 To understand the meaning of data communications
 To study the basic components of data communications as an industry
 To understand standards and regulations
 To have a general idea of the data communications industry challenges and solutions.
GOAL: introduce you to the industry of data communications.

 Subset of Telecommunications.
 It is the encoded transmission of data via electrical, optical or wireless means between computer or network processors.

 Forces that derive the data communication as an industry:



The Regulatory Process
The Standards Process
Manufacturing, Research and Technology

 Interacting components in data communication industry:

Judicial
Political / Legis lative
Internet Service
Providers
Standards m aking organizations
Technology /
Res earch
Regulatory
Agencies
Data com m unications
Vendors /
Cons ultants
Carriers
Manufacturers
Bus ines s cus tom ers
Res idential cus tom ers
FIG. 01-01

Rulings
Carriers
GOLDMAN & RAWLES: ADC3e
FIG. 01-02
Propos als
Regulatory agencies
Figure 1-2 Systems Relationship of Regulatory Agencies and Carriers

 We must understand first the basic telecommunications infrastructure and the components of PSTN

C.O.
Belongs to LEC
(Local-Exchange Carrier)
Phone
Phone
Local loop
Inter-exchange
LATA - B circuit
Local loop
LATA - A
P.O.P.
P.O.P.
Belongs to IXC
(Inter-eXchange Carrier)
GOLDMAN & RAW LES: ADC3e
FIG. 01-03
C.O.
Figure 1-3 Basic Telecommunications Infrastructure

Area Code Map
Michigan City
South Bend
Gary
(219)
Fort Wayne
West Lafayette
Russiaville
Attica
(765)
Indianapolis
Richmond
(317)
Terre Haute
(812)
Rising Sun
Columbus
New Albany
Evansville
GOLDMAN & RAWLES: ADC3e
FIG. 01-04
Figure 1-4 Area Codes vs. LATAs
LATA Map
Gary
Fort Wayne
West Lafayette
Russiaville
Attica
Indianapolis
Richmond
Terre Haute
Rising Sun
Columbus
New Albany
Evansville

 A Standard is an agreed upon protocol
 Thanks to standards users can be confident that devices will operate as specified and will interoperate successfully


1.
2.
3.
4.
7 Steps to make standards:
Recognize the need for a standard
Formation of a committee
Information gathering
Tentative standards issued
5.
6.
7.
Feedback on tentative standards is gathered
Final standards issued
Compliance with final standards

 Standard making organizations are two categories
 Officially-sanctioned
 Ad-Hoc (task force, user group, interest group…etc.)

 Usually vendor-initiated ad-hoc standard making organizations are organized into opposing camps with users left as victims between multiple standards for a single operation.
 Most often the development of a new technology precedes its standardization.
Standardization process can be very political

Introduction of first generation technology
Standards making lag time
{
Standards finalized
St and ards deve lop m ent
Ready for market introduction
Fir st ge ne rat ion tec hno log y de velo pme nt
Se co nd ge ne rat ion tec hno logy deve lopme nt
Time
Introduction of second generation technology
GOLDMAN & RAW LES: ADC3e
FIG. 01-08
Figure 1-8 Technology Development and Standards Creation


1.
2.
Two issues can lead to confusion and might cause bad purchase decisions:
Standards Extension
The Jargon Jungle.
“There is no data communications police”

 Supply and demand as driving forces of data communications.
 Technology push / Demand pull

 Technology should tie business demand for network services to carriers supply of these services:
Business demand + available technology = emerging network services

 In the business of data communications there are lots of challenges.
 Network analyst must identify key challenges to succeed in data communication field
 We will address two challenges:
 Investment Vs. Productivity (Productivity Paradox)
 Data Compatibility

 Something is wrong with an analysis and design process which recommends technology implementation that fails to meet the strategic business objective of increased productivity.
 We need a structured methodology to insure that the network implemented actually meets the business objectives
 For this we introduce: The Top-Down
Approach

BUSINESS
APPLICATION
DATA
NETWORK
TECHNOLOGY
GOLDMAN & RAWLES: ADC3e
FIG. 01-10
Figure 1-10 The Top-Down Model

 How can we measure the impact of the implemented network on the business process, in other words, how can we be sure that eventually the implemented network really meets the business requirements.
 We use Benchmarking: tying network cost to business value

 Examine and document quantifiable improvements to business process
 Measure customer satisfaction, maybe by surveys
 Compare actual implementation cost with the cost of purchasing similar services from outside vendor (outsourcing), or examine other companies in the same market to compare cost.

