HP MSR1002-4 Configuration Manual page 367

The LAN delay defines the IPv6 PIM message propagation delay. The override interval defines
a time period for a downstream router to override a prune message. If the propagation delay or
override interval on different IPv6 PIM routers on a shared-media LAN are different, the largest
ones apply.
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 IPv6 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 IPv6 PIM. The generation ID is a random value, but only changes when the status
of the router changes. If an IPv6 PIM router finds that the generation ID in a hello message from
the upstream router has changed, it considers 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 IPv6 PIM view or for the current
interface in interface view. The configuration made in interface view takes priority over the
configurations made in IPv6 PIM view.
Configuring hello message options globally
Step
1. Enter system view.
2. Enter IPv6 PIM view.
3. Set the DR priority.
4. Set the neighbor lifetime.
5. Set the IPv6 PIM message
propagation
shared-media LAN.
6. Set the override interval.
7. Enable neighbor tracking.
Configuring hello message options on an interface
Step
1. Enter system view.
2. Enter interface view.
Command
system-view
ipv6
vpn-instance-name ]
hello-option dr-priority priority
hello-option holdtime time
delay for a
hello-option lan-delay delay
hello-option
interval
hello-option neighbor-tracking
Command
system-view
interface
interface-number
pim [ vpn-instance
override-interval
interface-type
358
Remarks
N/A
N/A
The default setting is 1.
The default setting
seconds.
The default setting
milliseconds.
The default setting
milliseconds.
By default, neighbor tracking is
disabled.
Remarks
N/A
N/A
is 105
is 500
is 2500