Provided by: systemd_237-3ubuntu10_amd64 bug

NAME

       systemd.netdev - Virtual Network Device configuration

SYNOPSIS

       netdev.netdev

DESCRIPTION

       Network setup is performed by systemd-networkd(8).

       The main Virtual Network Device file must have the extension .netdev; other extensions are
       ignored. Virtual network devices are created as soon as networkd is started. If a netdev
       with the specified name already exists, networkd will use that as-is rather than create
       its own. Note that the settings of the pre-existing netdev will not be changed by
       networkd.

       The .netdev files are read from the files located in the system network directory
       /lib/systemd/network, the volatile runtime network directory /run/systemd/network and the
       local administration network directory /etc/systemd/network. All configuration files are
       collectively sorted and processed in lexical order, regardless of the directories in which
       they live. However, files with identical filenames replace each other. Files in /etc have
       the highest priority, files in /run take precedence over files with the same name in /lib.
       This can be used to override a system-supplied configuration file with a local file if
       needed. As a special case, an empty file (file size 0) or symlink with the same name
       pointing to /dev/null disables the configuration file entirely (it is "masked").

       Along with the netdev file foo.netdev, a "drop-in" directory foo.netdev.d/ may exist. All
       files with the suffix ".conf" from this directory will be parsed after the file itself is
       parsed. This is useful to alter or add configuration settings, without having to modify
       the main configuration file. Each drop-in file must have appropriate section headers.

       In addition to /etc/systemd/network, drop-in ".d" directories can be placed in
       /lib/systemd/network or /run/systemd/network directories. Drop-in files in /etc take
       precedence over those in /run which in turn take precedence over those in /lib. Drop-in
       files under any of these directories take precedence over the main netdev file wherever
       located. (Of course, since /run is temporary and /usr/lib is for vendors, it is unlikely
       drop-ins should be used in either of those places.)

SUPPORTED NETDEV KINDS

       The following kinds of virtual network devices may be configured in .netdev files:

