The transport layer provides communication services between DDS entities, being responsible of actually sending and receiving messages over a physical transport. The DDS layer uses this service for both user data and discovery traffic communication. However, the DDS layer itself is transport independent, it defines a transport API and can run over any transport plugin that implements this API. This way, it is not restricted to a specific transport, and applications can choose the one that best suits their requirements, or create their own.
eProsima Fast DDS comes with five transports already implemented:
- UDPv4: UDP Datagram communication over IPv4. This transport is created by default on a new :ref:`dds_layer_domainParticipant` if no specific transport configuration is given (see :ref:`transport_udp_udp`).
- UDPv6: UDP Datagram communication over IPv6 (see :ref:`transport_udp_udp`).
- TCPv4: TCP communication over IPv4 (see :ref:`transport_tcp_tcp`).
- TCPv6: TCP communication over IPv6 (see :ref:`transport_tcp_tcp`).
- SHM: Shared memory communication among entities running on the same host. This transport is created by default on a new :ref:`dds_layer_domainParticipant` if no specific transport configuration is given (see :ref:`transport_sharedMemory_sharedMemory`).
Although it is not part of the transport module, :ref:`intraprocess data delivery<intraprocess-delivery>` and :ref:`data sharing delivery<datasharing-delivery>` are also available to send messages between entities on some settings. The figure below shows a comparison between the different transports available in Fast DDS.
.. toctree::
:maxdepth: 2
/fastdds/transport/transport_api.rst
/fastdds/transport/udp/udp.rst
/fastdds/transport/tcp/tcp.rst
/fastdds/transport/shared_memory/shared_memory.rst
/fastdds/transport/datasharing.rst
/fastdds/transport/intraprocess.rst
/fastdds/transport/tcp/tls.rst
/fastdds/transport/listening_locators.rst
/fastdds/transport/whitelist.rst
/fastdds/transport/disabling_multicast.rst