vlan(4) - NetBSD Manual Pages

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VLAN(4)                   NetBSD Programmer's Manual                   VLAN(4)


NAME

     vlan - IEEE 802.1Q Virtual LAN network device


SYNOPSIS

     pseudo-device vlan


DESCRIPTION

     The vlan interface provides support for IEEE 802.1Q Virtual LANs.  This
     allows the trunking of more than one network on a single network inter-
     face.  This is particularly useful on routers or on hosts which must be
     connected to many different networks.

     To use a vlan interface, the administrator must first create the inter-
     face and then specify the VLAN tag and physical interface associated with
     the VLAN.  This can be done by using the ifconfig(8) `create', `vlan',
     and `vlanif' subcommands, or SIOCSIFCREATE and SIOCSIFVLAN ioctls.

     To be compatible with others 802.1Q devices, the vlan 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:
     -   drivers using the dp8390 core ( ec(4), we(4), ne(4), possibly others)
     -   ex(4)
     -   fxp(4)
     -   le(4)
     -   tlp(4)
     -   epic(4)
     -   ti(4)
     vlan can be used with devices not supporting the 802.1Q MTU, but then the
     MTU of the vlan interface will be 4 bytes too small and will not interop-
     erate properly with other 802.1Q devices, unless the MTU of the remote
     end is also lowered.


SEE ALSO

     ifconfig(8)


HISTORY

     The vlan device first appeared in NetBSD 1.5.1.


BUGS

     The vlan interfaces do not currently inherit changes made to the physical
     interfaces's MTU.


AUTHOR

     The vlan driver was integrated by Andrew Doran <ad@netbsd.org> and Jason
     R. Thorpe <thorpej@zembu.com>.  It was derived from a VLAN implementation
     that appeared in FreeBSD and

NetBSD 1.5.1                  September 27, 2000                             1