Posted on July 11, 2017 5:26 pm
 |  Asked by James List
 |  435 views
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Dear experts

two questions:

1) any experience in flooding PTP signal over L3 WAN (MPLS but also point2point with OSPF area 0) with no PTP aware gears in the middle ?

My customer is currently using Arista gears with PTP grandmaster as boundary, but he would like to spread the signal in remote locations.

I’m not currently sure it works with unicast and due to delay variation.

Any experience or field experience on the topic ?

I find difficult to replicate in lab.

2) is there a way to pool the Arista gears and see (monitor) the current PTP offset with the grand master ? Is it something viable with snmp ?

Cheers

James

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Posted by Alexis Dacquay
Answered on August 17, 2020 4:53 pm

Hi James,

It is practically bad to run PTP on the WAN on shared links. Even the underlaying transport equipment can cause high latency and jitter, unknowingly to the network architects.
Preferably you would have a dedicated link, if not then implement a good QoS policy.

Most places have the most important sites with their own time source.

It is difficult to state whether an unknown environment can have it working, it really depends on the particularities of you customer.
It may work, if done very carefully. Maybe not. Testing is the best way to validate. Without that, I would recommend to not commit.

The 7150S with an internal clock (OCXO) is quite accurate for relatively short holdover, but it cannot sustain that beyond a day or so, if you need to stay within regulatory obligations.

Even if not every kit supports PTP, do activate PTP wherever you can. BC will give you more monitoring; while TC will work in more use cases but might be more difficult to implement and it will be more difficult to monitor.

2)
Yes, EOS supports a lot of good monitoring information in BC.
There is "ptp monitor" and other "show ptp ..." commands
EOS supports SNMP RFC 8173 PTPBASE-MIB

Regards,
Alexis

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