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Hey Bill, I agree that mis-optioning will not block a signal, but the signal will not be clean in any way, shape or form. The end devices will always give plenty of indication that something is amiss. Coding does not usually come into play for cross-connects on high-speed cards (In a Titan 5500 for example, CST to CST cross-connects require you to specify only framing). LECs are not always passive. Run a circuit through a Fuji or a DDM-1000 and you add devices that must have some sort of coding specified. The surest way I can think of to prove the CPE is to swap the suspect circuit and a known working circuit, and see how the problem moves. If the problem follows the card, replace it. If the problem follows the circuit, have the LEC fix their problem. Paul
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Paul you and I could go at this for awhile. I think were both saying the same thing, but from different perspectives. Now again I'm talking AT&T to LEC, not switch to end user. All our T-3's were B8ZS..for all the issues you've stated. Very seldom would be find a DDM in the LEC misoptioned, it did happen but not often. It could easily be found with the test you mentioned, all zeros was our main one cause we were suppose to get B8ZS..you could send all 1's to verify AMI. I'd still like to know what trouble the end user was actually experiencing here to try to help on the trouble.
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I agree with ya on this one. I think we are saying pretty much the same thing from a different perspective, but mis-optioned DDM-1000s happen more often (especially with Verizon New England) than many people realize. Background static and slow data transmission can be caused by the problem being discussed. I'll cease posting on this subject.
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No need to cease posting on this. I'm sure something will come up we can both provide some insight to. Thanks for your input. Bill
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Thanks!
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Like Bill, I want to hear more about what actual problem is being experienced with the circuit and equipment. Seeing B8ZS on an AMI isn’t really getting to the meat of the matter. Dexman, Just bill, I think you two are missing each other one finer point of ya’lls discussion. I’m gon-na paraphrase so hope I’m not misquoting or misunderstanding either of ya… Bill’s correct in saying that a B8ZF facility will carry an AMI circuit all day every day. Paul is correct that a mis-optined piece of equipment can turn a circuit into a piece of steaming poo! Customer orders a T1 service D4/AMI... There’s a real good chance it will be carried over T3 or STS-1 virtual time slot B8ZS over its entire path end-to-end. BUT equipment and ports along the way… Fiber MUX ports, HDSL etc. will still need to be optioned for AMI at the DS1 level. If the T1 AMI order is incorrectly engineered and built the entire T1 circuit was provisioned B8ZS. Since that’s what nearly all customer T1’s are now days, it would be easy enough to do. There’s a real good chance the end-users AMI equipment will work just peachy. Also good chance no one will ever realize there’s a problem. 'Til there's a maintenance or repair issue that is. Now let’s say that same T1 AMI order is engineered correctly and ALMOST built correctly. Let’s say just one piece (again port or HDSL card) is mis-optioned for B8ZS where everything else along that circuit path is optioned AMI as ordered. Ain’t nuthin’ gon-na work right in this scenario.
----------------------- Bryan LEC Provisioning Engineer Cars -n- Guitars Racin' (retired racer Oct.'07)
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I could give further examples of B8ZS across a network, but think I'd just further confuse things, heck I'm getting confused. Thanks for the input Bryan. As you said, we are still far from the meat of the issue since we don't know what problems were being experienced.
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Originally posted by justbill: I could give further examples of B8ZS across a network, but think I'd just further confuse things, heck I'm getting confused. Thanks for the input Bryan. As you said, we are still far from the meat of the issue since we don't know what problems were being experienced. AMI/D4 .v. B8ZS/ESF -- First off, All digital (AKA ISDN) signaling in carriers is D4. That is the fundamental frame from which all others are derived. So yes, D4 will travel on ESF. All digital signaling is fundamentally AMI. It must be, because voltage must change regularly. B8ZS is merely a method by which voltage is required to alternate more frequently, to ensure there is a voltage change to be detected by the equipment (creating the proper density of voltage changes). Will AMI/D4 run over B8ZS/ESF-- to a degree-. You'll still see errors, but you can also force traffic to a point. Beyond a certain frequency, errors mitigate the gains and performance degrades-- not ideal. For a carrier to say they are seeing B8ZS- they need to tell you specifically what makes them think that. B8ZS will register on any signal where there is sufficiently frequent AMI occuring yielding _frames_. That is why a test set will register B8ZS on an AMI circuit-- but blinking on the test set, not solid-- because it is only seeing it every once in awhile when the pattern matches satisfactorily over a specific period of time-- but won't show frame. PMs should be run on the DCS, because it will register errors that test-sets may not see (for example, a Centest650 may miss EXZs where the Titan 5500 will see them). Problem should be isolated on one side of the demarc or the other, using hardloop and confirming frame. If frame is up- then whatever signal the source is sending to itself is what it should see and frame to. If CPE sees errors when hardlooped-- I suggest they check their cable lengths, and condition of cabling. Might also try reversing the pair. Only as a last resort do you assume there is a card problem or problem with the complex. And then of course swapping cards will show you if it's card if the problem follows a card. Now, with all that said-- if you can run B8ZS/ESF, you want to. AMI/D4 was fine for it's day-- but truthfully that is why this protocol and frame aren't used as much, now. They were _starting points_ for the better signaling and framing algs today (B8ZS/ESF). AMI/D4 is still subject to noise interference based on the data being passed-- whereas, B8ZS/ESF was written to add more error correction inherently, and to enforce a specific AMI density ratio-- all meaning, cleaner signalling in noisier environments. Now, regarding transporting DS1 signals over STS1 (T3), The STS1 cares not what the DS1 signal is. Its signalling and framing are on a higher order and has no impact by or to signal on a DS1 traveling on it. Neither will any piece of equipment along the path that carries that STS1 to higher-order superspans or back to STS1 even know or care what the STS1 signalling is doing.
-- Only the fool fears asking a question.
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Can the Dialogic card not be re-configured as B8ZS/ESF? Must be a fairly older dialogic.
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And over a year later we still don't know what the actual trouble was. I would sure assume it's fixed by now.
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