Configuring Ipv6 Pim; Overview; Ipv6 Pim-Dm Overview - HP MSR2003 Configuration Manual

Configuring IPv6 PIM

Overview

IPv6 Protocol Independent Multicast (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, IPv6 IS-IS, or IPv6 BGP. IPv6 PIM uses the underlying IPv6 unicast routing to generate
an IPv6 multicast routing table without relying on any particular IPv6 unicast routing protocol.
IPv6 PIM uses the RPF mechanism to implement multicast forwarding. When an IPv6 multicast packet
arrives on an interface of the device, the packet undergoes an RPF check. If the RPF check succeeds, the
device creates an IPv6 multicast routing entry and forwards the packet. If the RPF check fails, the device
discards the packet. For more information about RPF, see "Configuring IPv6 multicast routing and
forwarding."
Based on the implementation mechanism, IPv6 PIM includes the following categories:
IPv6 Protocol Independent Multicast–Dense Mode (IPv6 PIM-DM)
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• IPv6 Protocol Independent Multicast–Sparse Mode (IPv6 PIM-SM)
IPv6 Bidirectional Protocol Independent Multicast (IPv6 BIDIR-PIM)
•
IPv6 Protocol Independent Multicast Source-Specific Multicast (IPv6 PIM-SSM)
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In this document, an IPv6 PIM domain refers to a network composed of IPv6 PIM routers.

IPv6 PIM-DM overview

IPv6 PIM-DM uses the push mode for multicast forwarding and is suitable for small networks with densely
distributed IPv6 multicast members.
The following describes the basic implementation of IPv6 PIM-DM:
IPv6 PIM-DM assumes that all downstream nodes want to receive IPv6 multicast data from a source,
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so IPv6 multicast data is flooded to all downstream nodes on the network.
Branches without downstream receivers are pruned from the forwarding trees, leaving only those
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branches that contain receivers.
• The pruned state of a branch has a finite holdtime timer. When the timer expires, IPv6 multicast data
is again forwarded to the pruned branch. This flood-and-prune cycle takes place periodically to
maintain the forwarding branches.
The graft mechanism is used to reduce the latency for resuming the forwarding capability of a
•
previously pruned branch.
In IPv6 PIM-DM, the multicast forwarding paths for an IPv6 multicast group constitute a source tree. The
source tree is rooted at the IPv6 multicast source and has multicast group members as its "leaves."
Because the source tree consists of the shortest paths from the IPv6 multicast source to the receivers, it is
also called a "shortest path tree (SPT)."
Neighbor discovery
In an IPv6 PIM domain, each IPv6 PIM interface periodically multicasts IPv6 PIM hello messages to all
other IPv6 PIM routers on the local subnet. Through the exchanging of hello messages, all IPv6 PIM
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