Why do I see error 0x69 when using the multicast_mapping QoS?

Submitted by grayson on Wed, 08/14/2024 - 10:21

When using the multicast_mapping QoS, you may encounter this error:

NDDS_Transport_UDP_share_recvresource_rrEA:setsockopt(ADD_MEMBERSHIP) error 0X69

This error usually indicates that you've exhaused the kernel parameter called igmp_max_memberships on Linux-like operating systems. The default for igmp_max_memberships is 20, so if you are creating more than 20 readers with the multicast_mapping QoS, you may see this error.

To test out this resolution, you can increase /proc/sys/net/ipv4/igmp_max_memberships temporarily:

echo 40 > /proc/sys/net/ipv4/igmp_max_memberships

If increasing this parameter helps avoid the errors, you can increase it permanently:

echo "net.ipv4.igmp_max_memberships=40" >> /etc/sysctl.conf
sysctl -p
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