Date: Thu, 27 May 93 14:24:29 CDT
From: varney@ihlpl.att.com
Subject: Re: Movable Switches (was Re: Hinsdale)
Organization: AT&T Network Systems, Lisle, IL

In article <telecom13.356.2@eecs.nwu.edu> deej@cbnewsf.cb.att.com
(david.g.lewis) writes:

> In article <telecom13.351.7@eecs.nwu.edu> hhallika@tuba.calpoly.edu
> (Harold Hallikainen) writes:

   [In response to Hinsdale, IL outage...]

>> It does seem like telephone companies would have trucks with
>> switches and satellite terminals in them.  Just drive the truck up,
>> plug it in and you have a few thousand lines back in service.  All
>> calls that could not be switched locally would go to the satellite.

> AT&T has one or two of these trucks; latest use which got a lot of
> national attention was in Homestead, FL, after Hurricane Andrew.  I
> don't believe they necessarily have satellite terminals -- if you
> have to splice into a few thousand copper pairs to get out to the
> loops, splicing into a few dozen more fibers or coax cables to get
> trunk-side connectivity doesn't take much more time.  They're used
> for traveling roadshows when they're not in use somewhere for emerg-
> ency response.^^^^^^^^^

 (???????)

   Actually, the emergency 5ESS(tm) switch-on-a-trailer is used as a
training lab (attached to a building) when not in use elsewhere.  This
lab has the advantage (over "mothballed" ones) of being in continuous
use, with hardware/software upgrades installed, etc.

   The number of such emergencies vs. the cost of maintaining such a
backup facility would put it out of any TELCo budget.  You can't just
park a switch somewhere (powered down) and expect it to work 15-20
years later when you need it.  For one thing, the hardware would
probably be discontinued (so you have to stock spares too!), no
"fixes" would have been applied and support software (for quickly
building the local line data base, etc.) would probably be hard to
come by.

   For complex systems, the "backup from the vendor" method usually
yields a faster, more stable replacement.  This has certainly been the
method used by the old Bell System, and seems to have worked out
pretty well in the few emergencies that have followed the 1984
break-up.  Other vendors are probably expected to provide similar
methods of emergency support.

   I agree that "satellite" connectivity (today, anyway) is not that
useful for LEC switch emergencies.  The LECs (at least before U.S.West
joined a cable TV corp.) do not use satellites in normal trunking, so
any emergency system would add costs of other dishes and reserved
transponders (and delays in conversations, echo canceller problems,
etc.).  On the other hand, a few trunk-mounted microwave towers with
built-in power, etc. could be useful -- but costly.


Al Varney - just my opinion, of course

From: turner@Dixie.Com
Date: Sun, 6 Jun 93 22:39 EDT
From: rsiatl!turner@rsiatl.UUCP
Subject: Re: Disaster Recovery

Al Varney writes:

> Actually, the emergency 5ESS(tm) switch-on-a-trailer is used as a
> training lab (attached to a building) when not in use elsewhere.  This
> lab has the advantage (over "mothballed" ones) of being in continuous
> use, with hardware/software upgrades installed, etc.

> The number of such emergencies vs. the cost of maintaining such a
> backup facility would put it out of any TELCo budget.  You can't just
> park a switch somewhere (powered down) and expect it to work 15-20
> years later when you need it.  

BellSouth has a DMS on wheels (several semi trailers actually).  When
not in use for training or disaster recovery, it is parked outside an
Atlanta CO where it is in use.  I don't know how (or if) the traffic
is shared between the stationary CO and the portable one. An article
in {Telephony} said the CO could be on the road in something like an
hour.

Does anyone know what is done to restore the database of the old
switch?  Sure you can splice in at the cable entrance facility, but
how do you convert cable pairs to the CO's translations?  Can ESS tape
backups be converted to DMS format?

Trunk side connections would be easier.  Bellsouth has a portable
microwave tower, but I assume its just in case the existing link was
OTS.  SONET would make the trunks even easier to connect.

BTW, the FAA backs up many of it's facilities in the same way.  There
is a portable radar set up in Richmond, FL after the site's 60'
diameter antenna and radar dome crashed into the equipment building
during Andrew.  In our case Inmarsat can be used to restore the telco
circuit, because of the low bandwidth of the radar data (3X2400bps).
This was considered when the AT&T link into Key West (another radar
site) failed.  An Inmarsat rig and HF backup was prepped to send down
there, but AT&T had a replacement microwave tower (I assume) up before
too long.  Other radar sites provided overlapping coverage in the mean
time.

Not the opinions of the FAA ...


Pat Turner  KB4GRZ  FAA Telecommunications  turner@dixie.com