 Compatibility: Bridging the communications gap between two or more technology components (HW or SW)
 This gap is referred to as Interface, it can be
HW-to-HW or SW-to-SW or HW-to-SW.

Figure 1-12 Interfaces,
Protocols, and
Compatibility
Hardware to Hardware Interface
Serial cable
Serial port
DB-25
Physical interface: Serial cable to serial port
Mutually supported protocol: DB-25
The serial cable is compatible with the serial port.
Software to Software Interface
EXCEL.XLS
WORD.DOC
600
500
400
300
200
100
OLE
Six Year Profits
600
500
400
300
200
100
'91 '92 '93 '94 years
'95 '96
This graph depicts the
Company's growth over the past 6 years.
We have experienced massive gains in every corporate category.
'91 '92 '93 '94 '95 '96 years
Software interface: EXCEL to WORD
Mutually supported protocol: OLE2 (Object Linking and Embedding)
Incorporate a Microsoft Excel graphic within a Microsoft Word document.
Software to Hardware Interface
Implementing mutually supported protocols allows interfacing hardware and/or software technology to communicate, thereby insuring compatibility.
NOS Driver
Software - Windows using NDIS communication
NDIS
NDIS
Ethernet 10 Base-T
Network Interface
Card (NIC)
Interface: Network Operating System (NOS) driver to Network Interface
Card (NIC)
Mutually supported protocol: Network Driver Interface Specification (NDIS)
GOLDMAN & RAWLES: ADC3e
FIG. 01-12

 Compatibility is possible because we have
Protocols
 A Protocol is a set of rules about how communicating components can talk to each other.

 Protocols can be proprietary or open
 They can also be officially sanctioned or market driven (de facto)
 The sum of all protocols employed in a particular computer is referred to as “protocol stack”

 The problem with protocols is that they are too many.
 How can a network analyst keep track of all the potential interfaces and their associated protocols.


So, protocols must be organized in some kind of framework or most likely known as “communications architecture”
Two of the most popular communications architecture are: the 7-layer OSI model and the 4layer Internet Suite of Protocols (or TCP/IP) model

 Open Systems Interconnection
 It is neither a protocol nor a group of protocols.
 It is a standardized empty framework into which protocols can be listed to perform effective network analysis and design
 Each layer depends on previous layer to perform some function (transparency)
 Protocol Conversion

 Consists of 7 layers that loosely group the functional requirements for communication between two computing devices.
 Each layer relies on lower layers to perform more elementary functions and to offer total transparency to the intricacies of those functions.
At the same time, each layer provides the same transparent service to upper layers.

1.
2.
Physical Layer: responsible for the establishment, maintenance, & termination of physical connection between communicating devices “ Point-to-Point data link ”.
Data-Link Layer: responsible for the providing protocols that deliver reliability to upper layers for Pointto-Point connections established by physical layer protocols. To allow the OSI model to closely adhere to the protocol structure, & operation of a LAN, Data-Link layer was splitted into two sublayers.

 Media Access Control (MAC): interfaces with the physical layer & is represented by protocols that define how the shared LAN media is to be accessed by the many connected computers.
 Logical Link Control (LLC): interfaces to the network layer.
 The advantage of splitting the Data-Link layer & of having a single common LLC protocol is that it offers transparency to the upper layers while allowing the MAC sublayers protocols to vary independently.

3.
4.
Network Layer: responsible for the establishment, maintenance, & termination of end-to-end network links.
Network layer protocols are required when computers that aren’t physically connected to the same LAN must communicate.
Transport Layer: responsible for providing reliability for the end-to-end network layer connections. It provide end-to-end recovery & flow control. It also, provide mechanisms for sequentially organizing network layer packets into a coherent message .

