NDDS_Transport_UDPv4_Property_t Struct Reference
[UDPv4 Transport]

Configurable IPv4/UDP Transport-Plugin properties. More...

List of all members.

Public Attributes
struct NDDS_Transport_Property_t	parent
	Generic properties of all transport plugins.
RTI_INT32	send_socket_buffer_size
	Size in bytes of the send buffer of a socket used for sending.
RTI_INT32	recv_socket_buffer_size
	Size in bytes of the receive buffer of a socket used for receiving.
RTI_INT32	unicast_enabled
	Allows the transport plugin to use unicast for sending and receiving.
RTI_INT32	multicast_enabled
	Allows the transport plugin to use multicast for sending and receiving.
RTI_INT32	multicast_ttl
	Value for the time-to-live parameter for all multicast sends using this plugin.
RTI_INT32	multicast_loopback_disabled
	Prevents the transport plugin from putting multicast packets onto the loopback interface.
RTI_INT32	ignore_loopback_interface
	Prevents the transport plugin from using the IP loopback interface.
RTI_INT32	ignore_nonup_interfaces
	Prevents the transport plugin from using a network interface that is not reported as UP by the operating system.
RTI_INT32	ignore_nonrunning_interfaces
	Prevents the transport plugin from using a network interface that is not reported as RUNNING by the operating system.
RTI_INT32	no_zero_copy
	Prevents the transport plugin from doing a zero copy.
RTI_INT32	send_blocking
	Control blocking behavior of send sockets. CHANGING THIS FROM THE DEFAULT CAN CAUSE SIGNIFICANT PERFORMANCE PROBLEMS.
RTI_UINT32	transport_priority_mask
	Set mask for use of transport priority field.
RTI_INT32	transport_priority_mapping_low
	Set low value of output range to IPv4 TOS.
RTI_INT32	transport_priority_mapping_high
	Set high value of output range to IPv4 TOS.
RTI_UINT32	interface_poll_period
	Specifies the period in milliseconds to query for changes in the state of all the interfaces.
RTI_INT32	reuse_multicast_receive_resource
	Controls whether or not to reuse multicast receive resources.
RTI_INT32	protocol_overhead_max
	Maximum size in bytes of protocol overhead, including headers.

---

Detailed Description

Configurable IPv4/UDP Transport-Plugin properties.

The properties in this structure can be modified by the end user to configure the plugin. However, the properties must be set before the plugin is instantiated.

See also:

NDDSTransportSupport::set_builtin_transport_property()

NDDS_Transport_UDPv4_new

---

Member Data Documentation

struct NDDS_Transport_Property_t NDDS_Transport_UDPv4_Property_t::parent [read]

Generic properties of all transport plugins.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::send_socket_buffer_size

Size in bytes of the send buffer of a socket used for sending.

On most operating systems, setsockopt() will be called to set the SENDBUF to the value of this parameter.

This value must be greater than or equal to NDDS_Transport_Property_t::message_size_max. The maximum value is operating system-dependent.

By default, it will be set to be NDDS_TRANSPORT_UDPV4_MESSAGE_SIZE_MAX_DEFAULT.

If users configure this parameter to be NDDS_TRANSPORT_UDPV4_SOCKET_BUFFER_SIZE_OS_DEFAULT, then setsockopt() (or equivalent) will not be called to size the send buffer of the socket.

See also:

NDDS_TRANSPORT_UDPV4_MESSAGE_SIZE_MAX_DEFAULT

NDDS_TRANSPORT_UDPV4_SOCKET_BUFFER_SIZE_OS_DEFAULT

RTI_INT32 NDDS_Transport_UDPv4_Property_t::recv_socket_buffer_size

Size in bytes of the receive buffer of a socket used for receiving.

On most operating systems, setsockopt() will be called to set the RECVBUF to the value of this parameter.

This value must be greater than or equal to NDDS_Transport_Property_t::message_size_max. The maximum value is operating system-dependent.

By default, it will be set to be NDDS_TRANSPORT_UDPV4_MESSAGE_SIZE_MAX_DEFAULT.

If it is set to NDDS_TRANSPORT_UDPV4_SOCKET_BUFFER_SIZE_OS_DEFAULT, then setsockopt() (or equivalent) will not be called to size the receive buffer of the socket.

