Chapter 1
Introduction to Data Communications
Introduction

The second industrial revolution radically
changes the way we communicate virtually
eliminating information lag.

What problems does this create?
Recent Communications History
1834 Samuel Morse invents the telegraph
 1876 Alexander Graham Bell makes the
first long-distance phone call (10 miles)
 1915 First transatlantic and transcontinental
telephone service.
 1948 Microwave links for telephone calls
 1951 direct long distance dialing

Communications History Cont.
1962 Fax service is introduced
 1965 widespread use of satellite long
distance.
 1968 Non Bell equipment allowed on
phones system
 1969 Picturephones
 1969 DARPAnet

Communications History Cont.
1970 Limited long-distance competition
allowed
 1984 AT&T is broken up creating a
regulatory boundary between local phone
service and long distance
 1984 Cellular phone service starts
 1990’s Cellular phone service explodes

Communications History Cont.
1996 Telecommunications Competition and
Deregulation Act replaced all federal and
state telecommunications law
 1997 68 countries sign agreement to allow
foreign telecommunications competition

Information Systems History
1950’s Batch processing and punch cards
 1970’s Real-time transaction-oriented
database-driven systems emerge
 1990’s Macys is bankrupt in part due to
their “old” 1970’s era IS infrastructure
 Read comparison between Macys and
WalMart

Components of a Network
Server – a device that stores data and often
performs functions in addition to storage
 Client – A terminal or microcomputer from
which a user or other application performs a
work function
 Circuit – a wire, or set of wires and devices
(modem, router, switch etc…) that carry
information from the client to the server

Types of Networks
LAN – Local Area Network
 BN – Backbone Network
 MAN – Metropolitan Network
 WAN – Wide Area Network
 Intranet – A network used within an
organization
 Extranet – Access for people from outside

Network Models
Used to break networks into component
functions (layers) which then allows each
layer to be addressed independently.
 The use of layers and different standards
(and standards bodies) at these layers allows
great flexibility in design, and competition
between manufacturers.

OSI Model
Produced in 1984
 Consists of seven layers

Internet Model
Similar to the OSI model
 Compresses layers 5-7 into a single layer 5
 The textbook author claims the internet
model has won the “war”. Is this true?

Functions at Layer 4 (TCP)
Error detection/correction
 Linking higher layer software to the
network layer
 Name resolution
 Breaking messages into pieces small
enough to send over the network (MTU

Functions at Layer 3 (IP)
Responsible for end-to-end routing of
messages from sender to receiver
 Responsible for attaining the next address
for messages as they hop from router to
router across the internet

Functions at Layer 2
Responsible for moving messages from the
sender to the receiver within a LAN.
 Controls the physical layer
 Formats the messages
 Provides error detection and correction

Functions at Layer 1
Get the signal (electrical signal, light pulse,
smoke signal) from one LAN device to the
next.
 This layer includes hardware devices such
as modems and hubs.

Two Types of Standards

Formal
– Developed by an official industry or
government agency
– These are often slow in developing and follow
an already existing de facto standard

De facto
– Emerge in the marketplace and are supported
by multiple vendors but have to official
standing
Standards Making Bodies

IEEE
– The Institute of Electrical and Electronic
Engineers
– Professional organization based in the United
States
– Primarily responsible for existing LAN
standards
Standards Making Bodies

ITU-T
– Responsible for creating technical standards for
the united nations international
telecommunications union (ITU)
– Open to public or private operators of
communications networks from more then 200
countries
– Based in Geneva Switzerland
Standards Making Bodies

IETF
– Internet Engineering Task Force
– Open to everyone
– Manages consensus-building process through
the use of RFC’s
– Oversees creation of Internet protocols and
standards
Future Trends
Pervasive networking
 Integration of voice, video and data
 New information services

Chapter 2
Application Layer
Application Architectures

Host-Based Architectures
– Commonly a mainframe with terminals

Client-Based Architectures
– Distribute PC based architecture with the
computing power at the desktop

Client-Server Architecture
– Applications software divided between desktop
PC’s and central servers (fat vs. thin clients)
N-tier Architectures

Two-tier
– A client talks to a server (connecting to a web
server)

Three-tier
– A client talks to a web server which in turns
queries a database server to obtain the
requested data

