Re: [Xen-users] bridge interfaces in dom0

["Liang Yang" <multisyncfe991@xxxxxxxxxxx>]

Hi Steve,

I have one dual port network card. the first port eth0 is connected to the 
company's intranet and the second port eth1 is connected to the switch on my 
desk. The first port is configured as dhcp and the second port is configured 
as static IP address (192.168.2.2). Both port are set active on boot.
Question 1: Xen (3.0.3) only created peth0 for the first port while I have 
to create peth1 manually.
Question 2: I created a guest domain with two interfaces (the first 
interface eth0 is dhcp and the second interface eth1 has fixed ipaddress 
192.168.2.3). The eth0 in the domain get the dhcp address without problem. I 
can ping the dhcp address of eth0 in domain0 from eth0 in the guest domain. 
However, I can not ping the eth1 in domain0 from guest domain unless I 
configure the bridge xenbr1 with the IP address 192.168.2.6 (xenbr1 is 
created when peth1 is created)
Could you give me some explanation about this?

Thanks,

Liang

----- Original Message ----- 
From: "Steve Feehan" <sfeehan@xxxxxxxxx>
To: <xen-users@xxxxxxxxxxxxxxxxxxx>
Sent: Monday, November 13, 2006 8:17 AM
Subject: Re: [Xen-users] bridge interfaces in dom0


> On 11/10/06, Jaroslaw Zdrzalek <jz@xxxxxxxxxx> wrote:
> > Am Donnerstag 09 November 2006 23:11 schrieb Steve Feehan:
> > In dom0 you have physical interfaces, the naming is pethX,
> > and you have virtual ones, which are these named ethX.
> > Neighter the physical ones nor the bridges shoud have ip
> > configured. If you really nead ip traffic going from dom0 to
> > your domUs configure ip on ethX in Dom0 und DomU.
> > It is sufficient.
> Yes, I understand this.
>
> > > I thought that the interface would have to merely be "up" but not
> > > necessarily have an
> > > IP address configured since bridging is done at layer 2. But alas, if
> > > I don't configure
> > > an IP address on dom0 the bridge seems to not be usable from a guest 
> > > domain.
> > It shoult not happen. Did you have read the howto for multiple bridges:
> > at the bottom, starting with:
> > "With Xen 3.0 the best method for additional bridges is t..."
> > http://wiki.xensource.com/xenwiki/XenNetworking
> Yes, that is what I based my configuration on. Here is my custom network 
> script:
> #!/bin/sh
> /etc/xen/scripts/network-bridge $@ bridge=xenbr0 netdev=eth0 vifnum=0
> /etc/xen/scripts/network-bridge $@ bridge=xenbr1 netdev=eth1 vifnum=1
> /etc/xen/scripts/network-bridge $@ bridge=xenbr3 netdev=eth3 vifnum=3
>
> And this works fine as long as the virtual interfaces (eth0, etc.) have IP
> addresses configured.
>
> Actually, let me state this more completely:
>
> My custom network-script works if the phsical interfaces have IP addresses
> BEFORE xen starts.
>
> And when I say it works, I mean that:
>
> * bridges are created
> * the virtual interfaces exist in the guests
> * AND they are usable.
>
> It's the last point that is the important part. When I don't configure
> IP addresses
> on the physical interfaces in dom0 BEFORE starting Xen the bridges are 
> still
> created and the virtual interfaces exist in the guests, but they're
> not usable. And
> by not usable I mean if I configure them with an IP address and try to 
> ping from
> the guest I get "network unreachable" errors. At least, that is what I
> recall. This
> is all getting a bit fuzzy in my memory after the long weekend. I need
> to go back
> and reproduce the problem again.
>
> > > My motivation for this is that dom0 has 4 interfaces which could be on
> > > 4 networks. I
> > > didn't want to assign IP addresses for dom0 on ALL of these networks.
> > You need 4 bridges, no need to configure any ip in dom0
> Yes, this is what I think too. I will try and reproduce the problem
> and follow up with
> the result.
>
> Thanks,
>
> --
> Steve Feehan
>
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