vxlan — Virtual eXtensible LAN interface

       The vxlan driver was written by Bryan Venteicher <bryanv@freebsd.org>.

Debian                                          December 31, 2017                                       VXLAN(4)

       The  vxlan  driver  creates  a  virtual tunnel endpoint in a vxlan segment.  A vxlan segment is a virtual
       Layer 2 (Ethernet) network that is overlaid in a Layer 3 (IP/UDP) network.  vxlan is analogous to vlan(4)
       but is designed to be better suited for large, multiple tenant data center environments.

       Each vxlan interface is created at runtime using interface cloning.  This is most easily  done  with  the
       ifconfig(8)  create  command or using the cloned_interfaces variable in rc.conf(5).  The interface may be
       removed with the ifconfig(8) destroy command.

       The vxlan driver creates a pseudo Ethernet network interface that supports the  usual  network  ioctl(2)s
       and  is  thus  can  be  used  with  ifconfig(8)  like  any other Ethernet interface.  The vxlan interface
       encapsulates the Ethernet frame by prepending IP/UDP and vxlan headers.  Thus, the  encapsulated  (inner)
       frame is able to transmitted over a routed, Layer 3 network to the remote host.

       The  vxlan  interface  may  be configured in either unicast or multicast mode.  When in unicast mode, the
       interface creates a tunnel to a single remote host, and all traffic is transmitted to that host.  When in
       multicast mode, the interface joins an IP multicast  group,  and  receives  packets  sent  to  the  group
       address,  and  transmits  packets  to  either the multicast group address, or directly the remote host if
       there is an appropriate forwarding table entry.

       When the vxlan interface is brought up, a UDP(4) socket(9) is created based on the configuration, such as
       the local address for unicast mode or the group address for multicast mode,  and  the  listening  (local)
       port  number.   Since  multiple vxlan interfaces may be created that either use the same local address or
       join the same group address, and use the same  port,  the  driver  may  share  a  socket  among  multiple
       interfaces.   However,  each  interface  within  a  socket  must  belong  to a unique vxlan segment.  The
       analogous vlan(4) configuration would be a  physical  interface  configured  as  the  parent  device  for
       multiple  VLAN  interfaces,  each  with  a unique VLAN tag.  Each vxlan segment is identified by a 24-bit
       value in the vxlan header called the “VXLAN Network Identifier”, or VNI.

       When configured with the ifconfig(8) vxlanlearn parameter, the interface dynamically  creates  forwarding
       table  entries from received packets.  An entry in the forwarding table maps the inner source MAC address
       to the outer remote IP address.  During transmit, the interface attempts  to  lookup  an  entry  for  the
       encapsulated  destination  MAC  address.   If  an  entry is found, the IP address in the entry is used to
       directly transmit the encapsulated frame to the destination.  Otherwise,  when  configured  in  multicast
       mode, the interface must flood the frame to all hosts in the group.  The maximum number of entries in the
       table is configurable with the ifconfig(8) vxlanmaxaddr command.  Stale entries in the table periodically
       pruned.   The timeout is configurable with the ifconfig(8) vxlantimeout command.  The table may be viewed
       with the sysctl(8) net.link.vxlan.N.ftable.dump command.

       Create a vxlan interface in unicast mode with the vxlanlocal tunnel address  of  192.168.100.1,  and  the
       vxlanremote tunnel address of 192.168.100.2.

             ifconfig vxlan create vxlanid 108 vxlanlocal 192.168.100.1 vxlanremote 192.168.100.2

       Create  a  vxlan  interface  in  multicast  mode,  with the local address of 192.168.10.95, and the group
       address of 224.0.2.6.  The em0 interface will be used to transmit multicast packets.

             ifconfig vxlan create vxlanid 42 vxlanlocal 192.168.10.95 vxlangroup 224.0.2.6 vxlandev em0

       Once created, the vxlan interface can be configured with ifconfig(8).

       The following when placed in the file /etc/rc.conf will cause a vxlan interface  called  “vxlan0”  to  be
       created, and will configure the interface in unicast mode.

             cloned_interfaces="vxlan0"
             create_args_vxlan0="vxlanid 108 vxlanlocal 192.168.100.1 vxlanremote 192.168.100.2"

       Since the vxlan interface encapsulates the Ethernet  frame  with  an  IP,  UDP,  and  vxlan  header,  the
       resulting  frame  may be larger than the MTU of the physical network.  The vxlan specification recommends
       the physical network MTU be configured to use jumbo frames to accommodate the  encapsulated  frame  size.
       Alternatively,  the  ifconfig(8) mtu command may be used to reduce the MTU size on the vxlan interface to
       allow the encapsulated frame to fit in the current MTU of the physical network.

       vxlan — Virtual eXtensible LAN interface

inet(4), inet6(4), vlan(4), rc.conf(5), ifconfig(8), sysctl(8)

       M.  Mahalingam  and  et  al,  VirtualeXtensibleLocalAreaNetwork(VXLAN):AFrameworkforOverlayingVirtualizedLayer2NetworksoverLayer3Networks, August 2014, RFC 7348.

       To compile this driver into the kernel, place the following line in your kernel configuration file:

             devicevxlan

       Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

             if_vxlan_load="YES"