Network training present

@2006 - 2007 All rights Created by Mr. Sopon Tumchota Contact at.. sopont@gmail..com
Inter-Network
Training
Welcome to..

Course Outline
 Communication System Basic
 Computer Networks Fundamental
 Network Cabling System Concepts
 Advance Computer Network Technology
 Computer Network Protocol
 DATA Transmission System
 Computer Network Design Concepts
 Computer Network Management System
 Computer Network Security Concepts
 Network Operating System (NOS)

Chapter 1
Communication
System Basic

Communication System Concept.
Source
(Transmitter)
Destination
(Receiver)
Transmission Media

Communication Mode
 Simplex
 Half Duplex (HDX)
 Full Duplex (FDX)

Communication Protocols
 Asynchronous Protocols
Not clock signal needed
Serial Communication
Low Speed Communication
 Synchronous Protocols
Clock Signal Needed
Serial Communication
High Speed Communication

Transmission Timing - Asynchronous
vs. Synchronous
 Sampling timing – How to make the clocks in
a transmitter and a receiver consistent?
 Asynchronous transmission – sending
shorter bit streams and timing is maintained
for each small data block.
 Synchronous transmission – To prevent
timing draft between transmitter and receiver,
their clocks are synchronized. For digital
signal, this can be accomplished with
Manchester encoding or differential
Manchester encoding.

Digital Interfaces
 The point at which one device connects
to another
 Standards define what signals are sent,
and how
 Some standards also define physical
connector to be used

Generic Communications
Interface Illustration

DTE and DCE
DTE DTE
host computer terminal
interface interface
modem modem
DCE

RS-232C (EIA 232C)
 EIA’s “Recommended Standard” (RS)
 Specifies mechanical, electrical,
functional, and procedural aspects of
the interface
 Used for connections between DTEs and
voice-grade modems, and many other
applications

*EIA-232-D
 new version of RS-232-C adopted in
1987
 improvements in grounding shield, test
and loop-back signals
 the prevalence of RS-232-C in use made
it difficult for EIA-232-D to enter into the
marketplace

*RS-449
 EIA standard improving on capabilities of RS-
232-C
 provides for 37-pin connection, cable lengths
up to 200 feet, and data rates up to 2 million
bps
 covers functional/procedural portions of R-
232-C
electrical/mechanical specs covered by RS-422 &
RS-423

*Functional Specifications
 Specifies the role of the individual
circuits
 Data circuits in both directions allow
full-duplex communication
 Timing signals allow for synchronous
transmission (although asynchronous
transmission is more common)

*Procedural Specifications
 Multiple procedures are specified
 Simple example: exchange of
asynchronous data on private line
Provides means of attachment between
computer and modem
Specifies method of transmitting
asynchronous data between devices
Specifies method of cooperation for
exchange of data between devices

*Mechanical Specifications
 25-pin connector with a specific
arrangement of leads
 DTE devices usually have male DB25
connectors while DCE devices have
female
 In practice, fewer than 25 wires are
generally used in applications

DB-25 Female
DB-25 Male
*RS-232 DB-25 Connectors

*RS-232 DB-25 Pin-outs

*RS-232 DB-9 Connectors
 Limited RS-232

*RS-422 DIN-8
 Found on Macs
DIN-8 Male DIN-8 Female

*Electrical Specifications
 Specifies signaling between DTE and DCE
 Uses NRZ-L encoding
Voltage < -3V = binary 1
Voltage > +3V = binary 0
 Rated for <20Kbps and <15M
greater distances and rates are theoretically
possible, but not necessarily wise

*RS-232 Signals (Async)
Odd Parity
Even Parity
No Parity

What ?

