trace multicast source and receiver

[Mary]

we are using the multicast pim sparse mode, I find the RP, but there are more than 20 network device in the multicast domain, so how how to trace who is the multicast source or the switch which connects to the multicast souce? thanks

[konstantinoschiotakis]

Hi,

You can check this document for basic troubleshooting steps:

http://www.cisco.com/c/en/us/support/docs/ip/ip-multicast/13726-57.html

As for your questions you can see the active sources with the command "show ip mroute active" and you can check the interfaces that receive and send with the "show ip mroute" command.

Cheers,

[Mary]

Hi, I have switch 1--switch 2

switch 2 is RP, in switch2, Active IP Multicast Sources - sending >= 4 kbps, incoming interface: null, RPF nbr:0.0.0.0

switch1:Active IP Multicast Sources - sending >= 4 kbps  a negative (-) Rate counts pps being fast-dropped, incoming interface: GigabitEthernet1/0/10, RPF nbr IP address of switch2.

outgoing interface: vlan 23

(1) so the multicast source is in switch 2? but switch 2 we have a lot of ports, which port connect the source?

(2) in vlan 23 of switch 1, there are many ports assigned, so who is the subscriber of multicast?

[konstantinoschiotakis]

Hi,

1) You can also check "show ip igmp groups" and "show ip mroute" to identify source and interface. 

2) You can issue the command "show ip igmp groups ip_of_the_multicast_group" to give you the interface that receives multicast traffic.

Regards,

[Mary]

request not resolved

[konstantinoschiotakis]

This is an error message you get? 

Did you try 1) at the source and 2) at the receiver?

Cheers,

[Mary]

there is no error, we are trying to find multicast source and receiver, which we don't know.

show ip igmp groups does not help because i usually use sh ip mroute, which include display of the igmp group

I'm asking general approach to find source and destination, not troubleshooting problem ticket

[a.alekseev]

if you want to know receivers - IGMP is responsible for it.

If you infrastructure is multicast ready - so  you can look for sources on RP.

here is good explanation how it works

https://www.youtube.com/watch?v=QaNFiRJiTNM