6 pim configuration, Pim overview, Pim configuration – H3C Technologies H3C S7500E Series Switches User Manual
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PIM Configuration
When configuring PIM, go to these sections for information you are interested in:
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Configuring PIM Common Features
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Displaying and Maintaining PIM
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Troubleshooting PIM Configuration
The term “router” in this document refers to a router in a generic sense or a Layer 3 switch
running the PIM protocol.
PIM Overview
Protocol Independent Multicast (PIM) provides IP multicast forwarding by leveraging static
routes or unicast routing tables generated by any unicast routing protocol, such as routing
information protocol (RIP), open shortest path first (OSPF), intermediate system to intermediate
system (IS-IS), or border gateway protocol (BGP). Independent of the unicast routing protocols
running on the device, multicast routing can be implemented as long as the corresponding
multicast routing entries are created through unicast routes. PIM uses the reverse path
forwarding (RPF) mechanism to implement multicast forwarding. When a multicast packet
arrives on an interface of the device, it is subject to an RPF check. If the RPF check succeeds,
the device creates the corresponding routing entry and forwards the packet; if the RPF check
fails, the device discards the packet. For more information about RPF, refer to Multicast Routing
and Forwarding Configuration in the IP Multicast Configuration Guide.
Based on the implementation mechanism, PIM falls into two modes:
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Protocol Independent Multicast–Dense Mode (PIM-DM), and
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Protocol Independent Multicast–Sparse Mode (PIM-SM).