Chapter 2
Computer Network
Fundamentals

Contents
 Basic Network Understanding
Introduction to Computer Network
Standards Organization
OSI of ISO Reference Model
Basic Networks Equipment
Networking Topology
 Data-Communication Types
LAN (Local Area Networks)
MAN (Metropolitan Area Networks)
WAN (Wide Area Networks)

Basic Network Understanding
 Introduction to Computer
Network
 A group of computers linked
together
 Access from one computer
to another
 Communicated via the
network
 Sharing resources-Disk,
Data, Printer etc.
 Site extended
 Provide of physical routes
along which information can
flow

Basic Network Understanding …
 STANDARDS ORGANIZATION
CCITT =Consultative Committee for
International Telegraphy and Telephony
ISO = International Standards Organization
IEEE = Institute of Electrical and
Electronics Engineers

 CCITT
Consultative committee for international
telegraphy and telephony
World standards organization for
telecommunication (Telephony)
Makes technical recommendations on
telegraph, telephone and data
communication interfaces
Some popular CCITT standards are :
V.24,V.35,X.25 etc.

 ISO
International Standards Organization or
International Organization for
Standardization
Defines and develops standards on a vast
variety of topics
Almost 100 countries are represented in
ISO U.S. representative is ANSI ( American
National Standards Institute )
Well know ISO standards OSI

 IEEE
Institute of Electrical and Electronics
Engineers
Largest professional organization in the
world
Sponsors standardization group that
develops computing and electrical
standards
Well know IEEE standards : IEEE802 Series

 THE ISO’s OSI REFERENCE MODEL
The Open System Interconnection
Developed in 1977 by ISO
Data Communication standards
Multi-vendor inter-operability
Universal accessibility
Serves as function guideline for communication tasks
any communication standard
Concept behind model
Dividing difficult problems into subtasks
7 Layers model
Each layer executes specific functions
Each layer communicates with its peer in other
computers

 THE ISO’s OSI REFERENCE MODEL …
Application
Presentation
Session
Transport
Network
Data Link
Physical
7
6
5
4
3
2
1
• Reduce Complexity
• Standard Interfaces
• Modular Engineering
• Interoperable Technology
• Accelerate Evolution
• Teaching and Learning

Physical media for OSI
Peer Protocol
Seven Layer Reference Model and Peer Protocols
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
HOST A HOST B
Segments
Packets
Frames
Bits

Application
Presentation
Session
Transport
Network
Data Link
Physical
HOST A
Application
Presentation
Session
Transport
Network
Data Link
Physical
HOST B
Segments
PK
FR
Bit
PK
FR
Bit
Relay Open System
Physical media for OSI Physical media for OSI
Communication Involving Relay Open System Communication Involving Relay Open System

Application
Presentation
Session
Transport
Network
Data Link
Physical Options from CCITT, IEEE etc.
802-2 (LLC)
9314-2
FDDI
802-3
CSMA/CD
802-4
Token-Bus
802-5
Token-Ring
7776
X.25
LAP/LAPB
7809
HDLC
8473
Connectionless Network Service
8208/CCITT X.25
Packet Level Protocol
8073/CCITT X.224
Connection-Oriented Transport Protocol
8327/CCITT X.225
Connection-Oriented Session Protocol
8823/CCITT X.226
Connection-Oriented Presentation Protocol
9040/9041
VT
8831/8832
JTM
8571/8572
FTAM
9595/9596
CMIP
OSI Layer Example ISO Protocol
ISO Protocol Examples

 PHYSICAL LAYER OSI MODEL
Defines Mechanical
Defines Electrical
Specification of Media
Defines Network Interface
Defines Media :
# Coaxial,
# Fiber Optic,
# Twisted Pair,
# etc. Transmission Medium

 Data-LINK LAYER OSI MODEL
 MAC : Media Access Control
# Medium Access Management
# Framing
# Addressing
# Error Detection
# Example- CSMA/CD, Token Bus, Token Ring etc.
 LLC : Logical Link Control
# Organizes group of information
# Detects and some time corrects errors
# Control data flow
# Example
- IBM’s used SDLC (Synchronous Data Link Control)
- ISO’s used HDLC (High-level Data Link Control)

 Network LAYER OSI MODEL
 Moving information across a network
made up of multiple network segment
 Destination calculates best path
 According to path decided
 Network Managed and Traffic Control

 Transport LAYER OSI MODEL
Network Flow Control
User Multiplex Address
Network Service
Sequence Number Check

 Session LAYER OSI MODEL
Communication Control
Map Network Address to User
Connected and Disconnect Control

 Presentation LAYER OSI MODEL
Translation Data
Information show to User

 Application LAYER OSI MODEL
Communication with User
Manage Communication between Computer
and Applications
Examples
# Mail transfer services,
# Terminal emulation, etc.

