Pim Sparse Mode; Figure 10: Detecting Duplication - Juniper JUNOSE 11.0.X MULTICAST ROUTING Configuration Manual

JUNOSe 11.0.x Multicast Routing Configuration Guide

Figure 10: Detecting Duplication

The upstream routers responsible for the duplication send assert messages to
determine which router becomes the forwarder. Downstream routers listen to the
assert messages to discover which router becomes the forwarder.

PIM Sparse Mode

This implementation of PIM sparse mode supports the following features:
PIM sparse mode resolves situations that meet one or more of the following criteria:
Sparse-mode routing protocols use shared trees. In a shared tree, sources forward
multicast datagrams to a directly connected router, the designated router. The
designated router encapsulates the datagram and unicasts it to an assigned RP router,
which then forwards the datagram to members of multicast groups. See Figure 11
on page 83.
82
Overview
Rendezvous point (RP) routers
Designated routers and designated router election
Join/prune messages, hello messages, assert messages, and register messages
Switching from a shared tree to a shortest path tree (SPT)
(*,*,RP) support for interoperation with dense-mode protocols
RPF checks of multicast entries when unicast routing configuration changes
Timers for tree maintenance
Border, null, Rendezvous Point Tree (RPT), SPT, and wildcard flags
The multicast group contains few receivers.
Multicast traffic is infrequent.
Wide area networks (WANs) separate sources and receivers.