FreeBSD supports IEEE 802.1Q-VLANs. Example Configuration.
FreeBSD-Host ---Ethernet--- Cisco Switch
First you need to add the following Kernel Option to your kernel. (see Handbook for details about compiling and installing a customized kernel)
pseudo-device vlan 2 # IEEE 802.1Q VLAN SupportThe number at the end defines how many VLAN-devices your machine gets. (Don't panic, if you don't find the vlan0 Entry in your /dev. Pseudo-devices have none.)
Update Since December 2001 you don't need to specify a number. Instead you create the vlandevice dynamic:
ifconfig vlan_device create
The vlan0 device is configured this way:
ifconfig vlan_device vlan vlan_id vlandev parent_deviceUpdate: Since FreeBSD 5.3 a vlan device can be created and configured with one command:
ifconfig vlan_device.vlan_id createparent_device is the NIC which is connected to the 802.1q-Trunk.
ifconfig vlan0 vlan 34 vlandev xl0After that, you need an IP-adress for every vlan:
ifconfig vlan0 inet 126.96.36.199 netmask 255.255.255.128The output of ifconfig now looks like this:
xl0: flags=8843If you want to set up dot1q-Trunking on System startup, you may edit your /etc/rc.conf.
mtu 1500 inet 188.8.131.52 netmask 0xffffff80 broadcast 184.108.40.206 inet6 fe80::204:76ff:fe12:acba%xl0 prefixlen 64 scopeid 0x1 ether 00:04:76:12:ac:ba media: autoselect (100baseTX ) status: active supported media: autoselect 100baseTX 100baseTX 10baseT/UTP 10baseT/UTP 100baseTX vlan0: flags=8843 mtu 1496 inet 220.127.116.11 netmask 0xffffff00 broadcast 18.104.22.168 inet6 fe80::204:76ff:fe12:acba%vlan0 prefixlen 64 scopeid 0x3 ether 00:04:76:12:ac:ba vlan: 34 parent interface: xl0
cloned_interfaces="vlan0" #You need a recent STABLE for this else use: #network_interfaces="lo0 vlan0" ifconfig_vlan0="inet 22.214.171.124 netmask 255.255.255.128 vlan 34 vlandev xl0" #Note: If you do not assign an IP Adress to your parent device, you need to #start it explicitly: ifconfig_xl0="up"As an alternative you can create a script with the name /etc/start_if.xl0 (After the dot is the name of the Parent device) and add the necessary commands there. But this is less elegant. Now an example how to configure the other end, a Cisco switch with "Catalyst" OS.
switch#(enable) clear trunk 3/28 1-33,37-333,335,337-1005 switch#(enable) set trunk 3/28 on dot1q 34-36,334,336The first command disallows some VLANs, the second one allows specific VLANs.
If you do now connect your NIC to the switch, you should see something like this on the Switch Console:
2001 Jul 30 17:42:05 MDT +02:00 %DTP-5-TRUNKPORTON:Port 3/28 has become dot1q trunk 2001 Jul 30 17:42:18 MDT +02:00 %PAGP-5-PORTTOSTP:Port 3/28 joined bridge port 3/28sThe command
show trunkcan be used to control the trunk state.
An example for an Cisco Switch with "IOS". (The following commands should be entred in the "configure"-mode).
interface FastEthernet0/11 switchport trunk encapsulation dot1q switchport trunk allowed vlan 34 switchport mode trunk
With the VLAN-pseudodevices it is now possible to replace an expensive route-switch module with an old PC.
I would be glad about Comments, Corrections and Improvements. Please send an email to: arved@FreeBSD.org