Multicast very slow



  • @george1421 How can i make multicast on 1 computer? I can’t see this option


  • Moderator

    @plegrand said in Multicast very slow:

    @george1421
    unicast : 30minutes for 14 Computers
    multicast : 24hours for the same computers

    Sorry I was not clear in my request. I only want information on 1 computer (the same computer) One test via unicast and the second test via multicast. I want to compare the speeds between unicast and multicast on the same computer.

    To me you have too many variables in your environment. We need to understand the basics first.



  • @george1421
    unicast : 30minutes for 14 Computers
    multicast : 24hours for the same computers


  • Moderator

    Well the first thing I see here is that your clients are on 100MB links. So that will limit your transfer rates to 12MB/s maximum (all traffic).

    Once the network settles down you are getting 25MB/s transfer rate is very good. Also the slowest computer in the multicast will be the maximum speed of your multicast.

    So I would ask you in your network design. What is the average unicast transfer rate when you image one computer (direct download not multicast)? Then send a multicast image to that same 1 computer. Is there a large difference?



  • For information i’ve got these kinds of logs :
    http://plegrand1.free.fr/multicast.log.udpcast.6

    unicast works fine



  • @Sebastian-Roth
    Hello Sebastian and thanks for your answer.
    I made these tests (sorry for the french words) :

    Troubleshoot MultiCast
    https://wiki.fogproject.org/wiki/index.php/Multicasting

    Afficher le mode debug sur les clients
    Menu Fog Configuration
    iPXE Menu Item Settings
    fog.debug
    L’option “Menu Show with” est par défaut sur “Debug Options”. La mettre sur “All hosts”

    Test avec 4 clients
    Sur le serveur, lancer la commande suivante :
    udp-sender --file /opt/fog/.fogsettings --log /opt/fog/log/multicast.log --ttl 32 --nopointopoint

    Sur les clients
    Booter en mode debug
    Commande : udp-receiver
    Sur le serveur, on doit voir les 4 clients connectés
    “Enter” pour lancer le transfert

    Sur le serveur
    “Enter” pour lancer le transfert

    Tests avec les postes:
    192.168.39.181
    192.168.39.145
    192.168.39.121
    192.168.39.189
    Multicast litening : 232.168.39.243

    Logs sur le serveur :

    New connection from 192.168.39.181  (#0) 00000009
    Ready. Press any key to start sending data.
    New connection from 192.168.39.145  (#1) 00000009
    Ready. Press any key to start sending data.
    New connection from 192.168.39.189  (#2) 00000009
    Ready. Press any key to start sending data.
    New connection from 192.168.39.121  (#3) 00000009
    Ready. Press any key to start sending data.
    
    094  re-xmits=0000002 (100.0%) slice=0112 -   0
    
    09:24:59.309910 Using mcast address 232.168.39.243
    09:24:59.309962 UDP sender for /opt/fog/.fogsettings at 192.168.39.243 on eth0 
    09:24:59.309973 Broadcasting control to 192.168.39.255
    09:25:03.709692 Using mcast address 232.168.39.243
    09:25:03.709744 UDP sender for /opt/fog/.fogsettings at 192.168.39.243 on eth0 
    09:25:03.709756 Broadcasting control to 192.168.39.255
    09:30:03.457992 Using mcast address 232.168.39.243
    09:30:03.458037 UDP sender for /opt/fog/.fogsettings at 192.168.39.243 on eth0 
    09:30:03.458047 Broadcasting control to 224.0.0.1
    10:13:28.830979 Starting transfer: 00000009
    10:13:28.842773 RETX         1    1
    10:13:28.843867 RETX         2    1
    10:13:28.844919 Transfer complete.
    10:13:28.845001 Disconnecting #0 (192.168.39.181)
    10:13:28.845050 Disconnecting #1 (192.168.39.145)
    10:13:28.845063 Disconnecting #2 (192.168.39.189)
    10:13:28.845075 Disconnecting #3 (192.168.39.121)
    10:13:28.845090
    

    For me it works fine. What do you think about that?


  • Developer

    @plegrand Hey, welcome back to the forums! Reading your post I just remembered that we have been discussing this in the past already: https://forums.fogproject.org/topic/6655/multicast-very-slow

    the flow is very fast at the beginning then goes down to be very slow

    To me this sounds as if some of the clients are the bottleneck here. Maybe I am wrong but I think it’d be worth a try. Arrange your clients into smaller sub-groups of 3 machines in each group. Do multicast tests on each of those groups and see if the behaviour is exactly the same as before or if some sub-groups go faster than the others. Please note down the speeds and executing time of those multicast sessions and post results here.


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