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New Member

Router Interface multicast only

Hello !

When you have a vlan with multicast senders, how to have a router interface on this vlan to forward the multicast trafic, and without unicast routing.

Before, with IP of senders in 10.1.23/0/24 , on a (old) 6500, this config works fine:

interface vlan 123

  ip address

  no ip proxy-arp
  ip pim sparse-mode
  ip cgmp

ip mroute

But,  now,  "ip mroute" is not permited (same router).

I will be happy to have the trick to do that again...

JM Tetu

VIP Purple

Router Interface multicast only

What do you mean by "ip mroute x.x.x.x x.x.x.x" is not permitted.

waht is show ip route looks like ? What is the group address multicast traffic sending to ?

also  provide us "show ip  pim rp mapping"


New Member

Router Interface multicast only

Thanks for your help !

I give a graph for better explain my problem.

The multicast trafic can not be routed like unicast (A Wifi Lan Controller stop it).

So, the "show ip route" give a route (and unicast works very well), but i cannot use it. I try to have an multicast only interface.

Now, i add temporary a cisco 1841 router. It's the RP give by "show ip  pim rp mapping".

It woks fine. But it's a patch-up job....

VSS#show ip pim rp mapping
PIM Group-to-RP Mappings

Acl: 8, Static
    RP: xxxx (?)
Acl: 9, Static
    RP: xxxx (?)
Acl: 7, Static
    RP: xxxxx (?)
Group(s):, Static
    RP: (?)

On the multcast router:

interface fa 0/0

ip secondary


ip pim sparse-mode

==> As i have on the 1841 an IP in the same network than the multicast sender, it's forwarding the multicast. And as it's not the IP of gateway of the sender....

If i can find a solution to suppress the 1841, it will be very better.

VIP Purple

Router Interface multicast only

Thanks alot fo the diagram & additional detail. Diagram is really helped to understand your network better.

still i have few question prior to give your some recommendation

1. Is this Ghost client connect via wired or wirelessly ?

2. What is the WLC model & what version of software it is running (if it is a cisco WLC then you can enable multicast on that  & I can help if that is an option for you)



New Member

Router Interface multicast only

The ghost client connect via wired.

The WLC is a Cisco 5508. The software Version is

And multicast on wired guest lan with a cisco WLC is an option for me.

It will be very more simple!

VIP Purple

Re: Router Interface multicast only

Hi Jean,

I will test this (wired guest + multicast on WLC) & let you know. I think you may have a better solution that what you are doing today to get this working



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