VLANs are a way of virtually dividing up a network into many different subnetworks, also referred to as segmenting. Each segment will have its own broadcast domain and be isolated from other VLANs.
在 FreeBSD 上,要使用 VLANs 必須有網路卡驅動程式的支援,要查看那些驅動程式支援 vlan,請參考 vlan(4) 操作手冊。
When configuring a VLAN, a couple pieces of information must be known. First, which network interface? Second, what is the VLAN tag?
To configure VLANs at run time, with a
NIC of em0
and a
VLAN tag of 5
the
command would look like this:
#
ifconfig em0.5
create vlan 5
vlandev em0
inet 192.168.20.20/24
See how the interface name includes the NIC driver name and the VLAN tag, separated by a period? This is a best practice to make maintaining the VLAN configuration easy when many VLANs are present on a machine.
To configure VLANs at boot time,
/etc/rc.conf
must be updated. To duplicate
the configuration above, the following will need to be
added:
vlans_em0
="5
"
ifconfig_em0
_5
="inet 192.168.20.20/24"
Additional VLANs may be added, by simply
adding the tag to the
vlans_
field and adding an additional line configuring the network on
that VLAN tag's interface.em0
It is useful to assign a symbolic name to an interface so
that when the associated hardware is changed, only a few
configuration variables need to be updated. For example,
security cameras need to be run over VLAN 1 on
em0
. Later, if the em0
card is replaced with a card that uses the ixgb(4) driver,
all references to em0.1
will not have to
change to ixgb0.1
.
To configure VLAN
5
, on the
NIC em0
, assign the
interface name cameras
, and assign the
interface an IP address of
with a 192.168.20.20
24
-bit prefix,
use this command:
#
ifconfig em0.5
create vlan 5
vlandev em0
name cameras
inet 192.168.20.20/24
For an interface named video
, use the
following:
#
ifconfig video.5
create vlan 5
vlandev video
name cameras inet 192.168.20.20/24
To apply the changes at boot time, add the following lines to
/etc/rc.conf
:
vlans_video
="camera
"
create_args_camera
="vlan 5
"
ifconfig_camera
="inet 192.168.20.20/24
"
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