 Basic Network Equipment
Repeaters
Bridges
Routers
Gateways

 Repeater
 Connects between two segment of network
 Retimes and regenerates the signal and sends
them
 Used to extend the cable length
 Used if number of nodes on a segment has
limits
 Used if different physical media
 Repeaters do not provide Traffic Isolation

Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
PhysicalPhysical Physical
Repeater Function
Open System A Open System B
Comparing a Repeater to OSI

 Bridges
Unlike repeaters function
Extend the network
Provide segment network traffic (Filtering)
Forward packet from one segment to next
segment (Forwarding)
Bridges are Categorized as
# - Local Bridges
# - Remote Bridges

Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
Bridge Function
Comparing a Bridge to OSI
Physical Physical
Data Link Data Link

 Router
Routers do not know the exact Location of stations
Routers function using subnet address only
Routers use information in each packet or frame
Router determine destination address
Router repackage and retransmit data
Not responsible for end to end
Transmit packets up to next transmit point

Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
Router Function
Comparing a Router to OSI
Physical Physical
Data Link Data Link
Network Network

 Gate-Ways
Convert data moving between networks
Change format of message to application
program

Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
Gateway Function
Comparing a Gateway to OSI
Physical Physical
Data Link Data Link
Network Network
Transport Transport
Session Session
Presentation Presentation
ApplicationApplication

 Networking Topology
Bus Topology
Ring Topology
Star Topology
Mixed Topology (Bus-Star, etc.)

 Bus Topology
Terminator - BUS - Terminator
A B C D

 Ring Topology
Token
Ring

 Star Topology
CC

 Mixed Topology
A B C D
CC
CC

Data Communication Type
 Type of Computer Networks
Local Area Network ( LAN )
Metropolitan Area Network (MAN)
Wide Area Network (WAN

 Local Area Network (LAN)
Interlink age of Computer within a limited
location
High speed of Data exchange
( 10 - 100 Mbps or 1000 Mbps )
Low error rates
Inexpensive transmission media available
No Central control station
Connections to the outside world

 METROPOLITAN AREA NETWORK
(MAN)
Interlink age of many LANs within city
Uses LAN technology (Media, Access
method etc.)
Fairly large data transmission rate 10 - 100
Mbps or 1000 Mbps
Expensive transmission media (
Fiber Optic )

 Wide Area Networks (WAN)
Interlink age of many LANs and MANs
Low data transmission rate
# - below 1 or 2 Mbps
Example: Internet Network

LANs
(Local Area Network)

 Ethernet Local Area Network
 Token Ring Local Area Network(4/16Mb/s)
 FDDI (Fiber Distribution Data Interface)
 100BaseT ( High Speed LAN)
 ATM (Asynchronous Transfer Mode)
TYPE of LANs
( Local Area Network )

 CSMA/CD Protocol Used
 CSMA = Carrier Sent Multiple Access
 CD = Collision Detected
 Bus and Star Topology
 1024 Node Per 1 Collision Domain (Segment)
 28 Nodes Attach / Thin Net / 185 meters
 100 Nodes Attach / Thick Net / 500meters
 7 Bridges/Network
 4 Repeaters/Network
ETHERNET
LOCALAREA NETWORK

CSMA/CD PROTOCOL
Node A Node B Node C
Ethernet Media Access

CSMA/CD PROTOCOL (contd.)
TX RX RX

CSMA/CD PROTOCOL (contd.)
TXRX RX

SAMPLE ETHERNET LANs
Server
Direct Attach 28 Nodes for Thin Net. 185 meters
Direct Attach 100 Nodes for Thick Net. 500 meters

Server
Direct Attach 28 Nodes for Thin Net. 185 meters
Direct Attach 100 Nodes for Thick Net. 500 meters
Need More
Station OK !
Extend !

Server
Eth. Hub
8-16 W/S
Network Extended
Not Over 1024 W/S

Server
Eth. Hub
8-16 W/S
Network Extended
Not Over 1024 W/S
Need More
Station and Server
Extend !

