On Tue, Nov 15, 2011 at 02:25:26PM +0100, Pino de Candia wrote: > Please excuse me for posting this naive question, but I searched > online and looked at the source code and haven't figured this out. > > What is the difference between a port created with type=internal and > type=tap? > > It seems to me that if I create a port with type=tap, then OVS creates > the tap (makes the ioctl calls to /dev/net/tun) and opens the > user-side (raw block-device side) of the tap. But this seems to be > exactly what OVS does for internal ports - I read in INSTALL.userspace > that a tap is created for every internal port. However, I am using the > OVS kernel module so I don't know if that document applies.
It doesn't. Only the userspace version uses tap devices to implement internal ports. > Since internal and tap ports are so similar, what are the use-cases > for tap-ports for which internal ports are inappropriate? I don't know of any good uses for tap ports. We are thinking about removing them. > And just to spell my assumptions out a bit further - it seems to me > that in the common use-case of attaching a VM to an OVS bridge, a tap > is created externally to OVS (e.g. by scripts or cloud management > software) and the tap is added as a system port to OVS so that OVS > handles the kernel side of the tap, and the VM gets the user-side of > the tap. So VMs are not a use-case for OVS ports of type=tap. Is that > correct? Right. _______________________________________________ discuss mailing list [email protected] http://openvswitch.org/mailman/listinfo/discuss
