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CentOS 7 multiple VLANs on one interface

OK, so this was something I needed to do with CentOS 6: https://vivithemage.com/2014/08/08/centos-6-multiple-vlans-with-one-eth-device/

This is how to do it in CentOS 7. There are some slight changes required compared to CentOS 6, but they’re nominal. It’s possible it will work for CentOS 8, but it is untested. Where there is a command like vi bla/bla/file you will enter the following information in the line.

vi /etc/sysctl.conf
net.ipv4.ip_forward = 1
net.ipv4.conf.default.accept_source_route = 1
net.ipv4.conf.all.accept_source_route = 1

cd /etc/sysconfig/network-scripts/

vi ifcfg-em1
TYPE=Ethernet
DEVICE=em1
BOOTPROTO=none
ONBOOT=yes

vi ifcfg-em1.29
DEVICE=em1.29
BOOTPROTO=none
ONBOOT=yes
IPADDR=192.119.161.2
PREFIX=24
NETWORK=192.119.161.0
GATEWAY=192.119.161.1
VLAN=yes
ARPCHECK=no
NM_CONTROLLED=no

vi ifcfg-em1.33
DEVICE=em1.33
BOOTPROTO=none
ONBOOT=yes
IPADDR=192.119.165.2
PREFIX=24
GATEWAY=192.119.165.1
NETWORK=192.119.165.0
VLAN=yes
ARPCHECK=no
NM_CONTROLLED=no

vi ifcfg-em1.35
DEVICE=em1.35
BOOTPROTO=none
ONBOOT=yes
IPADDR=192.119.167.2
PREFIX=24
NETWORK=192.119.167.0
GATEWAY=192.119.167.1
VLAN=yes
ARPCHECK=no
NM_CONTROLLED=no

vi ifcfg-em1.29-range
IPADDR_START=192.119.161.3
IPADDR_END=192.119.161.254
PREFIX=24
CLONENUM_START=3
ARPCHECK=no

vi ifcfg-em1.33-range
IPADDR_START=192.119.165.3
IPADDR_END=192.119.165.254
NETMASK=255.255.255.0
CLONENUM_START=254
ARPCHECK=no

vi ifcfg-em1.35-range
IPADDR_START=192.119.167.3
IPADDR_END=192.119.167.254
NETMASK=255.255.255.0
CLONENUM_START=506
ARPCHECK=no

echo ‘default via 192.119.161.1 dev em1.29 table 1’ > route-em1.29
echo ‘default via 192.119.165.1 dev em1.33 table 2’ > route-em1.33
echo ‘default via 192.119.167.1 dev em1.35 table 3’ > route-em1.35
echo ‘from 192.119.161.2 tab 1 priority 500’ > rule-em1.29
echo ‘from 192.119.165.2 tab 2 priority 501’ > rule-em1.33
echo ‘from 192.119.167.2 tab 3 priority 502’ > rule-em1.35
echo ‘from 192.119.161.0/24 table 1’ >> rule-em1.29
echo ‘from 192.119.165.0/24 table 2’ >> rule-em1.33
echo ‘from 192.119.167.0/24 table 3’ >> rule-em1.35
THIS WORKS FOR TESTING
ip route add default via 192.119.161.1 dev em1.29 table 1
ip route add default via 192.119.165.1 dev em1.33 table 2
ip route add default via 192.119.167.1 dev em1.35 table 3
ip rule add from 192.119.161.2 tab 1 priority 500
ip rule add from 192.119.165.2 tab 2 priority 501
ip rule add from 192.119.167.2 tab 3 priority 502
ip rule add from 192.119.161.0/24 table 1
ip rule add from 192.119.165.0/24 table 2
ip rule add from 192.119.167.0/24 table 3
THIS IS REQUIRED TO PING DURING TEST – THIS ONE WIL NOT SUSTAIN REBOOT
ip route add default via 198.50.31.1
## THIS WILL SUSTAIN REBOOT – ONLY NEEDED FOR TESTING
echo 'default via 198.50.31.1' > route-em1.15
### END TESTING STUFFS

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