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How do I confirm good clocking on SONET on a Cisco router?

Posted on 2011-09-25
Last Modified: 2012-05-12
We had to juryrig a SONET connection over an ATM interface on a 3950 router.  Initial packets are fine, but long dataflows are always disrupted, even for NetCat-UDP.  I suspect timing issues.  What commands and debug statements are best?
Question by:jimmycher
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Author Comment

ID: 36598778
That would be a 3945 router, vice 3950, sorry.  How do I setup one router as the "master" timing?
LVL 32

Expert Comment

ID: 36599143

"show controller pos x/x" or something like that, you want to look at the output, specifically the NSE and PSE counters. (NSE = negative stuff events, PSE=positive stuff events)

here is a good sonet tining troubleshooting guide:


harbor235 ;}
LVL 32

Expert Comment

ID: 36599158

timing should be provided as part of the service on the line.

int pos 1/2
clock source line

harbor235 ;}
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Author Comment

ID: 36600120
Thanks Harbor235,
Our carrier says they are NOT providing clocking, but my "show controllers ATM" says
"clock source = line"
(Sadly, we are forcing SONET data over an ATM interface, which was not our choice.)
I have NTP on my side, and I believe the remote does as well, but my guess is that only one should be master, yes?   How do I do that?
What would the command "ATM clock internal provide"?
LVL 32

Expert Comment

ID: 36600459

While overall time syncronization is something you need to ensure is utilized it is not the same thing as timing on a point to point link. On a P2P link each side must be syncronized for sending and receiving data from the other, you do not want to be sending while expecting receiving, the actual offical time of day is not necessary. The key is that some time is used and that both ends agree that one is the source of time to ccordinate for sending and receiving frames between them.

So, make sure one side has the interface set to providing time and the other side is configured to use time off the line.

harbor235 ;}

Author Comment

ID: 36601140
My research indicates the default is timing is off the line.  The only other option is clock internal.  IF the carrier says it is not providing clocking, what next?   Should one side be "internal" and the other side "liine" ?
LVL 32

Accepted Solution

harbor235 earned 500 total points
ID: 36601324

Right, so on one side define clocking as internal and the other should be on line.You can also do internal internal, try them both and see what provides teh best results

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