Multicast troubleshooting

[mehsulsss]

He everyone,

I am new to multicast and have a question regarding receiving the multicast. what is the easiest way to figure out if the data is being sent by the source or not. Any tips will be a big help.

Regards

[mihanlin · Accepted solution]

Hello,

To troubleshoot multicast, I have found the "show ip mroute count" command is a good place to start.

When you do this command, you will see the multicast groups, and statistics for the source address - which you mention you want to check.

Looking at the line beginning with "Source", you can see the forwarding statistics for the group. They are separated by "/" and are as follows:

Sent Packet Count/Packets sent per second/Avg Pkt Size/Kilobits per second

An example is below:

show ip mroute count

IP Multicast Statistics

2 routes using 1714 bytes of memory

1 group, 0.50 average sources per group

Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per second

Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Group: 224.12.12.12, Source count: 1, Packets forwarded: 4, Packets received: 4

Source: 10.1.1.4/32, Forwarding: 4/1/100/0, Other: 4/0/0

[Thotsaphon Lueangwattanaphong]

hi Mehdi,

Michael has provided good information to you. Just add other information.

Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Other: 4/0/0

If you're experiencing with RPF Failure then this command can show you.

Please check this link out:

http://www.cisco.com/en/US/tech/tk828/technologies_tech_note09186a0080093f21.shtml

Toshi

[mehsulsss]

Great!! Thank you. In sparse mode,If I have a receiver trying to join the group, then I should see the count increase which means that the source is sending the stream for that particular group. If I don't see the count increase which will mean that the the source is not sending the stream for that group. Correct? Also, if I am in sparse mode, and have a receiver on my side, what will this indicate (*,g) & (s,g)?

Thanks again.

[Harold Ritter]

Mehdi,

There is a few things to consider.

- What is your topology like?

- Do you see the source (s,g) on the RP?

- Do you see that there is a receiver (*,g) on the RP?

Regards

[mehsulsss]

Topology is that I have two routers receiving the stream. I do have receiver trying to join the group and do see (*,g). In some stream is working fine and I do see the (s,g) but the others I only see (*,g). I did the ip mroute count and I see no packets and I even tried to do ip igmp join-group (Group ip) and still no luck. I think I am not receiving the group from the source just making sure that is the case.

Thank you

[Thotsaphon Lueangwattanaphong]

hi Mehdi,

We have to know exactly what the topology looks like. One is working fine. Another one is not? Have you correctly configured the RP? To make sure that the RP-C is advertiseting the correct group. To make a bit more clear on what's happening. Would you please post the configuration,excluding sensitive information?

Toshi

[mehsulsss]

Thank you all. I think I have the answers to my problem. It sure was a great help.

Regards

Mehdi