Where in the AES67 network should I place the Grandmaster clock (leader)

Clear-Com IP transceivers (IPTs) require a higher-than-average timing accuracy requirement due to the need to synchronize the devices in a radio frequency (RF) space. Clear-Com recommends the of 125μs PTP packet size when using IPTs

The placement of the Grand Master Clock (GMC) in the AES67 network can affect these timings especially the Offset From Master (OFM) value The IPT takes its OFM value from the GMC

The GMC could be an external (GPS locked) device like the Trilogy Mentor RG or in smaller systems the E-IPA card it self can be used as a GMC.

See our AES67 network guide for full details of Network and Ethernet switch requirements

Use external GMC (GPS preferred) clock like the Trilogy Mentor RG

Use 1GB Managed Layer 3 Ethernet switches

  • (preferably with the ability to support Boundary clock or Transparent clock mode for networks with more than 20x AES67 devices)

Set the IPA card to PTP slave mode (when using an external GMC )

Use 125μs or 1ms PTP packet size (125μs PTP packet size is recommended when using IPTs)

Use the AES67 media profile

Configure QoS, VLANS, IGMP snooping and IGMP querier

  • The use of QoS and VLANS to separate different data types on the network is recommended to ensure minimum delay of PTP clock and audio packets, along with the use of dedicated inter-switch trunk ports to carry only AES67 traffic


 

IF?? you are using non PTP aware Eth-Switches in your AES67 network , do not exceed more than 3 switch hops from the GMC

Example AES67 networks using NON-PTP aware Eth-Switches

IPT and Iris panels behave like non-ptp aware switches when daisy-chained