HP A5500 SI Switch Series Configuration Manual page 170

the largest value will take effect. If you want to enable neighbor tracking, be sure to enable the
neighbor tracking feature on all PIM routers on a multi-access subnet.
The LAN-delay setting will cause the upstream routers to delay processing received prune messages. The
override-interval sets the length of time that a downstream router can wait before sending a prune
override message. When a router receives a prune message from a downstream router, it does not
perform the prune action immediately. Instead, it maintains the current forwarding state for a period of
LAN-delay plus override-interval. If the downstream router needs to continue receiving multicast data, it
must send a join message within the prune override interval. Otherwise, the upstream router will perform
the prune action when the period of LAN-delay plus override-interval times out.
A hello message sent from a PIM router contains a generation ID option. The generation ID is a random
value for the interface on which the hello message is sent. Normally, the generation ID of a PIM router
does not change unless the status of the router changes (for example, when PIM is just enabled on the
interface or the device is restarted). When the router starts or restarts sending hello messages, it
generates a new generation ID. 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 neighbor is lost or that the
upstream neighbor has changed. In this case, it triggers a join message for state update.
If you disable join suppression (namely, enable neighbor tracking), be sure to disable the join
suppression feature on all PIM routers on a multi-access subnet. Otherwise, the upstream router will fail
to explicitly track which downstream routers have joined to it.
Configuring hello options globally
Follow these steps to configure hello options globally:
To do...
Enter system view
Enter public network PIM view or
VPN instance PIM view
Configure the priority for DR
election
Configure PIM neighbor timeout
time
Configure the prune message
delay time (LAN-delay)
Configure the prune override
interval
Disable join suppression
Configuring hello options on an interface
Follow these steps to configure hello options on an interface:
To do...
Enter system view
Enter interface view
Use the command...
system-view
pim [ vpn-instance vpn-instance-
name ]
hello-option dr-priority priority
hello-option holdtime interval
hello-option lan-delay interval
hello-option override-interval
interval
hello-option neighbor-tracking
Use the command...
system-view
interface interface-type interface-
number
158
Remarks
—
—
Optional
1 by default.
Optional
105 seconds by default.
Optional
500 milliseconds by default.
Optional
2,500 milliseconds by default.
Required
Enabled by default.
Remarks
—
—