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fkie multimaster connection issues - firewall?

Hello,

I have 3 hosts with a roscore each. Two of them are Ubuntu ARM and one is the normal desktop version of Ubuntu.

Starting the fkie multimaster discovery and sync does work perfect between the Ubuntu ARM hosts but the Desktop does not recognize either one. http://wiki.ros.org/multimaster_fkie

I'm wondering if my desktop might have a default firewall rule that prevents a proper broad cast between the master discovery instances. The three hosts can connect if I run roscore on one machine and set the others up for that particular one. I'm not sure which connections the discovery node uses (broadcast and so on) that's why I think there might be a firewall issue.

I hope somebody can help me with that.

Asked by chrisb on 2015-12-14 18:04:42 UTC

Comments

I remembered doing something similar to your case for multimaster system. I used 3pcs. I used this paper. Have you tried it?

Asked by Vinh K on 2015-12-15 03:34:50 UTC

Answers

Hello Vinh,

I did use the tutorial on the ROS page but the paper gives me a lot more information. Thanks for the info.

rosrun master_discovery_fkie master_discovery _mcast_group:=224.0.0.1

specifying the multicast address helped a little and my third host is visible to all others now. The syncronizer how ever gives me an error while publishing a test message:

Error while decode message: newer heartbeat version 3 (own: 2 ) detected, please update your master_discovery

Cause of that, it is not synchronizing the topics from this node. The master discovery is the latest version though.

Asked by chrisb on 2015-12-16 15:34:51 UTC

Comments

Hi chris try to not put that as an answer yet. By synchronizer did you mean the 

rosrun master_sync_fkie master_sync

that is giving you errors?

Asked by Vinh K on 2015-12-17 00:05:17 UTC

Yes I think so. The error occurs while publishing the first topic.

Asked by chrisb on 2015-12-17 01:15:04 UTC

i see. I'm not sure where the issue is. If this is something that is very urgent, I would keep updating this question so that way it will always be on the latest list of question ask.

Asked by Vinh K on 2015-12-18 21:53:18 UTC

I heard that many people say single master is much easier rather than multi-master. I am working on that right now for my 3 turtlebots. Soon it will be 6. Is single master an option for you to try at this point, Chris?

Asked by Vinh K on 2015-12-18 21:55:15 UTC

Thanks Vinh,

I could run my system as a single master in the lab. I did this for the developing phase. The issue is much more the in field usage where the network connection is not as good. I don't want any nodes crashing during network outage. And also a reconnection if the network comes back.

Asked by chrisb on 2015-12-29 14:19:43 UTC

so did you get it to work Chris?

Asked by Vinh K on 2016-01-15 13:03:55 UTC

unfortunately not. It works fine on my two embedded platforms but not on my desktop.

Asked by chrisb on 2016-01-28 12:35:44 UTC

It looks like this problem is not solved. Vinh: Did you figure out if this is firewall or processor architecture related?

Asked by chrisb on 2016-09-20 12:32:25 UTC

I have not been able to figure out yet.

Asked by Vinh K on 2016-10-07 18:15:23 UTC

Did you manage to make the package work? I still have problems in the very basic scenario of making the detection of masters that are running on the same platform. If you have any ideas, I would appreciate the input from more experienced source-http://answers.ros.org/question/252378/

Asked by KBOT on 2017-01-20 07:08:23 UTC