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

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

 

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From: Helder Rossa [mailto:rossa@xxxxxxxxx]
Sent: 05 September 2006 13:18
To: Petersson, Mats
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
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:

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From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Helder Rossa
Sent: 04 September 2006 22:34
To: xen-users@xxxxxxxxxxxxxxxxxxx
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' !!!


thanx

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