Configuring Pim Hello Message Options - HP FlexNetwork 7500 Series Configuration Manual

Step
Enter system view.
1.
Enter interface view.
2.
Configure a PIM hello policy.
3.

Configuring PIM hello message options

In either a PIM-DM domain or a PIM-SM domain, hello messages exchanged among routers contain
the following configurable options:
•
DR_Priority (for PIM-SM only)—Priority for DR election. The device with the highest priority
wins the DR election. You can configure this option for all the routers in a shared-media LAN
that directly connects to the multicast source or the receivers.
•
Holdtime—PIM neighbor lifetime. If a router does not receive a hello message from a neighbor
when the neighbor lifetime expires, it regards the neighbor failed or unreachable.
•
LAN_Prune_Delay—Delay of pruning a downstream interface on a shared-media LAN. This
option has LAN delay, override interval, and neighbor tracking support (the capability to disable
join message suppression).
The LAN delay defines the PIM message propagation delay. The override interval defines a
period for a router to override a prune message. If the propagation delay or override interval on
different 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 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 globally for all interfaces in PIM view or for an interface in
interface view. For an interface, the interface-specific configuration takes priority over the global
configuration.
Command
system-view
interface interface-type
interface-number
pim neighbor-policy acl-number
123
Remarks
N/A
N/A
By default, no PIM hello policy
exists.
If a PIM neighbor's hello
messages cannot pass the policy,
the neighbor is automatically
removed when its maximum
number of hello attempts is
reached.