N-tier
– Same concept applied N times
Advantages of Client-Server

Scalability
– N-tiered architecture gives a high degree of
scalability

Cost of infrastructure
– A set of smaller micro or mini computers and
the associated software is often far less
expensive then a mainframe approach
World Wide Web
Create in 1989 at the CERN lab in Geneva
Switzerland by Tim Berners-Lee
 A graphical interface was developed in
1993 by a team of students led by Marc
Andreessen at the NCSA lab at the
University of Illinois
 Adoption of the technology was immediate
and rapid

Electronic Mail
One of the earliest applications on the
Internet (Early “killer” app)
 Cost and speed are among it’s strengths
when compared with “snail mail”
 Important protocols and extensions to
understand

– SMTP (Simple Mail Transfer Protocol)
– IMAP (Internet Message Access Protocol)
– MIME (Multipurpose Internet Mail Extension)
Other Important Applications

Listserv
– A mailing list of users who have joined to
discuss a topic or receive specific information
updates

Usenet
– A repository of articles on many different
subjects
Other Important Applications

FTP – File Transfer Protocol
– Provides the ability to transfer data to and from
systems (primarily used in conjunction with
UNIX servers)

Telnet
– Provides the ability to login to a server from
anywhere within a connected network
– The name is derived from making a TELephone
connection via the NETwork.
Chapter 3
Physical Layer
Components in Physical Layer

Media
– Wires, fiber-optic strands
– Wireless

Special-purpose devices
– Modems
– Repeaters/hubs
Circuits

Physical Circuit
– Twisted pair cable, fiber, wireless link
– Exclusively committed to your data

Logical Circuit
– One of several, perhaps many circuits on a
single physical circuit
– Channel 12 on TV is a logical circuit, it rides on
a coaxial cable or wireless (a physical circuit)
along with many other logical circuits
Types of Data

Digital
– Two possible values for any data bit (1 or 0)
– In a fiber circuit a light being on could
represent a “1” while off represents a “0”
– In a copper circuit 5 volts could represent “1”
while 0 volts represents “0”

Analog
– Signals are shaped like sound waves and are
constantly changing
Modem/Codec

MOdulate/DEModulate
– Translates digital data into a form that can be
transmitted across an analog circuit such as a
standard telephone line

COder/DECoder
– Translates analog information into a form that
can be transmitted across a digital circuit
Circuit Configuration

Point-to-Point
– A circuit with a device at each end
– Home modem

Multipoint
– A single device at one end with many devices at
the other end with either time-slicing or circuit
switching
Data Flow

Simplex
– One way transmission (i.e. cable TV)

Half-duplex
– Communication in both directions, only one
way at a time (i.e. walkie-talkie)

Full-duplex
– Communication in both ways, at the same time
(i.e. telephone)
Communication Media

Guided media
– Twisted-pair, coaxial, fiber-optic

Wireless media
– Radio, infrared, satellite
Fiber Optic

Multi mode
– Attenuation (weakening of the signal)
– Dispersion (spreading of the signal)

Single mode
– Must use the precision of lasers as opposed to
LED’s
Coding

Character
– A symbol with a constant understood meaning

Byte
– A group of (typically) eight bits that is treated
as a character

ASCII (American Standard Code for
Information Interchange)
– 7 or 8 bit code (typically 8)
Transmission Modes

Parallel
– All bits are sent simultaneously, in a 32-bit
system then there must be paths to send all 32
bits at the same time

Serial
– Each bit is sent one at a time,
Digital Transmission

Transmission of 1’s and 0’s
– With electricity this can be voltages with
perhaps 0 volts representing a zero and 5 volts
representing a 1 (unipolar)
– With light this can be using the state of the light
with perhaps off representing a 0 and on
representing a 1
Manchester Encoding
Used in Ethernet
 Unipolar coding scheme with a twist

– Voltage moving from a lower level to a higher
level represents a “1”
– Voltage moving from high to low is a “0”
Analog Transmission
Telephone systems were originally designed
to carry analog transmissions, electrical
representations of the human voice
 Three key characteristics

– Amplitude
– Frequency
– Phase
Modulation
A carrier wave (ugly noise heard when
modems are negotiating) is sent between
modems, the shape of the wave is altered to
represent 1’s and 0’s
 These “shape changes” are referred to as
modulation

Modulation Techniques

Amplitude
– Modifying the height of the wave

Frequency
– Modifying the frequency (the number of waves
per second) of the wave

Phase
– Modifying the point in phase at which the wave
starts
Amplitude Modulation
Frequency Modulation
Phase Modulation
Two-bit Amplitude Modulation
Modulation Techniques
The various modulation techniques
discussed can be combined as well
 QAM (Quadrature Amplitude Modulation)

