Most operating systems are not set up out of the box to handle heavy multicast loads. With some, multicast reception is actually disabled. This article contains setup notes for the OS when using Net-X-Code Server, videoQC, or NetXScope/HDRScope/4KScope with network video sources.
CentOS/Red Hat 7
The main change needed here is the setting of the rp_filter for the ethernet card you are going to multicast to/from. This can be set up temporarily by changing
/proc/sys/net/ipv4/conf/all/rp_filter
/proc/sys/net/ipv4/conf/<ethernet>/rp_filter
to 2. This will allow the next run to read multicast packets from that ethernet device. These variables can also be changed via the sysctl utility
sudo sysctl -w "net.ipv4.conf.default.rp_filter=2"
sudo sysctl -w "net.ipv4.conf.all.rp_filter=2"
sudo sysctl -w "net.ipv4.conf.<ethernet>.rp_filter=2"
For a more permanent change, modify the contents of /etc/sysctl.conf to include
net.ipv4.conf.default.rp_filter = 2
net.ipv4.conf.all.rp_filter = 2
net.ipv4.conf.ens4.rp_filter = 2
You will also need to adjust your firewall to allow your ports/addresses through. For testing, you can temporarily disable the firewall with:
systemctl stop firewalld
You can also permanently disable your firewall, but this is NOT recommended.
systemctl disable firewalld
sysctl -w net.core.rmem_max=12582912
sysctl -w net.core.wmem_max=12582912
sysctl -w net.core.netdev_max_backlog=5000
Here is an optimized sysctl.con
Finally, most SMPTE 2110/2022 systems will be multi-homed (more than one ethernet adapter). To tell our software which is the video IP adapter, the ReceiveInterface, ReceiveAudInterface, and ReceiveAncInterface will need to be set. There are Transmit versions of each of these as well.
Microsoft Windows
Generally, Windows is not recommended for direct SMPTE 2110/2022, as its network stack is not as good as Linux. If you are going to use it, the following may help.
Firewalls
Windows firewall can end up blocking all multicast network traffic. This will definitely happen if your 10G/25G network card ends up in the 'public' group, rather than the private or domain. In that case, the firewall will have to be completely disabled on the public network for SMPTE 2110/2022 to be received. Ideally, the NIC should be in the domain or private, and your IT group can enable the correct ports and protocols. If you are having trouble, try temporarily disabling the firewall. If that works, then the firewall configuration is still too restrictive/improperly configured.
Buffering
To increase the default buffering for UDP, save this as a .reg file and double click to add it to your registry.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\AFD\Parameters]
"DefaultReceiveWindow"=dword:00200000
"DefaultSendWindow"=dword:00200000
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