Multicast Domain Name System

Introduction to mDNS Gateway

Multicast Domain Name System (mDNS) is an Apple service discovery protocol which locates devices and services on a local network with the use of mDNS service records.

The Bonjour protocol operates on service announcements and queries. Each query or advertisement is sent to the Bonjour multicast address ipv4 224.0.0.251 (ipv6 FF02::FB). This protocol uses mDNS on UDP port 5353.

The address used by the Bonjour protocol is link-local multicast address and therefore is only forwarded to the local L2 network. As, multicast DNS is limited to an L2 domain for a client to discover a service it has to be part of the same L2 domain, This is not always possible in any large scale deployment or enterprise.

In order to address this issue, the Cisco Catalyst 9800 Series Wireless Controller acts as a Bonjour Gateway. The controller then listens for Bonjour services, caches these Bonjour advertisements (AirPlay, AirPrint, and so on) from the source or host. For example, Apple TV responds back to Bonjour clients when asked or requested for a service. This way you can have sources and clients in different subnets.

By default, the mDNS gateway is disabled on the controller. To enable mDNS gateway functionality, you must explicitly configure mDNS gateway using CLI or Web UI.

Prerequisite

Since the Cisco Catalyst 9800 Series Wireless Controller will respond and advertise for services cached when acting as a Bonjour Gateway, it must have an SVI interface with a valid IP address on every VLAN where mDNS is allowed or used. This will be the source IP address of those mDNS packets that are coming out from the controller acting as mDNS Gateway.

Enabling mDNS Gateway (GUI)

Procedure

Step 1

Choose Configuration > Services > mDNS.

Step 2

In the Global section, toggle the slider to enable or disable the mDNS Gateway.

Step 3

From the Transport drop-down list, choose one of the following types:

  • ipv4

  • ipv6

  • both

Step 4

Enter an appropriate timer value in Active-Query Timer. The valid range is between 15 to 120 minutes. The default is 30 minutes.

Step 5

From the mDNS-AP Service Policy drop-down list, choose an mDNS service policy.

Note

 

Service policy is optional only if mDNS-AP is configured. If mDNS-AP is not configured, the system uses default-service-policy.

Step 6

Click Apply.

Enabling or Disabling mDNS Gateway (CLI)


Note

  • mDNS gateway is disabled by default globally on the controller.

  • You need both global and WLAN configurations to enable mDNS gateway.

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

mdns-sd gateway

Example:

Device(config)# mdns-sd gateway

Enables mDNS gateway.

Step 4

transport {ipv4 | ipv6 | both}

Example:

Device(config-mdns-sd)# transport ipv4

Processes mDNS message on a specific transport.

Here,

ipv4 signifies that the IPv4 mDNS message processing is enabled. This is the default value.

ipv6 signifies that the IPv6 mDNS message processing is enabled.

both signifies that the IPv4 and IPv6 mDNS message is enabled for each network.

Step 5

active-query timer active-query-periodicity

Example:

Device(config-mdns-sd)# active-query timer 15

Changes the periodicity of mDNS multicast active query.

Note

 

An active query is a periodic mDNS query to refresh dynamic cache.

Here,

active-query-periodicity refers to the active query periodicity in Minutes. The valid range is from 15 to 120 minutes. Active query runs with a default periodicity of 30 minutes.

Step 6

exit

Example:

Device(config-mdns-sd)# exit

Returns to global configuration mode.

Creating Custom Service Definition (GUI)

Procedure

Step 1

Choose Configuration > Services > mDNS.

Step 2

In the Service Definition section, click Add.

Step 3

In the Quick Setup: Service Definition page that is displayed, enter a name and description for the service definition.

Step 4

Enter a service type and click + to add the service type.

Step 5

Click Apply to Device.

Creating Custom Service Definition

Service definition is a construct that provides an admin friendly name to one or more mDNS service types or A pointer (PTR) Resource Record Name.

By default, few built-in service definitions are already predefined and available for admin to use.