– Combines eight phases (three bits) and two
amplitudes (one bit) for a total of four bits

TCM (Trellis Code Modulation)
– Similar to QAM but can transmit up to ten bits
per symbol
Bits Baud and Symbol
Bits (specifically bits per second) are
generally the important measurement in
data communications as symbols are
composed of bits
 There is a common misconception that
these terms are interchangeable, baud refers
to the number of symbols per second as
opposed to the number of bits per second

Voice Circuit Capacity
Home analog phone lines have a bandwidth
range from 0 to 4000 Hz
 The human ear can detect sounds up to
~14,000 Hz so very high pitch sounds can’t
be transmitted over an analog phone line
 Digital circuits used to tie analog phone
lines together have a bandwidth of 64,000
bits per second (bps)

Modem Technologies

V.34+
– Transmits up to 33,600 bps

V.44 (Compression)
– Builds a dictionary of character combinations
being sent over the circuit
– When a combination is repeated the dictionary
reference is sent as opposed to the characters
– Average throughput is ~ 6:1
Codec
Converts Analog data into a digital form for
transmission over a digital system and back
 The analog signal is translated into a binary
number
 This digital signal is an approximation of
the original with the quality depending on
the resolution by either increasing the
amplitude levels or increasing the sampling
rate

Telephone Transmission
The “local loop” is the circuit from the
phone company CO (the building between
3rd and 4th streets and Chestnut and Hazel
streets) uses analog transmission
 Once the signal reaches the phone company
office it is converted to digital form and is
then sent to it’s destination CO
 Even local calls are converted to digital

Pulse Code Modulation
PCM is used in phone company CODEC’s
in North America
 PCM samples the data 8,000 times (twice
the highest frequency within the phone
system
 Eight bits are generated for each sample,
thus the phone system uses the 8 bits *
8,000 samples for a data rate of 64,000 bps

ADPCM




Adaptive Differential Pulse Code Modulation
Similar to PCM except it only sends the difference
between the former and the new signal
Data rates as low as 8Kbps can be obtained,
32Kbps is the lowest providing sufficient quality
so that the user doesn’t notice
The use of ADPCM is the reason that some users
can’t get a modem connection above 26,200 bps
Analog/Digital Modems
Uses PCM backward
 Sends 8,000 samples per second
 Uses 7 bits (one is lost for control purposes
 7 bits * 8,000 samples = 56,000 bits
 V.92 modems do this in each direction and
due to technical constraints are limited to
~52,000 bps downstream and ~42,000 bps
upstream

Multiplexing
Using one high-speed circuit to carry the
traffic of multiple lower-speed circuits
 FDM
 TDM
 WDM (form of FDM)
 DWM (combination of FDM and TDM)

– Has reached 1.25 terabits already and is
expected to reach 1 petabit within a few years
Frequency Division Multiplexing
Time Division Multiplexing
Inverse Multiplexing
Using a series of lower-speed circuits to
connect two high-speed circuits together
 Technology has been proprietary until just
recently
 The BONDING (Bandwidth ON Demand
Interoperability Networking Group)
standard is allowing vendors to interoperate
today but this is still in its infancy

Inverse Multiplexing
Digital Subscriber Line
Much of the available bandwidth in the
local loop has gone unused for many years
 DSL uses this bandwidth by applying FDM
to create three circuits comprised of the
original phone line, a upstream data circuit
and a downstream data circuit
 TDM and PM are also used to obtain
various data rates and features

Chapter 4
Data Link Layer
Media Access Control
A mechanism used to control when
computers transmit
 Important when using half-duplex circuits
or multipoint configurations
 Two fundamental approaches

– Controlled Access
– Contention
Controlled Access
X-ON/X-OFF
 Polling

– Roll Call Polling: one device in the circuit is a
“master” and checks with each other device on
its wire to see if they have something to say
– Hub Polling (token passing): one computer
starts the poll and passes it to the next, when a
computer with something to say receives the
“token” then it can send its data
Contention
The opposite of controlled access, each
device listens to see if someone else is
talking, if not then it sends carrier and starts
to talk
 CSMA/CD (Carrier Sense Multiple Access
with Collision Detection) is used in
Ethernet networks

Network Errors

Two types of network errors
– Data loss
– Data corruption

Three approaches to dealing with errors
– Prevention
– Detection
– Correction
Sources of Errors
Line noise, distortion
 Line outages
 Impulse noise
 Cross-talk
 Attenuation
 Intermodulation noise
 Jitter

