[Lxc-users] lxc and UDP networking

[Massimo Cafaro]

Dear all,

I am using the latest lxc version on Fedora 17, providing networking among the containers using the ns-3 network simulator (following the configuration given in http://www.nsnam.org/wiki/index.php/HOWTO_Use_Linux_Containers_to_set_up_virtual_networks adapted to 32 containers).
I am experiencing a problem with UDP networking in my p2p application. If I launch 32 instances of the app (on different TCP and UDP ports) on the same machine, it works as expected: a query on one of the instances reaches all of the other instances and 32 results are returned. However, launching 32 instances each one in a different container, only two results are returned. It seems that the query only reaches a subset of the instances, and only one of these returns its local result to the instance issuing the query, which returns this result and its own.

Here is the container configuration I am using:

lxc.utsname = host-1
lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = br-1
lxc.network.ipv4 = 10.0.0.1/24
lxc.tty = 4
lxc.pts = 1024

the other containers are configured in the same way as host-2 and IP address 10.0.0.2/24 etc.
Is there any known issue related to UDP networking in lxc ? I understand that, of course, the problem may be due to the ns-3 network simulation, but a few specific UDP tests are working correctly as well (UPD echo server and client, run on different pairs of containers). This is driving me crazy: apparently, UDP networking is ok in the containers, but when I launch the app instances I am experiencing the weird behavior described. Launching the instances on the machine without the containers works correctly.

Any clue or suggestion ?
Thank you in advance.
With kind regards,

Massimo cafaro

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 Massimo Cafaro, Ph.D.                               Additional affiliations:
 Assistant Professor                                      Euro-Mediterranean Centre for Climate Change
 Dept. of Engineering for Innovation          SPACI Consortium  
 University of Salento, Lecce, Italy             E-mail massimo.cafaro at unisalento.it
 Via per Monteroni                                                     massimo.cafaro at cmcc.it
 73100 Lecce, Italy					                                cafaro at ieee.org
 Voice/Fax  +39 0832 297371 				                        cafaro at acm.org   
 Web     http://sara.unisalento.it/~cafaro                                                                 
       

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