ifconfig_fxp0="inet 192.168.1.5 netmask 255.255.255.0"
ifconfig_carp0="vhid 1 advskew 100 pass testpass 192.168.1.50/24"
ifconfig_carp1="vhid 2 advskew 100 pass testpass 192.168.1.51/24"
|Preemption is disabled in the [.filename]#GENERIC# FreeBSD kernel. If preemption has been enabled with a custom kernel, `hostc.example.org` may not release the IP address back to the original content server. The administrator can force the backup server to return the IP address to the master with the command:|
# ifconfig carp0 down && ifconfig carp0 up
|This should be done on the [.filename]#carp# interface which corresponds to the correct host.|
|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.|
|On FreeBSD, VLANs must be supported by the network card driver. To see which drivers support vlans, refer to the man:vlan manual page.|
|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, [.filename]#/etc/rc.conf# must be updated. To duplicate the configuration above, the following will need to be added:|
|Additional VLANs may be added, by simply adding the tag to the `vlans_em0` field and adding an additional line configuring the network on that VLAN tag's interface.|
|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 man:ixgb 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 `_192.168.20.20_` with a `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 [.filename]#/etc/rc.conf#:|