In addition to built-in service definitions, admin can also define custom service definitions.

You can execute the following command to view the list of all the service definitions (built-in and custom):

Device# show mdns-sd master-service-list

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

mdns-sd service-definition service-definition-name

Example:

Device(config)# mdns-sd service-definition CUSTOM1

Configures mDNS service definition.

Note

 

  • All the created custom service definitions are added to the primary service list.

  • Primary service list comprises of a list of custom and built-in service definitions.

Step 4

service-type string

Example:

Device(config-mdns-ser-def)# service-type _custom1._tcp.local

Configures mDNS service type.

Step 5

exit

Example:

Device(config-mdns-ser-def)# exit

Returns to global configuration mode.

Creating Service List (GUI)

Procedure

Step 1

Choose Configuration > Services > mDNS.

Step 2

In the Service List section, click Add.

Step 3

In the Quick Setup: Service List page that is displayed, enter a name for the service list.

Step 4

From the Direction drop-down list, choose IN for inbound filtering or OUT for outbound filtering.

Step 5

From the Available Services drop-down list, choose a service type to match the service list.

Note

 

To allow all services, choose the all option.

Step 6

Click Add Services.

Step 7

From the Message Type drop-down list, choose the message type to match from the following options:

  • any—To allow all messages.

  • announcement—To allow only service advertisements or announcements for the device.

  • query—To allow only a query from the client for a service in the network.

Step 8

Click Save to add services.

Step 9

Click Apply to Device.

Creating Service List

mDNS service list is a collection of service definitions.

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

mdns-sd service-list service-list-name {IN | OUT}

Example:

Device(config)# mdns-sd service-list Basic-In IN
Device(config)# mdns-sd service-list Basic-Out OUT

Configures mDNS service list.

  • IN: Provides inbound filtering.

  • Out: Provides outbound filtering.

Step 4

match service-definition-name message-type {announcement | any | query}

Example:

Device(config-mdns-sl-in)# match CUSTOM1 message-type query

Matches the service to the message type.

Here, service-definition-name refers to the names of services, such as, airplay, airserver, airtunes, and so on.

Note

 

To add a service, the service name must be part of the primary service list.

If the mDNS service list is set to IN, you get to view the following command: match service-definition-name message-type {announcement | any | query}.

If the mDNS service list is set to Out, you get to view the following command: match service-definition-name.

Step 5

show mdns-sd service-list {direction | name }

Displays inbound or outbound direction list of the configured service-list to classify matching service-types for service-policy. The list can be filtered by name or specific direction.

Step 6

exit

Example:

Device(config-mdns-sl-in)# exit

Returns to global configuration mode.

Creating Service Policy (GUI)

Procedure

Step 1

Choose Configuration > Services > mDNS.

Step 2

In the Service Policy section, click Add.

Step 3

In the Quick Setup: Service Policy page that is displayed, enter a name for the service policy.

Step 4

From the Service List Input drop-down list, choose one of the types.

Step 5

From the Service List Output drop-down list, choose one of the types.

Step 6

From the Location drop-down list, choose the location you want to associate with the service list.

Step 7

Click Apply to Device.

Creating Service Policy

mDNS service policy is used for service filtering while learning services or responding to queries.

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

mdns-sd service-policy service-policy-name

Example:

Device(config)# mdns-sd service-policy mdns-policy1

Enables mDNS service policy.

Step 4

location {lss | site-tag}

Example:

Device(config-mdns-ser-pol)# location lss

Filters mDNS service types based on LSS or site-tag.

Note

 

In Location Specific Services (LSS) based filtering, the mDNS gateway responds with the service instances learnt from the neighboring APs of the querying client AP. Other service instances for the rest of APs are filtered.

In Site tag based filtering, the mDNS gateway responds with the service instances that belong to the same site-tag as that of querying client.

The mDNS gateway responds back with wired services even if the location based filtering is configured.

