Multicast Configuration for only Layer 3 Switches

[Ken Lee]

Hi Expert,

Would like to get some advise here..

If there is C6509E as core switches and C3750 Switches running layer 3 at the User dept uplink to the C6509E Switches, what will be the multicast command that should be implemented at both end? CGMP or IGMP or do not need to implement this snooping as well?

Users (IPTV) -> C3750 (Access Switch) -> C6509E (Core Switch) -> C6509E (Server Farm Switch) -> IPTV Servers

Do we need to configure multicast at C3750 Switches (Access Level) at the User dept? Let's say the IPTV Mulitcast is 239.1.1.1. How can we build up this multicast configuration based on this scenario?

Thanks in advance!

KA

[Edison Ortiz]

If you are routing to the access layer (3750s), you need to configuring multicast routing in all switches.

Once you configure multicast routing, you need to select the Core as the RP and since you have a small setup, I recommend going with static RP.

If you want to get fancy and have some redundancy in case of failure with the dual Core switches, you can run Anycast RP with MSDP between them.

Goes without saying but the PIM mode should be sparse. Avoid dense at all costs.

Regards,

Edison

[Ken Lee]

Edison,

Thanks for the great explanation.

but what are the multicast configuration I need to "pump" at access layer (C3750) which running layer 3?

Besides, ip multicast-routing, any other configurations needed for the ports at the access layer to work? Would be great if you can provide me some insight on the access layer

As for the Core Switches, yup.. will be running RP but am thinking if redundancy between Core Switch 1 and 2 with RP will be good enough for this. Yeap, will be going with sparse as per what you mentioned.

Thanks again,

KA

[Edison Ortiz]

You don't need to enter any configuration on the physical access ports.

Basically, enable multicast-routing globally and configure PIM Spare Mode on the interface Vlan x.

Additionally, make sure to have the static RP configured on the switch which will be your Cat6k RPs.

[Ken Lee]

Edison,

Thanks. Last question on one of the scenario. I understand if I want to only multicast on some of the multicast group subnets , I can create access list to permit those that I want. Is that true?

If yes, do I need to create it at the access layer switch C3750 as well?

KA

[ashok_boin]

Hi Ken,

Yes. In your case, you can restrict the multicast groups mapped to RP with an ACL.

"ip pim rp-address xxx"

And if you want to enable filtering at interface level at access switches, you can do this with "ip multicast boundary xxx" command.

Pls refer the following Cisco command reference...

http://www.cisco.com/en/US/docs/ios/ipmulti/command/reference/imc_04.html#wp1041505

Regards...

-Ashok.