Multicast routing and PXE

[NJacobe]

We are using PXE as a form of imaging in our environment as well as SingleWire (Informacast). We have had some issues with both and both say they require multicasting to be enabled on the switch. My question is how do I enable it or verify it's enabled. I did see an option for Multicast routing on my switches and it's set to disabled on our data vLan. I was not sure if that is what I needed to enable or to which setting. 

Any help would be appreciated. Thanks! 

[Raj66]

Hello, @NJacobe If you have both the multicast source and the clients in the same VLAN, you do not need multicast routing. Just make sure that either "IGMP snooping" or "Flood unknown multicast" is enabled under "switch > switch settings" on the dashboard (Ideally, I would go with IGMP snooping). But if you have clients and the multicast source on different vlans, it is important to configure multicast routing. Check the below-mentioned document for more information on multicast routing.

https://documentation.meraki.com/MS/Layer_3_Switching/MS_Multicast_Routing_Overview

Cheers!

Raj

[NJacobe]

So the client and host are on the same vLan but different networks (ie same ORG but the network is different). IGMP and Flood Multicast are enabled in both networks. In this case would multicast need to be enabled? 

[Raj66]

Do they still have IP from the same range? Also, if the multicast client and the source are connected to different switches, you need to enable IGMP querier as mentioned in the above document.

[NJacobe]

They are on different ranges on different switches. I will enable IGMP querier on both configs and see what happens. I was just checking to see if multicast had to be enabled. 

[Raj66]

If they are on different subnet range, you need to enable/configure multicast routing and establish a rendezvous point for the multicast traffic to flow in between the broadcast domains. You can see the steps to configure multicast routing in the document that I mentioned above.

Cheers!

Raj

[Uberseehandel]

A significant percentage of multicast use cases require a functioning IGMP-Proxy on the Internet facing security appliance. Also required is activated IGMPv3/v2 Snooping on the switches.

Furthermore, network performance quickly deteriorates if multicast flooding is not strictly contained within its own VLAN. Additionally, firewall rules must be added to permit packets from the Class 4 address block, and the control channel used by the multicast source originator.

There is no way to set this up on an MX. Meraki is not alone in this amongst the major networking companies, but Cisco can do it.

I have come across situations where multicast dissemination is assisted by enabling features required by Bonjour forwarding (a Level 3 routable path must exist between Bonjour client and server).

It is very easy to end up chasing one's tail trying to enable multicast services. Very often it is better to recognise this early and develop an alternative solution.

It would be very nice to see Meraki upgrading Multicast services.

[PhilipDAth]

Wow, this is a simple question but the answer can be quite involved.

Could I get you to read this post by @m_Andrew and see if it helps out.

https://community.meraki.com/t5/Switching/Multicast-Basic-s/m-p/25867/highlight/true#M2125

[DekarColin]

@NJacobe did you ever get this issue resolved?

I am experiencing a similar issue with my Informacast Paging and Meraki Switches.

Thanks!