Step 5

service-list service-list-name {IN | OUT}

Example:

Device(config-mdns-ser-pol)# service-list VLAN100-list IN

Configures various service-list names for IN and OUT directions.

Note

 

If an administrator decides to create or use a custom service policy, then the custom service policy must be configured with service-lists for both directions (IN and OUT); otherwise, the mDNS Gateway will not work (will not learn services if there is no IN service-list, or will not reply or announce services learned if there is no OUT service-list).

Step 6

exit

Example:

Device(config-mdns-ser-pol)# exit

Returns to global configuration mode.

Configuring a Local or Native Profile for an mDNS Policy

When an administrator configures local authentication and authorization and does not expect to get any mDNS policy from the AAA server, the administrator can configure a local or native profile to select a mDNS policy based on user, role, or device type. When this local or native profile is mapped to the wireless profile policy, mDNS service policy is applied on the mDNS packets that are processed on that WLAN.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

service-template template-name

Example:

Device(config)# service-template mdns

Configures the service-template or identity policy.

Step 3

mdns-service-policy mdns-policy-name

Example:

Device(config-service-template)# mdns-service-policy mdnsTV

Configures the mDNS policy.

Step 4

exit

Example:

Device(config-service-template)# exit

Returns to global configuration mode.

Configuring an mDNS Flex Profile (GUI)

Procedure

Step 1

Choose Configuration > Services > mDNS.

Step 2

In the mDNS Flex Profile section, click Add.

The Add mDNS Flex Profile window is displayed.

Step 3

In the Profile Name field, enter the flex mDNS profile name.

Step 4

In the Service Cache Update Timer field, specify the service cache update time. The default value is 1 minute. The valid range is from 1 to 100 minutes.

Step 5

In the Statistics Update Timer field, specify the statistics update timer. The default value is 1 minute. The valid range is from 1 to 100 minutes.

Step 6

In the VLANs field, specify the VLAN ID. You can enter multiple VLAN IDs separated by commas, or enter a range of VLAN IDs. Maximum number of VLANs allowed is 16.

Step 7

Click Apply to Device.

Configuring an mDNS Flex Profile (CLI)

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

mdns-sd flex-profile mdns-flex-profile-name

Example:

Device(config)# mdns-sd flex-profile mdns-flex-profile-name

Enters the mDNS Flex Profile mode.

Step 3

update-timer service-cache service-cache timer-value <1-100>

Example:

Device(config-mdns-flex-profile)# update-timer service-cache 60

Configures the mDNS update service cache timer for the flex profile.

The default value is 1 minute. Value range is between 1 minute and 100 minutes.

Step 4

update-timer statistics statistics timer-value <1-100>

Example:

Device(config-mdns-flex-profile)# update-timer statistics 65

Configures the mDNS update statistics timer for the flex profile.

The default value is 1 minute. The valid range is from 1 to 100 minutes.

Step 5

wired-vlan-range wired-vlan-range value

Example:

Device(config-mdns-flex-profile)# wired-vlan-range 10 - 20

Configures the mDNS wired VLAN range for the flex profile.

The default value is 1 minute. The valid range is from 1 minute to 100 minutes.

Applying an mDNS Flex Profile to a Wireless Flex Connect Profile (GUI)

Procedure

Step 1

Choose Configuration > Tags & Profiles > Flex.

Step 2

Click Add.

The Add Flex Profile window is displayed.

Step 3

Under the General tab, from the mDNS Flex Profile drop-down list, choose a flex profile name from the list.

Step 4

Click Apply to Device.

Applying an mDNS Flex Profile to a Wireless Flex Connect Profile (CLI)

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

wireless profile flex wireless-flex-profile-name

Example:

Device# wireless profile flex wireless-flex-profile-name

Enters wireless flex profile configuration mode.

Step 3

mdns-sd mdns-flex-profile

Example:

Device(config-wireless-flex-profile)# mdns-sd mdns-flex-profile-name

Enables the mDNS features for all the APs in the profile

Location-Based Service Filtering

Prerequisite for Location-Based Service Filtering

You need to create the Service Definition and Service Policy. For more information, see Creating Custom Service Definition section and Creating Service Policy section.

