Ascend Archive
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(ASCEND) T1 provisoning hints
Nelson, et al.:
Here's some tips and comments that might help with both 56K and regular
line provisioning for PRI and T1 circuits to RAS equipment such as the
Max family of servers.
One of the questions below dealt with a mysterious quality of service
difference. Here may be the reason:
First, the way that the RBOC's deliver the customer's phone calls or
modem calls to the CO (Central office) from the various rate centers may
be (and often are) very different. For instance, in the neighborhoods
where you serve customers, some of those areas may be serviced directly
to the CO on dry copper, with no bridge taps, loading coils or repeaters
in the line. This is good for modems, and especially K56Flex or even x2;
expect happy customers.
Or, the customer could be on dry copper but *with* bridge taps, loading
coils or analog repeaters in the line. This normally happens because of
a distance greater than apx. 12000 feet from the CO or *shorter than*
4000 feet. This starts to make things marginal for the better data
connections, but still may be usable for mid level 40K or so K56
connections, and mid 20K V.34's. Expect customers questioning why they
can't get good connect rates.
Next, the neighborhood could be served by a SLC - Subscriber Loop
Concentrator. This ugly-data-crushing device takes the copper from the
home, and does at least one and often more A/D then D/A conversions, as
it passes the signal over digital facilities to the CO. There at the CO
the signal is "de-muxed" and often attached back onto the MDF
(Multipoint Distribution Frame) where it heads into the Line side of the
CO's switch. Some popular switch type examples are Northern Telecom DMS
series, AT&T/Lucent 5ESS, AT&T 1A. SLC's are often used where the RBOC
needs a high concentration of lines, or where the RBOC needs to feed a
residential or industrial area that is very far from the CO. They are
also being deployed due to cost efficiencies.
If you are fed from a SLC, expect nothing but trouble, and zero recourse
from the RBOC. Your customers will be unhappy, and there is nothing you
can do.
Also, it is not uncommon for half the neighborhood to be served by one
method above, and the other part from another. I had an instance where
two people lived right next to each other - one got great rates, his
friend didn't. Investigation showed two different paths into the CO from
the two homes.
Problem tracking:
It is very rare that the customer has the classic excuse of "bad phone
lines" at their home. Don't even go there first if the home is less
than 5 or 7 years old. It is just very unlikely and a better bet would
be one of the above. I have found that the phone company will at times
be very helpful in telling the customer how his/her circuit is actually
built and in some cases, can ever change a few things to the situation
better. You'll get more Bees with Honey with respect to this item!
The connection-results in the K56Flex modems at&v1 will show a bunch
of info. Two important fields are Line Quality and I think the other is
marked Receive Level. A receive level of 019 for instance, refers to an
incoming to-the-home modem signal that is -19dbm. -19dbm is very
marginal. Better numbers are -17dbm through -14 dbm, and more than
-20dbm will most likely never work. The Line quality indicator is a
factor derived from many sources, and is too complex for this
discussion. A Good Line quality is anywhere from 1-75 or so, anything
higher will begin to be detrimental to the connect rates.
Finally, ISP's that run their Maxen from T1 circuits (not PRI) need to
remember and be cognizant of the following:
1) The T1 *must* be "trunk-side provisioned, never Line-Side. Line side
will go through a D4 converter prior to being delivered. This is not
just bad - it's a show stopper. I have counseled many an ISP who was
told from the RBOC that "ya it's digital all the way!". Well it is
almost, but almost only counts in Horse-shoes and atomic bombs, me
thinks.
2) The receive level from the inbound ISP T1's must be within spec for
the equipment being used. The LBO (Line Build Out) parameter on the
Maxen's adjust the padding to the CSU to present the proper level as
derived from the incoming T1 circuit. The RBOC should (read probably
won't) be able to advise you on the proper setting for your specific
installation. It is an adjustment that you can play with on your own if
you are having troubles. The default of 0 is often correct, and that's
how Ascend sends the units out. It is important to remember that too
much signal is just as bad as too little.
3) The CO switch group that you are trunk-side provisioned from, must
*not* place voice-shaping pad groups on your circuits. For the NT DMS
series delivering trunk-side data service on a B8ZS ESF T1 to your Max,
the trunk group should have the NILPADGRP applied to the outbound side.
The Lucent switch has a similar setting called I believe NOOP. Both of
these mean essentially, NO PADDING or FREQUENCY RESPONSE SHAPING
APPLIED. It has been my experience that most RBOC's and CLEC's do not
understand this, and will just build things up as if they were to be
used for voice. You will have to really dig to get someone to tell you
this information, but you *can* get it...and it could easily be your
whole problem!
A note on PRI's:
PRI's are naturally trunk-side provisioned, and have less complications
based on install practices. They also have slightly better bandwidth
per channel characteristics because all signaling is done out of band on
the D channel. Use them if you can.
Hope this helps a bit, if not - I needed to practice typing anyway. :-)
Best regards,
David Van Allen - You Tools Corporation / FASTNET(tm)
dave@fast.net (610) 289-1100 http://www.fast.net
FASTNET - PA/NJ/DE Internet Solutions
>-----Original Message-----
>From: Nelson Lee [SMTP:lnelson@e-zone.e-z.net]
>Sent: Friday, June 27, 1997 1:40 PM
>To: Ascend User Group
>Subject: (ASCEND) 56k/telco
>
>
>We got our Max4048 about three weeks ago to go along with our fiber PRI.
>As I test from the various neighbourhoods that our ISP serves, I find that
>some people have no trouble getting connections as high as 50k to our Max.
>However, in other areas, the exact same equipment will give up on 56k and
>fall back to v.34. The odd part is that the v.34 connections are usually
>fast (26.4 - 31.2), which is just what I see when I force a v.34
>connection in those areas that can get 56k. When I check signal strength
>and line quality, I see similar results in both the areas that can get 56k
>and the areas that can't.
>
>So, the question is: Why can't some of these areas get 56k? Is this a
>telco problem? Could they be throwing an extra D/A and A/D in the loop
>somewhere? Is there any way to test for this?
>
>(BTW, when I refer to 56k, I mean 56k as opposed to v.34 -- 32000, 34000...).
>
>------------------------------------------------------
>| Lee Nelson |
>| lnelson@e-z.net |
>| http://www.e-z.net/~lnelson |
>|----------------------------------------------------|
>| System Administrator, E-Z.Net Inc. |
>| (360)260-1122 |
>| 209 NE 120th Ave. Suite B |
>| Vancouver, WA 98684 |
>------------------------------------------------------
>
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