Error Prevention
Shielded cabling
 Cable location
 Cable selection (fiber vs. twisted pair)
 Cable installation and maintenance

Error Detection
Parity
 Longitudinal redundancy checking
 Polynomial checking

– Checksum
– Cyclic Redundancy Check
» 16-bit CRC used in TCP
» 32-bit CRC used in Ethernet
Error Correction via Retrans.
Stop-and-wait ARQ
 Continuous ARQ

Forward Error Correction
Sufficient redundant data is included within
the transmission to correct errors without
retransmission
 Used heavily in satellite transmission

Ethernet Protocols

Ethernet (IEEE 802.3)
– Byte-count protocol
– Destination, length, LLC, SNAP, CRC-32

Point-to-Point Protocol (PPP)
– Address
– Protocol
– Message length = 1,500 bytes
Bridging/Switching
MAC-layer address table for each interface
 Addresses behind a port are stored in
memory
 Ethernet frames are checked at each
interface to determine if they should be
forwarded

Transmission Efficiency
Transmission efficiency = total information
bits/total bits
 Throughput = transmission efficiency
adjusted for errors and retransmissions
 TRIB

Chapter 5
Network and Transport Layers
TCP/IP

TCP
– Layer 4
– Provides error detection (CRC-16)
– Breaks data into appropriate size blocks (MTU)

IP
– Provides routing and addressing
– IPv4 (32-bit address)
– IPv6 (128-bit address)
TCP Ports
A computer can have multiple applications
running, i.e. a machine can be running both
a web server and an email server
 Commonly used ports

–
–
–
–
SMTP – port 26
WWW – port 80
FTP – port 21
Telnet – port 23
Packetizing
Taking an outgoing message with a length
too great to fit within the data-link
maximum frame length (MTU) and
breaking the message into appropriate
lengths
 Function is performed by the transport layer
 With IPv4 the packet size is set for the local
LAN and is adjusted if the message is sent
across a link that requires a smaller MTU

Connection-oriented Routing
A specific route “virtual route” is
determined when the session is created
 A SYN packet is sent to create the virtual
circuit
 A FIN packet is sent to tear the circuit down

Connectionless Routing
Uses UDP instead of TCP
 Packets can travel different routes
 Commonly used with applications such as
DNS and DHCP which are not likely to
send a packet that will have to be broken
into pieces

Quality of Service
A special type of connection-oriented
routing
 Classes of service are established and each
application is assigned one of the classes
 Applications such as VoIP and videoconferencing may be in a higher priority
class then SMTP or WWW

Internet Addresses
Assigned by ICANN (Internet Corporation
for Assigned Numbers and Names)
 Blocks of network addresses are assigned to
organizations
 Often a large block of addresses are
assigned to an organization
 These large blocks of addresses are broken
into smaller blocks referred to as “subnets”

Subnets
There are many possible combinations
when dividing a network address block into
subnets
 It is also possible to merge two adjacent
networks together into a single “supernet”
 Whether dividing a network into subnets or
combining two or more networks into a
supernet the subnet mask is the key

Subnet Mask
A subnet mask is a string of 1’s and 0’s
 A subnet mask of 255.255.255.0 indicates
the first three bytes of the IP address are
part of the network
 Another way of looking at this subnet mask
would be
11111111.11111111.11111111.00000000
 A 1 indicates the corresponding bit in the IP
address is part of the network designation

Dynamic Addressing
DHCP (Dynamic Host Configuration
Protocol)
 When the computer is started it sends a
message requesting that a DHCP server
provide an IP address and other
configuration allowing the computer to
communicate via IP

Layer 2 Address Resolution
ARP (Address Resolution Protocol)
 Broadcast Message (all 1’s)
 Whoever has IP address xxx.xxx.xxx.xxx
send me your Ethernet address

Domain Name Service
An Internet phone book
 When typing in www.csuchico.edu DNS
will translate this application-layer address
to the network-layer address of
132.241.82.24

Routing
Packets are routed between networks based
on a set of routing tables
 The routing tables can be manually
programmed (static routing) or created by a
routing protocol (dynamic routing)
 Routing Protocols

– Distance Vector (RIP)
– Link State (OSPF)
Routing Protocols

Interior routing protocols
– RIP, OSPF, EIGRP

Exterior routing protocols
– OSPF, BGP

Autonomous System
Multicasting

Three types of messages
– Unicast
– Broadcast
– Multicast

IGMP (Internet Group Management
Protocol)
– Each participating computer uses a common
data-link layer address
TCP/IP Example

Work through the entire TCP/IP example at
the end of chapter 5
–
–
–
–
Known addresses, same subnet
Known addresses, different subnet
Unknown addresses
TCP connections
Chapter 6
Local Area Networks
Why Use a LAN?

