Same multicast group from a different source‏

[James Lasky]

Hi,

I’ve a generic multicast question.

Let’s say I’ve two different source sending different multicast traffic over the same multicast group, how can I solve the problem for a customer receiver ?

S1=1.1.1.1      G1=224.1.1.1

S2=2.2.2.2      G2=224.1.1.1

Customer receiver is usually running IGMPv2 and I cannot force to use IGMPv3.

Network in the middle between source and receiver is not MPLS.

I’ve thought to NAT multicast group, but I’m not sure it works and if anyone has already implemented it…

Any different solution is appreciated…

Tks

Ric

[chryan]

What problem are you trying to solve? If I understand correctly, you have two different sources sending DIFFERENT multicast traffic to the same multicast group address. Right? Are you wanting to know how you can specify which source you wish to receive the multicast traffic from? Why are they sending to the same multicast group to begin with?

Regards,

Chuck

[James Lasky]

Your understanding is right.

I'm trying to solve a possible problem where the receiver at the beginning do not know the source and we have the same group running different data...

They're sending the same mcast group because they are different company...

Let's think two completely different broadcasting television running their channels with the same group...

Hope you understand my problem

best

[chryan]

Interesting problem. In order to solve this, you have to know something before you can implement a solution. In this case, the receivers obviously have to know what type of data they are interested in receiving (ie. from which company), despite the fact that data from two seperate companies is being transmitted on the same channel (or sent to the same mcast group).

For example, suppose company A is handing out apples and company B is handing out oranges. Both companies are handing out these fruits at the same store, but the customer is only interested in getting apples. You would have to specify that you are only interested in fruits being offered by company A, which in this case, are the apples.

So for mcast, the customer has to know what data feed he is looking for, and then you configure a filter to only accept mcast data from that particular source.

- Chuck

[James Lasky]

I guess you're right...

By the way do you mean igmp filter ?

Could you pls paste an example ?

Tks

[chryan]

What type of routers or switches are you wanting to implement this on? What version of code are they running?

[chryan]

I think what you are looking for is SSM (Source Specific Multicast). Take a look at this link.

http://www.cisco.com/en/US/docs/ios/12_2/ip/configuration/guide/1cfssm.html

HTH,

Chuck

[James Lasky]

Hi Chick

thanks for the feedback. At the moment is not clear to me what I'll use (maybe I'll also put something special for the project hence maybe Juniper as well)...

Ric

[smalderez]

Hi James,

Did you solve your poblem? I'm interested in knowing solution. I've seen Anycast could be a solution but it seems heavy for a simple LAN.

Best regards,

Sébastien

[mlund]

You may look at "service reflection" , a way to rewrite both source and the destination address.

http://www.cisco.com/en/US/partner/docs/ios/12_4t/12_4t4/mcastsrv.html

/Mikael

[James Lasky]

Hi Mikael

very interesting, I saw it for a customer of mine asking to translate from mcast to ucast... this is something I was not able to find similar with Juniper...

Have you got experience with Service Reflection ? Does it works properly ?

Tks

Ric

[mlund]

Hi Ric

No, I haven't any experience with it, I saw this when I was looking for a solution to a customer. But It turned out we didn't need it.

/Mikael