       Table 1. Supported kinds of virtual network devices
       ┌──────────┬──────────────────────────────────┐
       │KindDescription                      │
       ├──────────┼──────────────────────────────────┤
       │bond      │ A bond device is an aggregation  │
       │          │ of all its slave devices. See    │
       │          │ Linux Ethernet Bonding Driver    │
       │          │ HOWTO[1] for details.Local       │
       │          │ configuration                    │
       ├──────────┼──────────────────────────────────┤
       │bridge    │ A bridge device is a software    │
       │          │ switch, and each of its slave    │
       │          │ devices and the bridge itself    │
       │          │ are ports of the switch.         │
       ├──────────┼──────────────────────────────────┤
       │dummy     │ A dummy device drops all packets │
       │          │ sent to it.                      │
       ├──────────┼──────────────────────────────────┤
       │gre       │ A Level 3 GRE tunnel over IPv4.  │
       │          │ See RFC 2784[2] for details.     │
       ├──────────┼──────────────────────────────────┤
       │gretap    │ A Level 2 GRE tunnel over IPv4.  │
       ├──────────┼──────────────────────────────────┤
       │ip6gre    │ A Level 3 GRE tunnel over IPv6.  │
       ├──────────┼──────────────────────────────────┤
       │ip6tnl    │ An IPv4 or IPv6 tunnel over IPv6 │
       ├──────────┼──────────────────────────────────┤
       │ip6gretap │ A Level 2 GRE tunnel over IPv6.  │
       ├──────────┼──────────────────────────────────┤
       │ipip      │ An IPv4 over IPv4 tunnel.        │
       ├──────────┼──────────────────────────────────┤
       │ipvlan    │ An ipvlan device is a stacked    │
       │          │ device which receives packets    │
       │          │ from its underlying device based │
       │          │ on IP address filtering.         │
       ├──────────┼──────────────────────────────────┤
       │macvlan   │ A macvlan device is a stacked    │
       │          │ device which receives packets    │
       │          │ from its underlying device based │
       │          │ on MAC address filtering.        │
       ├──────────┼──────────────────────────────────┤
       │macvtap   │ A macvtap device is a stacked    │
       │          │ device which receives packets    │
       │          │ from its underlying device based │
       │          │ on MAC address filtering.        │
       ├──────────┼──────────────────────────────────┤
       │sit       │ An IPv6 over IPv4 tunnel.        │
       ├──────────┼──────────────────────────────────┤
       │tap       │ A persistent Level 2 tunnel      │
       │          │ between a network device and a   │
       │          │ device node.                     │
       ├──────────┼──────────────────────────────────┤
       │tun       │ A persistent Level 3 tunnel      │
       │          │ between a network device and a   │
       │          │ device node.                     │
       ├──────────┼──────────────────────────────────┤
       │veth      │ An Ethernet tunnel between a     │
       │          │ pair of network devices.         │
       ├──────────┼──────────────────────────────────┤
       │vlan      │ A VLAN is a stacked device which │
       │          │ receives packets from its        │
       │          │ underlying device based on VLAN  │
       │          │ tagging. See IEEE 802.1Q[3] for  │
       │          │ details.                         │
       ├──────────┼──────────────────────────────────┤
       │vti       │ An IPv4 over IPSec tunnel.       │
       ├──────────┼──────────────────────────────────┤
       │vti6      │ An IPv6 over IPSec tunnel.       │
       ├──────────┼──────────────────────────────────┤
       │vxlan     │ A virtual extensible LAN         │
       │          │ (vxlan), for connecting Cloud    │
       │          │ computing deployments.           │
       ├──────────┼──────────────────────────────────┤
       │geneve    │ A GEneric NEtwork Virtualization │
       │          │ Encapsulation (GENEVE) netdev    │
       │          │ driver.                          │
       ├──────────┼──────────────────────────────────┤
       │vrf       │ A Virtual Routing and Forwarding │
       │          │ (VRF[4]) interface to create     │
       │          │ separate routing and forwarding  │
       │          │ domains.                         │
       ├──────────┼──────────────────────────────────┤
       │vcan      │ The virtual CAN driver (vcan).   │
       │          │ Similar to the network loopback  │
       │          │ devices, vcan offers a virtual   │
       │          │ local CAN interface.             │
       ├──────────┼──────────────────────────────────┤
       │vxcan     │ The virtual CAN tunnel driver    │
       │          │ (vxcan). Similar to the virtual  │
       │          │ ethernet driver veth, vxcan      │
       │          │ implements a local CAN traffic   │
       │          │ tunnel between two virtual CAN   │
       │          │ network devices. When creating a │
       │          │ vxcan, two vxcan devices are     │
       │          │ created as pair. When one end    │
       │          │ receives the packet it appears   │
       │          │ on its pair and vice versa. The  │
       │          │ vxcan can be used for cross      │
       │          │ namespace communication.         │
       ├──────────┼──────────────────────────────────┤
       │wireguard │ WireGuard Secure Network Tunnel. │
       └──────────┴──────────────────────────────────┘

[MATCH] SECTION OPTIONS

       A virtual network device is only created if the "[Match]" section matches the current
       environment, or if the section is empty. The following keys are accepted:

       Host=
           Matches against the hostname or machine ID of the host. See "ConditionHost=" in
           systemd.unit(5) for details.

       Virtualization=
           Checks whether the system is executed in a virtualized environment and optionally test
           whether it is a specific implementation. See "ConditionVirtualization=" in
           systemd.unit(5) for details.

       KernelCommandLine=
           Checks whether a specific kernel command line option is set (or if prefixed with the
           exclamation mark unset). See "ConditionKernelCommandLine=" in systemd.unit(5) for
           details.

       KernelVersion=
           Checks whether the kernel version (as reported by uname -r) matches a certain
           expression (or if prefixed with the exclamation mark does not match it). See
           "ConditionKernelVersion=" in systemd.unit(5) for details.

       Architecture=
           Checks whether the system is running on a specific architecture. See
           "ConditionArchitecture=" in systemd.unit(5) for details.

[NETDEV] SECTION OPTIONS

       The "[NetDev]" section accepts the following keys:

       Description=
           A free-form description of the netdev.

       Name=
           The interface name used when creating the netdev. This option is compulsory.

       Kind=
           The netdev kind. This option is compulsory. See the "Supported netdev kinds" section
           for the valid keys.

