TELECOM Digest OnLine - Sorted: Re: Today's Long Distance Circuits?

Re: Today's Long Distance Circuits?

Justa Lurker (JustaLurker@att.net)
Thu, 04 Aug 2005 00:14:09 GMT

hancock4@bbs.cpcn.com wrote:

> By how, I mean what physical medium is chosen and how is it routed.
> Do they use satellite, microwave, fibre optic, coax, plain wire?

The vast majority of domestic "long distance" calls today would, of
course, go over fibre optic transmission systems. There are also some
digital radio (e.g., microwave) routes still out there where they make
economic or technical sense. Satellite routes are used predominantly
for overseas traffic to countries not served more directly by optical
fibre transport, or perhaps to some extremely remote locales (in for
example, the state of Alaska) which do not have fiber connectivity.
Satellite is also still used as backup for some of the submarine
cables, should they fail pending repair or perhaps during maintenance
[although increasingly infrequently --- since (a) many of the new
submarine cables tend to use SONET ring technology which greatly
increases availability and minimizes the need to use any sort of
satellite restoration, and (b) there is often extra capacity on other
undersea fiber systems which can be pressed into service by rerouting
traffic over them].

For a historical perspective, check out the URL

http://long-lines.net/

... if you haven't already. Lots of good stuff there.

> Are there direct routes or must it go to intermediate switching
> centers and transferred there? What happens if the primary circuits
> are busy -- do they go to a lot of trouble to reroute or just cut me
> off?

Take a look at

http://perso.rd.francetelecom.fr/chemouil/gcn_ieee/DynRout20.pdf

... for a throrough description written by 2 genuine experts.

> Does AT&T still have a big network control center in Bedminster?

Yes. In fact, it was enlarged and moved to a new building a few years
ago. For example, see:

http://www.extron.com/company/archive.asp?id=featureappatt
http://www.christiedigital.com/recentInstallations/networkOperation/att/att_noc.asp
http://www.emeapress.att.com/library/images/att_noc_01.jpg

> Does anyone even have such control centers or are they not needed
> anymore?

Certainly they serve as much of a "PR" (Public Relations) function as
anything else. Not to mention the "we always did it that way" factor.
And big execs like to build their empires to show off. Certainly, one
could debate whether (given today's technology) that all of those
people need to be (or even should be) in one physical location.

> By whom I mean does my designated long distance carrier actually
> physically carry the call or do they merely sublet to someone else who
> actually owns the wires to where I'm going. Who manages the switching
> centers?

Depends on your choice of designated long distance carrier, and the
extent to which it owns and operates its own facilities vs. buying
capacity 'wholesale' from one of the big guys or perhaps a "carrier's
carrier" (Wiltel comes to mind here).

> I suspect a heck of a lot of long distance traffic is carried by
> someone other than the designated carrier.

Once again, it varies from virtually none to virtually all, based upon
who you've specifically selected as your LD carrier. As a very rough
first-order estimate, next time you are out on your bicycle or driving
around the countryside, take a look at those little signs which are
posted along fiber optic right-of-ways ... do you see your carrier's
name on many (any) of them ? Certainly that's not a 100% foolproof
way to answer your question since there is a lot of capacity swaps &
dark fiber/optical wavelength leasing & reselling of bandwidth between
carriers, but it may give you a crude sense of who owns what in a
relative sense.

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