the userland TAP interface ? i.e.
> if some packets arrive on /dev/net/tap0 (kernel interface), those are
> sent to userspace TAP interface from where XORP s/w grabs the packet
> (??)..
> 
> Is my understanding correct ?

XORP doesn't listen or send anything on the TAP interface. In fact
it doesn't do anything special about the TAP interface.

Pavlin


> 
> Since ethertap works with ethernet frames.. i.e. frames are sent upto userland
> TAP interface as layer 2 frames, do they enter TCP/IP stack (kernel)
> at all, before
> XORP grabs them from userland ?? 
> 
> This is the grey area to me.. whether packets arriving on TAP
> interface enter the TCP/IP stack at all (?).. how do packets sent by
> XORP  into the userland TAP interface (Tx), go out on the wire ?  TX
> packets will make it to kernel TAP (/dev/net/tap0) interface ? but
> where do they go from there ? do they enter the IP stack again .. for
> IP forwarding ??