Centos vlan configuration

On our Centos boxes, we start with a minimal installation, and then add additional rpm packages as required. Today, we wanted to add a vlan trunk interface on an existing box. We created the config file as follows:

# cat /etc/sysconfig/network-scripts/ifcfg-eth5.800

# Intel Corporation 82546GB Gigabit Ethernet Controller (Copper)

DEVICE=eth5.800

BOOTPROTO=static

HWADDR=00:1B:21:52:09:0F

ONBOOT=yes

IPADDR=192.168.51.193

NETMASK=255.255.255.192

VLAN=yes

#

But when we tried to bring up the vlan interface, we got this error:

# ifup eth5.800

Device eth5.800 does not seem to be present, delaying initialization.

#

This was caused because the 'vconfig' program was missing, and so we had to install that package:

# which vconfig

/usr/bin/which: no vconfig in (/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin)

# yum install vconfig

# which vconfig

/sbin/vconfig

#

Then everything worked as expected:

# ifup eth5.800

Added VLAN with VID == 800 to IF -:eth5:-

# ls -l /proc/net/vlan

-rw------- 1 root root 0 Jul 12 10:35 config

-rw------- 1 root root 0 Jul 12 10:35 eth5.800

# lsmod | grep 8021q

8021q                  57425  0

#

BTW, the above commands were run on the following version of Centos:

# cat /etc/redhat-release

CentOS release 5.8 (Final)

#