User's Manual

49-2
the multicast packet will 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 two multicast router A and B in the same LAN segment have their own receiving paths to multicast source
S, they will respectively forward multicast data packet to LAN after receiving the packet from multicast
source S. Then downstream nodes multicast router C will receive two multicast packets that are exactly the
same. Once router detects such circumstance, a unique forwarder will be selected through “assert”
mechanism. The optimized forwarding path is selected through “assert” packet. If the priority and costs of
two or more than two paths are same, the node with a larger IP address will be selected as the upstream
neighbor of item (S, G), which will be responsible for forwarding the (S, G) multicast packet.
5. Graft
When the pruned downstream node needs to recover to forwarding status, this node uses Graft Message to
notify upstream nodes to resume multicast data forwarding.
49.1.2 PIM-DM6 Configuration Task List
1． Enable PIM-DM (Required)
2． Configure static multicast routing entries (Optional)
3． Configure additional PIM-DM parameters (Optional)
(1) Configure parameters for PIM-DM interfaces
1) Configure the interval for PIM-DM hello messages
2) Configure the interval for PIM-DM state-refresh messages
3) Configure the boundary interfaces
4) Configure the management boundary
4． Disable PIM-DM protocol
1. Enable the PIM-DM protocol
On SGS-6341 Series switches, PIM-DM can be enabled through two steps. Firstly PIM multicast routing
should be enabled in global configuration mode, then PIM-DM should be configured for the specific interfaces.
Command
Explanation
Command configuration mode
ipv6 pim multicast-routing
To enable PIM-DM
multicast routing global.
However, in order to enable PIM-DM for specific
interfaces, the following command must be
issued.
Enable PIM-SM for the specific interface:
Command
Explanation
Interface configuration mode