Server1
Eth. Hub
8-32 W/S
Network Extended
Not Over 1024 W/S
Server2
Eth. Hub
8-32 W/S
Repeater

Server1
Eth. Hub
8-32 W/S
Server2
Eth. Hub
8-32 W/S
Repeater
HO !
Traffic Traffic

Server1
Eth. Hub
8-32 W/S
Server2
Eth. Hub
8-32 W/S
Bridge
HO !
Good Good

 Token Passing Protocol
 Ring and Star Topology
 260 Nodes On Shielded Twisted Pair (100
meters)
 230 Nodes On Unshielded Twisted Pair (300
meters)
 Data Rate 4/16 Mb/s
 7 Bridges/Network
 4 Repeaters/Network
TOKEN RING
LOCALAREA NETWORK

SAMPLE TOKEN RING LANs
Server1
Server2
Server3
B
B
B
HUB
HUB
Ring 1
Ring 2
Ring 3

 Based on ANSI X3T9.5 Fiber Distributed Data Interface Standard
 100 Mbps Data Rate
 Ring and Star Topology
 Wide range of mainframe, workstation, and network interfaces
 Dual Attached Stations (DAS)
 Fault tolerance provided with dual
counter rotating ring
 Dual Attached Concentrators (DAC)
 Allow building of a tree configurations of SAS/SAC devices
 Single Attached Stations/Concentrators (SAS/SAC)
 Can be disconnected without affecting the DAC station
FDDI
LOCALAREA NETWORK

SAMPLE FDDI LANs
XYPLEX 6601
ETHERNET SWITCH
FDDI Backbone 100 Mb/s
with DAS file servers, hubs, all switch
Clients attached to
wiring hubs for shared
10 Mbps connections
High performance clients
attached via dedicated
10 Mbps Ethernet
WW W
K
W
W
W
W
K
K
Host
Server

 It’s Ethernet- Only faster !
 Based on existing standards and
technology
 Simple, low cost (Like Ethernet )
 Uses existing cabling
 Leverages network admin
understanding of Ethernet minimal
incremental training
 Broad multi-vendor support
100Base-T/Fast Ethernet
LOCALAREA NETWORK

Speed 10 Mbps 100 Mbps
IEEE standard 802.3 802.3
Media Access Protocol CSMA/CD CSMA/CD
Topology Bus or Star Star
Cable support Coax,UTP,FO UTP,FO
Media interface Yes Yes
Full duplex Yes Yes
Broad industry support Yes Yes
Availability Now Now
100Base-T/Fast Ethernet (contd.)
LOCALAREA NETWORK
Ethernet Fast Ethernet

SAMPLE 100Base-T LANs
ETHERNET SWITCH
WW WK WW WK
WW WK
Fast Ethernet Switch
Host A
100Mb
Host B
100Mb
100 100
100
10/100
100
100Mb/s W-Group
10Mb/s W-Group
100Mb/s W-Group

 Provide fast packet switching than X.25
 The packet very small fixed size
 Multiple logical connections over one physical
interface
 Links equipped with ATM port via ATM card
added to product
 Capacity 45 Mbps to 2.488 Gbps
 Application that current LAN/WANs can
support
ATM
(Asynchronous Transfer Mode )

SAMPLE ATM NETWORK
Centrally Located Servers
Directly Attached to ATM
Switch/Network
Switched Ethernet
ATM
Backbone
155 Mb/s
Or Higher

MANs
(Metropolitan Area Network)
WANs
(Wide Area Network)

 Remote Access Terminal (WANs)
 Used Lease or Line Dial up
 LAN to LAN
 Low speed in city called WANs
 High speed in city called MANs
 Low speed connect called WANs
 MAN to MAN (WANs)
 Low speed only
MANs and WANs CONNECTION

REMOTE ACCESS CONNECTION
Mod. or MUX
VAX Unix IBM
Mod. and MUX
Dial Line, ISDN or
Digital Lease Line

LANs to LANs
Low Speed CONNECTION
IBM
Remote
Bridge/Router
VAX
Remote
Bridge/Router
Dial up, Lease line, ISDN,
Satt., Micro wave etc.
WANs

