I am running the BasicPublisher/BasicSubscriber pair from https://github.com/real-logic/aeron binding them to the same multicast group+port. When they run on the same host they connect, but when they run on separate hosts (same switch+subnet+vlan) the publisher reports “Offer failed because publisher is not connected to subscriber”. Here are my configurations:
AERON PAIR:
java -Daeron.sample.channel="aeron:udp?endpoint=225.10.9.7:4050" -Daeron.sample.embeddedMediaDriver=true -cp ./aeron-all/build/libs/aeron-all-1.29.1-SNAPSHOT.jar io.aeron.samples.BasicPublisherjava -Daeron.sample.channel="aeron:udp?endpoint=225.10.9.7:4050" -Daeron.sample.embeddedMediaDriver=true -cp ./aeron-all/build/libs/aeron-all-1.29.1-SNAPSHOT.jar io.aeron.samples.BasicSubscriberI ran an iperf udp pair on the same hosts binding to the same group+port, which I think proves that the switch is not blocking the multicast traffic. My hope is that I’m just using Aeron incorrectly; or perhaps there’s some other networking issue I can check?
IPERF PAiR:
iperf -c 225.10.9.7 -p 4050 -u -T 32 -t 300 -I 1 -b 1G[ 3] 46.0-47.0 sec 128 MBytes 1.07 Gbits/sec…iperf -s -u -B 225.10.9.7 -p 4050 -I 1 -b 1G[ 3] 45.0-46.0 sec 128 MBytes 1.07 Gbits/sec 0.001 ms 35/91304 (0.038%)…Java: java-1.8.0-openjdk.x86_64
OS: Centos7 3.10.0-514.26.2.el7.x86_64
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Answer
When using multicast endpoints it is also necessary to provide the interface for some operating systems when going remote. The interface can have a mask to simplify configuration for all machines on a subnet. For example:
aeron:udp?endpoint=224.0.1.1:40456|interface=192.168.1.4aeron:udp?endpoint=224.0.1.1:40456|interface=192.168.1.0/24https://github.com/real-logic/aeron/wiki/Channel-Configuration