Guard Timer in msec. The guard timer is used to prevent ring nodes from receiving outdated R-APS messages. During the duration of the Guard Timer, all received R-APS messages, are ignored by the ring protection control process. This timer should be greater than the maximum expected forwarding delay for which one R-APS message, circles around the ring. Valid values are: 10..2,000 in steps of 10. Default=500 msec.