Mulicast SPT switching

Hello,

I have a problem with my SPT mechanish.
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I have R4 as the RP for my network, HE as receiver and HA as multicast source.Without SPT optimization, my multicast traffic follow this path: R2-> R4->R5->R6.What i want is that when i will activate SPT mechanish the traffic to go through R2->R1->R5->R6.When i activate it follows the same path even the costs are lower on the path i want to change.

Can you help me with a solution for this?
Thank you!

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