After disabling the default transport and setting up a single udpv4 transport for service discovery and communication, the data communication on the same host is still via shared memory (shm) and does not work as expected.

[lobmoo]

Is there an already existing issue for this?

• I have searched the existing issues

Expected behavior

`omainParticipantQos qos;
qos.transport().use_builtin_transports = false; // 禁用内置传输
std::shared_ptreprosima::fastdds::rtps::UDPv4TransportDescriptor udp_transport =
std::make_sharedeprosima::fastdds::rtps::UDPv4TransportDescriptor();
qos.transport().user_transports.push_back(udp_transport); // 添加 UDPv4 传输

// Explicitly disable SHM transport
qos.transport().user_transports.clear();
qos.transport().user_transports.push_back(udp_transport);`

The above is my configuration. After establishing the connection and starting data transmission, the communication on the same machine still uses shared memory (shm). This is because UDP packets cannot be captured, and files are generated under the directory “/dev/shm”.

Current behavior

none

Steps to reproduce

none

Fast DDS version/commit

none

Platform/Architecture

Ubuntu Focal 20.04 amd64

Transport layer

UDPv4

Additional context

No response

XML configuration file

Relevant log output

Network traffic capture

No response

[juanlofer-eprosima]

Hi @lobmoo ,

There are two shared memory communication mechanisms available in Fast-DDS: Shared Memory Transport and Data-sharing delivery. You might be missing to disable the latter: qos.data_sharing().off();