Configuring an mDNS Relay

Procedure

1. Run system-view

   The system view is displayed.

2. Run mdns gateway ip ip-address

   The IP address of the mDNS gateway is specified on the device as the mDNS relay.

   By default, the IP address of the mDNS gateway is not specified.

3. Run vlan vlan-id

   The VLAN view is displayed.

   The VLAN ID is the ID of the VLAN that the service provisioning devices or user terminals belongs to.

4. Run mdns relay enable

   The mDNS relay is enabled.

   By default, the mDNS relay is disabled.

   

   The device cannot function as both mDNS relay and gateway. A protection failure will occur if the mdns relay enable and mdns gateway enable commands are both configured on the device.

5. (Optional) Run mdns probe interval interval

   The mDNS gateway is enabled to periodically discover services and the discovery interval is set.

   By default, the mDNS gateway is not enabled to periodically discover services and the discovery interval is not set.

   The mDNS gateway needs to maintain service lists of all service provisioning devices. A service list records the service name, service type, TTL, host name, and IP address. The TTL is provided by a service provisioning device to the mDNS gateway, and represents the aging time of a service. If the mDNS gateway receives mDNS response packets from a service provisioning device within the aging time, the mDNS gateway updates its service information. If the mDNS gateway does not receive mDNS response packets from a service provisioning device within the aging time, the mDNS gateway deletes its service information.

   When an mDNS gateway already exists, a service provisioning device connected to the network advertises service information to the mDNS gateway. If a service provisioning device already exists before an mDNS gateway connects to the network, the service provisioning device does not advertise service information to the mDNS gateway. In this case, you can configure the mDNS relay to periodically discover services. This step is performed to configure the mDNS relay to periodically discover services and set the discovery interval. The mDNS relay sends mDNS request packets at discovery intervals to update available services in the local VLAN. After receiving response messages from the service provisioning device, the mDNS relay forwards them to the mDNS gateway so that service lists on the mDNS gateway are updated immediately.

6. Run quit

   Return to the system view.

7. (Optional) Run mdns source ip ip-address

   The device as the mDNS relay is configured to encapsulate the source IP address in mDNS packets to forward mDNS packets to the mDNS gateway. The device is also configured to encapsulate the source IP address in mDNS packets to periodically discover services.

   By default, the source IP address is configured.

   The mdns source ip command has two functions:

   • When the mDNS relay is enabled to periodically discover services, it encapsulates the configured source IP address into outgoing mDNS request packets so that it can receive response packets from service provisioning devices. If an IP address is assigned to the VLANIF interface corresponding to the VLAN where the mDNS relay periodically discovers services, the mDNS relay encapsulates the IP address of the VLANIF interface into outgoing mDNS request packets. In this case, ignore this step.

   • When the device as the mDNS relay forwards mDNS packets to the mDNS gateway, it encapsulates the source IP address as the next hop IP address of the outbound interface according to its routing table. If the mdns source ip command is used, the device preferentially uses the configured source IP address.

   

   It is recommended that the IP address of an interface on the mDNS relay connecting the mDNS gateway be used as the source IP address.