[CentOS-virt] Centos 6.2 / KVM troubles with network

Sat Jan 14 17:22:09 UTC 2012
Radek Bursztynowski <radek at bursztynowski.waw.pl>

Dnia 2012-01-14, sob o godzinie 11:11 -0600, Trey Dockendorf pisze:

> 
> 
> 
> On Sat, Jan 14, 2012 at 8:41 AM, Radek Bursztynowski
> <radek at bursztynowski.waw.pl> wrote:
> 
>         Dnia 2012-01-14, sob o godzinie 15:08 +0100, Dennis
>         Jacobfeuerborn pisze: 
>         
>         > On 01/14/2012 02:59 PM, Radek Bursztynowski wrote:
>         > > Hi,
>         > >
>         > > I have installed CentOS 6.2 x86_64 and KVM/Qemu and I have some troubles
>         > > with network.
>         > >
>         > > The first case:
>         > > -----------------
>         > >
>         > > The configuration is:
>         > > - CentOS 6.2 (hardware machine) has one Ethernet interface with static IP
>         > > address (eth0).
>         > > - Virtual machine has bridge network interface with eth0 interface on
>         > > CentOS 6.2. This bridge is created using wizard integrated with virt-manager.
>         > > - Bridge interface on virtual machine receives IP addres from DHCP server.
>         > > IP address is received well.
>         > > - All firewalls and SELinux are closed.
>         > >
>         > > Virtual machine has no any connection with CentOS 6.2 hardware machine, and
>         > > CentOS 6.2 has no any connection with virtual machine. But every others
>         > > machines have all connection with both virtual and CentOS 6.2 machine.
>         > >
>         > > The question: Why?
>         > >
>         > > The second case:
>         > > ----------------------
>         > >
>         > > The configuration is:
>         > > - On CentOS 6.2 (hardware machine) I created bridhe (br0) with eth0
>         > > hardware interface. Two situations:
>         > > + I force two different IP addresses for eth0 and br0 interfaces - there no
>         > > any connection with this server. So I don't test this case.
>         > > + I forced one IP addres for both eth0 and br0 interfaces. ifconfig shows
>         > > that eth0 has no IP address, br0 has IP address. So, I test this case.
>         > > - I use Red Hat documentation:
>         > > http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html-single/Virtualization/index.html#sect-Virtualization-Network_Configuration-Bridged_networking_with_libvirt)
>         > > - On virtual machine I created bridge connection with br0 interface on
>         > > CentOS 6.2.
>         > > - All machines have all connections.
>         > > - All firewalls and SELinux are closed.
>         > >
>         > > NFS server on CentOS 6.2 (hardware machine) doesn't serve exported file system.
>         > >
>         > > The questions:
>         > > 1. Is it proper that eth0 has no IP addres and bridge (br0) interface has?
>         > > 2. What about my NFS? NFS server worked well before starting virtualization.
>         > >
>         > > Who can me help with my troubles?
>         > 
>         > You say you create bridge interfaces in your virtual machines. Why? Usually 
>         > you don't do that you create a bridge only on the host.
>         > 
>         > You also say you "forced" one IP address for both eth0 and br0. There is no 
>         > need to force anything. eth0 shouldn't have an IP but br0 should have this 
>         > IP instead.
>         > 
>         > Regards,
>         >    Dennis
>         > _______________________________________________
>         
>         Dennis,
>         
>         Thanks for interesting. Few words explanation. 
>         I have one network segment, and I try to joint virtual
>         machines to this segment. So my hardvare machine has
>         192.168.0.1 address, gateway is 192.168.0.254, netmask =
>         255.255.255.0.
>         
>         Regarding bridge on my virtual machine. When I started
>         virtualization I had NAT only in another network segment. So,
>         I look for solution adding virtual machines to my base network
>         segment. Previously I used VMware Server, and it was proper
