[CentOS] CentOS 6 bridging problem.

Rafał Radecki
Mon, 25 Jun 2012 12:22:21 -0000

Hi all.

I have currently an OpenVZ server:

uname -a
Linux vader8.superhost.pl 2.6.32-042stab055.16 #1 SMP Fri Jun 8
19:22:28 MSD 2012 x86_64 x86_64 x86_64 GNU/Linux

cat /etc/redhat-release
CentOS release 6.2 (Final)

lspci | grep -i eth
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03)

cd /etc/sysconfig/network-scripts

cat ifcfg-eth0
DEVICE="eth0"
BOOTPROTO=none
NM_CONTROLLED="no"
ONBOOT="yes"
TYPE="Ethernet"
HWADDR=00:25:22:0D:C2:2A
DOMAIN=domain.eu
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System eth0"
UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03
BRIDGE=vmbr0

cat ifcfg-eth0.20
DEVICE=eth0.20
BOOTPROTO=none
ONBOOT=yes
VLAN=yes
BRIDGE=vmbr20

cat ifcfg-vmbr20
DEVICE=vmbr20
BOOTPROTO=none
DHCPCLASSIPADDR=10.20.0.108
NETMASK=255.255.0.0
ONBOOT=yes
TYPE=Bridge

cat ifcfg-vmbr0
DEVICE=vmbr0
BOOTPROTO=none
DHCPCLASSIPADDR=195.218.152.219
NETMASK=255.255.255.0
ONBOOT=yes
TYPE=Bridge

cat ifcfg-vmbr0:1
DEVICE=vmbr0:1
BOOTPROTO=none
IPADDR=192.168.2.203
NETMASK=255.255.255.0
ONBOOT=yes

cat ifcfg-venet0
DEVICE=venet0
ONBOOT=yes
STARTMODE=onboot

route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 vmbr0
195.218.152.0   0.0.0.0         255.255.255.0   U     0      0        0 vmbr0
10.20.0.0       0.0.0.0         255.255.0.0     U     0      0        0 vmbr20
169.254.0.0     0.0.0.0         255.255.0.0     U     1003   0        0 vmbr0
169.254.0.0     0.0.0.0         255.255.0.0     U     1006   0        0 vmbr20
0.0.0.0         193.218.152.1   0.0.0.0         UG    0      0        0 vmbr0

iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

So I have a setup in which:
- eth0 is my physical interface
   - it is bridged with vmbr0 with ip 195.218.152.219 and this address
is accessible across the network
- eth0.20 is a logical interface in VLAN 20 on eth0
   - it is bridged with vmbr20 with ip 10.20.0.108 and this address IS
NOT accessible across the network
- vmbr0 bridge has an alias vmbr0:1 with ip 192.168.2.203 and this
address is accessible across the network
When I set up the network for testing:
- eth0 as a physical interface 195.218.152.219
- eth0.20 as a VLAN interface 10.20.0.108
both addresses are accessible across the network (VLANs on the switch
are set up correctly, VLAN 1 untagged, VLAN 20 tagged).

Do you see an error in my configuration? Why is 10.20.0.108 not available?

Best regards,
Rafal.