Multicasting brings network to halt

  • Hey all,

    I just tried multicasting TWO laptops and it was working fine, getting normal speed on the image, about 1.5 gb/min//about the norm here. About 20% into it i started getting complaints that nothing on the network was working and they couldn’t open web pages. I couldn’t even remote into a server. I killed the task immediately and everything righted itself within seconds. Has anyone ever seen this or have any ideas? I’m using the latest version of FOG, and in the past year i have upgraded all of our switches to cisco sf300 series. Normal imaging works fine and no issues or complaints from users when i do that. Somehow it seems the multicast packets are flooding the network and bringing it down.

  • You may need to separate the Network into different scopes and filter the broadcasts to allow this to work.

    One of the biggest drawbacks to Multicast/UDP packets is they don’t care who’s receiving them, and don’t care who it’s intended for. It just “blasts” data. This blast is then picked up by EVERY system on the network. Seeing as imaging will continuously send packets of data out, it’s literally self DoSing your networking.

  • we currently have around 100 computers connected, 30 servers that are also on the same vlan.

  • Moderator


    Do you have some vlan ? How many computer are connected on your network ?
    In Cisco swith configuration you must add some option to optimize multicast.

    I run FoG on 20 vLan and arround 800 computers, and have not any problem when I multicast over 50/80 computers.


  • This is the nature of Multicast/UDP