MultiCast and Older Switches

krabilld1 · ‎12-15-2013

I need a little help with multicast and older switches. Here is some background and what I understand so far.

Basically I have a mutlple VLAN LAN with a Cisco 4006 running IOS as my core switch. On my Lan I have multiple switches of various models. Many are newer switches that will do IGMP snooping so if I understand it correctly I am good for multicast on those switches as long as IGMP snooping is working right?

The issue I have is I also have some older Catalyst 2900XL/3500XL switches. As I understand it my only option on these switches is to do CGMP? That is where I need some help. I have read various documents on CGMP but am having hard time understanding how to "make it all work" (please do not respond with it is time to upgrade these switches as that is not an option right now)

Any guidance with how to get multicast working where I have a 4006 as my core switch on a multiple VLAN LAN with Catalyst 2900XL/3500XL switches (and other switches that do IGMP snooping) would be appreciated. Also as a side note my multicast source would be connected to an ethernet port on the 4006. However I could move the multicast source to a switch that is trunked off of the 4006 if that makes the configuration easier?

Thanks for your help.

Jon Marshall · ‎12-16-2013

Many are newer switches that will do IGMP snooping so if I understand it correctly I am good for multicast on those switches as long as IGMP snooping is working right?

Yes, as loing as something is making the IGMP queries. If you are routing multicast between vlans then you would have PIM enabled on the L3 interfaces and this would mean the IGMP queries are being made. But if you are doing multicast within a single vlan then you need the enable the IGMP snoopign querier process which is supported on most modern switches but won't be on your older switches.

CGMP works by the router/L3 switch interface informing the switch about certain multicast information.

What exactly are you having problems with. Have you configured it and it is not working or can you not work out to configure it ?

Are you multicast routing between vlans or are you only doing multicast within the same vlan ?

Jon

krabilld1 · ‎12-16-2013

What I am doing is trying to setup video multicast at a school. The video multicast stream needs to be avaialable on all VLANs at the school but does not need to leave the schools LAN itself. I can either put the multicast source in a VLAN that potentially has clients in it as well, or I could configure it so that the source is in a VLAN that does not have any clients that need to recieve the stream.

I am pretty sure I have it working with newer switches and IGMP snooping. However on the older 2900XL/3500XL switches when I pull up the multicast video stream I appear to get a broadcast storm on these older switches. In doing reasearch it is my understanding I will need to setup CGMP on these older switches but I am having problems figuring out how to configure this.

Thanks,

Dennis

Jon Marshall · ‎12-16-2013

Dennis

Have a look at this link and see if it helps -

http://www.informit.com/library/content.aspx?b=CCNP_Studies_Switching&seqNum=65

and if it doesn't then please feel free to ask further questions.

Jon

krabilld1 · ‎12-16-2013

That looks promising. I will work through that as I have time and either mark your answer as correct or report back any questions if I still have issues. Thanks for your help.