       MTUBytes=
           The maximum transmission unit in bytes to set for the device. The usual suffixes K, M,
           G, are supported and are understood to the base of 1024. This key is not currently
           supported for "tun" or "tap" devices.

       MACAddress=
           The MAC address to use for the device. If none is given, one is generated based on the
           interface name and the machine-id(5). This key is not currently supported for "tun" or
           "tap" devices.

[BRIDGE] SECTION OPTIONS

       The "[Bridge]" section only applies for netdevs of kind "bridge", and accepts the
       following keys:

       HelloTimeSec=
           HelloTimeSec specifies the number of seconds between two hello packets sent out by the
           root bridge and the designated bridges. Hello packets are used to communicate
           information about the topology throughout the entire bridged local area network.

       MaxAgeSec=
           MaxAgeSec specifies the number of seconds of maximum message age. If the last seen
           (received) hello packet is more than this number of seconds old, the bridge in
           question will start the takeover procedure in attempt to become the Root Bridge
           itself.

       ForwardDelaySec=
           ForwardDelaySec specifies the number of seconds spent in each of the Listening and
           Learning states before the Forwarding state is entered.

       AgeingTimeSec=
           This specifies the number of seconds a MAC Address will be kept in the forwarding
           database after having a packet received from this MAC Address.

       Priority=
           The priority of the bridge. An integer between 0 and 65535. A lower value means higher
           priority. The bridge having the lowest priority will be elected as root bridge.

       GroupForwardMask=
           A 16-bit bitmask represented as an integer which allows forwarding of link local
           frames with 802.1D reserved addresses (01:80:C2:00:00:0X). A logical AND is performed
           between the specified bitmask and the exponentiation of 2^X, the lower nibble of the
           last octet of the MAC address. For example, a value of 8 would allow forwarding of
           frames addressed to 01:80:C2:00:00:03 (802.1X PAE).

       DefaultPVID=
           This specifies the default port VLAN ID of a newly attached bridge port. Set this to
           an integer in the range 1–4094 or "none" to disable the PVID.

       MulticastQuerier=
           A boolean. This setting controls the IFLA_BR_MCAST_QUERIER option in the kernel. If
           enabled, the kernel will send general ICMP queries from a zero source address. This
           feature should allow faster convergence on startup, but it causes some multicast-aware
           switches to misbehave and disrupt forwarding of multicast packets. When unset, the
           kernel's default setting applies.

       MulticastSnooping=
           A boolean. This setting controls the IFLA_BR_MCAST_SNOOPING option in the kernel. If
           enabled, IGMP snooping monitors the Internet Group Management Protocol (IGMP) traffic
           between hosts and multicast routers. When unset, the kernel's default setting applies.

       VLANFiltering=
           A boolean. This setting controls the IFLA_BR_VLAN_FILTERING option in the kernel. If
           enabled, the bridge will be started in VLAN-filtering mode. When unset, the kernel's
           default setting applies.

       STP=
           A boolean. This enables the bridge's Spanning Tree Protocol (STP). When unset, the
           kernel's default setting applies.

[VLAN] SECTION OPTIONS

       The "[VLAN]" section only applies for netdevs of kind "vlan", and accepts the following
       key:

       Id=
           The VLAN ID to use. An integer in the range 0–4094. This option is compulsory.

       GVRP=
           The Generic VLAN Registration Protocol (GVRP) is a protocol that allows automatic
           learning of VLANs on a network. A boolean. When unset, the kernel's default setting
           applies.

       MVRP=
           Multiple VLAN Registration Protocol (MVRP) formerly known as GARP VLAN Registration
           Protocol (GVRP) is a standards-based Layer 2 network protocol, for automatic
           configuration of VLAN information on switches. It was defined in the 802.1ak amendment
           to 802.1Q-2005. A boolean. When unset, the kernel's default setting applies.

       LooseBinding=
           The VLAN loose binding mode, in which only the operational state is passed from the
           parent to the associated VLANs, but the VLAN device state is not changed. A boolean.
           When unset, the kernel's default setting applies.

       ReorderHeader=
           The VLAN reorder header is set VLAN interfaces behave like physical interfaces. A
           boolean. When unset, the kernel's default setting applies.

