R21xx-HP FlexFabric 11900 IP Multicast Configuration Guide

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a prune message. If the prune message delay or override interval on different PIM routers on a
shared-media LAN are different, the largest value takes effect.
A router does not immediately prune an interface after it receives a prune message from the
interface. Instead, it starts a timer (the prune message delay plus the override interval). If interface
receives a join message before the override interval expires, the router does not prune the
interface. Otherwise, the router prunes the interface when the timer (the prune message delay plus
the override interval) expires.
You can enable the neighbor tracking function (or disable the join message suppression function)
on an upstream router to track the states of the downstream nodes that have sent the join message
and the joined state holdtime timer has not expired. If you want to enable the neighbor tracking
function, 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 in PIM view or interface view. The configurations made in PIM
view are effective on all interfaces and the configurations made in interface view are effective on only the
current interface. If you configure hello message options in both PIM view and interface view, the
configuration in interface view always takes precedence.
Configuring hello message options globally
Ste
p
Command Remarks
1. Enter system view.
system-view
N/A
2. Enter PIM view.
pim N/A
3. Set the DR priority.
hello-option dr-priority priority By default, the DR priority is 1.
4. Set the neighbor lifetime.
hello-option holdtime time
By default, the neighbor lifetime is
105 seconds.
5. Set the prune message delay.
hello-option lan-delay delay
By default, the prune message
delay is 500 milliseconds.
6. Set the override interval.
hello-option override-interval
interval
By default, the override interval is
2500 milliseconds.
7. Enable the neighbor tracking
function.
hello-option neighbor-tracking
By default, the neighbor tracking
function is disabled.