topic Re: IGMP traffic from one VLAN to another in Switches, Hubs, and Modems

IGMP traffic from one VLAN to another

Andrew Ferris — Tue, 19 Sep 2006 17:17:31 GMT

Hello,

I'm trying to set up a multicast image server for setting up new PCs in our network. The image server (Novell ZenWorks) is on one VLAN (VLAN 1)and the clients are on another (VLAN 2). This is also across a switch as the servers are on a 2848 and the clients are on a 2824. Both VLANS are configured on the two switches which are directly connected.

IGMP is not enabled on the 2848 but if I've read the manual right IGMP traffic will go to all ports in VLAN 1 by default.

The 2824 has two ports on it that are trunked in VLAN 1. IGMP is enabled on this switch for both VLANs. So I need to forward the IGMP traffic from VLAN1 to some ports on the 2824 that are in VLAN 2. I've been looking at the 2600-2800-etc Advanced Traffic Manual but haven't figured out this scenario. Could someone help me with this?

thanks
Andrew

Re: IGMP traffic from one VLAN to another

Matt Hobbs — Tue, 19 Sep 2006 19:36:01 GMT

Hi Andrew,

To route multicast traffic you would need a switch capable of IP multicast routing such as the 5300's.

Matt

Re: IGMP traffic from one VLAN to another

Andrew Ferris — Wed, 20 Sep 2006 12:43:16 GMT

Hi Matt,

Okay, thank you for the reply. I do have a 5308 that's already doing ip routing. So would it be matter of enabling UDP Broadcast Forwarding for whatever UDP ports the image server is using (going from VLAN1 to VLAN2)?

Andrew

Re: IGMP traffic from one VLAN to another

Matt Hobbs — Wed, 20 Sep 2006 14:04:36 GMT

What I have done in the past is enable 3 things.

1. Enable 'ip multicast routing'
2. Enable 'ip igmp' for each VLAN
3. Enable PIM for those VLANs.

With any luck that's all you should need.

Re: IGMP traffic from one VLAN to another

Andrew Ferris — Wed, 20 Sep 2006 18:43:42 GMT

Hi Matt,

I'm not that lucky. :) Ah well, here's how I have things set up:

5308 - IP Routing (global)
IGMP Routing (global)

VLAN1 ip igmp
ip pim
VLAN2 ip igmp
ip pim
2848
Default Gateway is the 5308
VLAN1 ip igmp
VLAN2 ip igmp

2824
Default Gateway is the 5308
VLAN1 ip igmp
VLAN2 ip igmp

The Multicast clients still don't seem to see the server. If I set up a multicast image session and run "sh ip igmp" on all the switches then I see the image session IP in both VLANs on the 5308 and 2848 but only on VLAN2 on the 2824 which is where the clients are. Is that how things should be?

thanks,
Andrew

Re: IGMP traffic from one VLAN to another

Andrew Ferris — Fri, 22 Sep 2006 11:53:46 GMT

Okay I've got it. The step I missed was to enable PIM globally on the 5308 as well as on the two VLANs via "router pim". Thanks again Matt for your help.