The length of the Graceful Restart backstop timer to run within DC-PIM, in seconds. Graceful Restart is currently only supported when running in IGMP Proxy, IGMP Snooping, Sparse and Dense modes - see pimTmEntMode. Note that in Sparse/Dense mode, the Backstop Duration must be greater than the Join Startup Duration, pimTmEntGRJoinStartupDuration. In IGMP Graceful Restart, processing is normally timed out by suitable protocol timers (e.g. IGMP Startup Query Interval), but this timer is provided as a backstop to allow the administrator to override any protocol timers. In PIM Graceful Restart, if the network is stable, processing is a finite action. However, when the network is unstable, data flows may change frequently enough to put DC-PIM in a permanent state of audit. The backstop timer overrides any excess processing, causing DC-PIM to break out of audit on expiry. This field together with pimTmEntGRJoinStartupDuration defines whether Graceful Restart is supported for this DC-PIM instance. If both of them are set to 0 then Graceful Restart is disabled and DC-PIM will not attempt to preserve data plane state on restart. The default value is 0 seconds, meaning that Graceful Restart is disabled.