007054f070
vxlan creates a virtual LAN by encapsulating the inner Ethernet frame in a UDP packet. This implementation is based on RFC7348. Currently, the IPv6 support is not fully compliant with the specification: we should be able to receive UPDv6 packets with a zero checksum, but we need to support RFC6935 first. Patches for this should come soon. Encapsulation protocols such as vxlan emphasize the need for the FreeBSD network stack to support batching, GRO, and GSO. Each frame has to make two trips through the network stack, and each frame will be at most MTU sized. Performance suffers accordingly. Some latest generation NICs have begun to support vxlan HW offloads that we should also take advantage of. VIMAGE support should also be added soon. Differential Revision: https://reviews.freebsd.org/D384 Reviewed by: gnn Relnotes: yes
236 lines
6.3 KiB
Groff
236 lines
6.3 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 October 20, 2014
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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 learn
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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 maxaddr
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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 timeout
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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.vlxan.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 local
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tunnel address of 192.168.100.1,
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and the
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.Cm remote
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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 vni 108 local 192.168.100.1 remote 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 vni 42 local 192.168.10.95 group 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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.Sh SEE ALSO
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.Xr ifconfig 8 ,
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.Xr inet 4 ,
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.Xr inet 6 ,
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.Xr sysctl 8 ,
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.Xr vlan 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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