LANs to LANs
High Speed CONNECTION
XYPLEX
VAX IBM
Unix
Remote
Bridge/Router
Remote
Bridge/Router
Remote
Bridge/Router
Remote
Bridge/Router
ATM
MANs
In City

MANs to MANs
CONNECTION
San
Francisco
Chicago
New
York
Atlanta
Dallas
Los
Angeles
64 Kbps
64 Kbps
64 Kbps
64 Kbps
64 Kbps
64 Kbps
64 Kbps
64 Kbps

Chapter 3
Network Cabling
System Concepts

Contents
 Cabling System Structure
 Type of Cables
 Cabling System Reference

Network Cabling System Concept.
Horizontal Cabling System
Backbone Cabling System
Work Area
 Type of Cable
Twisted Pairs
# Unshielded Twisted Pairs (UTP)
# Shielded Twisted Pairs (STP)
Fiber Optic Cable
# Multi-mode Fiber Optic
# Single-mode Fiber Optic

 Cabling System Concept
Cabling System Reference
# Cabling System Standard
# Modular Wiring
# Application Specific Pair Assignments

 Horizontal Cabling System

 Cabling System
Structure
Backbone Cabling
System

 Cabling System
Structure
 Work Area

 Type of Cable
 Unshielded Twisted Pairs (UTP)

 Type of Cable
 Shielded Twisted Pairs (STP)

 UTP Cable Category
 Category 3
# Transmission characteristics are specified up to 16 MHz.
 Category 4
 Category 5
 Category 5e
 Category 6
# Transmission characteristics will be specified up to 250 MHz.
 Category 7
# Transmission characteristics will be specified up to 600 MHz.

 Type of Cable
Fiber Optic Cable

 Fiber Optic Connector

 Sample Fiber Optic Cable

 Cabling System Reference
 ANSI/TIA/EIA-568 Cabling Standard
# Establish a generic telecommunications cabling
# Support a multi-vendor environment
# Enable the planning and installation of a structured
# Cabling system for commercial buildings
# Establish performance and technical cabling system
configurations
 The standard specifies:
# Minimum requirements for telecommunications cabling
# Recommended topology and distances
# Media parameters which determine performance
# Connector and pin assignments to ensure interconnect ability

Chapter 4
Advance Computer
Network Technology

Contents
 High Speed Technology Solution
 LAN Switching Technology
 VLAN Technology
 Gigabit Ethernet
 10 Gigabit Ethernet
 Wireless LAN Technology
 VPN (Virtual Private Networks)

HIGH SPEED
Technology Solution
for
Local Area Network
(LANs)

 Why High Bandwidth ?
 Related Concept Overviews
 LAN Switching
 dedicated bandwidth
 Performance micro segmentation
 Virtual LANs
Architecture

The Need for Speed-Applications
 CAD and CAE
 Database processing
 Deadline oriented, e.g. Publishing
 Time critical, e.g. Trading floors
 Multimedia
 Centralized servers
 Backup/Restore

Desktop CPU Performance
1983 1986 1990 1993
0
10
20
30
40
50
60
70
80
90
100
1983 1986 1990 1993
YEAR
Year of Introduction
MIPS
286 386
486
Pentium
Intel 80x86 MIPS

The Problem for High Performance Systems
 CPU Taxed by Hungry Applications
 Bottlenecks occur in I/O data transfers
 10 or 100 Mbps Network interface
cannot provide enough capacity for “ Big
Pipe” performance

BUS Performance
Micro channel Bus 32 Mbps
EISA Bus 33 Mbps
PCI Bus 132 Mbps
10 Mbps Ethernet
10 Mbps Ethernet
10 Mbps Ethernet
Are 10 Mbps Network Pipes Big Enough ?

