[Xen-devel] Re: [Xen-users] Domain0 cannot connect to the net while domainU can.How to make the domain0 go to the internet.

[SamuelCheng <chenghui2050@xxxxxxxxx>]

OK,I add CC this time.Sorry for the mistake made last time.

I don't make any changes actually.But I remember when this situation began.It was at the time I create a virtual machine by "virt-install" command,after I rebooted the system the next day,the domain0 cannot go to google.So now I was wandering whether this method of creating causes the network problem.And this is the third time this problem happen.

I remember last time I came across the same problem,but I didn't pay any attention to it.After I reinstall my OS,the problem is fixed.

The reason why  I sent an email to the list is that I want to make this problem out in my summer holiday.If it is a bug,I want to make the developers known.

Thank you very much for your reply and also thank you for this short passage about how the net in virtual machine works,it really teaches me a lot.At last, thank you again for your sharing of time on my problem.

Is it really a bug or not?How can this possible?I bet the solution lies on the changing from eth0 to peth0 with a real MAC,But I don't know where to change or modify.Hope for your further help.

Rgds.

Samuel.

2009/7/28 Pasi Kärkkäinen <pasik@xxxxxx>

On Tue, Jul 28, 2009 at 10:06:37AM +0800, SamuelCheng wrote:
> *Yes,But,When I use another kernel to start my Linux(the kernel is not

> modified by xen,that is to say,xend does not start),I can make my domain0 go
> to google and search.I was confused why my mac is FE:FF:FF:FF:FF:FF.At the
> very beginning,everything was fine in my CentOS,and the mac is

> 00:1b:fc:17:da:7a(I think).*
>

Please don't drop the CC to xen-users list.

when xend is started, with the default configuration (in /etc/xen/xend-config.sxp),
it'll execute /etc/xen/scripts/network-bridge to re-configure your networking.

It'll rename the physical eth0 interface to peth0, change it's MAC address
to FE:FF:FF:FF:FF:FF, and then create a virtual ethernet interface called
eth0, configure it with the real MAC address, and bridge both of those
interfaces to xenbr0 bridge.

This way the virtual eth0 interface should have a real MAC, and it can be
used for dom0 management, and at the same time allow other VMs/domUs to
share the physical ethernet interface by using xenbr0 bridge.

I don't know why that doesn't work for you.. Have you changed/tweaked your
network settings somehow?

When you start the machine with normal (non -xen) kernel, xend does not
start and network reconfiguration won't happen.

-- Pasi

> *Ok.here is the information of my OS:

> I have 2 OSs:
> one is Fedora 10 and the other is CentOS 5.3(updated from 5.2).
> here is some kernel information:*
>
> title CentOS (2.6.18-128.2.1.el5xen)
>     root (hd0,2)
>     kernel /boot/xen.gz-2.6.18-128.2.1.el5
>     module /boot/vmlinuz-2.6.18-128.2.1.el5xen ro root=LABEL=/1 rhgb quiet
>     module /boot/initrd-2.6.18-128.2.1.el5xen.img
> title CentOS (2.6.18-128.2.1.el5)
>     root (hd0,2)
>     kernel /boot/vmlinuz-2.6.18-128.2.1.el5 ro root=LABEL=/1 rhgb quiet
>     initrd /boot/initrd-2.6.18-128.2.1.el5.img
> title CentOS (2.6.18-128.1.16.el5xen)
>     root (hd0,2)
>     kernel /boot/xen.gz-2.6.18-128.1.16.el5
>     module /boot/vmlinuz-2.6.18-128.1.16.el5xen ro root=LABEL=/1 rhgb quiet
>     module /boot/initrd-2.6.18-128.1.16.el5xen.img
> title CentOS (2.6.18-128.1.16.el5)
>     root (hd0,2)
>     kernel /boot/vmlinuz-2.6.18-128.1.16.el5 ro root=LABEL=/1 rhgb quiet
>     initrd /boot/initrd-2.6.18-128.1.16.el5.img
> title CentOS (2.6.18-128.el5xen)
>     root (hd0,2)
>     kernel /boot/xen.gz-2.6.18-128.el5
>     module /boot/vmlinuz-2.6.18-128.el5xen ro root=LABEL=/1 rhgb quiet
>     module /boot/initrd-2.6.18-128.el5xen.img
> title CentOS-base (2.6.18-128.el5)
>     root (hd0,2)
>     kernel /boot/vmlinuz-2.6.18-128.el5 ro root=LABEL=/1 rhgb quiet
>     initrd /boot/initrd-2.6.18-128.el5.img
> title Fedora (2.6.27.21-170.2.56.fc10.i686)
>     root (hd0,5)
>     kernel /vmlinuz-2.6.27.21-170.2.56.fc10.i686 ro
> root=UUID=50e45426-575f-4112-bfa2-54d8741b5ae5 rhgb quiet
>     initrd /initrd-2.6.27.21-170.2.56.fc10.i686.img
>
>
>
>
>
> 2009/7/27 Pasi Kärkkäinen <pasik@xxxxxx>
>
> > On Thu, Jul 23, 2009 at 05:34:36PM +0800, SamuelCheng wrote:
> > > I attach the error I got in the attachment.
> > > The return of the following command:
> > > ifconfig -a
> > > route -n
> > > brctl show
> > >
> > > Here is the content,also you can see the attachment, a little long,so be
> > > patient, some information may be not of any use,but I don't know so I
> > copied
> > > all here,Thank you in advance very one,Good day.
> > > :
> > > [root@localhost ~]# ifconfig -a
> > > eth0      Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
> > >           inet addr:192.168.0.104  Bcast:192.168.0.255
> >  Mask:255.255.255.0
> > >
> >
> > Your problem is the MAC address of eth0: it shouldn't be FE:FF:FF:FF:FF:FF.
> >
> > eth0 is the virtual interface used for dom0 management, and it's bridged to
> > xenbr0, which is bridged to peth0 (physical eth0 interface).
> >
> > eth0 should have the original/real MAC address of the peth0.
> >
> > -- Pasi
> >
> >
> > > [root@localhost ~]# route -n
> > > Kernel IP routing table
> > > Destination     Gateway         Genmask         Flags Metric Ref    Use
> > > Iface
> > > 192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0
> > eth0
> > > 192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0
> > > virbr0
> > > 169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0
> > eth0
> > > 0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0
> > eth0
> > >
> > > [root@localhost ~]# brctl show
> > > bridge name     bridge id               STP enabled     interfaces
> > > virbr0          8000.000000000000       yes
> > > xenbr0          8000.feffffffffff       no              peth0
> > >                                                         vif0.0
> > >
> >
> >
> >
>
>
> --
> God more,self less.

--
God more,self less.

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