Ascend Archive
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Re: (ASCEND) Digital line quality issues
You also have to watch the copper between the phone companies fiber, and
your ascends - noise can be introduced there.
On Wed, 12 Aug 1998, R. P. McCormick wrote:
> On Tuesday, August 11, 1998 23:43 Marcel Brown <marcel@marcelbrown.com>
> wrote:
>
>
> >Just a quick, curious question. I feel pretty comfortable telling my
> >customers that since we have digital PRI trunks instead of regular analog
> >lines coming into our equipment, our end is free from line noise. Is there
> >any way that digital lines can experience noise (other than noise that
> >originates from the analog lines between the customer's house and the
> >central office)?
> [snip]
>
> I may not totally 100% correct on how I explain this, as its from
> bits and pieces of information.
>
> We pull ISDN PRI's into our MAX 4000 boxes ... and therefore
> get the full gambit of ISDN benefits, which includes features
> over and above what gets delivered on plain 'ole T1 circuits.
>
> But both T1 and ISDN are digitally delivered circuits ...
> and they have acceptable bit rates that ensure that if
> errors do happen (to the bit stream) its very low (and infrequent).
>
> As compared to taking an analogue line (POTS) into a modem
> (or bank of modems) - a world of difference. Plus: you're never
> going to provide v.90 style connections with anything BUT a
> digital connection on your end.
>
> Here's the kicker:
> In researching some "performance" problems that we have
> had - noting that this is somewhat subjective, in the sense
> that we get connections that are "slower" than expected ...
> we found the following:
>
> When a user makes that v.90 dial-up connection to you,
> quite possibly the call is originated on one CO ... and
> then crosses one or more trunks to get to the switch
> that finally provides the call via your (nice, clean)
> ISDN-PRI circuit.
>
> We did some tests ... from various locations that were
> one or more CO hops away, where we found that calls
> into our Max boxes were "slower" than calls to the
> local uunet/MSN numbers, or other local ISP's
> (running the 3Com stuff). Of course - that was unacceptable.
> In the end - I believe that what some of our problem was
> was due to the types of trunks that tie switches together.
> Something about some different types and encoding,
> where at least one setup was not favourable to the
> bandwidth required by a good v.90 connection.
>
> Therefore when people called in, going over these
> "undesirable" CO trunks (between switches?!)
> the modem would negotiate a slower baud rate connection.
> We've got a great CLEC who's done a lot of work to
> clean this kind of thing up (and for the most part,
> its not even their problem, but the ILEC).
>
> Hope this helps.
> Bob McCormick
>
>
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Steve Hovey
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BuffNET More Than Just a Connection!
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