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Incomprehension about the mDNS AP fonctionnality


I would like to use mDNS AP to send mDNS packet to the WLC (source vlan are not visible to the WLC).

I saw in the documentation that APs can either be in access or trunk mode to learn the mDNS packets from wired side and forward it to the controller.

According to the documentation

The trunk mode allows the user to specify the VLANs from which the AP should snoop the mDNS advertisements from wired side. The maximum number of VLANs that AP can snoop is 10.

If the AP is in access mode, AP will send untagged packets when a query is to be sent. When an mDNS advertisement is received by mDNS AP, VLAN information is not passed to the controller. Hence the service provider’s VLAN, learnt via mDNS AP’s access VLAN will be maintained as 0 in the controller.


In my understanding, AP in access mode logically transfert mDNS packets receive from his access vlan to the WLC. So,if I want to snoop and transfert mDNS packets receive from several vlan I need to configure APs in trunk mode and snoop up to 10 vlan.

According to the documentation below, APs in access mode can transfer mDNS packets from all the vlan to the WLC.

So, I don't understand how mDNS works with APs in access mode (and it's my case). Unfortunaly I can't try it to my lab.

Please could you help me to understand this fonctionnality ?





Everyone's tags (1)
Fed Beginner

Re: Incomprehension about the mDNS AP fonctionnality

Hi Thibault,

You have probably solved this issue already, but for whoever is reading this with he hope of finding an answer..
From my understanding when the AP is connected to an interface configured in access mode it can only forward mDNS advertisements received on his access VLAN, e.g. the Bonjour service must be on the same VLAN as the AP's.
So when the AP and Bonjour service are on VLAN 10 (both interfaces are in access mode), any Bonjour services connected to VLAN 20 won't be visible to the AP and therefore not visible to the WLC and its wireless clients.

That doco is not 100% clear about AP in access mode but it doesn't say "APs in access mode can transfer mDNS packets from all the vlan to the WLC".



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