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Is it suported to have a multicast PTP Grandmaster for boundary/ordinary clock setup?

Is it suported to have a multicast PTP Grandmaster for boundary/ordinary clock setup?

Toni_Comerma
New Contributor
I'm trying to setup an EXOS device as boundary or ordinary clock, but our grandmaster is set up to work in multicast. Reading documentation, I've just seen examples for unicast grandmasters. Is it possible to sync to a multicast grandmaster?

7 REPLIES 7

Chad_Smith1
Extreme Employee
Toni,

This is a common misconception. AES67 has been developed to work on any standard ethernet switch. It has no requirement for PTP on the switching infrastructure. There is a PTP requirement on the endpoints. An excerpt from this FAQ.

"What is the difference between AES67 and AVB?The AVB standards define improvements to the standard Ethernet layer 2 protocol to provide synchronization, Quality of Service (QoS) and an admission control behaviour that prevents the network from becoming overloaded by media traffic; an AVB network requires use of specific AVB Ethernet switches. AES67 utilizes protocols on layer 3 or above, so is able to function using standard Ethernet switches. While it is entirely possible for AES67 to function over an AVB network, AES67 will not receive any performance benefits from the capabilities of the AVB network, except if the AES67 device fully supports the AVB layer 2 protocol stack."

I am not as familiar with SMPTE ST-2059-2, but I know it uses AES67 for the audio transport and therefore I suspect it has similar requirements (standard network switch).

Toni_Comerma
New Contributor
Thanks Chad,

It's a pity, because for audio&video, the ptp profiles used (SMPTE ST-2059-2 and AES-67) require the use of multicast.

This makes our EXOS switches useless for this scenario.

Kind regards,

Toni

Chad_Smith1
Extreme Employee
EXOS does not currently support multicast PTP operation.

A list of EXOS PTP supported features can be found here:
http://documentation.extremenetworks.com/exos/EXOS_21_1/Slots_and_Ports/c_supported-ptp-features.sht...

A list of EXOS PTP limitations can be found here:
http://documentation.extremenetworks.com/exos/EXOS_21_1/Slots_and_Ports/c_limitations-of-ptp.shtml
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