Multicast transport problem

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Multicast transport problem


I'm currently testing the performance of DDS on a system for my bachelor thesis and I'm experiencing a strange behaviour when I measure the throughput on the Subscriber side. Each node on my system has two network interfaces, the nodes are connected through a Gigabit switch and they're running on RHEL5. I need to use only one of those network interfaces so, in my XML configuration file, I've configured the dds.transport.UDP.builtin.parent.allow_interfaces_list property with the interface name I need to use.

When I publish messages of 4KB, I can see a throughput of 600 Mb/s on the Subscriber side, but if I bind the writer to a multicast address (configuring the TransportMulticastQosPolicy), the throughput drops to 200 Mb/s. I was expecting similar results using either multicast or unicast on a 1 Pub - 1 Sub test case. Is there a QoS policy, that I forgot to configure, to improve the performance of multicast data transmission?



fercs77's picture
Last seen: 3 weeks 1 day ago
Joined: 01/15/2011
Posts: 30

Hi Alessandro,

By default, the UDPv4 transport in RTI Connext DDS will send multicast packets on all available interfaces. You can restrict the number of interfaces used to send and receive multicast traffic using the following two properties:

  • dds.transport.UDPv4.builtin.allow_multicast_interfaces_list
  • dds.transport.UDPv4.builtin.deny_multicast_interfaces_list

Notice that the previous two properties affect both the sending and receiving of multicast traffic. However, that should be OK in your use case.

For additional information on these configuration properties see Table 15.2 in the RTI Connext Core Libraries and Utilities User's Manual 5.0

- Fernando