Cisco PIM Sparse Mode Configuration with Auto-RP

Cisco PIM Sparse Mode Configuration with Auto-RP

Cisco`s Auto RP protocol distributes RP information to across the multicast domain.

There are two multicast groups for auto-rp

224.0.1.39: candidate RPs announce itself to mapping agent.
224.0.1.40: Mapping Agent distributes the RP information to all Multicast Routers.

ip pim autorp listener  command will be used on all routers to cause IP multicast traffic for the two Auto-RP groups 224.0.1.39 and 224.0.1.40 to be Protocol Independent Multicast dense mode flooded across interfaces operating in PIM sparse mode.

Instead of using ip pim autorp listener command we could use ip pim sparse-dense-mode on all interfaces.But we prefer ip pim autorp listener command.

Here is the topology for this example:

R1 is the multicast client for group 224.1.1.1
R2 is RP for all multicast groups:
R3 is the mapping agent.
R4 has the multicast source for group 224.1.1.1


Configuration of R2(RP)
ip multicast-routing

ip pim autorp listener
ip pim send-rp-announce Loopback0 scope 255

interface Loopback0
 ip address 2.2.2.2 255.255.255.255
 ip ospf 1 area 0
ip pim sparse-mode
!
interface FastEthernet0/0
 ip address 192.168.23.2 255.255.255.0
 ip pim sparse-mode
 no ip mroute-cache
!
interface FastEthernet0/1
 ip address 192.168.12.2 255.255.255.0
 ip pim dense-mode
 no ip mroute-cache
!
interface FastEthernet1/0
 ip address 192.168.24.2 255.255.255.0
 ip pim sparse-mode
 no ip mroute-cache
!
router ospf 1
 log-adjacency-changes
 network 192.168.0.0 0.0.255.255 area 0
!
Configuration of R3(Mapping Agent):

ip multicast-routing
ip pim autorp listener
ip pim send-rp-discovery Loopback0 scope 255

interface Loopback0
 ip address 3.3.3.3 255.255.255.255
 ip pim sparse-mode
 ip ospf 1 area 0
!
interface FastEthernet0/0
 ip address 192.168.23.3 255.255.255.0
 ip pim sparse-mode
 !
interface FastEthernet0/1
 ip address 192.168.34.3 255.255.255.0
 ip pim sparse-mode
!
router ospf 1
 log-adjacency-changes
 network 192.168.0.0 0.0.255.255 area 0
!
Configuration R4
ip multicast-routing
ip pim autorp listener

interface Loopback0
 ip address 4.4.4.4 255.255.255.255
 ip ospf 1 area 0
!
interface FastEthernet0/0
 ip address 192.168.34.4 255.255.255.0
 ip pim sparse-mode
!
interface FastEthernet1/0
 ip address 192.168.24.4 255.255.255.0
 ip pim sparse-mode
!
router ospf 1
 log-adjacency-changes
 network 192.168.0.0 0.0.255.255 area 0

Lets debug Auto RP from R3(Mapping Agent)

R3#debug ip pim auto-rp
PIM Auto-RP debugging is on
*Mar  1 01:25:22.339: Auto-RP(0): Received RP-announce packet of length 48, from 2.2.2.2, RP_cnt 1, ht 181
*Mar  1 01:25:22.343: Auto-RP(0): Added with (224.0.0.0/4, RP:2.2.2.2), PIMv2 v1
*Mar  1 01:25:22.371: Auto-RP(0): Build RP-Discovery packet
*Mar  1 01:25:22.371: Auto-RP:  Build mapping (224.0.0.0/4, RP:2.2.2.2), PIMv2 v1,
*Mar  1 01:25:22.375: Auto-RP(0): Send RP-discovery packet of length 48 on FastEthernet0/0 (1 RP entries)
*Mar  1 01:25:22.379: Auto-RP(0): Send RP-discovery packet of length 48 on FastEthernet0/1 (1 RP entries)
*Mar  1 01:25:22.383: Auto-RP(0): Send RP-discovery packet of length 48 on Loopback0(*) (1 RP entries)

Debug from R4

R4#debug ip pim auto-rp
*Mar  1 01:25:17.983: Auto-RP(0): Received RP-discovery packet of length 48, from 3.3.3.3, RP_cnt 1, ht 181
*Mar  1 01:25:17.987: Auto-RP(0): Added with (224.0.0.0/4, RP:2.2.2.2), PIMv2 v1
R4#show ip pim rp mapping
PIM Group-to-RP Mappings

Group(s) 224.0.0.0/4
  RP 2.2.2.2 (?), v2v1
    Info source: 3.3.3.3 (?), elected via Auto-RP
         Uptime: 00:00:21, expires: 00:02:37