Lab 151 - PIM DR Election

Prerequisites: CCNP level skills.

Note!
All routers are running EIGRP protocol as well as multicast routing. All transit interfaces have been configured as Sparse Mode.

Topology

Pic. 1 - Topology Diagram.

Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task 1
All routers in the topology run PIM Sparse Mode. Configure R1 as both the RP and the Mapping Agent for all multicast groups. Use Auto-RP to disseminate this information. Do not change the PIM Mode (Sparse Mode). RP should advertise itself as RP every 10 seconds.

Task 2
Configure R4's Et0/0 interface to join the group 224.40.40.40. Ensure that R2 registers the group with the RP.

Solution

Task 1

All routers in the topology run PIM Sparse Mode. Configure R1 as both the RP and the Mapping Agent for all multicast groups. Use Auto-RP to disseminate this information. Do not change the PIM Mode (Sparse Mode). RP should advertise itself as RP every 10 seconds.

All Routers Configuration:

!

ip pim autorp listener

!

R1 Configuration:

!

interface Loopback0
 ip address 172.16.101.1 255.255.255.0
 ip pim sparse-mode
!

ip pim send-rp-announce Loopback0 scope 16 interval 10
ip pim send-rp-discovery Loopback0 scope 16 interval 10

!

Task 2

Configure R4's Et0/0 interface to join the group 224.40.40.40. Ensure that R2 registers the group with RP. 

Before configuring the 'igmp join-group' let's see which router is the DR on the subnet.

Pic. 1 - DR on 10.1.234.0/24

Note!
Since all routers have the same priority (p=1), the highest IP address (here: R4) has been elected to be PIM DR on this segment. DR is responsible for registering multicast clients/multicast feed with RP (group/multicast traffic registration). Unlike OSPF's DR, the PIM DR role is preemptive.

R2 Configuration:

!

interface Ethernet0/0
 ip address 10.1.234.2 255.255.255.0
 ip pim dr-priority 50
 ip pim sparse-mode

!

Pic. 3 - R2 Becomes PIM DR.

R2 is the PIM DR now. It registers the group 224.40.40.40 with RP (look below).

Pic 4 - R2's Group Registration.