Building Rp And Sp Trees When The Source Begins Multicasting First - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

5.
Figure 11-6 shows the multicast routing table of a ProCurve Secure Router
acting as the DR for a source.
The DR is sending
multicasts to the RP
over the SP tree.
Figure 11-6. Multicast Routing Table of the DR for a Source
Building RP and SP Trees When the Source Begins
Multicasting First
The above description of joining a shared tree and switching to an SP tree
assumes that all receivers join a group before a source begins multicasting.
However, this assumption is often untrue. The first host in a subnet to join a
group may do so after a source has begun sending multicasts. The source may
even begin sending multicasts before any hosts join the group.
PIM-SM provides for both of these situations. Trees are built and traffic
forwarded in much the same way as that described above, but with several
modifications that are described below.
A Source Begins Multicasting Before Any Hosts Join Its
Group
1.
The DR continues forwarding multicasts over the SP tree.
ProCurve# show ip mroute
IP Multicast Routing Table
Flags: S - Sparse, C - Connected, P - Pruned, J - Join SPT, T - SPT-
bit Set,
F - Register, R - RP-bit Set
Timers: Uptime/Expires
(*, 239.255.255.1), 01:10:08/00:00:00, RP 10.1.1.1, Flags: SP
Incoming interface: fr 1.2, RPF nbr 10.3.3.1
Outgoing interface list: Null
(192.168.100.2, 239.255.255.1), 00:16:08/00:03:30, Flags: ST
Incoming interface: eth 0/1, RPF nbr 192.168.100.2
Outgoing interface list:
fr 1.2, Forward, 00:15:08/00:02:11
eth 0/2, Forward, 00:06:08/00:02:11
When a source registers with an RP that does not yet have an active (*, G)
entry for the group, the RP creates both a (*, G) and an (S, G) entry for
the traffic.
Configuring Multicast Support with PIM-SM
The multicast
source.
Overview
The DR will
prune itself
from the
RP tree.
11-15