Bidirectional Multicast with PIM & Behavior of Routing Tables

Applications like Video Conferencing demands multicast traffic to be bidirectional. In this mode, there is no (S, G) entry created in routing table which means no Source Path Trees. Only the Shared Tree will be built which uses (*, G) entry. Also in this mode traffic will move up and down the Shared Tree..

Another difference is that this mode does not use PIM Register / PIM Register Stop Mechanism.
Any source can send the feed any time to the RP and if no listeners, traffic will be dropped by RP.

Also there is no RPF check. Loops will be prevented using the Designated Forwarder (DF) concept.
DF is the only router which is permitted to send traffic to RP from a segment.

DF Election

1. Router with the best route to RP
2. If the route is equivalent, router with the highest IP address will be chosen

I am configuring the above network to support Bidirectional PIM,
What is needed is to enable it globally in all routers and specify a RP. I am taking R2 as the RP.

R1(config)#ip pim bidir-enable
R1(config)#ip pim rp-address 2.2.2.2 bidir

R2(config)#ip pim bidir-enable
R2(config)#ip pim rp-address 2.2.2.2 bidir

R3(config)#ip pim bidir-enable
R3(config)#ip pim rp-address 2.2.2.2 bidir

R4(config)#ip pim bidir-enable
R4(config)#ip pim rp-address 2.2.2.2 bidir

Routing tables will show a new entry with the Auto-RP default entry slightly changed..

Looks like a new entry is created for (*, 224.0.0.0/4). All the PIM enabled interfaces are Accepting.
Bidir-Upstream is pointed to the RP connecting interface.

You can also see the default (*, 224.0.1.40) group has become bidirectional too.

Let's look at the RP's routing table.

R3's table will look like the following..

Let's join the both ends to a group and ping from both sides..

PC(config)#int e0/0
PC(config-if)#ip igmp join-group 239.1.1.1

IPTV_Svr(config)#int e0/0
IPTV_Svr(config-if)#ip igmp join-group 239.1.1.1

From both sides the replies are coming.. Routing tables have changed in the following way..