unicast vs multicast & ideal network setup

Discussion in 'DMX, E1.31 & Networking' started by djgra79, May 11, 2017.

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What is best for running a show...

  1. Unicast

    4 vote(s)
    66.7%
  2. Multicast

    2 vote(s)
    33.3%
  1. djgra79

    djgra79 Senior Elf

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    I'm sure this could have been covered before, and it may even be a case of Ford Vs Holden (Kia man now myself btw) but looking for feedback on broadcasting your show via unicast vs multicast.
    As discussed at the Melb Mini this year, it was pointed out that for larger channel count shows, multicast would be best, but you need to make sure that the show network is completely separate form your home network (examples given was angry family member's internet access dropping out!)
    Using my own show as an example, I'm currently using unicast, (where the IP address of each controller is sought out and sent data.) I haven't really noticed any lag or flickering (yet) but once I add more elements I could be hitting some large channel counts.

    As for best practise for network setup, Damona shared his setup at the mini (link here)
    I run my show from a Raspberry Pi & FPP, but I have this connected to an 8port switch, which is linked to our home network (using one of the 4 ports on our main router.) So if multicast is the way to go as per above, that means the controllers don't need a specific IP address? If I remember the terminology, it was recommended to get a good switch that has DHCP, which gives the controllers a new IP of it's own?? I may have gotten this wrong so looking forward to expert opinions.

    Annnnnnnd, GO!
     
  2. scamper

    scamper Senior Elf

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    I too run a pi and fpp and have 2 f16v2's that have their own static ip. The network they are on is a private network, but I have a wipi plugged into the Pi and that is set to my home network, meaning I can startup, shutdown, update and monitor the show without any effect to the home network. So the wifi is on 192.168.x.x and the Ethernet cable (hardwired to the f16's) is on 10.0.x.x
    Not sure if this is the acceptable method, but it works fine for me.
     
  3. keithsw1111

    keithsw1111 Full Time Elf

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    Unicast always for anything large given most home switches/routers broadcast multicast traffic.That means likely as not every device sees every multicast packet.
     
  4. damona

    damona Full Time Elf

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    That's fine. Your using the Pi as a wireless access into your Pi. As long as its only sending the E1.31 down the Pi 100 Mbit/s wired network connection. (WirelessN is about 80-100 Mbit/s shared network).

    Recommendation is not to use your home network switch, esp. if you run the cables outside. (just encase someone decides to plug a device into cables left outside or a lighting strike near miss). Falcon Play does not support being a DHCP server (via GUI interface) The old ADSL Wireless Modem response to DHCP requests, my setup its configured to send the Pi a fixed/constant IP address so the Pi Address does not change, everything else has dynamic IP DHCP address. If your using an OLD ADSL Modem then you should only have one connection in use which is used to plug into the IGMP Switch. Most old ADSL modems also act as a DNS Server as well.
     
    Last edited: May 15, 2017
  5. buzzdude

    buzzdude Full Time Elf

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    I started running unicast when after using multicast, found it was a hit and miss when trying to get controllers to work. (May have been my configuration, but needing to reset switches to get it going was a pain, especially when I have then in the roof).

    My dumbed down understanding of unicast was it was more of a direct route, rather than mulitcast, packets going all over the place.... :)

    I'm Running gigabit network switches, 2 x E682 and 2 x F16V2 also have 6 IP Cameras, DLNA server, 3 x chromecasts and streaming that much stuff internally, plus the show all on the home network, now without a problem. (Did have slowness last year, when I found the xlights scheduler flooded the internet connection, but after I put a firewall rule in, internet speed was ok)
    Agree with the concern maybe someone finding a cable and plugging in, but I have these locked in cabinet, so I feel ok.

    I'm going to stick with unicast, as it's working for me, at this stage, and I feel my setup is clean, with xlights matching controllers, etc.
     
  6. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Unicast is better for any wireless connections as multicast can flood the wireless connection with data from everything in your network, Multicast is easier to setup as you don't need an IP setup for each controller in software, so the more universes then the less amount of effort to setup compared to unicast. In some cases some controllers may not work very well with lots of multicast traffic as each controller sees all the multicast traffic and picks out what data is for it. Unicast doesn't see all the network traffic as the data is specifically sent to that controller.
    In most cases for most users the differences are minimal until you start using large amounts of universes and there is lots of data
     
  7. bluzervic

    bluzervic 65,768 Channels, 185 Universes

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    Unicast sends IP packets to a single recipient on a network. Multicast sends IP packets to a group of hosts on a network. Multicasting is a relatively new technology and some legacy devices that are part of your network might not support Multicasting. Multicasting may also flood your network with broadcasts.
    For most shows Unicast is good enough, even with thousands of channels. I have 64,000 plus channels and I still use unicast.
    You still have to define it all in Xlights regardless.
     
  8. damona

    damona Full Time Elf

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    Multicast only = Broadcast if your switch does not support IGMP and the device/controller does not support IGMP. IGMPv2 has existed since 1997 and
    "Like ICMP, IGMP is a integral part of IP. It is required to be implemented by all hosts wishing to receive IP multicasts"

    The device/control announces it wants one or more multicast group on an Ethernet port on your switch, after this occurs only that Ethernet port will get the packets for that Universe. (Unless another device/control also announces the same Universe/Multicast Group then another port will get the packets)

    From the 2014 Standard:
    "This standard uses multicast addressing to provide a mechanism to partition traffic for distinct universes of DMX512-A [DMX] and synchronization data. Direct unicast of DMX512-A [DMX] data is also supported."
     
  9. multicast

    multicast Senior Elf Generous Elf

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    Thats from the 2016 standard. :)
     

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