NetBSD/share/man/man4/vlan.4

.\"	$NetBSD: vlan.4,v 1.10 2001/04/26 09:36:26 wiz Exp $
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.\" Copyright (c) 2000 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jason R. Thorpe of Zembu Labs, Inc.
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.Dd September 27, 2000
.Dt VLAN 4
.Os
.Sh NAME
.Nm vlan
.Nd 802.1Q Virtual LAN network device
.Sh SYNOPSIS
.Cd "pseudo-device vlan"
.Sh DESCRIPTION
The
.Nm
interface provides support for 802.1Q Virtual LANs.  This allows the
trunking of more than one network on a single network interface.
This is particularly useful on routers or on hosts which must be
connected to many different networks.
.Pp
To use a
.Nm vlan
interface, the administrator must first create the interface and then
specify the VLAN tag and physical interface associated with the VLAN.
This can be done by using the
.Xr ifconfig 8
.Sq create ,
.Sq vlan ,
and
.Sq vlanif
subcommands, or
.Dv SIOCSIFCREATE
and
.Dv SIOCSIFVLAN
ioctls.
.Pp
To be compatible with others 802.1Q devices, the
.Nm
interface shall support a 1500 bytes MTU, which means that the parent
interface will have to handle frames that are 4 bytes larger than the
ethernet MTU. Drivers supporting this increased MTU are:
.Bl -dash -compact indent
.It
drivers using the dp8390 core (
.Xr ec 4 ,
.Xr we 4 ,
.Xr ne 4 ,
possibly others)
.It
.Xr ex 4
.It
.Xr fxp 4
.It
.Xr le 4
.It
.Xr tlp 4
.It
.Xr epic 4
.It
.Xr ti 4
.El
.Nm
can be used with devices not supporting the 802.1Q MTU, but then the MTU of the
.Nm
interface will be 4 bytes too small and will not interoperate properly with
other 802.1Q devices, unless the MTU of the remote end is also lowered.
.Sh SEE ALSO
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
device first appeared in
.Nx 1.6 .
.Sh BUGS
The
.Nm
interfaces do not currently inherit changes made to the physical
interfaces's MTU.
.Sh AUTHOR
The
.Nm
driver was integrated by
.An Andrew Doran
.Aq ad@netbsd.org
and
.An Jason R. Thorpe
.Aq thorpej@zembu.com .
It was derived from a VLAN implementation that appeared in
.Fx
and
.Ox .