59 lines
2.6 KiB
ReStructuredText
59 lines
2.6 KiB
ReStructuredText
.. _net_if_interface:
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Network Interface
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#################
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Overview
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********
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The network interface is a nexus that ties the network device drivers
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and the upper part of the network stack together. All the sent and received
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data is transferred via a network interface. The network interfaces cannot be
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created at runtime. A special linker section will contain information about them
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and that section is populated at linking time.
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Network interfaces are created by ``NET_DEVICE_INIT()`` macro.
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For Ethernet network, a macro called ``ETH_NET_DEVICE_INIT()`` should be used
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instead as it will create VLAN interfaces automatically if
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:option:`CONFIG_NET_VLAN` is enabled. These macros are typically used in
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network device driver source code.
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The network interface can be turned ON by calling ``net_if_up()`` and OFF
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by calling ``net_if_down()``. When the device is powered ON, the network
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interface is also turned ON by default.
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The network interfaces can be referenced either by a ``struct net_if *``
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pointer or by a network interface index. The network interface can be
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resolved from its index by calling ``net_if_get_by_index()`` and from interface
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pointer by calling ``net_if_get_by_iface()``.
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The IP address for network devices must be set for them to be connectable.
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In a typical dynamic network environment, IP addresses are set automatically
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by DHCPv4, for example. If needed though, the application can set a device's
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IP address manually. See the API documentation below for functions such as
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``net_if_ipv4_addr_add()`` that do that.
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The ``net_if_get_default()`` returns a *default* network interface. What
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this default interface means can be configured via options like
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:option:`CONFIG_NET_DEFAULT_IF_FIRST` and
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:option:`CONFIG_NET_DEFAULT_IF_ETHERNET`.
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See Kconfig file :file:`subsys/net/ip/Kconfig` what options are available for
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selecting the default network interface.
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The transmitted and received network packets can be classified via a network
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packet priority. This is typically done in Ethernet networks when virtual LANs
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(VLANs) are used. Higher priority packets can be sent or received earlier than
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lower priority packets. The traffic class setup can be configured by
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:option:`CONFIG_NET_TC_TX_COUNT` and :option:`CONFIG_NET_TC_RX_COUNT` options.
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If the :option:`CONFIG_NET_PROMISCUOUS_MODE` is enabled and if the underlaying
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network technology supports promiscuous mode, then it is possible to receive
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all the network packets that the network device driver is able to receive.
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See :ref:`promiscuous_interface` API for more details.
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API Reference
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*************
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.. doxygengroup:: net_if
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:project: Zephyr
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