HP A8800 Configuration Manual page 167

DR_Priority (for PIM-SM only)—Priority for DR election. The device with the highest priority wins the
•
DR election. You can configure this parameter on all the routers in a multi-access network directly
connected to multicast sources or receivers.
• Holdtime—The timeout time of PIM neighbor reachability state. When this timer times out, if the
router has received no hello message from a neighbor, it assumes that this neighbor has expired or
become unreachable.
LAN_Prune_Delay—The delay of prune messages on a multi-access network. This option consists of
•
LAN-delay (namely, prune message delay), override-interval, and neighbor tracking flag. If the
LAN-delay or override-interval values of different PIM routers on a multi-access subnet are different,
the largest value takes effect. If you want to enable neighbor tracking, the neighbor tracking feature
should be enabled 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 a downstream router is allowed to 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 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), the join suppression feature should
be disabled 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
Step
1. Enter system view.
2. Enter public network PIM view
or VPN instance PIM view.
3. Configure the priority for DR
election.
4. Configure PIM neighbor
timeout time.
5. Configure the prune message
delay time (LAN-delay).
6. Configure the prune override
interval.
7. Disable join suppression.
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
155
Remarks
N/A
N/A
Optional.
1 by default.
Optional.
105 seconds by default.
Optional.
500 milliseconds by default.
Optional.
2500 milliseconds by default.
Enabled by default.