Re: Network Bridgeing

"Ing. Ramon Resendiz" <rresendiz@xxxxxxxxxxxxxxxxxx> · Mon, 9 Jun 2014 14:38:50 -0500

Hi Zoltan,

I did the eth0 bridge to br0. As you explain i did the assignment the ip from eth0 to the br0 interface. And is working I could ping between interface from IP eth0 (br0) to VM and from VM to IP eth0. As well I tried to configure my VM with the valid IP address and the connectivity loss until I get back to the original configuration (dhcp).

Here is my ifconfig output:

br0       Link encap:Ethernet  HWaddr 00:26:9E:XX:XX:XX
          inet addr:208.66.XX.XX  Bcast:208.66.XX.XX  Mask:255.255.255.248
          inet6 addr: fe80::226:9eff:fe82:5538/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8096 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10438 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:629208 (614.4 KiB)  TX bytes:6818121 (6.5 MiB)

eth0      Link encap:Ethernet  HWaddr 00:26:9E:XX:XX:XX
          inet6 addr: fe80::226:9eff:fe82:5538/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6768417 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1952736 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:9696354264 (9.0 GiB)  TX bytes:305746274 (291.5 MiB)
          Memory:df6e0000-df700000

eth0:1    Link encap:Ethernet  HWaddr 00:26:9E:XX:XX:XX
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:468 (468.0 b)
          Memory:df6e0000-df700000

eth1      Link encap:Ethernet  HWaddr 00:26:9E:XX:XX:XX
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Memory:df660000-df680000

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:312493 errors:0 dropped:0 overruns:0 frame:0
          TX packets:312493 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:188275585 (179.5 MiB)  TX bytes:188275585 (179.5 MiB)

virbr0    Link encap:Ethernet  HWaddr 52:54:00:ED:EC:C7
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:67131 errors:0 dropped:0 overruns:0 frame:0
          TX packets:110832 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:4087482 (3.8 MiB)  TX bytes:163016646 (155.4 MiB)

vnet0     Link encap:Ethernet  HWaddr FE:54:00:85:AE:AF
          inet6 addr: fe80::fc54:ff:fe85:aeaf/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2735 errors:0 dropped:0 overruns:0 frame:0
          TX packets:54661 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500
          RX bytes:292355 (285.5 KiB)  TX bytes:2884496 (2.7 MiB)

Here is my brctrl show:
bridge name     bridge id               STP enabled     interfaces
br0             8000.00269e825538       no              eth0
virbr0          8000.525400edecc7       yes             virbr0-nic
                                                        vnet0
Here is my vm network config (Windows Server 2003 Standard x64):
Windows IP Configuration

DHCP: Yes
IP Address: 192.168.122.77
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.122.1
DHCP Server: 192.168.122.1
DNS Server: 192.168.122.1

De: centos-virt-bounces@xxxxxxxxxx [mailto:centos-virt-bounces@xxxxxxxxxx] En nombre de Zoltan Frombach
Enviado el: lunes, 09 de junio de 2014 01:03 a.m.
Para: Discussion about the virtualization on CentOS
Asunto: Re:  Network Bridgeing

You need to add eth0 to the bridge (br0) which you already did. But do NOT assign an IP address to eth0. Instead, assign the host's IP to br0.
Then just use another of your IPs for your VM (which can also be called eth0 inside your VM).
This way your host and your VM(s) can communicate with each other via the bridge.

Note: If you want to use more than one IP address to access your host, then create alias interfaces on the host for the bridge such as br0:0, br0:1, etc.
Do not create alias interfaces on eth0. Also do not create an alias interface on your host for the IP(s) which you'll be using inside your VM(s).

I hope this helps.
On 6/9/2014 2:30 AM, Ing. Ramon Resendiz wrote:
Hi,

I have the following issue i recently installed a VM with qemu and libvirtd, everything is almost ok. The problem is that i have 5 usable IP address (valid ip address on internet) for eth0, and i want to use one of this IP for my VM (Windows 2008 Standard R2 by the way). I did the bridge between my eth0 and br0, the VM could browse into internet and download patches, etc. etc. 

I tried to use a networking alias, this is the network interface eth0 assign a IP address and for the eth0:1 assign other IP address, and this bridged to the br0 instead of eth0 to eth0:1; after restart the network service the connectivity lost, and then get in back the original configuration everything seems to work again. But my goal is not archived.

Goal:

eth0 must have a valid ip address to be accesed, eth0:1 (bridged to br0) must have a valid address to be assigned to the VM. Through iptables assign ACL to each IP address (valid IP address) depending of the services to host (web server and db server,  rdp host) and between interfaces could be possible to communicate between them (virtual host and virtual machine).

eth0: Virtual Host
eth0:1: Virtual  machine (bridged to br0)

Thank you very much for you time.

Best regards,
RR

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