Configuring mDNS Location-Based Filtering Using SSID

When a service policy is configured with the SSID as the location name, the response to the query will be the services that were learnt on that SSID.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

mdns-sd service-policy service-policy-name

Example:

Device(config)# mdns-sd service-policy mdns-policy1

Configures the service policy.

Step 3

location ssid

Example:

Device(config-mdns-ser-pol)# location ssid

Configures location-based filtering using SSID.

Step 4

end

Example:

Device(config-mdns-ser-pol)# end

Returns to privileged EXEC mode.

Alternatively, you can also press Ctrl-Z to exit global configuration mode.

Configuring mDNS Location-Based Filtering Using AP Name

When a service policy is configured with the AP name as the location, the response to the query will be the services that were learnt on that AP.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

mdns-sd service-policy service-policy-name

Example:

Device(config)# mdns-sd service-policy mdns-policy1

Configures the service policy.

Step 3

location ap-name

Example:

Device(config-mdns-ser-pol)# location ap-name

Configures location-based filtering using an AP name.

Step 4

end

Example:

Device(config-mdns-ser-pol)# end

Returns to privileged EXEC mode.

Alternatively, you can also press Ctrl-Z to exit global configuration mode.

Configuring mDNS Location-Based Filtering Using AP Location

When a service policy is configured with location as the AP-location, the response to the query will be the services that were learnt on all the APs using the same AP "location" name (not to be confused with "site-tag").

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

mdns-sd service-policy service-policy-name

Example:

Device(config)# mdns-sd service-policy mdns-policy1

Configures the service policy.

Step 3

location ap-location

Example:

Device(config-mdns-ser-pol)# location ap-location

Configures location-based filtering using the AP location.

Step 4

end

Example:

Device(config-mdns-ser-pol)# end

Returns to privileged EXEC mode.

Alternatively, you can also press Ctrl-Z to exit global configuration mode.

Configuring mDNS Location-Based Filtering Using Regular Expression

  • When a service policy is configured with the location as a regular expression that matches the corresponding AP name, the response to the query will be the services that were learnt on a group of APs based on the AP name.

  • When a service policy is configured with the location as a regular expression that matches the corresponding AP location, the response to the query will be the services that were learnt on a group of APs based on the AP location.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

mdns-sd service-policy service-policy-name

Example:

Device(config)# mdns-sd service-policy mdns-policy1

Configures the service policy.

Step 3

location regex {ap-location regular-expression | ap-name regular-expression}

Example:

Device(config-mdns-ser-pol)# location regex ap-location dns_location
Device(config-mdns-ser-pol)# location regex ap-name dns_name

Configures location-based filtering using regular expression.

Step 4

end

Example:

Device(config-mdns-ser-pol)# end

Note

 

To filter the services for which AP names have the specific keyword such as AP-2FLR-SJC-123, you can use the regex AP name as AP-2FLR- to match the services that are learnt from the set of access points.

Returns to privileged EXEC mode.

Alternatively, you can also press Ctrl-Z to exit global configuration mode.

Configuring mDNS AP

In most of the deployments, the services may be available in VLANs that the APs can hear in the wired side (allowed in the switchport where the AP is directly connected: its own VLAN, or even more VLANs if switchport is a trunk).

The following procedure shows how to configure mDNS AP:

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

mdns-sd gateway

Example:

Device(config)# mdns-sd gateway

Configures the mDNS gateway.

Step 3

ap name ap-name mdns-ap enable vlan vlan-id

Example:

Device# ap name ap1 mdns-ap enable vlan 22

Enables mDNS on the AP, and configures a VLAN for the mDNS AP.

Step 4

ap name ap-name mdns-ap vlan add vlan-id

Example:

Device# ap name ap1 mdns-ap vlan add 200

Adds a VLAN to the mDNS AP. vlan-id ranges from 1 to 4096.

