LSS (Location Specific Services) and mDNS AP

In release 7.5 additional Bonjour enhancements were added on the WLC. One of them is processing of mDNS service advertisements to support LSS. Basically all valid mDNS service advertisements received at the WLC will be tagged with the MAC address of the AP associated with the service advertisement from the Service Provider device, so in essence only clients connected to the same AP as the SP will have access to that service. LSS only applies to wireless SP-DB entries. There is no location awareness for wired SP devices.

To summarize,
  • LSS filtering applies only to wireless SP-DB entries.
  • Wireless SP-DB entries are filtered based on the AP-NEIGHBOR-LIST if LSS is enabled for the service.
  • Only client in the same “RF neighborhood” as the service provider will be granted permission to use that service

The location of clients and service providers is established by the MAC address of their associated AP's. The RRM DB provides the list of neighboring AP for any given AP and this information will be acted upon while filtering the SP-DB wireless entries in response to mDNS queries originating from wireless clients.

For Wired clients / service providers there is no sense of location that could be applied similarly and so the wired SP-DB entries cannot be filtered similarly.

Below is the network diagram of LSS enabled Bonjour gateway.

When the client query for the service the WLC using the client AP MAC address look up the RRM DB for the neighbor AP-list and filter the SP-DB for the service with the service provider's associate with the AP-list while responding to the query.





mDNS AP

Bonjour mDNS as mentioned earlier, is a link local multicast and thus forwarded on Local L2 domain. Therefore mDNS services behind the Router or not L2 adjacent will not be seen by WLC in release 7.4 as illustrated below.





In release 7.5 the mDNS AP was added as enhancement and to correct the mDNS L2 limitations. mDNS AP has the ability to snoop wired Services on VLANs invisible to WLC

  • This enhancement allows the controller to have the visibility of wired service providers, which are on VLANs that are not visible to the controller.
  • VLAN visibility at the WLC is achieved by APs forwarding the mDNS advertisements to the controller.
  • The maximum number of VLANs that AP can snoop is 10.
  • This feature is supported on local and monitor mode AP.