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Testing a T3 with a VZ loopback or head to head wi
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doug   Offline
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Testing a T3 with a VZ loopback or head to head wi
Sep 28th, 2005 at 7:51am
 
While testing with VZ on a newly delievered T3, I was not able to see my injected errors come back to me, after VZ had provided a loopback at the far end.
Utilizing the Sunset OC3 test set, the configuration was properly setup while terminating into LTP's ds3 jackfield with a pattern of 2e23.  As mentioned previously Vz has provided a lpbk and all indications were good, pattern sync,etc. but when injecting errors I was not seeing them. I provided a lpbk condition in the swrm by looping back from VZ's T3 panel just after coming out of their entrance facilities(FUJITSU muxes). The lpbk is now facing me and I'm testing my cables and the test set for proper setup. No problem...all indications are good and I can transmit and receive injected errors.
Here lies the problem...after setting up the test set from the main menu there lies an additional menu labeled OTHER FEATURES. Under this menu lies ERROR INJECTION. I was setup for BPV whereas I should have utilized BIT with a burst rate of 1. What happens is that the M13 muxes within VZ's infrastructure will clean up any BPV and that was the reason I was not seeing my injected errors returned. Once setup proberly I had no problem testing to VZ's lpbks.
Keep this in mind when testing HEAD TO HEAD with our own field eng.'s. They also will need to configure their test set with error injections set for BIT. If not you might think you have a one way path and thereby delay the acceptance of the T3.
HAPPY TESTING!
 
 
 
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Bryan   Offline
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Re: Testing a T3 with a VZ loopback or head to head wi
Reply #1 - Sep 22nd, 2008 at 5:46pm
 
I've had something similar happen with many of our T1 tests.  I have often noticed that when testing a T1 that goes through a dacs (Tellabs primarily but I've seen it happen in muxes too), any type of error gets cleaned up as if the dacs is seeing it and retransmitting it with some sort of error correction.  It can be a blessing but when it comes to testing a T1 (especially a long haul one), it can be frustrating.  I can't even begin to imagine what it'd be like with an DS3, where you can't pass COT.
 
 
 
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Bryan   Offline
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Re: Testing a T3 with a VZ loopback or head to head wi
Reply #2 - Oct 26th, 2009 at 2:31pm
 
Bryan wrote on Sep 22nd, 2008 at 5:46pm:
I've had something similar happen with many of our T1 tests.  I have often noticed that when testing a T1 that goes through a dacs (Tellabs primarily but I've seen it happen in muxes too), any type of error gets cleaned up as if the dacs is seeing it and retransmitting it with some sort of error correction.  It can be a blessing but when it comes to testing a T1 (especially a long haul one), it can be frustrating.  I can't even begin to imagine what it'd be like with an DS3, where you can't pass COT.


Testing a DS3, where the DS1's aren't passing COT.  Man...I'm a great communicator...sheesh.
 
 
 
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