11 replies to this topic

[40H3X]

Does anyone has an opinion to the pro's and con's of IGMP snooping (managed switch) vs an IGMP proxy (router)?

[WanWizard]

Planning on building a multicast network?

 

These options aren't mutually exclusive, and depend on your requirements and design.

[40H3X]

Can you explain/enlighten that with examples. In my case, I want to "spread" the multicast to my VLAN's and it works with a IGMP proxy.

[mrbeam]

Some usefull information in this pp.

https://alor.antifor...lks/IGMP-v3.ppt

[WanWizard]

IGMP proxy is something you would use on your network gateway, i.e. your firewall or your border router. IGMP snooping is something you would use in the LAN, it is a technique the switch uses to build a multicast topology.

[40H3X]

Thanks to you both for your reply, @WanWizard, yes, I understand that, as I want the multicast on different subnets, the switch seems the logic choice to send the multicast over all VLAN's? For now, I use the firewall/router with a IGPM proxy option to do so, as the various options the switch offers, I'm not familiar with.

[WanWizard]

That is not how it works. IGMP snooping is a layer-2 thing, IGMP proxy is a layer-3 thing.

 

You need IGMP snooping to make sure multicast traffic only goes to LAN subscribers. If you don't have it, it is flooded (broadcasted) to all ports in the LAN by the router, which can considerably increase your network load. The IGMP proxy routes incoming multicast steams to the different internal networks (VLANs in your case).

[40H3X]

Yes, that's why I choose the router to do the job, using an IGMP proxy. As IMHO flooding was a risk to set multicast using my switch across my VLANs using IGMP snooping. I got confused as most people only use the router/firewall (IGMP proxy) when they want to let something from the WAN into the LAN as in TV and this is not the case here, I just want a multicast across my VLAN's.

[WanWizard]

From a technical point of view, the proxy distributes inbound multicast, like any other proxy will do (for example an HTTP proxy). Although people tend to define "inbound" as "WAN", technically that is incorrect, any source of multicast traffic that you want to distribute is inbound, whether that comes from outside, or from servers in your own datacenter for example.

[40H3X]

I choose to do "it" using the router/firewall using an IGMP proxy. As apart from the getting the multicast across the VLAN's there was the access to and from the different subnets and this is solemnly done by the firewall. So to speak, to keep it all into one hand and not devide it between a switch and the router/firewall.

[WanWizard]

Which is the logical place to do "it".

[40H3X]

I thought so too , yet still interesseted if someone has other thoughts?