HP MSR ASM Configuration Manual page 312

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Neighbor discovery
IPv6 PIM-SM uses the similar neighbor discovery mechanism as IPv6 PIM-DM does. For more information,
see "Neighbor
DR election
IPv6 PIM-SM also uses hello messages to elect a DR for a shared-media network (such as a LAN). The
elected DR will be the only IPv6 multicast forwarder on this shared-media network.
In the case of a shared-media network, a DR must be elected, no matter this network connects to IPv6
multicast sources or to receivers. The DR at the receiver side sends join messages to the RP. The
source-side DR sends register messages to the RP.
A DR is elected on a shared-media subnet by means of comparison of the priorities and IPv6 link-local
addresses carried in hello messages.
MLD must be enabled on a device that acts as a receiver-side DR before receivers attached to this device
can join IPv6 multicast groups through this DR. For more information about MLD, see "Configuring MLD."
Figure 84 DR election
As shown in
1. Routers on the shared-media network send hello messages to one another. The hello messages
contain the router priority for DR election. The router with the highest DR priority will become the
DR.
2. In the case of a tie in the router priority, or if any router in the network does not support carrying
the DR-election priority in hello messages, the router with the highest IPv6 link-local address will
win the DR election.
When the DR works abnormally, a timeout in receiving a hello message triggers a new DR election
process among the other routers.
RP discovery
The RP is the core of an IPv6 PIM-SM domain. For a small-sized, simple network, one RP is enough for
forwarding IPv6 multicast information throughout the network, and the position of the RP can be statically
discovery."
Figure 84, the DR election process is as follows:
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