Step 5

ap name ap-name mdns-ap vlan del vlan-id

Example:

Device# ap name ap1 mdns-ap vlan del 2

Deletes a VLAN from the mDNS AP.

Step 6

ap name ap-name mdns-ap disable

Example:

Device# ap name ap1 mdns-ap disable

(Optional) Disables the mDNS AP.

Step 7

end

Example:

Device# end

Returns to privileged EXEC mode.

Alternatively, you can also press Ctrl-Z to exit global configuration mode.

Note

 

You can configure a maximum of 10 VLANs per AP.

Associating mDNS Service Policy with Wireless Profile Policy (GUI)

Procedure

Step 1

Choose Configuration > Tags & Profiles > Policy.

Step 2

Click the policy profile name.

Step 3

In the Advanced tab, choose the mDNS service policy from the mDNS Service Policy drop-down list.

Step 4

Click Update & Apply to Device.

Associating mDNS Service Policy with Wireless Profile Policy


Note

You must globally configure the mDNS service policy before associating it with the wireless profile policy.

A default mDNS service policy is already attached once the wireless profile policy is created. You can use the following commands to override the default mDNS service policy with any of your service policy:

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

wireless profile policy profile-policy

Example:

Device(config)# wireless profile policy default-policy-profile

Configures wireless profile policy.

Here, profile-policy refers to the name of the WLAN policy profile.

Step 3

mdns-sd service-policy custom-mdns-service-policy

Example:

Device(config-wireless-policy)# mdns-sd service-policy custom-mdns-service-policy

Associates an mDNS service policy with the wireless profile policy.

The default mDNS service policy name is default-mdns-service-policy.

Note

 

The default-mdns-profile-policy uses default-mdns-service-list configuration for filtering mDNS service announcement and queries.

In wireless network, the mDNS packets are consumed by the mDNS gateway and clients or device is deprived of learning this service. To share the service with the device and provide ease of configuration to the administrator, a list of few standard service types are shared by default on the wireless network. The list of such standard service types is termed as default service policy that comprises a set of service types.

The table covers a sample service list in the default service policy.

Table 1. Default Name and mDNS Service Type

Default Name

mDNS Service Type

Apple HomeSharing

_home-sharing._tcp.local

Printer-IPPS

_ipps._tcp.local

Google-chromecast

_googlecast._tcp.local

Note

 

  • Location would be disabled on mDNS default service policy.

  • You cannot change the contents of the mDNS default service policy. However, you can create separate mDNS service policies and associate them under the wireless policy profile.

Step 4

exit

Example:

Device(config-wireless-policy)# exit

Returns to global configuration mode.

Enabling or Disabling mDNS Gateway for WLAN (GUI)

Procedure

Step 1

Choose Configuration > Tags & Profiles > WLANs.

Step 2

Click on the WLAN.

Step 3

In the Advanced tab, choose the mode in mDNS Mode drop-down list.

Step 4

Click Update & Apply to Device.

Enabling or Disabling mDNS Gateway for WLAN


Note

Bridging is the default behaviour. This means that the mDNS packets are always bridged.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 2

wlan profile-name wlan-id ssid-name

Example:

Device(config)# wlan test 24 ssid1

Specifies the WLAN name and ID.

  • profile-name is the WLAN name which can contain 32 alphanumeric characters

  • wlan-id is the wireless LAN identifier. The valid range is from 1 to 512.

  • ssid-name is the SSID which can contain 32 alphanumeric characters.

Note

 

Global configuration must be in place for mDNS gateway to work.

Step 3

mdns-sd-interface {gateway | drop}

Example:

Device(config-wlan)# mdns-sd gateway
Device(config-wlan)# mdns-sd drop

Enables or disables mDNS gateway and bridge functions on WLAN.

Step 4

exit

Example:

Device(config-wlan)# exit

Returns to global configuration mode.

