Precision Time Protocol (PTP) and Multi-Pod

[udo.konstantin]

Hello, 

for a customer, I would like to use PTP in a given ACI Multi-Pod environment. NTP will be deactivated. 

I have different question: 

- As per Cisco recommendation a grandmaster clock should be attached to the IPN!

--> Doesn't it matter whether to the OoB or directly to the IPN?

- Assume we have three Timeserver!

--> Should each timeserver connect to the IPN device in a different POD?  

--> AFAIK it doesn't matter if it's copper or fiber because of send and receiver (Master/Slave)

Configuration on the IPN Switches:

The IPN consists of second generation Nexus 9300 Switches

What does the command ptp source <IP> mean? Is this the grandmaster clock? Or is this the source interface from the Nexus perspective? 

How can we configure redundancy with the three timeserver (each server get it's own IP address)

Thanks 

Udo 

[Gaurav Gambhir]

1. I dont think you can connect the PTP grandmaster clock via OOB interface.

from my lab, PTP command is not available at the mgmt interface level 

N9K-1(config-if)# interface mgmt 0
N9K-1(config-if)# ptp ?
*** No matching command found in current mode, matching in (config) mode ***
domain Ptp clock domain
priority1 Priority1
priority2 Priority1
source Source IP address

however if I go to any ethernet interface it allows me to configure it.

N9K-1(config-if)# int ethernet 1/1
N9K-1(config-if)# ptp ?
<CR>
announce Announce
delay-request Delay-request
sync Sync
vlan Vlan

2.

from ACI prospective IPN is one network and not considered to be part of PODs. from my understanding you have two options.

To configure GM for MPOD you need to:

• Enable PTP on IPN node such that it acts as Boundary clock (OR)
• Pass-through mode [PTP not enabled on IPN but PTP packets passed as regular multicast]

you have to make sure that they all point to same device.

3. ptp source <IP> This command specifies the source IP address for the PTP packets generated by the switch.

https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-733921.html#_Toc413144480

[newtonr]

Can anyone confirm if an external hardware Grandmaster Clock is mandatory in all Multi-Pod deployments, or only when PTP is enabled/required?

I have a customer wishing to use ACI as a pure L2/L3 underlay for NSX between 3 campus comms rooms and they do not have an external GC or a need to run PTP.

Rob

[udo.konstantin]

Hi,

A GC is only required when you need PTP. There is noch requirement for ACI Multi-Pod

BR
Udo