From EHX V12.4 or later ,
AES67/ ST2110-30 is designed to work across very low latency IP networks with high PTP stability and minimum jitter.
The AES67 design implies that audio packets should not be delayed by more than 2ms / 20ms if using 125us/ 1ms RTP packet sizes and the tight PTP jitter values must be maintained
see FAQ What PTP values do I need to get good RF roaming between IPT antennas (#2)
Customers can now create AES67/ST2110-30 streams across WAN networks. For projects where the customer wants to use AES67/ST2110-30 streams across WAN links with longer delays, Clear-Com has added the extra function of RX link-offset into EHX V12.4 or later. The customer can enter a value for RX link-offset (in μs) in order to make sure the overall packet travel time is less than 2ms / 20ms if using 125us / 1ms RTP packet sizes respectively.
Example network layout using dedicated WAN/ fibre/ MPLS links
125 µs: The max packet travel time is 2 ms. This means packets taking more than 2 ms from Tx to Rx will be dropped. 1 ms: The max packet travel time is 20 ms. This means packets taking more than 20 ms from Tx to Rx will be dropped. The maximum jitter values for PTP must still be maintained across the network |
The easiest way to calculate RX link-offset is to ping a device from one side of the network to the other. The ping round-trip time can be halved and input into the EHX RX link-offset field (in μs).
RX link-offset setting in EHX
The RX link-offset can be used for Clear-Com Iris and IPTs
The RX link-offset can be used for 3rd party AES67/ST2110-30 audio streams*
*Note 3rd party AES67 receivers must be adjusted for any link delay for TX streams from the E-IPA card towards the receiver, as Clear-Com does not control the internal settings of the 3rd party AES67 audio device
