Wireless Access

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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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mDNS not reaching server

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  • 1.  mDNS not reaching server

    MVP
    Posted Aug 25, 2020 03:09 PM

    We have an AOS 8 environment with a VMM and (2) MDs onsite split between network closets. I have a wireless client on our guest network that is doing mDNS queries, but those queries do not seem to be getting to a server listening for them on the same VLAN as the guest device. The VLAN is trunked down to the switch and the server is on an access port for that VLAN. I'm not finding anything that shows me blocking mDNS traffic - in fact the datapath table shows allowed traffic to 224.0.0.251 on port 5353. 

     

    We disabled AirGroup in our environment as this server acts as a bridge between clients and airplay/googlecast devices on a separate network. I also disabled any BCMC Optimization options as it did seem to affect our initial setup, but when unchecked, things started working.

     

    We have this working at one location, but this location it is not and I'm running short of ideas as to what could be blocking mDNS traffic if at anything it at all. 

     

    Any ideas would be greatly appreciated. 



  • 2.  RE: mDNS not reaching server

    Posted Sep 30, 2020 12:45 PM

    Do you have Deny inter user traffic enabled on the guest vap profile?



  • 3.  RE: mDNS not reaching server
    Best Answer

    MVP
    Posted Sep 30, 2020 02:09 PM

    This issue turned out to be a bug on our Cisco 6807-XL core switch running version 15.2(1)SY3. Apparently IGMP Snooping is supposed to exclude the Multicast address of 224.0.0.251, but in our case it was filtering the traffic and not allowing it to be passed through to our access switch stacks. Resolved by disabling IGMP Snooping on the guest VLAN interface.