Step 5

show wlan name wlan-name | show wlan all

Example:

Device# show wlan name test | show wlan all

Verifies the status of mDNS on WLAN.

Step 6

show wireless profile policy

Example:

Device# show wireless profile policy

Verifies the service policy configured in WLAN.

Verifying mDNS Gateway Configurations

To verify the mDNS summary, use the following command:

Device# show mdns-sd summary
mDNS Gateway: Enabled
Active Query: Enabled
  Periodicity (in minutes): 30
Transport Type: IPv4

To verify the mDNS cache, use the following command:

Device# show mdns-sd cache
----------------------------------------------------------- PTR Records ---------------------------------------
RECORD-NAME                     TTL      WLAN   CLIENT-MAC       RR-RECORD-DATA                                
--------------------------------------------------------------------------------------------------------------
_airplay._tcp.local             4500     30     07c5.a4f2.dc01   CUST1._airplay._tcp.local                    
_ipp._tcp.local                 4500     30     04c5.a4f2.dc01   CUST3._ipp._tcp.local2                       
_ipp._tcp.local                 4500     15     04c5.a4f2.dc01   CUST3._ipp._tcp.local4                       
_ipp._tcp.local                 4500     10     04c5.a4f2.dc01   CUST3._ipp._tcp.local6                        
_veer_custom._tcp.local         4500     10     05c5.a4f2.dc01   CUST2._veer_custom._tcp.local8

To verify the mDNS cache from wired service provider, use the following command:

Device# show mdns-sd cache wired
----------------------------------------------------------- PTR Records ---------------------------------------
RECORD-NAME                                TTL      VLAN      CLIENT-MAC       RR-RECORD-DATA                  
---------------------------------------------------------------------------------------------------------------
_airplay._tcp.local                        4500     16        0866.98ec.97af   wiredapple._airplay._tcp.local   
_raop._tcp.local                           4500     16        0866.98ec.97af   086698EC97AF@wiredapple._raop._tcp.local 

---------------------------------------------------------- SRV Records -----------------------------------------
RECORD-NAME                                TTL      VLAN      CLIENT-MAC       RR-RECORD-DATA                   
-----------------------------------------------------------------------------------------------------------------
wiredapple._airplay._tcp.local             4500     16        0866.98ec.97af   0 0 7000 wiredapple.local          
086698EC97AF@wiredapple._raop._tcp.local   4500     16        0866.98ec.97af   0 0 7000 wiredapple.local          

---------------------------------------------------------- A/AAAA Records ----------------------------------------
RECORD-NAME                                TTL      VLAN      CLIENT-MAC       RR-RECORD-DATA                     
------------------------------------------------------------------------------------------------------------------
wiredapple.local                           4500     16        0866.98ec.97af   2001:8:16:16:e5:c446:3218:7437     

----------------------------------------------------------- TXT Records -------------------------------------------
RECORD-NAME                                TTL      VLAN      CLIENT-MAC       RR-RECORD-DATA                                      
--------------------------------------------------------------------------------------------------------------------
wiredapple._airplay._tcp.local             4500     16        0866.98ec.97af   [343]'acl=0''deviceid=08:66:98:EC:97:AF''features=  
086698EC97AF@wiredapple._raop._tcp.local   4500     16        0866.98ec.97af   [193]'cn=0,1,2,3''da=true''et=0,3,5''ft=0x5A7FFFF7

To verify the mdns-sd type PTR, use the following command:

Device# show mdns-sd cache type {PTR | SRV | A-AAA | TXT}
RECORD-NAME                                    TTL      WLAN      CLIENT-MAC       RR-Record-Data                                     
-------------------------------------------------------------------------------------------------------------------------------------
_custom1._tcp.local                            4500     2         c869.cda8.77d6   service_t1._custom1._tcp.local                      
_custom1._tcp.local                            4500     2         c869.cda8.77d6   vk11._custom1._tcp.local                       
_ipp._tcp.local                                4500     2         c869.cda8.77d6   service-4._ipp._tcp.local

