In Hazelcast, multicast auto discovery for the same vpc instances is not working

Question

We have opened TCP ports from 5701 to 5709 and also opened UDP port of 54327 which includes inbound and out bound rules in aws console.

We have enabled multicast mode as true, TCP/IP mode as false in both machines Hazelcast configuration.

And also added the following line in iptables

iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT

But two machines Hazelcast cluster members are not connected. Are there any other reasons. Could you please provide if there are any other missed points here.

score 3 · Answer 1 · answered Mar 28 '14 at 12:16

3

Amazon EC2 networking does not support multicast communication. See http://aws.amazon.com/vpc/faqs/.

Would it be possible to configure Hazelcast to implement clustering with regular TCP or UDP traffic only ?

answered Mar 28 '14 at 12:16

Sébastien Stormacq

14,301
5
41
64

Yes. we support 3 discovery modes: tcp/ip, multicast, ec2 (which does a lookup of the public ip addresses and then uses tcp-ip). Once the discovery phase is over, internal communication relies on tcp/ip. – pveentjer Mar 28 '14 at 14:25
Thanks for having clarified this ! – Sébastien Stormacq Mar 28 '14 at 14:55
I am also having problems with Hazelcast with "AWS" discovery plugin inside VPCs. – ajkret Jan 23 '17 at 13:18

score 3 · Answer 2 · edited Jul 08 '14 at 07:12

First try with regular TCP/IP setup to make sure nothing else is in the way.

Once that is working try out the following (from the Hazelcast book)

If you don't see members joining, then it is likely because multicast is not available. A cause can be the firewall; you can test this by disabling the firewall or enable multicast in the firewall [see firewall section]. Another cause can be that it is disabled on the network or the network doesn't support it. On *NIX environments you can check if your network interface supports multicast by calling ifconfig | grep -i multicast, but it doesn't mean that it is available. To check if multicast is available, iperf is a useful tool which is available for Windows/*NIX/OSX. To test multicast using multicast-group 224.2.2.3, open a terminal one 2 machines within the network and run the following in the first terminal:

iperf -s -u -B 224.2.2.3 -i 1

and

iperf -c 224.2.2.3 -u -T 32 -t 3 -i 1

in the other terminal. If data is being transferred then multicast is working.

As I explained in my answer below : multicast is not available on EC2 instances — Sébastien Stormacq, Mar 28 '14 at 14:56
You are right. I didn't see the EC2 part in his question. Only when I inspected his tags, it became clear. — pveentjer, Mar 28 '14 at 18:12

In Hazelcast, multicast auto discovery for the same vpc instances is not working

2 Answers2