See also:

NDDS_TRANSPORT_UDPV4_MESSAGE_SIZE_MAX_DEFAULT

NDDS_TRANSPORT_UDPV4_SOCKET_BUFFER_SIZE_OS_DEFAULT

RTI_INT32 NDDS_Transport_UDPv4_Property_t::unicast_enabled

Allows the transport plugin to use unicast for sending and receiving.

This value turns unicast UDP on (if set to 1) or off (if set to 0) for this plugin. By default, it will be turned on (1). Also by default, the plugin will use all the allowed network interfaces that it finds up and running when the plugin is instanced.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::multicast_enabled

Allows the transport plugin to use multicast for sending and receiving.

This value turns multicast UDP on (if set to 1) or off (if set to 0) for this plugin. By default, it will be turned on (1) for those platforms that support multicast. Also by default, the plugin will use the all network interfaces allowed for multicast that it finds up and running when the plugin is instanced.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::multicast_ttl

Value for the time-to-live parameter for all multicast sends using this plugin.

This value is used to set the TTL of multicast packets sent by this transport plugin.

See also:

NDDS_TRANSPORT_UDPV4_MULTICAST_TTL_DEFAULT

RTI_INT32 NDDS_Transport_UDPv4_Property_t::multicast_loopback_disabled

Prevents the transport plugin from putting multicast packets onto the loopback interface.

If multicast loopback is disabled (this value is set to 1), then when sending multicast packets, RTI Connext will not put a copy of the packets on the loopback interface. This prevents applications on the same node (including itself) from receiving those packets.

This value is set to 0 by default, meaning multicast loopback is enabled.

Disabling multicast loopback (setting this value to 1) may result in minor performance gains when using multicast.

[NOTE: Windows CE systems do not support multicast loopback. This field is ignored for Windows CE targets.]

RTI_INT32 NDDS_Transport_UDPv4_Property_t::ignore_loopback_interface

Prevents the transport plugin from using the IP loopback interface.

Currently three values are allowed:

• 0: Forces local traffic to be sent over loopback, even if a more efficient transport (such as shared memory) is installed (in which case traffic will be sent over both transports).

• 1: Disables local traffic via this plugin. The IP loopback interface is not used, even if no NICs are discovered. This is useful when you want applications running on the same node to use a more efficient plugin (such as shared memory) instead of the IP loopback.

• -1: Automatic. Lets RTI Connext decide between the above two choices.

The current "automatic" (-1) RTI Connext policy is as follows.

• If a shared memory transport plugin is available for local traffic, the effective value is 1 (i.e., disable UPV4 local traffic).
• Otherwise, the effective value is 0 (i.e., use UDPv4 for local traffic also).

[default] -1 Automatic RTI Connext policy based on availability of the shared memory transport.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::ignore_nonup_interfaces

Prevents the transport plugin from using a network interface that is not reported as UP by the operating system.

The transport checks the flags reported by the operating system for each network interface upon initialization. An interface which is not reported as UP will not be used. This property allows the user to configure the transport to start using even the interfaces which were not reported as UP.

Two values are allowed:

• 0: Allow the use of interfaces which were not reported as UP.

• 1: Do not use interfaces which were not reported as UP.

[default] 1

RTI_INT32 NDDS_Transport_UDPv4_Property_t::ignore_nonrunning_interfaces

Prevents the transport plugin from using a network interface that is not reported as RUNNING by the operating system.

The transport checks the flags reported by the operating system for each network interface upon initialization. An interface which is not reported as UP will not be used. This property allows the same check to be extended to the IFF_RUNNING flag implemented by some operating systems. The RUNNING flag is defined to mean that "all resources are allocated", and may be off if there is no link detected, e.g., the network cable is unplugged.

Two values are allowed:

• 0: Do not check the RUNNING flag when enumerating interfaces, just make sure the interface is UP.

• 1: Check the flag when enumerating interfaces, and ignore those that are not reported as RUNNING. This can be used on some operating systems to cause the transport to ignore interfaces that are enabled but not connected to the network.

[default] 0 (i.e., do not check RUNNING flag)

RTI_INT32 NDDS_Transport_UDPv4_Property_t::no_zero_copy

Prevents the transport plugin from doing a zero copy.

