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[Xen-users] HVM Guests and tap interfaces

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Subject: [Xen-users] HVM Guests and tap interfaces
From: Eric S <ericseligman@xxxxxxxxxxx>
Date: Fri, 30 Oct 2009 02:56:14 -0700
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Hello all,

I have a some what convoluted/complex question regarding the automatically generated tap interfaces . I just recently installed several HVM hosts, and noticed that along with the normal 'vifX.Y' interfaces, a number of 'tap.X.Y' interfaces have sprung up equal to the number of vifs. My question is, why are they there, and what purpose do they serve?

I ask because I am attempting to set up an IDS monitor on each vif interface to monitor traffic coming out of individual VM guests, but the presence of the tap interfaces confuses the issue since I cannot seem to set their MAC address in the vm configuration file (typically vif=['mac=...]), and they appear to have broken my bridging configuration. So ANOTHER question would be: is there anyway to configure them, or disable them all together, or in-fact any documentation on this HVM tap phenomenon at all?

I've spent a number of hours looking into this and all I can glean from various forums and mailing lists is that they are only created with HVM hosts, and that they are very mysterious in nature, since no-one really has an explanation as to why they are there...

In any case, if anyone has answers, I would definitely appreciate a reply.



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