Information Technology Reference
In-Depth Information
7.5
Communications (Voice and Data): An example
Communications includes person to person, person to groups (e.g., presentation),
group (e.g., meetings), person to technology (e.g., desktop PC), and technology
to technology (e.g., client/server). The communications infrastructure includes
voice and data in traditional and emerging configurations. Voice communications
include public switched telephone network (PSTN) and private branch exchanges
(PBXs); data communications include networking.
Communications is the core of operations. Without communications, there
are no operations, or at most, there are
flying-blind
operations, based on the last
communication. Continuity of operation plans (COOP), business continuity, and
disaster recovery planning for communications are essential in today's information-
critical environment, and even more critical when considering the time sensitivity
of information is measured more in terms of (micro-)seconds than hours or days.
7.5.1
Traditional Communications
Traditional communications consist of disparate infrastructure and functionality
separating voice and data. Voice communications essentially separates into private
and public; only rarely do private voice communications not interface with the
public voice infrastructure. The public switched telephone network (PSTN) pro-
vides central office service for local residential or commercial connectivity. Central
offices connect regionally, often under one operating entity, the regional Bell oper-
ating companies (RBOCs). RBOCs in turn interconnect via interexchange carriers
(IXCs). RBOCs typically provide local service and IXCs provide long-distance ser-
vice; this distinction is recently blurring with RBOCs' ability to offer long distance
and vice versa for the IXCs.
Private branch exchanges (PBXs) offer organizations the ability to set up private
voice services where station-to-station calls occur exclusively within the PBX and
do not involve the PSTN for phone calls. PBXs may support voice service within a
building, campus, metropolitan, regional, national, or global scope. Long physical
PBX connections (e.g., Washington, D.C., to San Francisco) are typically via leased
line (e.g., T1) and may be via wired or wireless (e.g., satellite) medium.
These options provide a complex array of choices for voice-related emergency
preparedness with respect to PSTN connectivity and intra-PBX connectivity. Fur-
ther emergency preparedness concerns include redundant processor choices, redun-
dant intercabinet connections, redundant inbound/outbound voice services and
paths, and much more.
7.5.2
Emerging Communications
Emerging communications are converging communications. More robust data
communications are available over voice infrastructure (e.g., Digital Subscriber