5.
6.
7.
Session Layer: responsible for establishing, maintaining, & terminating sessions between user application programs.
Presentation Layer: provide an interface between user applications & various presentation-related services required by those applications. An example is data encryption/decryption protocols.
Application Layer: it includes utilities that support enduser application programs but it does not include enduser application programs.

LAYER USER APPLICATION
7 APPLICATION Provides common services to user applications.
X.400 E-MAIL interoperability specification
X.500 E-MAIL directory synchronization specification
Strictly speaking, does not include user applications
6 PRESENTATION Provides presentation services for network communications.
Encryption
Code translation (ASCII to
EBCDIC)
Text compression
Not to be confused with
Graphical User Interfaces(GUIs)
5 SESSION Establishes, maintains, terminates node-to-node interactive sessions.
DATA
FORMAT
ENABLING
TECHNOLOGY
4 TRANSPORT
3
2
1
NETWORK
DATA LINK
PHYSICAL
Assures reliability of end-to-end network connections.
Establishes, maintains, and terminates end-to-end network connections.
sessions
Interactive, realtime dialogue between 2 user nodes
Distributed applications, middleware, or network operating systems.
messages
Asembles packets into messages.
Network
Operating
Systems packets
Embedded within frames.
Network
Operating
Systems.
HARDWARE/SOFTWARE INTERFACE
Logical Link control sub-layer.
Specified by
802.X protocols.
Media access control sub-layer.
Assures reliability of point-topoint data links.
Establishes, maintains, and terminates point-to-point data links.
NIC DRIVERS frames
Recognizable as data.
Network
Interface
Cards.
bits
Unrecognizable as data
Media
GOLDMAN & RAWLES: ADC3e
FIG. 05-01

 Known as TCP/IP protocol suite or TCP/IP architecture
 TCP/IP: Transmission Control Protocol /
Internet Protocol
 Like the OSI model but it has 4 layers

Layer
7
6
5
4
3
OSI
Application
INTERNET
Pres entation
Application
Ses s ion
Trans port
Network
Data Format
Mes s ages or
Stream s
Trans port or
Hos t-Hos t
Internet
Trans port
Protocol
Packets
IP Diagram s
Protocols
TELNET
FTP
TFTP
SMTP
SNMP
CMOT
MIB
TCP
UDP
IP
2 Data Link Network
Acces s
Fram es
1 Phys ical
GOLD MAN & R AW LES: AD C 3e
F IG. 01-14
Figure 1-14 Internet Suite of Protocols vs. OSI

 Input – Processing – Output
 Ex. Connecting the computer (serial port) to the printer (parallel port)
 Identify and document the process you want to make on the input and what kind of output it should provide.

 What critical skills are required for data communications professionals. To know the skills you must know the environment in which they will work, which is a knowledgebased economy.
 Data Communications professionals are thought of today more as partners or change agents rather than consultants.

1.
2.
4.
5.
6.
3.
7.
Speak the language of Business
Demonstrate the ability to solve business problems in a partnership role
Demonstrate the ability to look outside their own expertise for solutions
Understand the need for lifelong learning
Demonstrate the ability to evaluate technology as to cost/benefit
Understand comparative value and proper applications of available network services
Communicate effectively, both verbally and orally, with both technology oriented people and business management personnel

Bus ines s knowledge
Comm unication and understanding
Interpers onal s kills
Comm unication and understanding
Data com m unications profes s ionals
Comm unication and understanding
Technological s kills
GOLDMAN & RAW LES: ADC3e
FIG. 01-16
Figure 1-16 Critical Skills for Data Communications Professionals

 Why seek certification?

It is an indication of mastery of a particular vendor’s technology, that may be important in some employment situations
 The problem with certification:



The amount of material required to earn a certificate
The amount of continuing education and experience required to retain this certificate
Vendor-specific certifications do not provide the broad background required for today’s multivendor internetworks