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diff --git a/share/man/man4/vlan.4 b/share/man/man4/vlan.4 new file mode 100644 index 000000000000..8467d1afbf65 --- /dev/null +++ b/share/man/man4/vlan.4 @@ -0,0 +1,198 @@ +.\" +.\" 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 November 12, 2008 +.Dt VLAN 4 +.Os +.Sh NAME +.Nm vlan +.Nd "IEEE 802.1Q VLAN network interface" +.Sh SYNOPSIS +To compile this driver into the kernel, +place the following lines in your +kernel configuration file: +.Bd -ragged -offset indent +.Cd "device vlan" +.Ed +.Pp +Alternatively, to load the driver as a +module at boot time, place the following line in +.Xr loader.conf 5 : +.Bd -literal -offset indent +if_vlan_load="YES" +.Ed +.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 +Each +.Nm +interface is created at runtime using interface cloning. +This is +most easily done with the +.Xr ifconfig 8 +.Cm create +command or using the +.Va cloned_interfaces +variable in +.Xr rc.conf 5 . +.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 +Initially +.Nm +assumes the same minimum length for tagged and untagged frames. +This mode is selected by the +.Xr sysctl 8 +variable +.Va net.link.vlan.soft_pad +set to 0 (default). +However, there are network devices that fail to adjust frame length, +should it fall below the allowed minimum due to untagging. +Such devices should be able to interoperate with +.Nm +after changing the value of +.Va net.link.vlan.soft_pad +to 1. +In the latter mode, +.Nm +will pad short frames before tagging them +so that their length stays not less than the minimum value +after untagging by the non-compliant devices. +.Sh HARDWARE +The +.Nm +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 sophistication 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-controlled by the respective parameters to +.Xr ifconfig 8 , +.Cm vlanhwtag +and +.Cm 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. +.Pp +By now, the list of physical interfaces able of full VLAN processing +in the hardware is limited to the following devices: +.Xr ae 4 , +.Xr age 4 , +.Xr ale 4 , +.Xr bce 4 , +.Xr bge 4 , +.Xr cxgb 4 , +.Xr em 4 , +.Xr ixgb 4 , +.Xr jme 4 , +.Xr msk 4 , +.Xr nge 4 , +.Xr re 4 , +.Xr stge 4 , +.Xr ti 4 , +.Xr txp 4 , +and +.Xr vge 4 . +.Pp +The rest of the Ethernet interfaces can run +VLANs using software emulation in the +.Nm +driver. +However, some of them lack the capability +of transmitting and receiving long frames. +Assigning such an interface as the parent to +.Nm +will result in 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 following interfaces support long frames for +.Nm +natively: +.Xr bfe 4 , +.Xr dc 4 , +.Xr fwe 4 , +.Xr fxp 4 , +.Xr gem 4 , +.Xr hme 4 , +.Xr le 4 , +.Xr nfe 4 , +.Xr nve 4 , +.Xr rl 4 , +.Xr sf 4 , +.Xr sis 4 , +.Xr sk 4 , +.Xr ste 4 , +.Xr tl 4 , +.Xr tx 4 , +.Xr vr 4 , +and +.Xr xl 4 . +.Pp +The +.Nm +driver automatically recognizes devices that natively support long frames +for +.Nm +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 ability of theirs. +The MTU setting on +.Nm +can be corrected manually if used in conjunction with such a parent interface. +.Sh SEE ALSO +.Xr ifconfig 8 , +.Xr sysctl 8 +.Sh BUGS +No 802.1Q features except VLAN tagging are implemented. |