[MACVLAN] SECTION OPTIONS

       The "[MACVLAN]" section only applies for netdevs of kind "macvlan", and accepts the
       following key:

       Mode=
           The MACVLAN mode to use. The supported options are "private", "vepa", "bridge", and
           "passthru".

[MACVTAP] SECTION OPTIONS

       The "[MACVTAP]" section applies for netdevs of kind "macvtap" and accepts the same key as
       "[MACVLAN]".

[IPVLAN] SECTION OPTIONS

       The "[IPVLAN]" section only applies for netdevs of kind "ipvlan", and accepts the
       following key:

       Mode=
           The IPVLAN mode to use. The supported options are "L2","L3" and "L3S".

       Flags=
           The IPVLAN flags to use. The supported options are "bridge","private" and "vepa".

[VXLAN] SECTION OPTIONS

       The "[VXLAN]" section only applies for netdevs of kind "vxlan", and accepts the following
       keys:

       Id=
           The VXLAN ID to use.

       Remote=
           Configures destination multicast group IP address.

       Local=
           Configures local IP address.

       TOS=
           The Type Of Service byte value for a vxlan interface.

       TTL=
           A fixed Time To Live N on Virtual eXtensible Local Area Network packets. N is a number
           in the range 1–255. 0 is a special value meaning that packets inherit the TTL value.

       MacLearning=
           A boolean. When true, enables dynamic MAC learning to discover remote MAC addresses.

       FDBAgeingSec=
           The lifetime of Forwarding Database entry learnt by the kernel, in seconds.

       MaximumFDBEntries=
           Configures maximum number of FDB entries.

       ReduceARPProxy=
           A boolean. When true, bridge-connected VXLAN tunnel endpoint answers ARP requests from
           the local bridge on behalf of remote Distributed Overlay Virtual Ethernet (DVOE)[5]
           clients. Defaults to false.

       L2MissNotification=
           A boolean. When true, enables netlink LLADDR miss notifications.

       L3MissNotification=
           A boolean. When true, enables netlink IP address miss notifications.

       RouteShortCircuit=
           A boolean. When true, route short circuiting is turned on.

       UDPChecksum=
           A boolean. When true, transmitting UDP checksums when doing VXLAN/IPv4 is turned on.

       UDP6ZeroChecksumTx=
           A boolean. When true, sending zero checksums in VXLAN/IPv6 is turned on.

       UDP6ZeroChecksumRx=
           A boolean. When true, receiving zero checksums in VXLAN/IPv6 is turned on.

       RemoteChecksumTx=
           A boolean. When true, remote transmit checksum offload of VXLAN is turned on.

       RemoteChecksumRx=
           A boolean. When true, remote receive checksum offload in VXLAN is turned on.

       GroupPolicyExtension=
           A boolean. When true, it enables Group Policy VXLAN extension security label mechanism
           across network peers based on VXLAN. For details about the Group Policy VXLAN, see the
           VXLAN Group Policy[6] document. Defaults to false.

       DestinationPort=
           Configures the default destination UDP port on a per-device basis. If destination port
           is not specified then Linux kernel default will be used. Set destination port 4789 to
           get the IANA assigned value. If not set or if the destination port is assigned the
           empty string the default port of 4789 is used.

       PortRange=
           Configures VXLAN port range. VXLAN bases source UDP port based on flow to help the
           receiver to be able to load balance based on outer header flow. It restricts the port
           range to the normal UDP local ports, and allows overriding via configuration.

       FlowLabel=
           Specifies the flow label to use in outgoing packets. The valid range is 0-1048575.

[GENEVE] SECTION OPTIONS

       The "[GENEVE]" section only applies for netdevs of kind "geneve", and accepts the
       following keys:

       Id=
           Specifies the Virtual Network Identifier (VNI) to use. Ranges [0-16777215].

       Remote=
           Specifies the unicast destination IP address to use in outgoing packets.

       TOS=
           Specifies the TOS value to use in outgoing packets. Ranges [1-255].

       TTL=
           Specifies the TTL value to use in outgoing packets. Ranges [1-255].

       UDPChecksum=
           A boolean. When true, specifies if UDP checksum is calculated for transmitted packets
           over IPv4.

       UDP6ZeroChecksumTx=
           A boolean. When true, skip UDP checksum calculation for transmitted packets over IPv6.

