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$FreeBSD: releng/10.2/share/man/man4/epair.4 281571 2015-04-16 00:27:53Z allanjude $
.Dd March 18, 2015 .Dt EPAIR 4 .Os .Sh NAME .Nm epair .Nd A pair of virtual back-to-back connected Ethernet interfaces .Sh SYNOPSIS To compile this driver into the kernel, place the following line in your kernel configuration file: d -ragged -offset indent .Cd "device epair" .Ed
p Alternatively, to load the driver as a module at boot time, place the following line in .Xr loader.conf 5 : d -literal -offset indent if_epair_load="YES" .Ed .Sh DESCRIPTION The .Nm is a pair of Ethernet-like software interfaces, which are connected back-to-back with a virtual cross-over cable.
p Each .Nm interface pair 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 . While for cloning you only give either
a epair or
a epair<n> the .Nm pair will be named like
a epair<n>[ab] . This means the names of the first .Nm interfaces will be
a epair0a and
a epair0b .
p Like any other Ethernet interface, an .Nm needs to have a network address. Each .Nm will be assigned a locally administered address by default, that is only guaranteed to be unique within one network stack. To change the default addresses one may use the SIOCSIFADDR ioctl(2) or ifconfig(8) utility.
p The basic intent is to provide connectivity between two virtual network stack instances. When connected to an .Xr if_bridge 4 , one end of the interface pair can also be part of another (virtual) LAN. As with any other Ethernet interface, .Nm epair can have a .Xr vlan 4 configured on top of it. .Sh SEE ALSO .Xr ioctl 2 , .Xr altq 4 , .Xr bpf 4 , .Xr if_bridge 4 , .Xr vlan 4 , .Xr loader.conf 5 , .Xr rc.conf 5 , .Xr ifconfig 8 .Sh HISTORY The .Nm interface first appeared in .Fx 8.0 . .Sh AUTHORS The .Nm interface was written by .An Bjoern A. Zeeb, CK Software GmbH, under sponsorship from the FreeBSD Foundation.