Name

Synopsis

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 /usr/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 /usr/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 /usr/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 /usr/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.)

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.

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 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.

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.

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.

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 document. Defaults to false.

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,
and destination port 0 to get default values.

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.

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.

Configures the 20-bit flow label (see
RFC 6437) field in the IPv6 header (see
RFC 2460), 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.

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".

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).
The valid range is 0–255 and "none". Defaults to 4.

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 for details. It is only used for VTI/VTI6
tunnels.

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".

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".

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.

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.

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".

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".

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.

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".

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".

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.

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.

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.

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).