Hello Ovidiu,
With SPT, it should pick the shortest path to the source. Can you verify this on R5?
For example, here’s a router with two uplinks. I’m sending some traffic from my source:
R1#ping 239.1.1.1 repeat 10000 source 1.1.1.1
R4 uses this route:
R4#show ip route | include 1.1.1.1
O 1.1.1.1 [110/3] via 192.168.34.3, 00:11:24, GigabitEthernet0/2
And we have these multicast route entries:
R4#show ip mroute 239.1.1.1
(*, 239.1.1.1), 00:16:44/stopped, RP 1.1.1.1, flags: SJCL
Incoming interface: GigabitEthernet0/2, RPF nbr 192.168.34.3
Outgoing interface list:
Loopback0, Forward/Sparse, 00:16:44/00:02:21
(1.1.1.1, 239.1.1.1), 00:14:52/00:01:49, flags: LJT
Incoming interface: GigabitEthernet0/2, RPF nbr 192.168.34.3
Outgoing interface list:
Loopback0, Forward/Sparse, 00:14:52/00:02:21
Let’s increase the metric:
R4(config)#interface GigabitEthernet 0/2
R4(config-if)#ip ospf cost 50000
Now check the routing tables:
R4#show ip route | include 1.1.1.1
O 1.1.1.1 [110/1002] via 192.168.24.2, 00:00:20, GigabitEthernet0/1
R4#show ip mroute 239.1.1.1
(*, 239.1.1.1), 00:18:49/stopped, RP 1.1.1.1, flags: SJCL
Incoming interface: GigabitEthernet0/1, RPF nbr 192.168.24.2
Outgoing interface list:
Loopback0, Forward/Sparse, 00:18:49/00:02:15
(1.1.1.1, 239.1.1.1), 00:16:57/00:01:43, flags: LJT
Incoming interface: GigabitEthernet0/1, RPF nbr 192.168.24.2
Outgoing interface list:
Loopback0, Forward/Sparse, 00:16:57/00:02:15
Rene