The Solution for High
Performance Systems
 Maximizes Server-Client Performance
File, Printer, Storage, and Other
Network data throughput
 High Capacity PCI bus Extends power of Pentium
processor onto the LAN
 Eliminate wire, Bus bottlenecks and bottlenecks are in
the PC
 Need an Adapter for Total System

Solution for Response Time
0 10 20 30 40 50 60
Local Hard
Drive
W10-SER10
W10-SER100
W100-
SER100
Seconds
SECONDS
Reference
Existing
Step 1
Step 2

Network Infrastructure Follow Application
and Network Performance
83 85 87 89 91 93 95
Intel 286
Intel 386
Intel 486
Pentium
Processor
10 Mbps
Switched 10 Mbps
100Base-T
Switched
100Base-T
Spreadsheets
Graphics Intensive
Documents
Replicated
Databases
Processor Speed Network Performance

Shared Media Connectivity
 Typically lower cost per port
 All shared media are subject to collisions
 Ethernet star
 Token Ring
 FDDI
 100Base
SERV. SERV.
Example of Ethernet Bus Topology Shared media

LAN Switching
Technology

Understand Switching Basics
 Describe packet-switch technologies
 Such as Link Access Procedure
 Balanced (LAPB)
 Frame Relay
 Switched Multimegabit Data Service (SMDS)
 X.25 Switching Networks
 Refers to the technology a bridge many ways
 Switches Connecting LAN segments
 Use of MAC addresses to determine datagram needs
to transmitted and reduce traffic.

Switched Connectivity
 Other Switched
 ATM
 Switched Ethernet
 High performance you need it
 Dedicated bandwidth on other users
SERV.SERV.
SERV.
SERV.
Example of Switch 10/100 Mbps
Fast Ethernet

 Switching in Ethernet Environment

VLANs
(Virtual LANs)
Technology

Understanding Virtual LANs
 Virtual LAN (VLAN) is group hosts or network
devices
 That forms a single bridging domain
 Layer 2 bridging protocols such as IEEE
802.10
 VLANs network can take advantage of
Broadcast control
Security
Performance
Network management

Understanding Virtual LANs

Construction Basics
Using an Ethernet port-switching hub.
Server
S1
Server
S2
0 1
2 3 4 5 6 7
C1
C2 C4 C6
C3 C5
Switching

Construction Basics
 Implicit versus Explicit Tagging
The actual criteria used to define the logical
grouping of nodes into a VLAN can be
based upon implicit or explicit tagging.
Implicit tagging, which in effect eliminates
the use of a special tagging field inserted
into frames to packets,

Construction Basics
Establishing vLANs based upon the use of switch ports..
Server
S1
Server
S2
0 1
2 3 4 5 6 7
C1
C2 C4 C6
C3 C5
Switching

Construction Basics
can be based upon MAC address, port
number of a switch used by a node,
protocol, or another parameter that node
can be logically grouped into.
Explicit tagging requires the addition of a
field into a frame or packet header.

VLAN Construction Basics
 PORT-GROUPING VLANS
A port-grouping vLAN represents a virtual
LAN created by defining a group of ports on
a switch or router to form a broadcast
domain.

 Thus, another common name for this
type of vLAN is a port-based virtual LAN.
 The hardware used to form a port-
grouping vLAN can range in scope from
an intelligent wiring hub to a switch or
sophisticated router;

Port-Group vLAN via an intelligent hub
VLAN 1 VLAN 3VLAN 2 VLAN 1
0 1 2 3 4 5 6 7

MAC-BASED SWITCHING
 MAC-based switching in recognition of
the use of media access control
addresses.
 this method of vLAN creation is also
referred to as a “layer-2 vLAN”.
 A vLAN-capable switch can provide a
high degree of versatility.

MAC-BASED SWITCHING
4 5
0 1 32
1 2 3 4 11 12 13 14
5 6 7 8 9 10
1615
server server
LAN Switch
vLAN 1 vLAN 2
Layer-2 vLAN
n
n
= Port n
= MAC address

MAC-BASED SWITCHING
Moving stations when using a layer-2 vLAN
n
n
= Port n
= MAC address
4 5
0 1 32
1 2 3 4 11 12 13 14
5 6 7 8 9 10
1615
server server
LAN Switch
vLAN 1 vLAN 2

MAC-BASED SWITCHING
 For example, selective users on a
segment connected to a port, as well as
individual workstations connected to
other ports on a switch, can be
configured into a broadcast to main
representing a virtual LAN.

MAC-BASED SWITCHING
 It should be noted that the “partitioning”
of a segment into two vLANs can result
in upper-layer problems.
 This is because upper-layer protocols,
such as IP, require all stations on a
segment to have the same network
address.

