vlan(4)
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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), ne(4), we(4), possibly others)
- ea(4)
- eb(4)
- epic(4)
- ex(4)
- fxp(4)
- hme(4)
- le(4)
- tlp(4)
- ti(4)
- xi(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.
AUTHORS
The vlan driver was integrated by Andrew Doran <ad@netbsd.org> and
Jason R. Thorpe <thorpej@zembu.com>. It was derived from a VLAN imple-
mentation that appeared in FreeBSD and OpenBSD.
BUGS
The vlan interfaces do not currently inherit changes made to the physical
interfaces's MTU.
NetBSD 1.6 June 26, 2001 1
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