man-pages/man4/veth.4

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.TH veth 4 2017-10-03 "Linux" "Linux Programmer's Manual"
.SH NAME
veth \- Virtual Ethernet Device
.SH DESCRIPTION
The
.B veth
devices are virtual Ethernet devices.
They can act as tunnels between network namespaces to create
a bridge to a physical network device in another namespace,
but can also be used as standalone network devices.
.PP
.B veth
devices are always created in interconnected pairs.
A pair can be created using the command:
.PP
.in +4n
.EX
# ip link add <p1-name> type veth peer name <p2-name>
.EE
.in
.PP
In the above,
.I p1-name
and
.I p2-name
are the names assigned to the two connected end points.
interconnected with each other.
.PP
Packets transmitted on one device in the pair are immediately received on
the other device.
When either devices is down the link state of the pair is down. 
.PP
.B veth
device pairs are useful for combining the network
facilities of the kernel together in interesting ways.
A particularly interesting use case is to place one end of a
.B veth
pair in one network namespace and the other end in another network namespace,
thus allowing communication between network namespaces.
.PP
.BR ethtool (8)
can be used to test if a networking device is a
.B veth
device, and to find the peer network interface.
.SH "SEE ALSO"
.BR clone (2),
.BR ip (8),
.BR ip-link (8),
.BR ip-netns (8)