HP VSR1000 Configuration Manual page 115

On the shared-media LAN, the propagation delay and override interval are used as follows:
If a router receives a prune message on its upstream interface, it means that there are
downstream routers on the shared-media LAN. If this router still needs to receive multicast
data, it must send a join message to override the prune message within the override
interval.
When a router receives a prune message from its downstream interface, it does not
immediately prune this interface. Instead, it starts a timer (the propagation delay plus the
override interval). If interface receives a join message before the timer expires, the router
does not prune the interface. Otherwise, the router prunes the interface.
If you enable neighbor tracking on an upstream router, this router can track the states of the
downstream nodes for which the joined state holdtime timer has not expired. If you want to
enable neighbor tracking, you must enable it on all PIM routers on a shared-media LAN.
Otherwise, the upstream router cannot track join messages from every downstream routers.
•
Generation ID—A router generates a generation ID for hello messages when an interface is
enabled with PIM. The generation ID is a random value, but only changes when the status of
the router changes. If a PIM router finds that the generation ID in a hello message from the
upstream router has changed, it assumes that the status of the upstream router has changed.
In this case, it sends a join message to the upstream router for status update. You can configure
an interface to drop hello messages without the generation ID options to promptly know the
status of an upstream router.
You can configure hello message options for all interfaces in PIM view or for the current interface in
interface view. The configuration made in interface view takes priority over the configuration made in
PIM view.
Configuring hello message options globally
Step
Enter system view.
1.
Enter PIM view.
2.
Set the DR priority.
3.
Set the neighbor lifetime.
4.
Set the PIM message
5.
propagation delay for a
shared-media LAN.
Set the override interval.
6.
Enable neighbor tracking.
7.
Configuring hello message options on an interface
Step
Enter system view.
1.
Enter interface view.
2.
Set the DR priority.
3.
Set the neighbor lifetime.
4.
Command
system-view
pim [ vpn-instance
vpn-instance-name ]
hello-option dr-priority priority
hello-option holdtime time
hello-option lan-delay delay
hello-option override-interval
interval
hello-option neighbor-tracking
Command
system-view
interface interface-type
interface-number
pim hello-option dr-priority
priority
pim hello-option holdtime time
107
Remarks
N/A
N/A
The default setting is 1.
The default setting is 105
seconds.
The default setting is 500
milliseconds.
The default setting is 2500
milliseconds.
By default, neighbor tracking is
disabled.
Remarks
N/A
N/A
The default setting is 1.
The default setting is 105
seconds.