RE: [Xen-users] Re: How to Networking Bridge?

Petersson, Mats
Tue, 05 Sep 2006 12:28:57 -0000

________________________________

	From: Helder Rossa [mailto:rossa@kimus.net]
	Sent: 05 September 2006 13:18
	To: Petersson, Mats
	Cc: xen-users@lists.xensource.com
	Subject: RE: [Xen-users] Re: How to Networking Bridge?


	You are saying that the real transfer rate will be the one that
the real device will have. rigth?
	What do I need to configure to emulate the realtec?


Depends on what you mean... The bits sent by your real network card as a
result of a packet being sent by the DomU will be transmitted at
whatever rate your real network card is sending it, yes.

The actual rate of bits that your guest will transmit at is limited by a
combination of factors, one of which is how quickly the QEMU device
model can actually process the requests to send, and the intercepts that
are involved with that. I explained in a post this morning (BST/GMT+1)
that the disk-rate is limited by QEMU + hypervisor intercept due to the
emulation of hardware, and it''s really the same story for networking -
although I don''t know exactly how the network card works, so I
don''t
know how many intercepts are required for each send/receive request. But
I can gurantee that it''s slower than the real hardware solution with a
modern 1Gbps network card!



	Is it possible to pass a physical device to the VM not an
emulated?
	If could be possible to assign a real device to the VM then no
bridge, routing or nat would be necessary. right?


No you can''t. See a post about two hours ago on the same subject, and
several more posts on this subject previous to that.

--
Mats



	thanx

	kimus



	On Tue, 2006-09-05 at 13:52 +0200, Petersson, Mats wrote:




________________________________


			From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Helder Rossa
			Sent: 04 September 2006 22:34
			To: xen-users@lists.xensource.com
			Subject: [Xen-users] Re: How to Networking
Bridge?





			I DID IT!!

			I had to compile tun kernel module (Universal
TUN/TAP device driver, 1.6) . After this all worked Fine!!

			Another question: my network is at 10Mbps (?!)
is there some configuration? My ethX is 1Gb!!!



		That doesn''t really matter. It''s just a VIRTUAL network
card anyways, so you''re not going to be limited by the
"10Mbps" in any
real way... It''s just part of the emulation of the network card that
uses a pretty basic PCNet32 device, which doesn''t say 100Mbps or
1Gbps... It wouldn''t be very hard to change that, but what''s
the point -
it never hits any real hardware, so whatever the number reported, it''s
not actually reflecting anything real. Having said all that, the latest
QEMU version (in xen unstable) also supports a couple of new network
cards, including a 100Mbps realtek 8139. Not that it will make much of a
difference to the ACTUAL transfer rate tho''.



		--

		Mats



			thanx

			On Mon, 2006-09-04 at 21:44 +0100, Helder Rossa
wrote:

				Hi,

				I''ve a working xen 3.0.2 booting a
gentoo linux on Dom0.

				I have setup a Windows XP in a DomU OK
with no problems except the
				network!!

				My problem is that I wanted to give a
working network interface on the
				DomU and the best I could. making the
windows detect an network adapter,
				was putting:

				    vif = [''type=ioemu'']

				I also tryied:

				    vif = [''type=ioemu, bridge=xenbr0'']


				Could never ping a external from DomU!!


				What I know:

				    - the ethX device is a logical
device and the physical device is
				renamed to pethX;
				    - the vifX.Y devices are linked with
ethY from DomX (ie.: vif1.0 <->
				Dom1 eth0);
				    - there is also a vethX ...

				What configuration I have to do on Dom0?
				What configuration I have to do on DomU?


				When rebooting I have always need to do
''ifconfig ethX up'' !!!