Manual

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connected to Multicast source indicated by Unicast routing, then this Multicast packet is
considered to be from the correct path. Otherwise the Multicast packet is to be discarded as
redundant message. The Unicast routing message used as path judgment can root in any
Unicast Routing Protocol, such as messages found by RIP, OSPF, etc. It doesn’t rely on any
specific Unicast Routing Protocol.
4. Assert Mechanism
If each of two Multicast routers A and B on the same LAN segment has a receiving route
respectively and both will transmit the Multicast packet to the LAN after receiving the Multicast
data packet sent by the Multicast Source S, then the downstream node Multicast router C will
receive two exactly same Multicast packets. The router needs to choose a unique transmitter
through Assert mechanism after it detects this situation. An optimal transmission path is
selected through sending out Assert packet. If the priority and cost of two or more path are
same, then the node with larger IP address is taken as the upstream neighbor of the (S, G)
entry and in charge of the transmission of the (S, G) Multicast packet.
5. Graft
When the pruned downstream node needs to recover to transmission status, this node uses
Graft Packet to notify upstream nodes to restore multicast data transmission.
28.2.2 PIM-DM Configuration Task List
Enable PIM-DM (Required)
Configure static multicast routing entries(Optional)
Configure additional PIM-DM parameters(Optional)
Configure the interval for PIM-DM hello messages
Configure the interval for state-refresh messages
Configure the boundary interfaces
Configure the management boundary
Disable PIM-DM protocol
1. Enable the PIM-DM protocol
When configuring the PIM-DM protocol on QTECH series Layer 3 switches, PIM multicasting
should be enabled globally, then PIM-DM can be enabled for specific interfaces.
Command
Explanation
Global Mode
ip pim multicast-routing
no ip pim multicast-routing
To enable PIM-DM globally for all the interfaces
(However, in order to make PIM-DM work for specific
interfaces, the following command should be issued).
And then turn on PIM-SM switch on the interface
Command
Explanation
Interface Configuration Mode