Multicast routing failure

[Cisco Freak]

Hi All,

I am newbie to the multicast world.

I was testing the PIM sparse mode in a simple scenario. I have attached the network diagram.

R1,R4 and R6 are configured to listen to 239.1.1.1

R5#ping 239.1.1.1
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 239.1.1.1, timeout is 2 seconds:

Reply to request 0 from 123.1.1.1, 100 ms
Reply to request 0 from 46.1.1.2, 304 ms
Reply to request 0 from 123.1.1.4, 176 ms

The ping the same multicast IP won't work if I initiate the ping from the loopback interface.

R5#ping 239.1.1.1 so lo0
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 239.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 5.5.5.5
.
R5#

I have ensured that this not due to the RPF check failure.

This is debug output from the downstream router:

R1#
*Oct 27 02:44:51.591: MFIBv4(0x0): Pkt (5.5.5.5,239.1.1.1) from Ethernet1/0 (TS) Entry IC set, punting
*Oct 27 02:44:51.595: MFIBv4(0x0): Pkt (5.5.5.5,239.1.1.1) from Ethernet1/0 (FS) Entry IC set, punting
*Oct 27 02:44:51.599: MFIBv4(0x0): Pkt (5.5.5.5,239.1.1.1) from Ethernet1/0 (PS) Acceptance check failed - dropping
R1#

R1 is the RP router.

R1#sh run | i pim
ip pim sparse-mode
ip pim sparse-mode
ip pim rp-address 1.1.1.1
R1#

R1#sh ip rpf 1.1.1.1
failed, no route exists

R1#sh ip route 1.1.1.1
Routing entry for 1.1.1.1/32
Known via "connected", distance 0, metric 0 (connected)
Routing Descriptor Blocks:
* directly connected, via Loopback0
Route metric is 0, traffic share count is 1
R1#

R1#sh ip mroute | b 239.1.1.1
(*, 239.1.1.1), 01:24:06/00:02:48, RP 1.1.1.1, flags: SJCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
FastEthernet0/0, Forward/Sparse, 01:11:04/00:02:57

(*, 224.0.1.40), 02:22:15/00:03:27, RP 1.1.1.1, flags: SJCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Ethernet1/0, Forward/Sparse, 00:20:43/00:03:27
FastEthernet0/0, Forward/Sparse, 02:22:15/00:03:11

Any help would appreciated.

[Cisco Freak]

Any help would appreciated.

CF

[Pawan Raut · Accepted solution]

L0 has ip pim sparse-mode? is the Loopback0 IP address has route on R1?

[Cisco Freak]

Enabling the PIM sparse-mode on the loopback interface resolved that problem. But I wonder why its needed?

CF

[Pawan Raut]

It is very simple whoever will take part of multicast has to be multicast enable. Here in case you are generating multicast traffic from Loopback0 so you need to enable multicast mode on it.

[Cisco Freak]

Pawan,

Thanks for clearing my doubt.

CF

[Evgeniy Prichinin]

Any need to use only one router as RP (or you should config msdp between all routers (full mesh like iBGP) to sync information about groups.

In our current case R1 doesn't know anything about 239.1.1.1.

[Georg Pauwen]

Make sure that you have basic layer 3 connectivity for your loopback interfaces. You won't be able to reach them without either a static route, or a routing protocol. So, at the very least you need:

R5

ip route 1.1.1.1 255.255.255.255 x.x.x.x (x.x.x.x is the next hop on R1)

R1

ip route 5.5.5.5 255.255.255.255 x.x.x.x (x.x.x.x is the next hop on R5)

[chrihussey]

Might be a good idea to provide the configs, at a minimum for R1 & R5.