By default, this plugin will use the zero copy on OSs that offer it. While this is good for performance, it may sometime tax the OS resources in a manner that cannot be overcome by the application.

The best example is if the hardware/device driver lends the buffer to the application itself. If the application does not return the loaned buffers soon enough, the node may error or malfunction. In case you cannot reconfigure the H/W, device driver, or the OS to allow the zero copy feature to work for your application, you may have no choice but to turn off zero copy use.

By default this is set to 0, so RTI Connext will use the zero-copy API if offered by the OS.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::send_blocking

Control blocking behavior of send sockets. CHANGING THIS FROM THE DEFAULT CAN CAUSE SIGNIFICANT PERFORMANCE PROBLEMS.

Currently two values are defined:

• NDDS_TRANSPORT_UDPV4_BLOCKING_ALWAYS: Sockets are blocking (default socket options for Operating System).

• NDDS_TRANSPORT_UDPV4_BLOCKING_NEVER: Sockets are modified to make them non-blocking. THIS IS NOT A SUPPORTED CONFIGURATION AND MAY CAUSE SIGNIFICANT PERFORMANCE PROBLEMS.

[default] NDDS_TRANSPORT_UDPV4_BLOCKING_ALWAYS.

RTI_UINT32 NDDS_Transport_UDPv4_Property_t::transport_priority_mask

Set mask for use of transport priority field.

This is used in conjunction with NDDS_Transport_UDPv4_Property_t::transport_priority_mapping_low and NDDS_Transport_UDPv4_Property_t::transport_priority_mapping_high to define the mapping from DDS transport priority (see TRANSPORT_PRIORITY) to the IPv4 TOS field. Defines a contiguous region of bits in the 32-bit transport priority value that is used to generate values for the IPv4 TOS field on an outgoing socket.

For example, the value 0x0000ff00 causes bits 9-16 (8 bits) to be used in the mapping. The value will be scaled from the mask range (0x0000 - 0xff00 in this case) to the range specified by low and high.

If the mask is set to zero, then the transport will not set IPv4 TOS for send sockets.

[default] 0.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::transport_priority_mapping_low

Set low value of output range to IPv4 TOS.

This is used in conjunction with NDDS_Transport_UDPv4_Property_t::transport_priority_mask and NDDS_Transport_UDPv4_Property_t::transport_priority_mapping_high to define the mapping from DDS transport priority to the IPv4 TOS field. Defines the low value of the output range for scaling.

Note that IPv4 TOS is generally an 8-bit value.

[default] 0.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::transport_priority_mapping_high

Set high value of output range to IPv4 TOS.

This is used in conjunction with NDDS_Transport_UDPv4_Property_t::transport_priority_mask and NDDS_Transport_UDPv4_Property_t::transport_priority_mapping_low to define the mapping from DDS transport priority to the IPv4 TOS field. Defines the high value of the output range for scaling.

Note that IPv4 TOS is generally an 8-bit value.

[default] 0xff.

RTI_UINT32 NDDS_Transport_UDPv4_Property_t::interface_poll_period

Specifies the period in milliseconds to query for changes in the state of all the interfaces.

The value of this property is ignored if ignore_non_interfaces is 1. If ignore_nonup_interfaces is 0 then the UDPv4 transport creates a new thread to query the status of the interfaces. This property specifies the polling period in milliseconds for performing this query.

[default] 500 milliseconds.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::reuse_multicast_receive_resource

Controls whether or not to reuse multicast receive resources.

Setting this to 0 (FALSE) prevents multicast crosstalk by uniquely configuring a port and creating a receive thread for each multicast group address.

[default] 0.

RTI_INT32 NDDS_Transport_UDPv4_Property_t::protocol_overhead_max

Maximum size in bytes of protocol overhead, including headers.

This value is the maximum size, in bytes, of protocol-related overhead. Normally, the overhead accounts for UDP and IP headers. The default value is set to accommodate the most common UDP/IP header size.

Note that when NDDS_Transport_Property_t::message_size_max plus this overhead is larger than the UDPv4 maximum message size (65535 bytes), the middleware will automatically reduce the effective message_size_max, to 65535 minus this overhead.

[default] 28.

See also:

NDDS_Transport_Property_t::message_size_max