How To| Access Attero Tech AES67 Networking Guide

This guide provides best practices and troubleshooting tips for setting up secure AES67 networking.

Updated at June 8th, 2023

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Table of Contents


AES67 uses a set of standard IP-based protocols that are combined to allow uncompressed, low latency audio to be passed over a network. AES67-capable devices therefore are similar to many other network connected devices.

Some Attero Tech Dante® enabled products support AES67 and for these types of devices, the network should be setup per Audinates® recommendations. The following products are based on either the Audinate Ultimo or Brooklyn platforms”

  • All “unD” series endpoint products
  • All “Synapse” series products
  • Axon D2FLEXio

Some Attero Tech products are built on Attero Tech’s proprietary AES67 networked audio platform. While proprietary, these products are approved for interoperability with any Dante device that supports AES67 interoperability mode and all QSC Q-SYS Core DSP products. The following products are based on the Attero Tech AES67 implementation:

  • All “unA” series products
  • Axon A4FLEX
  • Axon A4Mio
  • Axon A8Mio

The remainder of this document is focused on addressing the integration guidelines for these proprietary Attero Tech AES67 products.

While AES67 in general is consistent in its methods of clocking and audio transport, some operations such as device discovery and device configuration are not covered by the AES67 specifications. As a result, device configuration and stream assignments remain proprietary for many AES67 implementations, including Attero Tech’s. The following sections identify the basic capabilities and technical details of the Attero Tech AES67 implementation.

IP Address Assignment

The devices use DHCP by default to obtain an IP address. If a DHCP server is not available, the device will assign itself a local link address in the 169.254.x.y range, just like a PC, MAC

Devices can also be configured to use a static IP if required, using the unIFY Control Panel software application.


Attero AES67 uses SAP (Session Announcement Protocol) for stream advertisement. The SAP announcements describe the stream contents and all audio associated with the stream is sent using multicast transmission. In order to provide bandwidth and traffic management, all Attero Tech AES67 products support IGMP.

While IGMP support on the network is not a requirement, its use is very much recommended due to the multicast nature of the AES67 traffic especially if network has 100Mbit devices connected. It is important to note, that while the devices support IGMP, it is imperative that IGMP Snooping be properly configured on the target network hardware in order to benefit from IGMP. This includes ensuring that a single IGMP querier is present.


All unA series devices currently only support IGMPv2. All other new AES67 products support both IGMPv2 and v3.



Attero AES67 makes use of DiffServ QoS. It tags packets it sends out and these tags can be used to determine packet priority. They use the same values for the tags as QSC does for its AES67 implementation. However, if the device is being used in a shared network with Dante, the tag values can be changed to match those that Dante use thus making the configuration simpler. The table below shows the default QSC-compatible settings:













QoS should be configured to use “strict” priority queueing and can be used on any network but is most useful when devices connected have different connection speeds and/or where there are lots of different types of traffic using the network.

Detailed Protocol Information

  • mDNS – Used for device discovery on port 5353
  • SAP/SDP - Stream descriptors messages that describe the stream on port 9875
  • PTPv2 (Precision Time Protocol) – Used for time synchronization between devices on ports 319 and 320
  • AES67 Audio streams - A typical stream contain up to 8 channels. Each channel takes up approximately 1.5Mbps in bandwidth. The streams are in the 239.69.x.x IP range on port 5004
  • TFTP – firmware update 65024
  • Proprietary messages / port utilization:
    • Device Status Messages - port 49495
    • Asynchronous event messages – user configured IP and port