247 lines
6.7 KiB
Groff
247 lines
6.7 KiB
Groff
.\" Copyright (c) 2014 Bryan Venteicher
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 31, 2017
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.Dt VXLAN 4
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.Os
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.Sh NAME
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.Nm vxlan
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.Nd "Virtual eXtensible LAN interface"
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device vxlan"
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.Ed
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.Pp
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Alternatively, to load the driver as a
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module at boot time, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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if_vxlan_load="YES"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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driver creates a virtual tunnel endpoint in a
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.Nm
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segment.
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A
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.Nm
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segment is a virtual Layer 2 (Ethernet) network that is overlaid
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in a Layer 3 (IP/UDP) network.
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.Nm
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is analogous to
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.Xr vlan 4
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but is designed to be better suited for large, multiple tenant
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data center environments.
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.Pp
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Each
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.Nm
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interface is created at runtime using interface cloning.
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This is most easily done with the
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.Xr ifconfig 8
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.Cm create
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command or using the
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.Va cloned_interfaces
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variable in
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.Xr rc.conf 5 .
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The interface may be removed with the
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.Xr ifconfig 8
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.Cm destroy
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command.
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.Pp
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The
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.Nm
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driver creates a pseudo Ethernet network interface
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that supports the usual network
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.Xr ioctl 2 Ns s
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and is thus can be used with
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.Xr ifconfig 8
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like any other Ethernet interface.
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The
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.Nm
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interface encapsulates the Ethernet frame
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by prepending IP/UDP and
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.Nm
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headers.
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Thus, the encapsulated (inner) frame is able to transmitted
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over a routed, Layer 3 network to the remote host.
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.Pp
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The
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.Nm
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interface may be configured in either unicast or multicast mode.
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When in unicast mode,
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the interface creates a tunnel to a single remote host,
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and all traffic is transmitted to that host.
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When in multicast mode,
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the interface joins an IP multicast group,
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and receives packets sent to the group address,
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and transmits packets to either the multicast group address,
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or directly the remote host if there is an appropriate
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forwarding table entry.
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.Pp
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When the
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.Nm
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interface is brought up, a
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.Xr UDP 4
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.Xr socket 9
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is created based on the configuration,
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such as the local address for unicast mode or
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the group address for multicast mode,
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and the listening (local) port number.
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Since multiple
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.Nm
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interfaces may be created that either
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use the same local address
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or join the same group address,
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and use the same port,
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the driver may share a socket among multiple interfaces.
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However, each interface within a socket must belong to
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a unique
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.Nm
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segment.
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The analogous
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.Xr vlan 4
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configuration would be a physical interface configured as
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the parent device for multiple VLAN interfaces, each with
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a unique VLAN tag.
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Each
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.Nm
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segment is identified by a 24-bit value in the
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.Nm
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header called the
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.Dq VXLAN Network Identifier ,
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or VNI.
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.Pp
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When configured with the
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.Xr ifconfig 8
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.Cm vxlanlearn
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parameter, the interface dynamically creates forwarding table entries
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from received packets.
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An entry in the forwarding table maps the inner source MAC address
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to the outer remote IP address.
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During transmit, the interface attempts to lookup an entry for
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the encapsulated destination MAC address.
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If an entry is found, the IP address in the entry is used to directly
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transmit the encapsulated frame to the destination.
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Otherwise, when configured in multicast mode,
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the interface must flood the frame to all hosts in the group.
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The maximum number of entries in the table is configurable with the
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.Xr ifconfig 8
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.Cm vxlanmaxaddr
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command.
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Stale entries in the table periodically pruned.
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The timeout is configurable with the
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.Xr ifconfig 8
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.Cm vxlantimeout
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command.
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The table may be viewed with the
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.Xr sysctl 8
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.Cm net.link.vxlan.N.ftable.dump
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command.
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.Sh MTU
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Since the
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.Nm
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interface encapsulates the Ethernet frame with an IP, UDP, and
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.Nm
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header, the resulting frame may be larger than the MTU of the
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physical network.
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The
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.Nm
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specification recommends the physical network MTU be configured
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to use jumbo frames to accommodate the encapsulated frame size.
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Alternatively, the
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.Xr ifconfig 8
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.Cm mtu
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command may be used to reduce the MTU size on the
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.Nm
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interface to allow the encapsulated frame to fit in the
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current MTU of the physical network.
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.Sh EXAMPLES
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Create a
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.Nm
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interface in unicast mode
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with the
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.Cm vxlanlocal
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tunnel address of 192.168.100.1,
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and the
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.Cm vxlanremote
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tunnel address of 192.168.100.2.
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.Bd -literal -offset indent
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ifconfig vxlan create vxlanid 108 vxlanlocal 192.168.100.1 vxlanremote 192.168.100.2
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.Ed
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.Pp
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Create a
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.Nm
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interface in multicast mode,
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with the
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.Cm local
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address of 192.168.10.95,
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and the
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.Cm group
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address of 224.0.2.6.
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The em0 interface will be used to transmit multicast packets.
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.Bd -literal -offset indent
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ifconfig vxlan create vxlanid 42 vxlanlocal 192.168.10.95 vxlangroup 224.0.2.6 vxlandev em0
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.Ed
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.Pp
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Once created, the
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.Nm
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interface can be configured with
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.Xr ifconfig 8 .
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.Ed
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.Pp
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The following when placed in the file
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.Pa /etc/rc.conf
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will cause a vxlan interface called
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.Dq Li vxlan0
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to be created, and will configure the interface in unicast mode.
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.Bd -literal -offset indent
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cloned_interfaces="vxlan0"
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create_args_vxlan0="vxlanid 108 vxlanlocal 192.168.100.1 vxlanremote 192.168.100.2"
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.Sh SEE ALSO
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.Xr inet 4 ,
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.Xr inet6 4 ,
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.Xr vlan 4 ,
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.Xr rc.conf 5 ,
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.Xr ifconfig 8 ,
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.Xr sysctl 8
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.Rs
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.%A "M. Mahalingam"
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.%A "et al"
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.%T "Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks"
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.%D August 2014
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.%O "RFC 7348"
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.Re
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.Sh AUTHOR
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.An -nosplit
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The
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.Nm
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driver was written by
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.An Bryan Venteicher Aq bryanv@freebsd.org .
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