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Need Help with Multicast Implementation

Level 1
Level 1

I am trying to implement multicast for video streaming in our production network. So currently I have some configs set up in our test lab made up of two 3750 switches as the core layer connecting to one 4506 as the access layer. The source is a video server that's directly connected to the RP core switch. Here are the multicast configs that's on the 3750 switch.

ip multicast-routing distributed

ip igmp snooping querier address x.x.x.x <-- default gateway for vlan 142

ip igmp snooping vlan 142 immediate-leave

interface Vlan142

description Test Lab Workstation Access

ip address x.x.x.x

no ip redirects

ip pim sparse-mode

no ip route-cache cef

ip pim rp-address

I'm setting up VLAN 142 to be the only group to be receiving the multicast stream.

Now when I do a sh ip mroute, this comes up.

(*,, 1d01h/00:02:46, RP, flags: SJCL

Incoming interface: Null, RPF nbr

Outgoing interface list:

Vlan142, Forward/Sparse, 1d01h/00:02:46

As for the test, I configured the video server to stream data to A laptop was connected to the 4506 switch whose ports are configured on vlan 142. However when I tried opening the url using the multicast address from Windows Media Player, I get an error of file not found. Anyone care to advise what the problem could be in this scenario?


- Stan

5 Replies 5

Level 5
Level 5

The first comment id the multicast address you are using - is Cisco RP Discovery. Really you should be using addresses in the range I would try doing that first.

Are the 3750s a stack, or separate? Are you running layer 3 to the access switch?

In the first instance, I would hard configure one 3750 to be the RP


int Lo0

ip add

ip pim sparse-mode

no sh

and make sure it is advertised.

ip pim rp-address


ip pim rp-address

Which VLAN is the source in? That vlan also needs to have sparse mode set.

If you are running L3 to the access switch, that will also need

ip pim rp-address

and all interfaces/VLANs between it and the core will need sparse mode set.

That should be a start...

Paul, thanks for taking the time to look at this for me. How do I create a multicast address in that range? To answer your questions, the 3750's are not stacked and the 4506 is strictly layer 2. I have already designated one of the 3750's as the RP ( <--- 3750A). As per your recommendation, I have configured the source VLAN with sparse mode. There are no other routed interfaces in this test set up to configure sparse mode.

I don't know what streaming software you use so I can't comment beyond "just pick one"

Does the second 3750 have the RP-Address configured?

Yes the other 3750 switch also has the IP PIM RP statement pointing to The streaming software I'm using is VLC. How would I get a 239.x.x.x address? All I see now in mroute is the address.

Just a quick update. I got a 239.x.x.x address in the routing table and figured out what the problem was I had originally. It seems like Windows Media Player did not have some drivers required for the video stream. Problem was resolved once I downloaded VLC and the video played flawlessly. Now I just need to do the transition over to the production network since the commands are slightly different for the 6513's.

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