LAYER-3-BASES VLANS
 A layer-3-based vLAN is constructed
using information contained in the
network layer header of packets.
 There are a variety of methods that can
be used to create layer-3 vLANs.

Subnet-Based vLANs
 Advantages
Flexibility of layer-3 vLANs, as a user moves to
another segment but retains his or her subnet
number, many switches will “follow” the
relocation, permitting moves to be accomplished
without requiring the reconfiguration of a LAN
switch.

Subnet-Based vLANs
vLAN creation based upon IP subnets
4 5
0 1 32
server server
LAN Switch
vLAN 1 vLAN 2
192.78.55.xxx
192.78.55.xxx
192.78.55.xxx
192.78.42.xxx
192.78.55.xxx
192.78.42.xxx
192.78.42.xxx

Advantages
The configuration of vLANs can be
automatically formed, unlike port and MAC-
based virtual networks whose setup can be
tedious and time consuming.
A layer-3 vLAN is the fact that it supports
routing.

Disadvantages
Two limitations associated with vLAN using
Sub-netting.
configuration required to ensure network
stations are using the correct protocol and
network address.
the inability of some switches to support
multiple subnets on a port.

Protocol-Bases vLANs
 The use of the layer-3 transmission protocol
as a method for vLAN creation provides a
mechanism which enables vLAN formation
to be based upon the layer-3 protocol.
 Through the use of this method of vLAN
creation, it becomes relatively easy for
stations to belong to multiple vLANs.

4 5
0 1 32
I/X X I/X I X X I I
I/X X I I/X X I
XI/X
server server
vLAN creation based upon protocol
n
I
= Port n
= IP Protocol
= IPX Protocol
= IPX & IP Protocols
X
I/X

 Advantages
A major benefit associated with vLAN creation
based upon protocol is networking flexibility.
This flexibility enables stations to be moved
from one network segment to another without
losing vLAN membership.

Advantages
Another aspect associated with networking flexibility is
the ability to obtain the bandwidth advantages
associated with the use of LAN switches while tailoring
traffic to support different services.
To support this new requirement you could add a port
the LAN switch and connect a router to that port.

Advantages
Expanding a vLAN to support internet access
n
I
= Port n
= IP Protocol
= IPX Protocol
= IPX & IP Protocols
X
I/X
4 6
0 1 32
I/X X I/X I X X I I
I/X X I I/X X I
I/X
server
5
X
server
I
router Internet

Disadvantages
You must obtain equipment that supports
the use of protocols for vLAN creation as
well as verifies that stations are configured
correctly.

Gigabit Ethernet
1000Base-XX Standard

Gigabit Ethernet Technology
 Gigabit Ethernet
Is the IEEE by the 802.3z
Conform to the Ethernet Standard
# – Frame format
# – Minimum and maximum frame sizes
# – CSMA/CD access method
# – 802.2 LLC specifications
Provide forwarding between 10/100/1000 Mbps
10 times the performance of Fast Ethernet

 Uses of Gigabit Ethernet
Aggregating traffic between Ethernet clients and
centralized file or compute servers
Connecting multiple 100Base-T Fast Ethernet
switches through 100/1000 Mbps switches
Connecting both workstations and servers with
Gigabit Ethernet to run high-bandwidth
Applications, such as CAD/CAM, medical imaging,
and pre-press

10 Gigabit Ethernet

What is 10 Gigabit Ethernet?
 Uses
IEEE 802.3 MAC
IEEE 802.3 Ethernet Frame Format
IEEE 802.3 Ethernet Frame Size
No Auto Negotiation
Full Duplex and Optics Only
Provides 10x Speed of 1 GigE
It’s simply 10 GigE or 802.3ae !

