H3C Technologies H3C S10500 Series Switches - Manual (Page 370)

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IPv6 PIM configuration
NOTE:
•
The term router in this document refers to both routers and Layer 3 switches.
• The term interface in the IPv6 PIM features refers to Layer 3 interfaces, including VLAN interfaces and
route-mode (or Layer 3) Ethernet ports. You can set an Ethernet port to operate in route mode by using
the port link-mode route command (see Layer 2—LAN Switching Configuration Guide).
IPv6 PIM overview
Protocol Independent Multicast for IPv6 (IPv6 PIM) provides IPv6 multicast forwarding by leveraging IPv6
unicast static routes or IPv6 unicast routing tables generated by any IPv6 unicast routing protocol, such
as RIPng, OSPFv3, IS-ISv6, or BGP4+. IPv6 PIM uses an IPv6 unicast routing table to perform reverse
path forwarding (RPF) check to implement IPv6 multicast forwarding. Independent of the IPv6 unicast
routing protocols running on the device, IPv6 multicast routing can be implemented as long as the
corresponding IPv6 multicast routing entries are created through IPv6 unicast routes. IPv6 PIM uses the
reverse path forwarding (RPF) mechanism to implement IPv6 multicast forwarding. When an IPv6
multicast packet arrives on an interface of the device, RPF check is performed on it. 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, see the chapter “IPv6 multicast
routing and forwarding configuration.”
Based on the implementation mechanism, IPv6 PIM supports the following types:
• Protocol Independent Multicast–Dense Mode for IPv6 (IPv6 PIM-DM)
• Protocol Independent Multicast–Sparse Mode for IPv6 (IPv6 PIM-SM)
• Bidirectional Protocol Independent Multicast for IPv6 (IPv6 BIDIR-PIM)
• Protocol Independent Multicast Source-Specific Multicast for IPv6 (IPv6 PIM-SSM)
NOTE:
To facilitate description, a network comprising IPv6 PIM–supporting routers is referred to as an “IPv6 PIM
domain” in this document.
IPv6 PIM-DM overview
IPv6 PIM-DM is a type of dense mode IPv6 multicast protocol. It uses the push mode for IPv6 multicast
forwarding, and is suitable for small-sized networks with densely distributed IPv6 multicast members.
The basic implementation of IPv6 PIM-DM is as follows:
• IPv6 PIM-DM assumes that at least one IPv6 multicast group member exists on each subnet of a
network. Therefore, IPv6 multicast data is flooded to all nodes on the network. Then, branches
without IPv6 multicast forwarding are pruned from the forwarding tree, leaving only those branches
that contain receivers. This flood-and-prune process takes place periodically. That is, pruned
branches resume IPv6 multicast forwarding when the pruned state times out and then data is
flooded again down these branches, and then the branches are pruned again.