       UDP6ZeroChecksumRx=
           A boolean. When true, allows incoming UDP packets over IPv6 with zero checksum field.

       DestinationPort=
           Specifies destination port. Defaults to 6081. If not set or assigned the empty string,
           the default port of 6081 is used.

       FlowLabel=
           Specifies the flow label to use in outgoing packets.

[TUNNEL] SECTION OPTIONS

       The "[Tunnel]" section only applies for netdevs of kind "ipip", "sit", "gre", "gretap",
       "ip6gre", "ip6gretap", "vti", "vti6", and "ip6tnl" and accepts the following keys:

       Local=
           A static local address for tunneled packets. It must be an address on another
           interface of this host.

       Remote=
           The remote endpoint of the tunnel.

       TOS=
           The Type Of Service byte value for a tunnel interface. For details about the TOS, see
           the Type of Service in the Internet Protocol Suite[7] document.

       TTL=
           A fixed Time To Live N on tunneled packets. N is a number in the range 1–255. 0 is a
           special value meaning that packets inherit the TTL value. The default value for IPv4
           tunnels is: inherit. The default value for IPv6 tunnels is 64.

       DiscoverPathMTU=
           A boolean. When true, enables Path MTU Discovery on the tunnel.

       IPv6FlowLabel=
           Configures the 20-bit flow label (see RFC 6437[8]) field in the IPv6 header (see RFC
           2460[9]), which is used by a node to label packets of a flow. It is only used for IPv6
           tunnels. A flow label of zero is used to indicate packets that have not been labeled.
           It can be configured to a value in the range 0–0xFFFFF, or be set to "inherit", in
           which case the original flowlabel is used.

       CopyDSCP=
           A boolean. When true, the Differentiated Service Code Point (DSCP) field will be
           copied to the inner header from outer header during the decapsulation of an IPv6
           tunnel packet. DSCP is a field in an IP packet that enables different levels of
           service to be assigned to network traffic. Defaults to "no".

       EncapsulationLimit=
           The Tunnel Encapsulation Limit option specifies how many additional levels of
           encapsulation are permitted to be prepended to the packet. For example, a Tunnel
           Encapsulation Limit option containing a limit value of zero means that a packet
           carrying that option may not enter another tunnel before exiting the current tunnel.
           (see RFC 2473[10]). The valid range is 0–255 and "none". Defaults to 4.

       Key=
           The Key= parameter specifies the same key to use in both directions (InputKey= and
           OutputKey=). The Key= is either a number or an IPv4 address-like dotted quad. It is
           used as mark-configured SAD/SPD entry as part of the lookup key (both in data and
           control path) in ip xfrm (framework used to implement IPsec protocol). See ip-xfrm 
           transform configuration[11] for details. It is only used for VTI/VTI6 tunnels.

       InputKey=
           The InputKey= parameter specifies the key to use for input. The format is same as
           Key=. It is only used for VTI/VTI6 tunnels.

       OutputKey=
           The OutputKey= parameter specifies the key to use for output. The format is same as
           Key=. It is only used for VTI/VTI6 tunnels.

       Mode=
           An "ip6tnl" tunnel can be in one of three modes "ip6ip6" for IPv6 over IPv6, "ipip6"
           for IPv4 over IPv6 or "any" for either.

       Independent=
           A boolean. When true tunnel does not require .network file. Created as "tunnel@NONE".
           Defaults to "false".

       AllowLocalRemote=
           A boolean. When true allows tunnel traffic on ip6tnl devices where the remote endpoint
           is a local host address. Defaults to unset.

[PEER] SECTION OPTIONS

       The "[Peer]" section only applies for netdevs of kind "veth" and accepts the following
       keys:

       Name=
           The interface name used when creating the netdev. This option is compulsory.

       MACAddress=
           The peer MACAddress, if not set, it is generated in the same way as the MAC address of
           the main interface.

[VXCAN] SECTION OPTIONS

       The "[VXCAN]" section only applies for netdevs of kind "vxcan" and accepts the following
       key:

       Peer=
           The peer interface name used when creating the netdev. This option is compulsory.