To verify the mdns-sd cache for a client MAC, use the following command:

Device# show mdns-sd cache {ap-mac <ap-mac> | client-mac <client-mac> | wlan-id <wlan-id> | wired}
RECORD-NAME                                    TTL      WLAN      CLIENT-MAC       RR-Record-Data                                     
-------------------------------------------------------------------------------------------------------------------------------------
_custom1._tcp.local                            4500     2         c869.cda8.77d6   service_t1._custom1._tcp.local                      
_custom1._tcp.local                            4500     2         c869.cda8.77d6   vk11._custom1._tcp.local                       
_ipp._tcp.local                                4500     2         c869.cda8.77d6   service-4._ipp._tcp.local                           

----------------------------------------------------------- SRV Records -------------------------------------------------------------
RECORD-NAME                                    TTL      WLAN      CLIENT-MAC       RR-Record-Data                                  
-------------------------------------------------------------------------------------------------------------------------------------
service-4._ipp._tcp.local                      4500     2         c869.cda8.77d6   0 0 1212 mDNS-Client1s-275.local                    
vk11._custom1._tcp.local                       4500     2         c869.cda8.77d6   0 0 987 mDNS-Client1s-275.local                     
service_t1._custom1._tcp.local                 4500     2         c869.cda8.77d6   0 0 197 mDNS-Client1s-275.local                     

---------------------------------------------------------- A/AAAA Records -----------------------------------------------------------
RECORD-NAME                                    TTL      WLAN      CLIENT-MAC       RR-Record-Data                                   
-------------------------------------------------------------------------------------------------------------------------------------
mDNS-Client1s-275.local                        4500     2         c869.cda8.77d6   120.1.1.33                                          

----------------------------------------------------------- TXT Records -------------------------------------------------------------
RECORD-NAME                                    TTL      WLAN      CLIENT-MAC       RR-Record-Data                                    
-------------------------------------------------------------------------------------------------------------------------------------
service-4._ipp._tcp.local                      4500     2         c869.cda8.77d6   'CLient1'                                           
vk11._custom1._tcp.local                       4500     2         c869.cda8.77d6   'txtvers=11'                                        
service_t1._custom1._tcp.local                 4500     2         c869.cda8.77d6   'txtvers=12'

To verify the mdns-sd cache in detail, use the following command:

Device# show mdns-sd cache detail

Name: _custom1._tcp.local
  Type: PTR
  TTL: 4500
  WLAN: 2
  WLAN Name: mdns120
  VLAN: 120
  Client MAC: c869.cda8.77d6                  
  AP Ethernet MAC: 7069.5ab8.33d0                  
  Expiry-Time: 09/09/18 21:50:47
  Site-Tag: default-site-tag
  Rdata: service_t1._custom1._tcp.local

To verify the mdns-sd statistics, use the following command:

Device# show mdns-sd statistics

------------------------------------------------------
Consolidated mDNS Packet Statistics
------------------------------------------------------
mDNS stats last reset time: 03/11/19 04:17:35
mDNS packets sent: 61045
  IPv4 sent: 30790
    IPv4 advertisements sent: 234
    IPv4 queries sent: 30556
  IPv6 sent: 30255
    IPv6 advertisements sent: 17
    IPv6 queries sent: 30238
  Multicast sent: 57558
    IPv4 sent: 28938
    IPv6 sent: 28620
mDNS packets received: 72796
  advertisements received: 13604
  queries received: 59192
  IPv4 received: 40600
    IPv4 advertisements received: 6542
    IPv4 queries received: 34058
  IPv6 received: 32196
    IPv6 advertisements received: 7062
    IPv6 queries received: 25134
mDNS packets dropped: 87
 
