Reducing Multicast airtime

[Raphael_L]

Hi ,

We have a fairly large Meraki setup. Approx 5500 APs scatered on 800 sites. Some sites are super small , and some have more than 40-50 APs.

https://www.ciscolive.com/c/dam/r/ciscolive/apjc/docs/2025/pdf/BRKEWN-2046.pdf

This document seems to suggest that we should block mDNS to save some airtime.

This video is also a great one : https://www.youtube.com/watch?v=miRV8qDOKBE

We have 4 SSIDs. 2 of them are for Guests with L2 isolation , 1 for IOT and 1 for Corp ( no L2 isolation on both ).

We have 0 use case for mDNS on Corp.

For people that have medium to large campuses , what do you do about it ?

EDIT : IGMP snooping is enabled , Flood unknown multicast is disabled , Multicast to Unicast conversion is enabled.

[aleabrahao]

In my case, I usually do the following:

On the corporate network: I completely block mDNS.

On guest networks: With Layer 2 isolation, mDNS is irrelevant, so I block it anyway.

On the IoT network: I allow mDNS, but I use Bonjour Gateway and filter only the necessary services.

Consider enabling IGMP snooping and multicast-to-unicast conversion, when available.

[Raphael_L]

So you did create a L3 rule to block UDP 5353 on your corp ssid ?

And yes M2U is enabled and is enabled by default

[aleabrahao]

Yes, to be honest, our network is quite restricted, so we only allow what is necessary.

[RWelch-USA]

Thanks for sharing the video (had not seen it before) but have seen BRKEWN-2046 slide deck before.

Good stuff.

[Philip D'Ath]

That is a great video and provides a lot to think about.