This read-create integer, from 1 to 255, sets the IGMP Robustness Variable, tuning how many query packet losses the switch's IGMP implementation can tolerate on a subnet before mistakenly assuming no members remain. An administrator increases this value on a lossy subnet to make IGMP snooping more resilient to dropped query or report packets. For example, on a subnet with known Wi-Fi-related packet loss, an operator might raise swIGMPRobustness above its default to avoid premature multicast group timeouts.