3com S7906E 安装指导
1-6
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RP discovery
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Embedded RP
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RPT establishment
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IPv6 Multicast source registration
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Switchover to SPT
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Assert
Neighbor discovery
IPv6 PIM-SM uses the similar neighbor discovery mechanism as IPv6 PIM-DM does. Refer to
.
DR election
IPv6 PIM-SM also uses hello messages to elect a DR for a multi-access network (such as a LAN). The
elected DR will be the only IPv6 multicast forwarder on this multi-access network.
In the case of a multi-access 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 DR at
the IPv6 multicast source side sends register messages to the RP.
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A DR is elected on a multi-access subnet by means of comparison of the priorities and IPv6
link-local addresses carried in hello messages.
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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 details about MLD, refer to MLD Configuration in the IP Multicast Volume.
Figure 1-3 DR election
Join message
RP
DR
DR
Hello message
Register message
Source
Receiver
Receiver
As shown in
, the DR election process is as follows: