144 lines
4.0 KiB
Groff
144 lines
4.0 KiB
Groff
.\"
|
|
.\" Copyright (c) 2001 Yar Tikhiy
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd July 25, 2001
|
|
.Dt VLAN 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm vlan
|
|
.Nd IEEE 802.1Q VLAN network interface
|
|
.Sh SYNOPSIS
|
|
.\" In -stable: .Cd pseudo-device vlan Op Ar count
|
|
.Cd device vlan Op Ar count
|
|
.\"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
driver demultiplexes frames tagged according to
|
|
the IEEE 802.1Q standard into logical
|
|
.Nm
|
|
network interfaces, which allows routing/bridging between
|
|
multiple VLANs through a single switch trunk port.
|
|
.Pp
|
|
To function, a
|
|
.Nm
|
|
interface must be assigned a parent interface and
|
|
numeric VLAN tag using
|
|
.Xr ifconfig 8 .
|
|
A single parent can be assigned to multiple
|
|
.Nm
|
|
interfaces provided they have different tags.
|
|
The parent interface is likely to be an ethernet card connected
|
|
to a properly configured switch port.
|
|
The VLAN tag should match one of those set up in the switched
|
|
network.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
driver supports physical devices that do
|
|
the VLAN demultiplexing in firmware.
|
|
The
|
|
.Ar link0
|
|
flag should be set on a
|
|
.Nm
|
|
interface
|
|
.Pq Em not on its parent
|
|
using
|
|
.Xr ifconfig 8
|
|
in that case to indicate that the hardware support for
|
|
the 802.1Q VLANs is present in its parent.
|
|
.\"
|
|
.Ss "Selecting the Right Network Interface Card to Run VLANs Through"
|
|
By now, the only NICs that have both hardware support and proper
|
|
driver hooks for the 802.1Q VLAN technology in
|
|
.Fx
|
|
are
|
|
.Xr nge 4 ,
|
|
.Xr ti 4 ,
|
|
and
|
|
.\" not in -stable
|
|
.Xr txp 4 .
|
|
.Pp
|
|
The rest of the ethernet NICs supported by
|
|
.Fx
|
|
can run
|
|
VLANs using the software emulation in the
|
|
.Nm
|
|
driver.
|
|
However, most of them lack the capability
|
|
of transmitting and/or receiving oversized frames.
|
|
Using such a NIC as a parent interface for a
|
|
.Nm
|
|
implies a reduced MTU on the corresponding
|
|
.Nm
|
|
interfaces.
|
|
In the modern Internet, this is likely to cause
|
|
.Xr tcp 4
|
|
connectivity problems due to massive, inadequate
|
|
.Xr icmp 4
|
|
filtering that breaks the Path MTU Discovery mechanism.
|
|
.Pp
|
|
The NICs that support oversized frames are as follows:
|
|
.Bl -tag -width "fxp(4)" -compact -offset indent
|
|
.It Xr de 4
|
|
requires defining
|
|
.Dv BIG_PACKET
|
|
in the
|
|
.Pa /usr/src/sys/pci/if_de.c
|
|
source file and rebuilding the kernel
|
|
.\" not in -stable
|
|
or module.
|
|
The hack works only for the 21041, 21140, and 21140A chips.
|
|
.It Xr fxp 4
|
|
supports long frames for the
|
|
.Nm
|
|
natively.
|
|
.It Xr tl 4
|
|
does support long frames.
|
|
.It Xr tx 4
|
|
may begin supporting long frames soon.
|
|
.It Xr xl 4
|
|
supports long frames only if the card is built on a newer chip
|
|
.Pq Cyclone and above .
|
|
.El
|
|
Note:
|
|
Except for
|
|
.Xr fxp 4 ,
|
|
none of the above drivers inform the
|
|
.Nm
|
|
driver about their support for long frames.
|
|
Just fix the MTU of a
|
|
.Nm
|
|
interface if it appears to be lower that 1500 bytes after
|
|
attaching the
|
|
.Nm
|
|
to a parent interface that is known to support long frames.
|
|
.Sh SEE ALSO
|
|
.Xr ifconfig 8
|
|
.Sh BUGS
|
|
No 802.1Q features except VLAN tagging are implemented.
|