LCM over newtork

[Joe]

I am trying to communicate between two different machines using lcm, does any one have any working examples.

I have changed the LCM_DEFAULT_URL=udpm/192.168.1.120:7667?ttl=1, with 192.168.1.120 being the IP address of my machine however I get the following error;

setsockopt (IPPROTO_IP, IP_ADD_MEMBERSHIP): Invalid argument
Traceback (most recent call last):
  File "listener.py", line 16, in <module>
    lc = lcm.LCM()
RuntimeError: Couldn't create LCM

what am I doing wrong?

[Anthony Bonkoski]

LCM normally communicates over UDP Multicast.

You need to use an IP in the range 224.0.0.0 through 239.255.255.255

The default IP with ttl=1 should suffice, given you don't have any routing issues (udpm://239.255.76.67:7667?ttl=1)

-Anthony

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Anthony J Bonkoski
University of Michigan Computer Science BSE 2013

Roboticist, Security Hobbyist, and Compiler Enthusiast (jabsoft.io)

[Joe]

Hi Anthony, Thanks for the pointer. I have it working now. My mistake was using the IP address of my machine rather than a UDP Multicast address. After using the same UDP Multicast address on both sides, I got it working.

Thanks again.

[Pradeep]

Hi Joe,

I'm facing a similar issue. I have to run my client and the server on separate PCs. Its using LCM and the default LCM url, which is "udpm://239.255.76.67?ttl=1". But I'm unable to make them communicate between each other. The code is in Java. Could you please suggest on how you got them to work ? Do I need to change the IP address of both the machines ? 

Thanks & Regards,

Pradeep

[Jonathan Bendes]

Hey Pradeep,

I think your issue is small. You forgot the port in your URL and your URL prefix is wrong.

http://239.255.76.67/?ttl=1

Should be

udpm://239.255.76.67:7667?ttl=1

Hope that works.

Jonathan

Visit this group at https://groups.google.com/group/lcm-users.

[Pradeep]

Hey Jon,

I forgot to mention in the above thread. Sorry about that. Its lcm  = new LCM("udpm://239.255.76.67:7667?ttl=1");

Thanks & Regards,

Pradeep