M and MSM Series

Enabling "IP IGMP" on switch ports for MSM APs

Regular Advisor

Enabling "IP IGMP" on switch ports for MSM APs

In most wired/LAN environments where customers make use of Multicast for things like Symantec Ghost/Imaging, etc. I typically enable "IP IGMP" per VLAN.  This helps minimizes the broadcast of Multicast packets to only the switchports actively participating in the Multicast session, etc. instead of flooding the multicast packets to ALL switchports.


In wireless environment, where a lot of Apple-centric wireless devices (which use Bonjour/Multicast) are in place, I'm wondering if enabling "IP IGMP" on each of the wireless VLANs a given AP is untagged/tagged for, is also a GOOD idea.  It seems obvious that, yes it's a good idea, but for some reason I never enabled IP IGMP on my wireless VLANs so far, and I'm thinking that I probably should to help minimize the potential isses from those chatty Apple wireless devices. 


Only concern I have is whether it will break things that rely on Bonjour such as wireless Apple-TV devices, iPads using MDM for configurations,etc.  


Also wondering that, since the MSM AP radio configuration generally sets up Multicast Tx Rate to the lowest rate avalable, if having IP IGMP enabled on the wireless VLAN would even make much difference at all since the APs supposedly limit this anyways.(?)


(I find this especially interesting in that these Apple devices still maintain an active wireless connection even when they're in sleep-mode and supposed to be doing nothing... )


Anyone have experience with this?



Jesse R
Source One Technology, Inc.
HP Partner

MSM 5.7.x deployment guide:

Valued Contributor

Re: Enabling "IP IGMP" on switch ports for MSM APs

In my limited experience with my still- pretty new 5406zl/2910al wired infrastructure and MSM765zl/430/460 wireless network and lots of Apple devices (a high school), enabling IP IGMP on relevant VLANS on the switches, and on the MSM controller, under "Controlled APs"-> Configuration-> Multicast I have enabled "IGMP snooping helpers". With these settings, Bonjour seems to work quite well, better than in the early weeks, but many settings have changed since then, so it's hard to credit it all to the IGMP settings. 

I am kind of disappointed that Aerohive just came out with this apparently very functional Bonjour proxy functionality for its wireless APs so that you can break up networks into smaller broadcast domains but still make use of Bonjour multicast notifications to find/use services. I'm still not sure how I am going to set this up for 1,500 iPads and 70 Apple TV's, and they want to be able to access snything from anywhere... ugh..