Differential D26436 Diff 77093 share/man/man4/vlan.4

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share/man/man4/vlan.4

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	.\" SUCH DAMAGE.			.\" SUCH DAMAGE.
	.\"			.\"
	.\" $FreeBSD$			.\" $FreeBSD$
	.\"			.\"
	.Dd May 8, 2018			.Dd May 8, 2018
	.Dt VLAN 4			.Dt VLAN 4
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm vlan			.Nm vlan ,
	.Nd "IEEE 802.1Q VLAN network interface"			.Nm svlan
				.Nd "IEEE 802.1Q/802.1ad VLAN network interfaces"
	.Sh SYNOPSIS			.Sh SYNOPSIS
	To compile this driver into the kernel,			To compile this driver into the kernel,
	place the following line in your			place the following line in your
	kernel configuration file:			kernel configuration file:
	.Bd -ragged -offset indent			.Bd -ragged -offset indent
	.Cd "device vlan"			.Cd "device vlan"
	.Ed			.Ed
	.Pp			.Pp
	Alternatively, to load the driver as a			Alternatively, to load the driver as a
	module at boot time, place the following line in			module at boot time, place the following line in
	.Xr loader.conf 5 :			.Xr loader.conf 5 :
	.Bd -literal -offset indent			.Bd -literal -offset indent
	if_vlan_load="YES"			if_vlan_load="YES"
	.Ed			.Ed
	.Sh DESCRIPTION			.Sh DESCRIPTION
	The			The
	.Nm			.Nm
	driver demultiplexes frames tagged according to			driver demultiplexes frames tagged according to
	the IEEE 802.1Q standard into logical			the IEEE 802.1Q and IEEE 802.1ad standards into logical
	.Nm			.Nm
	network interfaces, which allows routing/bridging between			and
	multiple VLANs through a single switch trunk port.			.Nm svlan
				network interfaces, respectively, allowing routing/bridging
				between multiple VLANs through a single switch trunk port.
	.Pp			.Pp
	Each			Each
	.Nm			.Nm vlan
				or
				.Nm svlan
	interface is created at runtime using interface cloning.			interface is created at runtime using interface cloning.
	This is			This is
	most easily done with the			most easily done with the
	.Xr ifconfig 8			.Xr ifconfig 8
	.Cm create			.Cm create
	command or using the			command or using the
	.Va cloned_interfaces			.Va cloned_interfaces
	variable in			variable in
	.Xr rc.conf 5 .			.Xr rc.conf 5 .
	.Pp			.Pp
	To function, a			To function, a
	.Nm			.Nm vlan
				or
				.Nm svlan
	interface must be assigned a parent interface and			interface must be assigned a parent interface and
	numeric VLAN tag using			numeric VLAN tag using
	.Xr ifconfig 8 .			.Xr ifconfig 8 .
	A single parent can be assigned to multiple			A single parent can be assigned to multiple
	.Nm			.Nm vlan
				or
				.Nm svlan
	interfaces provided they have different tags.			interfaces provided they have different tags.
	The parent interface is likely to be an Ethernet card connected			The parent interface is likely to be an Ethernet card connected
	to a properly configured switch port.			to a properly configured switch port.
	The VLAN tag should match one of those set up in the switched			The VLAN tag should match one of those set up in the switched
	network.			network.
	.Pp			.Pp
	.Nm			.Nm
	initially assumes the same minimum length for tagged and untagged frames.			initially assumes the same minimum length for tagged and untagged frames.
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	.Xr vge 4 .			.Xr vge 4 .
	.Pp			.Pp
	Other Ethernet interfaces can run VLANs using software emulation in the			Other Ethernet interfaces can run VLANs using software emulation in the
	.Nm			.Nm
	driver.			driver.
	However, some lack the capability			However, some lack the capability
	of transmitting and receiving long frames.			of transmitting and receiving long frames.
	Assigning such an interface as the parent to			Assigning such an interface as the parent to
	.Nm			.Nm vlan
	will result in a reduced MTU on the corresponding			or
	.Nm			.Nm svlan
	interfaces.			will result in a reduced MTU on the child interfaces.
	In the modern Internet, this is likely to cause			In the modern Internet, this is likely to cause
	.Xr tcp 4			.Xr tcp 4
	connectivity problems due to massive, inadequate			connectivity problems due to massive, inadequate
	.Xr icmp 4			.Xr icmp 4
	filtering that breaks the Path MTU Discovery mechanism.			filtering that breaks the Path MTU Discovery mechanism.
	.Pp			.Pp
	These interfaces natively support long frames for			These interfaces natively support long frames for
	.Nm :			.Nm :
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