[pim] PIM graceful restart (non-stop forwarding) capability

Hi,

How do PIM routers know about the graceful-restart capability of their
peers? In BGP, OSPF and other protocols, this capability is advertised
upfront when the adjacencies are formed. So that when their neighbor
liveliness is lost, they hold on to the routes to support the non stop
forwarding of traffic. 

In PIM, a new GenID in the Hello message indicates that the router
restarted. But that doesn't necessarily mean that router is capable of
doing non stop forwarding. So, in other words, when a PIM speaker
detects that its neighbor has gone down (or restarting), what is the
criterion on which it holds on to the updates from its neighbor in
non-stop forwarding mode? Is there any standardized option or mechanism
for this? If this has been already discussed, can someone point me to
the discussion?

Thanks

Srikanth