Frequency Synchronization for NCS540

[Kumar Pradeep]

Hi Team,

Could you explain frequency Synchronization. 

Flags: > - Up D - Down S - Assigned for selection
d - SSM Disabled x - Peer timed out i - Init state
s - Output squelched
Fl Interface QLrcv QLuse Pri QLsnd Output driven by
==== ======================== ===== ===== === ===== ========================
>S TenGigE0/0/0/20 PRC PRC 5 DNU TenGigE0/0/0/20
>S TenGigE0/0/0/23 PRC PRC 10 PRC TenGigE0/0/0/20

[balaji.bandi]

Can you elaborate more what sync you looking ?

what version of code running,what command you used to get that ouput - on tht output what is the issue ?

refer documents :

https://www.cisco.com/c/en/us/support/routers/network-convergence-system-540-series-routers/products-installation-and-configuration-guides-list.html

[Kumar Pradeep]

> what version of code running: 7.5.2 v2

> what command you used to get that output: show frequency synchronization interfaces brief

> on that output what is the issue: There is no issue, i wanted to know actually how this thing work and what is the meaning of QLrcv, QLuse, QLsnd purpose? 

[Ramblin Tech]

Synchronizing clocks across a network is a very complicated process, which a few hundred words in this forum cannot truly explain.

If you are asking specifically about "QL", then see ITU-T Rec G.781, which provides definitions for the various values of "Quality Level".

If you are interested in a deep-dive into synchronization, then take a look at the Cisco Press book Synchronizing 5G Mobile Networks by Hagarty, Ajmeri, and Tanwar, or search for CiscoLive! presentations by Dennis Hagarty or Shahid Ajmeri.

If you want a brief, very high-level analogy of frequency sync vs phase sync, then I had two favorites when I was a Cisco SE:

1 - Imagine driving down a multi-lane highway and looking out your window and seeing another automobile driving in the next lane at precisely your same speed. Your two automobiles are in frequency sync as you both have the same mph (or kph). Furthermore, you are in phase sync if your front bumpers are even with each other; you pass each milestone on the highway at precisely the same time. (I heard this from Dennis some time ago and my apologies if I have mangled it).

2 - Two clocks are in frequency sync if they precisely agree on how long an hour is (ie, neither clock runs faster than the other). The two clocks are also in phase sync if they precisely agree on when that hour started.