svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
vlan(4)
VLAN(4) BSD Kernel Interfaces Manual VLAN(4)
NAME
vlan — IEEE 802.1Q VLAN network interface
SYNOPSIS
To compile this driver into the kernel, place the following line in your
kernel configuration file:
device vlan
Alternatively, to load the driver as a module at boot time, place the
following line in loader.conf(5):
if_vlan_load="YES"
DESCRIPTION
The vlan driver demultiplexes frames tagged according to the IEEE 802.1Q
standard into logical vlan network interfaces, which allows rout‐
ing/bridging between multiple VLANs through a single switch trunk port.
Each vlan interface is created at runtime using interface cloning. This
is most easily done with the ifconfig(8) create command or using the
cloned_interfaces variable in rc.conf(5).
To function, a vlan interface must be assigned a parent interface and
numeric VLAN tag using ifconfig(8). A single parent can be assigned to
multiple vlan interfaces provided they have different tags. The parent
interface is likely to be an Ethernet card connected to a properly con‐
figured switch port. The VLAN tag should match one of those set up in
the switched network.
vlan initially assumes the same minimum length for tagged and untagged
frames. This mode is selected by setting the sysctl(8) variable
net.link.vlan.soft_pad to 0 (default). However, there are network
devices that fail to adjust frame length when it falls below the allowed
minimum due to untagging. Such devices should be able to interoperate
with vlan after changing the value of net.link.vlan.soft_pad to 1. In
the latter mode, vlan will pad short frames before tagging them so that
their length is not less than the minimum value after untagging by the
non-compliant devices.
HARDWARE
The vlan driver supports efficient operation over parent interfaces that
can provide help in processing VLANs. Such interfaces are automatically
recognized by their capabilities. Depending on the level of sophistica‐
tion found in a physical interface, it may do full VLAN processing or
just be able to receive and transmit long frames (up to 1522 bytes
including an Ethernet header and FCS). The capabilities may be user-con‐
trolled by the respective parameters to ifconfig(8), vlanhwtag, and
vlanmtu. However, a physical interface is not obliged to react to them:
It may have either capability enabled permanently without a way to turn
it off. The whole issue is very specific to a particular device and its
driver.
At present, these devices are capable of full VLAN processing in hard‐
ware: ae(4), age(4), alc(4), ale(4), bce(4), bge(4), bxe(4), cxgb(4),
cxgbe(4), em(4), igb(4), ixgbe(4), jme(4), liquidio(4), msk(4), mxge(4),
nge(4), re(4), sge(4), stge(4), ti(4), txp(4), and vge(4).
Other Ethernet interfaces can run VLANs using software emulation in the
vlan driver. However, some lack the capability of transmitting and
receiving long frames. Assigning such an interface as the parent to vlan
will result in a reduced MTU on the corresponding vlan interfaces. In
the modern Internet, this is likely to cause tcp(4) connectivity problems
due to massive, inadequate icmp(4) filtering that breaks the Path MTU
Discovery mechanism.
These interfaces natively support long frames for vlan: axe(4), bfe(4),
cas(4), dc(4), et(4), fwe(4), fxp(4), gem(4), hme(4), le(4), nfe(4),
rl(4), sf(4), sis(4), sk(4), ste(4), tl(4), tx(4), vr(4), vte(4), and
xl(4).
The vlan driver automatically recognizes devices that natively support
long frames for vlan use and calculates the appropriate frame MTU based
on the capabilities of the parent interface. Some other interfaces not
listed above may handle long frames, but they do not advertise this abil‐
ity. The MTU setting on vlan can be corrected manually if used in con‐
junction with such a parent interface.
SEE ALSO
ifconfig(8), sysctl(8)
BSD May 8, 2018 BSD