Lab 147 - Cisco Auto-RP

Prerequisites: CCNP level skills.

Note!
All routers are running EIGRP protocol as well as multicast routing.

Topology

Pic. 1 - Topology Diagram.

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

Task 1
Configure PIM on all router's transit interfaces in the topology diagram (pic.1) allowing Cisco Auto-RP. R1's Loopback should be advertised  as RP candidate for the groups 224.6.6.0 - 224.6.6.255. R5's Loopback should be advertised as the Mapping Agent. Auto-RP advertisements should be sent every 10 seconds. Ensure, that routers do not use PIM Dense-Mode for the unknown groups.

Solution

Task 1

Configure PIM on all router's transit interfaces in the topology diagram (pic.1) allowing Cisco Auto-RP. R1's Loopback should be advertised as RP candidate for the groups 224.6.6.0 - 224.6.6.255. R5's Loopback should be advertised as the Mapping Agent. Auto-RP advertisements should be sent every 10 seconds. Ensure, that the routers do not use PIM Dense-Mode for the unknown groups.

All Transit Interfaces:

!

ip pim sparse-dense-mode

!

All PIM-Sparse-Dense-Mode Routers

!

no ip pim dm-fallback

!

Note!
PIM Sparse-Dense-Mode is used to resolve the problem of advertising a router as the RP candidate. Auto-RP uses two multicast addresses:

• 224.0.1.39 - Cisco-RP-Announce
• 224.0.1.40 - Cisco-RP-Discover

In order to advertise itself as a RP, the router must know which router is RP first to register 224.0.1.39 group (its multicast announcement). Since, there is no RP elected yet, the candidate RP cannot register itself and announce itself as RP. Sparse-Dense-Mode solves this vicious circle. The groups 224.0.1.39 and 224.0.1.40 are flooded as the Dense-Mode since the RP is not know for these groups. The caveat with the Sparse-Dense-Mode is that the groups not registered will also be treated as Dense-Mode flooding all subnets. To prevent this from happening the 'no ip pim dm-fallback' command is used.

R1 Configuration:

!

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

!

access-list 1 permit 224.6.6.0 0.0.0.255

!

ip pim send-rp-announce Loopback0 scope 16 group-list 1 interval 10

!

R5 Configuration:

!

interface Loopback0
 ip address 172.16.105.5 255.255.255.0
 ip pim sparse-dense-mode
!

!

ip pim send-rp-discovery loopback0 scope 16 interval 10

!

Note!
Both the candidate RP and Mapping Agent, must have their loopback enabled for any PIM mode.

Verification (on all routers: here R6 only):

Pic. 2 - R6's Auto-RP Info.

R6 Configuration:

!

interface Ethernet0/0
 ip address 10.1.56.6 255.255.255.0
 ip pim sparse-dense-mode
 ip igmp join-group 224.6.6.6

!

Pic. 3 - Ping Test.

Pic. 4 - RP Announcements.