1.\" $NetBSD: vlan.4,v 1.18 2001/12/18 13:31:45 ad Exp $ 2.\" 3.\" Copyright (c) 2000 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Jason R. Thorpe of Zembu Labs, Inc. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd June 26, 2001 38.Dt VLAN 4 39.Os 40.Sh NAME 41.Nm vlan 42.Nd IEEE 802.1Q Virtual LAN network device 43.Sh SYNOPSIS 44.Cd "pseudo-device vlan" 45.Sh DESCRIPTION 46The 47.Nm 48interface provides support for IEEE 802.1Q Virtual LANs. This allows the 49trunking of more than one network on a single network interface. 50This is particularly useful on routers or on hosts which must be 51connected to many different networks. 52.Pp 53To use a 54.Nm vlan 55interface, the administrator must first create the interface and then 56specify the VLAN tag and physical interface associated with the VLAN. 57This can be done by using the 58.Xr ifconfig 8 59.Sq create , 60.Sq vlan , 61and 62.Sq vlanif 63subcommands, or 64.Dv SIOCSIFCREATE 65and 66.Dv SIOCSIFVLAN 67ioctls. 68.Pp 69To be compatible with others 802.1Q devices, the 70.Nm 71interface shall support a 1500 bytes MTU, which means that the parent 72interface will have to handle frames that are 4 bytes larger than the 73Ethernet MTU. Drivers supporting this increased MTU are: 74.Pp 75.Bl -dash -compact 76.It 77drivers using the dp8390 core 78.Ns ( Ns Xr ec 4 , 79.Xr ne 4 , 80.Xr we 4 , 81possibly others) 82.It 83.Xr ea 4 84.It 85.Xr eb 4 86.It 87.Xr epic 4 88.It 89.Xr ex 4 90.It 91.Xr fxp 4 92.It 93.Xr hme 4 94.It 95.Xr le 4 96.It 97.Xr tlp 4 98.It 99.Xr ti 4 100.It 101.Xr xi 4 102.El 103.Pp 104.Nm 105can be used with devices not supporting the 802.1Q MTU, but then the MTU of the 106.Nm 107interface will be 4 bytes too small and will not interoperate properly with 108other 802.1Q devices, unless the MTU of the remote end is also lowered. 109.Sh SEE ALSO 110.Xr ifconfig 8 111.Sh HISTORY 112The 113.Nm 114device first appeared in 115.Nx 1.5.1 . 116.Sh AUTHORS 117The 118.Nm 119driver was integrated by 120.An Andrew Doran 121.Aq ad@netbsd.org 122and 123.An Jason R. Thorpe 124.Aq thorpej@zembu.com . 125It was derived from a VLAN implementation that appeared in 126.Fx 127and 128.Ox . 129.Sh BUGS 130The 131.Nm 132interfaces do not currently inherit changes made to the physical 133interfaces's MTU. 134