This sets how long the device continues filtering, i.e. still delivering, a multicast stream to a group after the last known host in that group has left, giving the upstream router extra time to actually stop sending the stream before the local device tears down forwarding state. An admin tuning channel-change responsiveness on an IPTV deployment would shorten this linger timeout to reduce the delay viewers experience when switching channels, while a longer timeout smooths over brief flaps in group membership. A value of 30 seconds, for instance, means the multicast filter stays active for half a minute after the last viewer leaves before the device stops passing that stream.