[TUN] SECTION OPTIONS

       The "[Tun]" section only applies for netdevs of kind "tun", and accepts the following
       keys:

       OneQueue=
           Takes a boolean argument. Configures whether all packets are queued at the device
           (enabled), or a fixed number of packets are queued at the device and the rest at the
           "qdisc". Defaults to "no".

       MultiQueue=
           Takes a boolean argument. Configures whether to use multiple file descriptors (queues)
           to parallelize packets sending and receiving. Defaults to "no".

       PacketInfo=
           Takes a boolean argument. Configures whether packets should be prepended with four
           extra bytes (two flag bytes and two protocol bytes). If disabled, it indicates that
           the packets will be pure IP packets. Defaults to "no".

       VNetHeader=
           Takes a boolean argument. Configures IFF_VNET_HDR flag for a tap device. It allows
           sending and receiving larger Generic Segmentation Offload (GSO) packets. This may
           increase throughput significantly. Defaults to "no".

       User=
           User to grant access to the /dev/net/tun device.

       Group=
           Group to grant access to the /dev/net/tun device.

[TAP] SECTION OPTIONS

       The "[Tap]" section only applies for netdevs of kind "tap", and accepts the same keys as
       the "[Tun]" section.

[WIREGUARD] SECTION OPTIONS

       The "[WireGuard]" section accepts the following keys:

       PrivateKey=
           The Base64 encoded private key for the interface. It can be generated using the wg
           genkey command (see wg(8)). This option is mandatory to use wireguard.

       ListenPort=
           Sets UDP port for listening. Takes either value between 1 and 65535 or "auto". If
           "auto" is specified, the port is automatically generated based on interface name.
           Defaults to "auto".

       FwMark=
           Sets a firewall mark on outgoing wireguard packets from this interface.

[WIREGUARDPEER] SECTION OPTIONS

       The "[WireGuardPeer]" section accepts the following keys:

       PublicKey=
           Sets a Base64 encoded public key calculated by wg pubkey (see wg(8)) from a private
           key, and usually transmitted out of band to the author of the configuration file. This
           option is mandatory for this section.

       PresharedKey=
           Optional preshared key for the interface. It can be generated by the wg genpsk
           command. This option adds an additional layer of symmetric-key cryptography to be
           mixed into the already existing public-key cryptography, for post-quantum resistance.

       AllowedIPs=
           Sets a comma-separated list of IP (v4 or v6) addresses with CIDR masks from which this
           peer is allowed to send incoming traffic and to which outgoing traffic for this peer
           is directed. The catch-all 0.0.0.0/0 may be specified for matching all IPv4 addresses,
           and ::/0 may be specified for matching all IPv6 addresses.

       Endpoint=
           Sets an endpoint IP address or hostname, followed by a colon, and then a port number.
           This endpoint will be updated automatically once to the most recent source IP address
           and port of correctly authenticated packets from the peer at configuration time.

       PersistentKeepalive=
           Sets a seconds interval, between 1 and 65535 inclusive, of how often to send an
           authenticated empty packet to the peer for the purpose of keeping a stateful firewall
           or NAT mapping valid persistently. For example, if the interface very rarely sends
           traffic, but it might at anytime receive traffic from a peer, and it is behind NAT,
           the interface might benefit from having a persistent keepalive interval of 25 seconds.
           If set to 0 or "off", this option is disabled. By default or when unspecified, this
           option is off. Most users will not need this.

[BOND] SECTION OPTIONS

       The "[Bond]" section accepts the following key:

       Mode=
           Specifies one of the bonding policies. The default is "balance-rr" (round robin).
           Possible values are "balance-rr", "active-backup", "balance-xor", "broadcast",
           "802.3ad", "balance-tlb", and "balance-alb".

       TransmitHashPolicy=
           Selects the transmit hash policy to use for slave selection in balance-xor, 802.3ad,
           and tlb modes. Possible values are "layer2", "layer3+4", "layer2+3", "encap2+3", and
           "encap3+4".

       LACPTransmitRate=
           Specifies the rate with which link partner transmits Link Aggregation Control Protocol
           Data Unit packets in 802.3ad mode. Possible values are "slow", which requests partner
           to transmit LACPDUs every 30 seconds, and "fast", which requests partner to transmit
           LACPDUs every second. The default value is "slow".

