The value of tmnxOspfGRHelperMode specifies whether the
graceful restart helper mode is enabled or disabled for this
instance of OSPF on the router.
tmnxOspfGRHelperMode is valid only if the value of
tmnxOspfGREnable is 'true'.
When tmnxOspfGRHelperMode has a value of 'true' graceful
restart helper capabilities are enabled. When it has a value
of 'false' the graceful restart helper capabilities are disabled.