ECS4660-28F_Management Guide-R03

C HAPTER 21 | Multicast Routing
Configuring PIMv6 for IPv6
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determines that there are no group members or downstream routers,
or when a prune message is received from a downstream router.
PIM6-SM
◆ A PIM6-SM interface is used to forward multicast traffic only if a join
message is received from a downstream router or if group members
are directly connected to the interface. When routers want to receive a
multicast flow, they periodically send join messages to the RP, and are
subsequently added to the shared path for the specified flow back up to
the RP. If routers want to join the source path up through the SPT, they
periodically send join messages toward the source. They also send
prune messages toward the RP to prune the shared path once they
have connected to the source through the SPT, or if there are no longer
any group members connected to the interface.
PARAMETERS
These parameters are displayed:
Common Attributes
◆ VLAN – Layer 3 VLAN interface. (Range: 1-4094)
◆ Mode – PIMv6 routing mode. (Options: Dense, Sparse, None)
The routing mode must first be set to None, before changing between
Dense and Sparse modes.
◆ IPv6 Address – IPv6 link-local address assigned to the selected VLAN.
◆ Hello Holdtime – Sets the interval to wait for hello messages from a
neighboring PIM router before declaring it dead. Note that the hello
holdtime should be greater than or equal to the value of Hello Interval,
otherwise it will be automatically set to 3.5 x the Hello Interval.
(Range: 1-65535 seconds; Default: 105 seconds, or 3.5 times the hello
interval if set)
◆ Hello Interval – Sets the frequency at which PIM hello messages are
transmitted out on all interfaces. (Range: 1-65535 seconds;
Default: 30 seconds)
Hello messages are sent to neighboring PIM routers from which this
device has received probes, and are used to verify whether or not these
neighbors are still active members of the multicast tree. PIM-SM
routers use these messages not only to inform neighboring routers of
their presence, but also to determine which router for each LAN
segment will serve as the Designated Router (DR).
When a router is booted or first configured to use PIM, it sends an initial
hello message, and then sets its Hello timer to the configured value. If
a router does not hear from a neighbor for the period specified by the
Hello Holdtime, that neighbor is dropped. This hold time is included in
each hello message received from a neighbor. Also note that hello
messages also contain the DR priority of the router sending the
message.