       MIIMonitorSec=
           Specifies the frequency that Media Independent Interface link monitoring will occur. A
           value of zero disables MII link monitoring. This value is rounded down to the nearest
           millisecond. The default value is 0.

       UpDelaySec=
           Specifies the delay before a link is enabled after a link up status has been detected.
           This value is rounded down to a multiple of MIIMonitorSec. The default value is 0.

       DownDelaySec=
           Specifies the delay before a link is disabled after a link down status has been
           detected. This value is rounded down to a multiple of MIIMonitorSec. The default value
           is 0.

       LearnPacketIntervalSec=
           Specifies the number of seconds between instances where the bonding driver sends
           learning packets to each slave peer switch. The valid range is 1–0x7fffffff; the
           default value is 1. This option has an effect only for the balance-tlb and balance-alb
           modes.

       AdSelect=
           Specifies the 802.3ad aggregation selection logic to use. Possible values are
           "stable", "bandwidth" and "count".

       FailOverMACPolicy=
           Specifies whether the active-backup mode should set all slaves to the same MAC address
           at the time of enslavement or, when enabled, to perform special handling of the bond's
           MAC address in accordance with the selected policy. The default policy is none.
           Possible values are "none", "active" and "follow".

       ARPValidate=
           Specifies whether or not ARP probes and replies should be validated in any mode that
           supports ARP monitoring, or whether non-ARP traffic should be filtered (disregarded)
           for link monitoring purposes. Possible values are "none", "active", "backup" and
           "all".

       ARPIntervalSec=
           Specifies the ARP link monitoring frequency in milliseconds. A value of 0 disables ARP
           monitoring. The default value is 0.

       ARPIPTargets=
           Specifies the IP addresses to use as ARP monitoring peers when ARPIntervalSec is
           greater than 0. These are the targets of the ARP request sent to determine the health
           of the link to the targets. Specify these values in IPv4 dotted decimal format. At
           least one IP address must be given for ARP monitoring to function. The maximum number
           of targets that can be specified is 16. The default value is no IP addresses.

       ARPAllTargets=
           Specifies the quantity of ARPIPTargets that must be reachable in order for the ARP
           monitor to consider a slave as being up. This option affects only active-backup mode
           for slaves with ARPValidate enabled. Possible values are "any" and "all".

       PrimaryReselectPolicy=
           Specifies the reselection policy for the primary slave. This affects how the primary
           slave is chosen to become the active slave when failure of the active slave or
           recovery of the primary slave occurs. This option is designed to prevent flip-flopping
           between the primary slave and other slaves. Possible values are "always", "better" and
           "failure".

       ResendIGMP=
           Specifies the number of IGMP membership reports to be issued after a failover event.
           One membership report is issued immediately after the failover, subsequent packets are
           sent in each 200ms interval. The valid range is 0–255. Defaults to 1. A value of 0
           prevents the IGMP membership report from being issued in response to the failover
           event.

       PacketsPerSlave=
           Specify the number of packets to transmit through a slave before moving to the next
           one. When set to 0, then a slave is chosen at random. The valid range is 0–65535.
           Defaults to 1. This option only has effect when in balance-rr mode.

       GratuitousARP=
           Specify the number of peer notifications (gratuitous ARPs and unsolicited IPv6
           Neighbor Advertisements) to be issued after a failover event. As soon as the link is
           up on the new slave, a peer notification is sent on the bonding device and each VLAN
           sub-device. This is repeated at each link monitor interval (ARPIntervalSec or
           MIIMonitorSec, whichever is active) if the number is greater than 1. The valid range
           is 0–255. The default value is 1. These options affect only the active-backup mode.

       AllSlavesActive=
           A boolean. Specifies that duplicate frames (received on inactive ports) should be
           dropped when false, or delivered when true. Normally, bonding will drop duplicate
           frames (received on inactive ports), which is desirable for most users. But there are
           some times it is nice to allow duplicate frames to be delivered. The default value is
           false (drop duplicate frames received on inactive ports).

       MinLinks=
           Specifies the minimum number of links that must be active before asserting carrier.
           The default value is 0.

