Routing Media

Routing Terminology

  • Device: A device means a Dante-enabled device, and more specifically that component of the equipment that implements the Dante interface. A Dante device typically has Tx and Rx channels and other routing-related properties.
  • Transmit (Tx) channel: A transmit channel transmits media from the media hardware onto the network.
  • Receive (Rx) channel: A receive channel receives media from the network and sends it to the media hardware.
  • Flow: Dante media routing creates flows. Each flow carries several channels of audio, or one channel of video from a transmitter to one or more receivers. Unicast routing creates flows to single receivers. Multicast routing creates flows that can be received by multiple receivers. Multicast flows are assigned IDs enabling them to be identified in Dante Controller.
  • Unicast routing: Unicast flows are point-to-point from a single transmitter to a single receiver. Unicast flows typically have room for 4 channels of audio or 1 channel of video.
  • Multicast routing: Multicast flows are one-to-many from a single transmitter to any number of receivers. Use Dante Controller to choose which channels are to be multicast. Unlike unicast routing, multicast flows consume network bandwidth even if there are no receivers, but do not require additional bandwidth to add more receivers.
  • Subscription: A subscription configures a receive channel to receive media from a transmit channel on another Dante device.
  • Subscription status: For a receive channel, subscription status indicates whether it is subscribed, whether it is receiving unicast or multicast media, whether the subscription is OK, or whether an error has occurred.

Subscription

Dante routing is performed by associating a receiving (Rx) channel with a transmitting (Tx) channel. This is called 'subscription'.

Example: Route Tx channels 1 and 2 (named “Audio L” and “Audio R”) on the device named “Source” to Rx channels 3 and 4 on the device named “Dest”.

Rx channels 3 and 4 on “Dest” are subscribed as follows:

  • 3. Audio L@Source
  • 4. Audio R@Source

Dante will perform the necessary routing to deliver the media from the Tx channels to the Rx channels.

Redundancy

Many Dante devices support redundant media routing. These devices have two network interfaces, named primary and secondary. Primary interfaces should be connected to one physical network. If redundancy is being used, secondary interfaces should be connected to a second separate network. Secondary interfaces cannot communicate with primary interfaces.

If the secondary network is connected to a device that supports redundancy, it is enabled automatically. The same media data is transmitted on both the primary and secondary networks simultaneously. In the event of a failure on one network, media will continue to flow via the other network.

Note:  Dante redundancy requires that both the primary and secondary interfaces on any redundant device are connected using the same link speed. For example, if the primary interface is connected to a 1 Gbps switch port, the secondary interface must also be connected to a 1 Gbps switch port. Similarly, if the primary interface is connected to a 100 Mbps switch port, the secondary interface must also be connected to a 100 Mbps switch port.

Note:  Dante devices that do not support redundancy must be connected to the primary network only.

Media Formats

Most Dante devices support a range of media formats (audio sample rates, or video resolutions). Devices can usually be switched between media formats, but will not support more than one at a time.

It is only possible to set up a subscription between channels which have a common media format. Channels on devices with incompatible formats will be shown in grey, and will not be routable.

Flows

Dante media routing creates 'flows'. Each flow carries one or more channels of audio, or one channel of video from a transmitting device to one or more receiving devices. There are two types of flow, unicast and multicast.

Unicast routing creates flows to a single receiving device; a unicast flow typically assigns space for 4 channels of audio, or 1 channel of video. Unicast flows are set up when a receiver subscribes to an available media channel, and are automatically removed when the receiver unsubscribes from all channels in that flow.

Multicast routing creates flows that can be received by multiple receivers. Multicast flows are assigned IDs, enabling them to be identified in Dante Controller, and to facilitate their removal. In contrast to unicast flows, multicast flows must be set up on the transmitting Dante device before receivers can subscribe to these flows.

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Advanced Routing: Using Multicast

Dante routing is unicast by default. This means that a separate flow is set up between each transmitter and receiver. If several receivers are all subscribed to the same channels of a transmitter, it may sometimes be more efficient to use multicast.

Multicast sends the same set of channels to multiple receivers. In practice, this usually means that the flow is flooded throughout the network. If many receivers want the same channels, using multicast can reduce overall network use, especially on the transmitter, because only one copy of each channel needs to be sent, rather than many.

Dante receivers will automatically prefer multicast to unicast if it is available. This means that if a new multicast flow is created containing the channels that a receiver is currently receiving as unicast, the receiver will switch over to receiving media from the multicast flow and the unicast flow will be removed.

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