It looks like when vzctl 3.0.18 is installed vzethdev is not getting loaded.
This is with 3.0.16:
[root@nd1 packages]# lsmod|grep vze
vzethdev 10768 0
vzmon 35216 5 vzethdev,vzrst,vzcpt,vznetdev
vzdev 4360 4 vzethdev,vzdquota,vznetdev,vzmon
[root@nd1 packages]# rpm -Uvh vzctl-3.0.18-1.x86_64.rpm vzctl-lib-3.0.18-1.x86_64.rpm
Preparing... ########################################### [100%]
1:vzctl-lib ########################################### [ 50%]
2:vzctl ########################################### [100%]
[root@nd1 packages]# init 6
[root@nd1 packages]# exit
Then after the upgrade to 3.0.18 and a reboot:
johnb@booboo:~$ ssh root@nd1.xxxx.com
[root@nd1 ~]# lsmod|grep vze
[root@nd1 ~]#
[root@nd1 ~]# vzctl start 29
Starting VE ...
VE is mounted
Setting CPU units: 24554
Configure meminfo: 308092
Set hostname: dev2.xxxx.com
File resolv.conf was modified
Configure veth devices: veth29.0 veth29.1
Error: veth feature is not supported by kernel
VE start failed
Stopping VE ...
VE was stopped
VE is unmounted
[root@nd1 ~]# modprobe vzethdev
[root@nd1 ~]# vzctl start 29
Starting VE ...
VE is mounted
Setting CPU units: 24554
Configure meminfo: 308092
Set hostname: dev2.xxxx.com
File resolv.conf was modified
Configure veth devices: veth29.0 veth29.1
VE start in progress...
I will take a look at /etc/init.d/vz and see if I can figure out why the module is not being loaded.
--John