vxlan (4)

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Copyright (c) 2014 Bryan Venteicher
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(The comments found at the beginning of the groff file "man4/vxlan.4freebsd".)

NAME

vxlan - Virtual eXtensible LAN interface

SYNOPSIS

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

device vxlan

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf5:

if_vxlan_load="YES"

DESCRIPTION

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

Each 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.conf5. The interface may be removed with the ifconfig(8) destroy command.

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

The 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 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 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 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 segment is identified by a 24-bit value in the 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.

MTU

Since the interface encapsulates the Ethernet frame with an IP, UDP, and header, the resulting frame may be larger than the MTU of the physical network. The 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 interface to allow the encapsulated frame to fit in the current MTU of the physical network.

EXAMPLES

Create a 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 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 interface can be configured with ifconfig(8).

SEE ALSO

inet(4), inet6(4), vlan(4), ifconfig(8), sysctl(8)

"M. Mahalingam" "et al" "Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks" August 2014 "RFC 7348"

AUTHOR

An -nosplit The driver was written by An Bryan Venteicher Aq bryanv@freebsd.org .