>         solution.
>         
>         Regarding my force one IP addres for both interface. I used
>         this solution because eth0 has no any IP addres and I couldn't
>         find CentOS 6.2 server in the network. Using exactly Red Hat
>         configuration I have:
>         
>         # more ifcfg-eth0
>         DEVICE=eth0
>         TYPE=Ethernet
>         BOOTPROTO=none
>         IPADDR=192.168.0.1
>         NETMASK=255.255.255.0
>         PREFIX=24
>         GATEWAY=192.168.0.254
>         DNS1=192.168.0.199
>         DNS2=194.204.159.1
>         DNS3=194.204.152.34
>         DEFROUTE=yes
>         IPV4_FAILURE_FATAL=yes
>         IPV6INIT=no
>         NAME=eth0
>         ONBOOT=yes
>         BRIDGE=br0
>         MTU=9000
>         DOMAIN=bursztynowski.waw.pl
>         UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03
>         
>         # more ifcfg-br0
>         DEVICE=br0
>         TYPE=Bridge
>         BOOTPROTO=dhcp
>         #IPADDR=192.168.0.1
>         #NETMASK=255.255.255.0
>         #PREFIX=24
>         #GATEWAY=192.168.0.254
>         #DNS1=192.168.0.199
>         #DNS2=194.204.159.1
>         #DNS3=194.204.152.34
>         ONBOOT=yes
>         DELAY=0
>         
>         (previous configuration br0 was: 
>         BOOTPRO=static
>         and with no '#' characters. Then all worked excluding NFS.
>         
>         
>         # ifconfig                            
>         br0       Link encap:Ethernet  HWaddr
>         00:50:8D:94:2F:B7            
>                   inet addr:192.168.0.92  Bcast:192.168.0.255
>         Mask:255.255.255.0
>                   inet6 addr: fe80::250:8dff:fe94:2fb7/64
>         Scope:Link             
>                   UP BROADCAST RUNNING MULTICAST  MTU:9000
>         Metric:1             
>                   RX packets:16 errors:0 dropped:0 overruns:0
>         frame:0            
>                   TX packets:26 errors:0 dropped:0 overruns:0
>         carrier:0          
>                   collisions:0
>         txqueuelen:0                                      
>                   RX bytes:3034 (2.9 KiB)  TX bytes:4313 (4.2
>         KiB)               
>         
>         eth0      Link encap:Ethernet  HWaddr 00:50:8D:94:2F:B7  
>                   inet6 addr: fe80::250:8dff:fe94:2fb7/64 Scope:Link
>                   UP BROADCAST RUNNING PROMISC MULTICAST  MTU:9000
>         Metric:1
>                   RX packets:57255 errors:0 dropped:0 overruns:0
>         frame:0
>                   TX packets:60263 errors:0 dropped:0 overruns:0
>         carrier:0
>                   collisions:0 txqueuelen:1000
>                   RX bytes:21481457 (20.4 MiB)  TX bytes:15768417
>         (15.0 MiB)
>                   Interrupt:23 Base address:0x8000
>         
>         lo        Link encap:Local Loopback
>                   inet addr:127.0.0.1  Mask:255.0.0.0
>                   inet6 addr: ::1/128 Scope:Host
>                   UP LOOPBACK RUNNING  MTU:16436  Metric:1
>                   RX packets:30723 errors:0 dropped:0 overruns:0
>         frame:0
>                   TX packets:30723 errors:0 dropped:0 overruns:0
>         carrier:0
>                   collisions:0 txqueuelen:0
>                   RX bytes:92725098 (88.4 MiB)  TX bytes:92725098
>         (88.4 MiB)
>         
>         Should I replace static and dhcp addresses between eth0 and
>         br0 interface?
>         
>         Regards,
>         Radek
>         
>         
>         
>         
>         
>         
>         
>         
>         
>         _______________________________________________
>         CentOS-virt mailing list
>         CentOS-virt at centos.org
>         http://lists.centos.org/mailman/listinfo/centos-virt
>         
> 
> 
> 
> To use bridging on the virtual host you have to assign the IPs to br0
> and then add "Bridge=br0" to ifcfg-eth0.  I have working examples
> here, http://itscblog.tamu.edu/startup-guide-for-kvm-on-centos-6/.


Thanks. I used this advice as above. All work excluding my NFS.

Regards,
Radek

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