Information Sharing
– Email
– File access
– Video conferencing

Resource Sharing
– Printers
– Applications servers
Dedicated Server vs. Peer-to-Peer

Dedicated Server
– One or more server computers permanently
assigned to being a network server
» File servers
» Print servers

Peer-to-Peer
– No dedicated server
LAN Components
NIC (Network Interface Card)
 Network cables

– Twisted pair
» UTP/STP
» See Category Ratings in Technology Focus
– Coaxial cables
» BALUNs
– Fiber-optic cables
» Single-mode vs. multi-mode
LAN Components Cont.
Network hubs
 Network bridges/switches
 Network routers
 Network Operating System

– Server/client software
Network profile
 Storage Area Networks (SAN)
 Network Attached Storage (NAS)

Ethernet (IEEE 802.3)

Topology
– Logical vs. physical
The logical topology of a traditional
Ethernet network is a bus
 The physical topology is often a star

Media Access Control
With a bus topology there must be a
mechanism to either prevent, or detect and
deal with, collisions on the media
 CSMA/CD
 Full-duplex Ethernet

Types of Ethernet
10Base-5
 10Base-2
 10Base-T
 100Base-T
 10/100 Ethernet
 1000Base-T

Switched Ethernet
The switch replaces the hub in the network
 The hub repeats every bit of data out every
port
 The switch sends the data out the port
which is connected to the message recipient
 The switch uses a forwarding table that
contains the Ethernet addresses of the
computers connected to each port

Wireless Ethernet
IEEE 802.11
 The WEP standard has been completely
cracked
 Uses CSMA/CA for media control
 Subject to the “hidden node” problem
 Has VCSM (Virtual Carrier Sense Method)
as an option to work around the hidden
node problem

Types of Wireless Ethernet

IEEE 802.11b
– DSSS – Allows speeds from 1 – 11 Mbps
depending on distance and interference
– FHSS – Allows speeds from 1 – 2 Mbps

IEEE 802.11a
– The standard is still incomplete
– Data rate is likely to be 54 Mbps on first
iteration
– Actual throughput will likely be ~20Mbps
Other Wireless Technologies

Infrared wireless
– Requires line of site or white ceilings and walls
with diffused infrared

Bluetooth
– Slated to become standardized as IEEE 803.15
– Short range networks referred to as piconets
with no more then 8 devices
– Uses controlled access media access control
– Less then 1Mbps throughput
Reducing Network Demand
Placing heavily-used applications or data
modules on each client computer
 Network segmentation – note this is really
increasing supply rather then reducing
demand

Chapter 7
Backbone Networks
Backbone Network Components

Bridges
– Operating at the data-link layer (MAC address)

Routers
– Operating at the network layer (IP address)

Gateways
– Operating at the transport layer (note that this
disagrees with the authors table 7-1)
Backbone Network Components

Collapsed backbone
– Chassis-based
– Rack-based

VLAN’s
–
–
–
–
Port-based
MAC-based
IP-based
Application-based
ATM

Four key differences between Ethernet and
ATM in the backbone
– 53-byte fixed-length cells
– No error correction
– Virtual Channel addressing as opposed to fixed
addresses with the path and circuit numbers
– Built in Class-of-Service (CoS) and Quality-ofService (QoS)
ATM

Classes of Service
–
–
–
–
–
CBR
VBR-RT
VBR-NRT
ABR
UBR
LANE vs. MPOA
 SVC vs. PVC

Chapter 8
MAN’s and WAN’s
MAN’s
Generally constrained to a city or small
region between 3 and 30 miles
 Generally deployed via either wireless
technology or services leased from a carrier
 Moderate levels of regulation

WAN’s
Connecting over potentially great distances
 Generally deployed via circuits leased from
Common Carriers
 Very heavily regulated within North
America and usually even worse oversees

Circuit Switched Networks
Usually depicted by a cloud with your
organizations data traveling with many
others across the same physical circuits
 POTS
 ISDN

– BRI
– PRI
– Broadband
Dedicated Circuit Networks
Dedicated circuits or dedicated bandwidth
within carrier circuits
 Ring Architecture
 Star Architecture
 Mesh Architecture

