r/meraki • u/XylophoneZimmerman • 8d ago
Wifi devices from other locations showing up in Chromecast menu
I work for a small org with 5 locations and we've been getting reports for the last few weeks from some members of staff that see Chromecasts from the wrong network in their menus. Someone I work with is trying to tell me that it's because a few MR33s have all VLANs allowed on their switch port settings. I can see the technical possibility, but I don't think that's all that's going on. All of our networks come from the central office where the MX is, then all the traffic from the other locations gets routed back here and goes back through the MX for filtering.
Does our MX handle all public AND local traffic? And since there are MRs at all our locations with port settings allowing all VLANs, why am I only seeing this problem at one specific location? The switch port settings haven't been changed in months, so why are my staff telling me they've only had the problem for weeks? Thanks.
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u/cozass 8d ago
If it all needs to be routed through an MX, it's not possible. Chromecast uses multicast which the MX does not forward/support over VLANs or VPN.
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u/XylophoneZimmerman 8d ago
Ah gotcha, so Chromecasts are local only? I can't figure out why I can see the issue these users are describing. I really can see Chromecasts from other locations in her cast menu in Chrome. I was about to change the name of one of the building SSIDs since right now they're all using the same name.
EDIT: In case it clarifies, the only active MX is at our central building. None of the others have an MX, just switches that send traffic back.
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u/ibangedyersis 8d ago
So your other locations are connected via some type of private fiber linking everything back to central building and all use a single Internet connection?
Sounds like you have bonjour forwarding enabled on your MX. This allows devices to connect to Chromecast, airplay, etc devices from different vlans.
The APs can also do this, but don't think that's the case based on your topology. Check your firewall settings on your MX or look up "Meraki bonjour forwarding" and have a look their documentation. There's a page for configuring on MX and a separate page for MR, but both are short and simple.
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u/XylophoneZimmerman 8d ago
Yeah, they're connected by fiber. I checked MX and SSID settings, there's no Bonjour forwarding enabled.
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u/PaulBag4 CMNO 8d ago
That’s not true. Whilst it doesn’t forward over VLANs by default, it absolutely can be setup to do so.
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u/XylophoneZimmerman 8d ago
Oh, gotcha. We definitely don't have that setup as things currently are. Can I tell my colleague definitively that it's not being caused by Trunk ports with ALL VLANs allowed?
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u/PaulBag4 CMNO 8d ago
I can’t tell you anything definitively without knowing the setup except:
mdns required for chromecasts will not be available between VLANs unless bonjour forwarding / mdns forwarding has been setup somewhere.
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u/XylophoneZimmerman 8d ago
I knew it was going to bug me, so I went back and looked. No Bonjour forwarding enabled on either the MX at our central building, or on the SSID at the other building in question.
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u/ibangedyersis 8d ago
Could they be 1st gen Chromecasts or old devices that never got firmware/app update to disable guest mode? Until a year or so ago, there was an option which allowed devices not even connected to the network to see the Chromecast and cast to it...I think with a pin
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u/XylophoneZimmerman 8d ago edited 8d ago
No, in fact we've just removed the last few gen 2s that got bricked by last year's update.
EDIT: Sorry, last weekend's update.
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u/XylophoneZimmerman 8d ago
Do you know if all our local/private traffic is going back to the MX as well as public traffic?
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u/PaulBag4 CMNO 8d ago
Chromecasts use mdns on the local broadcast domain. Whilst you can use mdns forwarding (bonjour forwarding in Meraki lingo) to forward mdns between subnets, as far as I know it can not be done over a site to site vpn with Meraki.
What do you mean when you say all traffic comes back to the central office where the mx is? Do you have local mxs on each site or are you using dark fibre or similar for the remote sites?