2010-01-25T00:34:12Z

Tony: New page: This describes a method of setting up networking for a host and its VEs such that the networking configuration for the VEs can be configured exactly as if the VEs were standalone hosts of ...

This describes a method of setting up networking for a host and its VEs
such that the networking configuration for the VEs can be configured
exactly as if the VEs were standalone hosts of their own in the same
subnets or VLAN as the host. This method makes use of the Virtual
Ethernet device and bridges between the host and its containers. This
technique has the advantage of allowing IPv6 network configurations to
work on VEs and hosts as they normally would. In particular, both hosts
and VEs can use IPv6 autoconfiguration. The network configuration of a VE
can be identical to that of a non-VE system.

In the following example the host has two physical interfaces and we are
setting up the network configuration for VE 100. The host IP
configuration is moved out of the ethN interface configs and into the
vzbrN interface config scripts (ifcfg-vzbr0 and ifcfg-vzbr1). Ie. the
host IP configuration will now reside on the vzbrN interfaces instead of
the ethN interfaces.

1. (Optional) Verify that you can create a bridge interfaces for each
physical interface on the host.

/usr/sbin/brctl addbr vzbr0
/usr/sbin/brctl addbr vzbr1

2. Make note of the existing IP configuration in the hosts ifcfg-ethN
files. Then, modify the ifcfg-ethN files on the host so that they ONLY
bridge to the corresponding vzbrN interface.
/etc/sysconfig/network-scripts/ifcfg-eth0 should look like:

DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
BRIDGE=vzbr0

Similarly ifcfg-eth1 will look like:

DEVICE=eth1
BOOTPROTO=none
ONBOOT=yes
BRIDGE=vzbr1

Note that the ifcfg-ethN files on the host do not contain any IP
information anymore.

3. Create ifcfg-vzbrN files and copy the IP configuration that was
previously in the ifcfg-ethN files into ifcfg-vzbrN. Here's what
host:/etc/sysconfig/network-scripts/ifcfg-vzbr0 would look like assuming
the IPv4 address is assigned statically and IPv6 auto-configuration
(SLAAC) is used:

DEVICE=vzbr0
BOOTPROTO=static
IPADDR=xxx.xxx.xxx.xxx
NETMASK=aaa.aaa.aaa.aaa
ONBOOT=yes
TYPE=bridge

Similarly, ifcfg-vzbr1 should look like:

DEVICE=vzbr1
BOOTPROTO=static
IPADDR=yyy.yyy.yyy.yyy
NETMASK=bbb.bbb.bbb.bbb
ONBOOT=yes
TYPE=bridge

4. On the host, do a 'service network restart' and verify the host has
both IPv4 and IPv6 connectivity to its vzbrN interfaces.

5. Create the VE as you normally would except do NOT specify any IP
address, just the hostname. Specifying an IP address during VE creation
creates an unwanted venet interface which is not used in this
configuration.

However, if the VE already exists, remove any venet devices - they will
not be used:

/usr/sbin/vzctl set 100 --ipdel all --save

6. For each VE, create ethN devices (ignore warnings about "Container
does not have configured veth") on the host:

/usr/sbin/vzctl set 100 --netif_add eth0
/usr/sbin/vzctl set 100 --netif_add eth1

The above creates corresponding veth100.0 and veth100.1 devices on the
host and updates the host /etc/vz/conf/100.conf file with generated MAC
addresses for the veth devices.

7. Next we add the host vethN interfaces to the host bridged
interfaces (vzbrN).

Create host:/etc/sysconfig/network-scripts/ifcfg-veth100.0

DEVICE=veth100.0
ONBOOT=yes
BRIDGE=vzbr0

Create host:/etc/sysconfig/network-scripts/ifcfg-veth100.1

DEVICE=veth100.1
ONBOOT=yes
BRIDGE=vzbr1

To make the above take effect, either do another 'service network restart'
on the host, or manually add each VE interface to its corresponding bridge
by running:

/usr/sbin/brctl addif vzbr0 veth100.0
/usr/sbin/brctl addif vzbr1 veth100.1

8. Verify each bridge includes the host interface and the veth interfaces
for each VE:

/usr/sbin/brctl show

9. In the container create the ifcfg network scripts for each interface
eth0 and eth1. The scripts should look like standard ifcfg network
scripts for a host.

/usr/sbin/vzctl enter 100

After entering the VE:

vi /etc/sysconfig/network-scripts/ifcfg-eth0
vi /etc/sysconfig/network-scripts/ifcfg-eth1

As noted above, the ifcfg-ethN files in the VE should be identical to
standard ifcfg-eth* files containing any required IP configuration info.

10. Initialize the interfaces and restart the network service on the
container.

/sbin/ifconfig eth0 0
/sbin/ifconfig eth1 0
/sbin/service network restart

Alternatively, just restart the VE from the host.

11. Add FORWARD ACCEPT statements to the host iptables and ip6tables for
each VE IPv4 and IPv6 address. You do NOT need to enable any special
network forwarding via sysctl.

iptables:
-A FORWARD -s xxx.xxx.xxx.xxx -j ACCEPT
-A FORWARD -d xxx.xxx.xxx.xxx -j ACCEPT

ip6tables:
-A FORWARD -s xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx -j ACCEPT
-A FORWARD -d xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx -j ACCEPT

Then restart both iptables and ip6tables on the host:

service iptables restart
service ip6tables restart

12. Verify the host and VE have connectivity to each other as well as to
the rest of the network.

13. For each additional VE, start at step #5.