T Carrier Services
Based on the 64Kbps channel required for a
digitized voice connection
 T1 – 24 channels * 64Kbps = 1.536 Mbps

– Control information is included bringing the
total circuit bandwidth for a stand-alone T1 to
1.544 Mbps

T3 – 28 T1’s – 28 * 1.544Mbps =
43.008Mbps
– With control information = 44,736Mbps
SONET
SONET is a North American standard but
the ITU recently adopted the SDH standard
set which is nearly identical
 OC-1 = 51.84Mbps
 OC-3 = 3*OC-1 = 155.52 Mbps
 OC-12 = 12*OC-1 = 622.08 Mbps

Packet Switched Networks
X.25 – older standard now seldom used in
North America
 ATM
 Frame Relay
 Ethernet/IP Networks

Virtual Private Networks

Intranet
– Used to connect your organizations office via
the Internet

Extranet
– In addition to your organizations office you
may also include other organizations with
which you do business

Access
– Remote access for employees
Chapter 9
The Internet
Internet Structure
Internet architecture
 NAP’s, MAE’s, and ISP’s

– POP’s
Peering
 Autonomous systems

Internet Access Technologies

DSL
– Digital Subscriber Line
– Uses the local-loop
– A modem is placed in the home converting the
data from the DSL format to Ethernet

ADSL
– G.Lite

VDSL
Internet Access Technologies

Cable Modems
– DOCSIS
Shared media means users compete with
each other for bandwidth and unscrupulous
neighbors could intercept your data
 Throughput suffers due to hardware
compatibility issues that stem from cable
TV infrastructure differences

Wireless

Fixed wireless
– Wireless DSL
– Satellite

Mobile Wireless
– WAP
– WAE
Internet Governance

ISOC (Internet SOCiety)
– www.isoc.org
IETF (Internet Engineering Task Force)
 IESG (Internet Engineering Steering Group)

– Each IETF working group is chaired by a
member of the IESG
IAB
 IRTF

Internet Domain Name Reg.
Internet name and address registration was
handled by John Postel until his death in
1998
 In 1998 ICANN (Internet Corporation for
Assigned Names and Numbers) was formed
 In 1999 ICANN established the SRS and
has now authorized more then 80
companies to issue Internet names and
numbers

Internet 2

Next Generation Internet
– vBNS
Abilene
 CA*net 3

Chapter 10
Network Security
Why Networks Need Security
The average cost to companies for a single
security breach is slightly less then $1M
 This is a minor cost when compared to the
loss of customer confidence
 The text indicates that 24 hours of
downtime would cost Bank of America
$50M

Types of Security Threats

Disruptions
– Minor cable breaks to earthquakes

Unauthorized Access
– More often the work of an employee then an
outside hacker
Network Controls
Controls are processes or steps to reduce or
eliminate threats
 Three types of controls

– Controls that prevent threats
– Controls that detect threats
– Controls that correct threats
LAN Security
Although sometimes overlooked a good
first step is to ensure that the LAN hardware
is physically secure
 Firewalls

– Packet-level
– Application-level

NAT (Network Address Translation)
LAN Security

Encryption
– Symmetric
» DES
» Triple DES
» AES
– Asymmetric (PKI)
» PGP (Pretty Good Privacy)
» SSL (Secure Sockets Layer)
» IPSec (IP Security)
Detecting Unauthorized Access

IDS (Intrusion Detection Systems)
– Network-based
– Host-based
– Application-based

Two IDS Techniques
– Misuse detection
– Anomaly detection
Chapter 11
Network Design
Network Design Process
Traditional design process
 Building Block Design Process

– Needs analysis
– Technology design
– Cost assessment

Why network projects fail
– Management focus 11-2
Request For Proposal
Background information
 Network requirements
 Service requirements
 Bidding process
 Information required from vendor

Chapter 12
Network Management
Network Management
Tasks performed by the network manager
 Five key management tasks
 Key network management skills
 Configuration management

Performance & Failure Statistics
Availability
 MTBF
 MTTRepair
 Policy-Based Management
 Service-Level Agreements

Cost Management
Sources of cost
 TCO (Total Cost of Ownership)

– $8,000 - $12,000 per device per year?
– $1,500 - $3,500 per device per year? (NCO)

Five steps to reduce network costs
Network Management Tools

Three types of network management
software
– Device management
– System management
– Application management

SNMP
– MIB
– RMON