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Today’s transmission methods and equipment are robust and reliable and feature integrated network

only of the wires that carried our conversations. Switching instructions created by dialing
were sent on the same lines that carry voice conversations, as was information for long
distance billing. Thus, all signaling was in-band. In the late 1970s, a new system was
created to provide out-of-band signaling. Basically, a separate data network was created
between switching offices to work in conjunction with the voice networks. Phone com-
pany computers could use the signaling system to check and make sure a call could be
completed before actually switching the call all the way to the local loop only to find a
busy line. Later enhancements of the system allowed for information to be sent to specific
locations in the telephone network, and allowed for a way to send information from the
data line over the local loop in a short in-band burst of information.
How SS7 Works
There are three elements of the SS7 network:
• Service Switching Point (SSP) - A central office switch
• Signal Transfer Point (STP) - Packet switched data network
• Service Control Point (SCP) - A shared data base
Service Switching Points (SSP) are
central office switches that originate or
terminate telephone calls. Signaling
messages are sent between SSPs to set
up, manage, and release voice circuits
required to complete a call. An SSP may
also send a query message to a
centralized database to determine how
to route a call, for example the routing
of a toll-free 1-800/888 call in North America.
A Service Control Point (SCP) sends a response to the originating SSP which contains the routing
number(s) associated with the dialed number. An alternate routing number may be used by the SSP if
the primary number is busy or the call is unanswered within a specified time.
Network traffic between signaling points is routed via a packet switch called a Signal Transfer Point
(STP). An STP routes each incoming message to an outgoing signaling link based on the routing

services as well as improve the interconnection and inter-working of separate networks.
In addition to the inside network support applications such as SS7, the public networks
are also increasingly involved in providing narrowband data transport services such as
ATM and ISDN. While these services are usually “bundled up” into more traditional
wideband transport paths, at the individual customer interface point, they commonly
exist as narrowband (generally sub-56kbps rate) RS232, V.35, or ANSI/EIA-530 signal
interfaces on CSU’s, ATM switches, and other similar devices.
Clearly a means of gaining rapid and organized physical access to these circuits is
needed. They are simply too important to ignore.
Because of their physical complexity, these circuits cannot be gracefully integrated into
traditional access hardware such as jackfields or DSX systems. Fortunately, however,
a concept called “network tech control” has long existed in large private data centers in
the military and in data-transport-intensive industries such finance, transportation
reservations and similar applications. The products that have long provided organized
physical accesses to those networks are ready-made to fill the growing need in SS7,
ATM, and other public network applications.
In addition to referring to a family of physical products, the term network tech control
also refers to a network management concept. This concept is essentially identical to
the concept of a DSX installation, with a few enhancements based on the circuit-health
information inherently available on most data interfaces.
Network Tech
Control:
An old solution solves
new problems
4
10/97
440
Network Tech Control White Paper
In its simplest implementation, network tech
control is absolutely functionally identical to the

directly to the cable. Frequently these connector locations are almost impossible to
reach because they are hidden deep in the back of equipment cabinets and obscured
by dozens of overlying cables. Mistakes are common, and adjacent circuits are also
often inadvertently disturbed in these congested areas.
Figure 2
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Figure 3 shows a basic panel used for V.35 patching. These panels fit in 19-
inch wide racks and are 5.25 inches high. Other versions are available for
RS232, ANSI/EIA-530, and X.21 interface standards.
Besides the “plain” patch panels described so far, ADC also has designed a
series of patching equipment with extended features such as circuit activity
indicators (LEDs) and a variety of alarming functions.
Patching with these additional features is commonly installed on particularly
high-value circuits, such as the data lines at SS7 signal transfer points (STPs)
where a failure of a link could be especially disruptive. The alarm function
could be programmed for an anticipated alarm circumstance, such as lack of
data flow, and would alert personnel in the vicinity of the circuit problem.
The activity indicators give an “at a glance” status of circuit behavior without
the attachment of test equipment. A V.35 panel with these features is shown
in Figure 4. Power supplies are available for AC and 48VDC environments.
Patch panels that are augmented with remote control “AB” switching are also
available. These panels are can be used in situations (dark sites or offices not
staffed 7x24) where circuit reconfiguration must be accomplished by
craftpersons at another location. These panels include the usual patching for
use by on-site personnel, plus local control of the switch settings. Such a
panel for RS232 circuits is shown in Figure 5. Some of these panels can also
be configured as “automatic fallback” switches, switching to alternate equip-
ment or routing based on pre-determined alarm conditions on the primary
path.
For a more complete description of this network tech control equipment,
including various application examples, obtain the ADC “Network Control
Products” catalog , 6
th
edition, literature number 517. This information can
be ordered by calling (612) 946-3434, or 1-800-366-3891, or on the internet
at: />Figure 3