       For more detail information see Linux Ethernet Bonding Driver HOWTO[1]

EXAMPLE

       Example 1. /etc/systemd/network/25-bridge.netdev

           [NetDev]
           Name=bridge0
           Kind=bridge

       Example 2. /etc/systemd/network/25-vlan1.netdev

           [Match]
           Virtualization=no

           [NetDev]
           Name=vlan1
           Kind=vlan

           [VLAN]
           Id=1

       Example 3. /etc/systemd/network/25-ipip.netdev

           [NetDev]
           Name=ipip-tun
           Kind=ipip
           MTUBytes=1480

           [Tunnel]
           Local=192.168.223.238
           Remote=192.169.224.239
           TTL=64

       Example 4. /etc/systemd/network/25-tap.netdev

           [NetDev]
           Name=tap-test
           Kind=tap

           [Tap]
           MultiQueue=true
           PacketInfo=true

       Example 5. /etc/systemd/network/25-sit.netdev

           [NetDev]
           Name=sit-tun
           Kind=sit
           MTUBytes=1480

           [Tunnel]
           Local=10.65.223.238
           Remote=10.65.223.239

       Example 6. /etc/systemd/network/25-gre.netdev

           [NetDev]
           Name=gre-tun
           Kind=gre
           MTUBytes=1480

           [Tunnel]
           Local=10.65.223.238
           Remote=10.65.223.239

       Example 7. /etc/systemd/network/25-vti.netdev

           [NetDev]
           Name=vti-tun
           Kind=vti
           MTUBytes=1480

           [Tunnel]
           Local=10.65.223.238
           Remote=10.65.223.239

       Example 8. /etc/systemd/network/25-veth.netdev

           [NetDev]
           Name=veth-test
           Kind=veth

           [Peer]
           Name=veth-peer

       Example 9. /etc/systemd/network/25-bond.netdev

           [NetDev]
           Name=bond1
           Kind=bond

           [Bond]
           Mode=802.3ad
           TransmitHashPolicy=layer3+4
           MIIMonitorSec=1s
           LACPTransmitRate=fast

       Example 10. /etc/systemd/network/25-dummy.netdev

           [NetDev]
           Name=dummy-test
           Kind=dummy
           MACAddress=12:34:56:78:9a:bc

       Example 11. /etc/systemd/network/25-vrf.netdev

       Create a VRF interface with table 42.

           [NetDev]
           Name=vrf-test
           Kind=vrf

           [VRF]
           Table=42

       Example 12. /etc/systemd/network/25-macvtap.netdev

       Create a MacVTap device.

           [NetDev]
           Name=macvtap-test
           Kind=macvtap

       Example 13. /etc/systemd/network/25-wireguard.netdev

           [NetDev]
           Name=wg0
           Kind=wireguard

           [WireGuard]
           PrivateKey=EEGlnEPYJV//kbvvIqxKkQwOiS+UENyPncC4bF46ong=
           ListenPort=51820

           [WireGuardPeer]
           PublicKey=RDf+LSpeEre7YEIKaxg+wbpsNV7du+ktR99uBEtIiCA=
           AllowedIPs=fd31:bf08:57cb::/48,192.168.26.0/24
           Endpoint=wireguard.example.com:51820

SEE ALSO

       systemd(1), systemd-networkd(8), systemd.link(5), systemd.network(5)

NOTES

        1. Linux Ethernet Bonding Driver HOWTO
           https://www.kernel.org/doc/Documentation/networking/bonding.txt

        2. RFC 2784
           https://tools.ietf.org/html/rfc2784

        3. IEEE 802.1Q
           http://www.ieee802.org/1/pages/802.1Q.html

        4. VRF
           https://www.kernel.org/doc/Documentation/networking/vrf.txt

        5. (DVOE)
           https://en.wikipedia.org/wiki/Distributed_Overlay_Virtual_Ethernet

        6. VXLAN Group Policy
           https://tools.ietf.org/html/draft-smith-vxlan-group-policy

        7. Type of Service in the Internet Protocol Suite
           http://tools.ietf.org/html/rfc1349

        8. RFC 6437
           https://tools.ietf.org/html/rfc6437

        9. RFC 2460
           https://tools.ietf.org/html/rfc2460

       10. RFC 2473
           https://tools.ietf.org/html/rfc2473#section-4.1.1

       11. ip-xfrm — transform configuration
           http://man7.org/linux/man-pages/man8/ip-xfrm.8.html