Bonjour (MDNS) + 802.11r

[florian.hanig1]

Hi Guys,

we've a VWLC on Sofware 8.10.130 with Flexconnect Local Switchting.

AP's are all AP3802I.

We have some iOS Devices (iPhones 12 Pro) with latest iOS 14.4.

If 802.11r (FT) is in adaptive Mode or in "normal enabled Mode", we've Issues with Bonjour / MDNS but only sometimes.

If the Issues occours, no MDNS Pakets received on the iPhones, no Bonjour Services.

You must wait a lot of time (approx. 10 minutes) that the MDNS comes back.

Normal traffic works. If i disable, reenable WLAN on iPhone, Problem persists.

If I disable the Wifi in WLC and reenable it, all services come back instantly.

The iPhones and SSID and the printers, that I want to reach via MDNS are all in the same VLAN.

Are there any known issues with this constellation ?

Edit:

It seems the issue is really more often, when "Adaptive" Mode is activated.

[patoberli]

IOS 14.4 has some wireless bugs, but I think the latest update some days ago might have fixed them. 

Other than that, you could try to give 8.10.142.0 a go, but couldn't find a fixed bug that matches your description. 

[florian.hanig1]

Which update do you mean?

14.4 is the newest iOS version... ?

8.10.142 shows the same behavior...

[patoberli]

You are right, 14.4 is the new version, was thinking about 14.3.

In all my environments I have completely disabled 802.11r, but I nowhere use mdns. 

[florian.hanig1]

Okay, with disabled 802.11r  havent Issues... 

But I want to use 802.11r.... 

So ios related problem ?

[patoberli]

IOS issue or WLC firmware. You could try to open a TAC and doing some PCAPs, but you must hurry if it's a bug in WLC and you would need a fix for 8.5, as it's EoL end of year.

https://www.cisco.com/c/en/us/products/collateral/wireless/8500-series-wireless-controllers/bulletin-c25-744139.html

[dennypage]

This same problem is present in the current version of the CBW series.

[dennypage]

FWIW, this defect isn't particular to mDNS. Testing on a cluster of CBW240AC with 10.6.1.0 shows this to be a basic problem with both multicast and broadcast when using 802.11r. If 802.11r is enabled (or adaptive), clients permanently loose the stream when roaming between APs. It isn't a IGMP issue as it happens with broadcast as well as multicast. Happens with both iOS and with MacOS.