------------------------------------------------------
Wired mDNS Packet Statistics
------------------------------------------------------
mDNS stats last reset time: 03/11/19 04:17:35
mDNS packets sent: 61033
  IPv4 sent: 30778
    IPv4 advertisements sent: 222
    IPv4 queries sent: 30556
  IPv6 sent: 30255
    IPv6 advertisements sent: 17
    IPv6 queries sent: 30238
  Multicast sent: 57558
    IPv4 sent: 28938
    IPv6 sent: 28620
mDNS packets received: 52623
  advertisements received: 1247
  queries received: 51376
  IPv4 received: 32276
    IPv4 advertisements received: 727
    IPv4 queries received: 31549
  IPv6 received: 20347
    IPv6 advertisements received: 520
    IPv6 queries received: 19827
mDNS packets dropped: 63
 
------------------------------------------------------
mDNS Packet Statistics, for WLAN: 2
------------------------------------------------------
mDNS stats last reset time: 03/11/19 04:17:35
mDNS packets sent: 12
  IPv4 sent: 12
    IPv4 advertisements sent: 12
    IPv4 queries sent: 0
  IPv6 sent: 0
    IPv6 advertisements sent: 0
    IPv6 queries sent: 0
  Multicast sent: 0
    IPv4 sent: 0
    IPv6 sent: 0
mDNS packets received: 20173
  advertisements received: 12357
  queries received: 7816
  IPv4 received: 8324
    IPv4 advertisements received: 5815
    IPv4 queries received: 2509
  IPv6 received: 11849
    IPv6 advertisements received: 6542
    IPv6 queries received: 5307
mDNS packets dropped: 24

To verify the default service list details, use the following command:

Device# show mdns-sd default-service-list

--------------------------------------------
        mDNS Default Service List
--------------------------------------------
 
Service Definition: airplay
Service Names: _airplay._tcp.local
 
Service Definition: airtunes
Service Names: _raop._tcp.local
 
Service Definition: homesharing
Service Names: _home-sharing._tcp.local
 
Service Definition: printer-ipp
Service Names: _ipp._tcp.local
 
Service Definition: printer-lpd
Service Names: _printer._tcp.local
 
Service Definition: printer-ipps
Service Names: _ipps._tcp.local
 
Service Definition: printer-socket
Service Names: _pdl-datastream._tcp.local
 
Service Definition: google-chromecast
Service Names: _googlecast._tcp.local
 
Service Definition: itune-wireless-devicesharing2
Service Names: _apple-mobdev2._tcp.local

To verify the primary service list details, use the following command:

Device# show mdns-sd master-service-list

--------------------------------------------
        mDNS Master Service List
--------------------------------------------
 
Service Definition: fax
Service Names: _fax-ipp._tcp.local
 
Service Definition: roku
Service Names: _rsp._tcp.local
 
Service Definition: airplay
Service Names: _airplay._tcp.local
 
Service Definition: scanner
Service Names: _scanner._tcp.local
 
Service Definition: spotify
Service Names: _spotify-connect._tcp.local
 
Service Definition: airtunes
Service Names: _raop._tcp.local
 
Service Definition: airserver
Service Names: _airplay._tcp.local
               _airserver._tcp.local
 
.
.
.
 
Service Definition: itune-wireless-devicesharing2
Service Names: _apple-mobdev2._tcp.local

To verify the mDNS-AP configured on the controller and VLAN(s) associated with it, use the following command:

Device# show mdns-sd ap

Number of mDNS APs.................................. 1

AP Name 		Ethernet MAC 		Number of Vlans			Vlanidentifiers
----------------------------------------------------------------------------------------------------
AP3600-1 		7069.5ab8.33d0	         1					 300

Further Debug

To debug mDNS further, use the following procedure:

  1. Run this command at the controller:

    set platform software trace wncd <0-7> chassis active R0 mdns debug

  2. Reproduce the issue.

  3. Run this command to gather the traces enabled:

show wireless loadbalance ap affinity wncd 0 

AP MAC 		Discovery Timestamp 	Join Timestamp                Tag				Vlanidentifiers
---------------------------------------------------------------------------------------
0cd0.f894.0600      06/30/21 12:39:48	   06/30/21 12:40:021	default-site-tag				 300