10 GigE Standards – IEEE Groups
 New Standards begins with
the Sponsor Group
 Call for Interest and then,
Study Group Formed
 Project Authorization Request
to NesCom
 Working Group Formed
 Standards must be completed
within 4 Years as of the PAR
approval
 Standards Review by RevCom
before the Sponsor Ballot
IEEE
IEEE-SA
Standards Board IEEE 802
Sponsor Group
IEEE 802.3
Working Group
IEEE 802.3ae
Task Force
RevCom* NesCom**
Start Here!
End Here!
* Review Committee
** New Standard Committee

10 GigE Standards Time Table
Study Group
Formed (HSSG*)
802.3ae
Formed
802.3
Ballot
Sponsor
Ballot
1999 2000 2001 2002
1st Draft Final Draft Standard
IEEE-SA
Approval
* High Speed Study Group

10 GigE Standard Interface
IEEE 802.ae LAN/MAN Fiber Type PMD Distance
10GBase-SR LAN
MMF 850nm Serial 25, 65, 300m
10GBase-SW WAN
10GBase-LR LAN
SMF
1310nm
Serial
10km
10GBase-LW WAN
10GBase-ER LAN
SMF
1550nm
Serial
40km
10GBase-EW WAN
10GBase-LX4 LAN
MMF 1310nm
WWDM
300m
SMF 10km
 WAN: 9.953 Gbits/s; OC-192c Compatible
 Serial: Wave length
 WWDM: Wideband WDM (4 wave lengths: 4 x 3.125 Gbits/s)

10 GigE Interface Nomenclature
 M: Media Type (or Wave Length)
 Short(850nm), Long(1310nm), Extra Long(1550nm)
 C: Coding Scheme
 X(8B/10B), R(64B/66B), W(64B/66B with simplified
SONET/SDH)
 W: Number of Wavelengths
 1 (Implied), 4
10GBASE- M WC

10GBASE-R/10GBASE-W/10GBASE-X

Multi Mode Fiber Consideration:
Modal Dispersion
 The PMDs for MMF supports at most 300 meters
 Typically, 30 meter or 80 meter
 The Distance limitation due to Modal Bandwidth
 Approx. Distance = Modal Bandwidth / Bandwidth
 E.g., 10 GigE over 62.5um MMF with 200 MHzKm modal
bandwidth
# 20 meter = 200 MhzKm / 10000 MHz
 To overcome this issue, LX4 has been proposed
 But it has brought out more problems in terms of complexity
and cost; it’s WDM any!

Architecture of 802.3ae
WAN PHY LAN PHY
* Figure from 802.3ae Draft

10 GigE Concept View
* Source: 10GEA White Paper
Optics
(PMD) PHY MAC
Fiber
Fiber
Reconciliation
PCS
PMA
XGMII
WIS(Option)
LAN PHY WAN PHY LAN PHY-WDM
 Reconciliation: Converting messages of MAC layer into electrical signal
 PCS: Physical Coding Sub layer, Coding(64B/66B, 8B/10B)
 WIS: WAN Interface Sub layer, For WAN PHY
 PMA: Physical Media Attachment, Serialize or desterilize signals
 XGMII: 10G Media Independent Interface

Essential 10 GigE Features
 Redundancy, Reliability, Scalability
 802.3ad aggregation
 802.1w (Rapid Spanning Tree Protocol)
 802.1s VLAN Grouping
 Ring and Mesh Topology Support
 Optimal deployment of Ethernet networks in Metro Area
 Rapid protection mechanism for fail-over on Ring and Mesh
topology
 Integrated Switching and Routing
 Simultaneous L2 and L3 support
 QoS?
 10 GigE = Over Provisioning = Simple to manage, Rocket
performance

Solutions where 10 GigE Bright Light

Metro Solution: The Keys
 Minimum TCO (Total Cost of Ownership)
Implementation (Reuse of Backbone IP Networks if
Any)
Operation
Maintenance
Training
 Services
Abundant bandwidth supply for a fraction of price
for the legacy service
A variety of services and accounting schemes
There is 10 GigE !

Metro Service Network Leveraging Existing IP Backbones
Existing Regional
IP Backbone - Seoul
Existing Regional
IP Backbone - Daejun
Existing Regional
IP Backbone - Bussan
Existing Regional
IP Backbone - Gwangju
Metro Ring in 10GBASE-LR/ER
Legacy POS interface
10 GigE
1 GigE
POS

Inside Internet Exchange: Enhanced Traffic
Load Balancing and Simplified Topology
 Massive 1 GigE
Trunk
 Inefficient Traffic
Load Balancing
 Wiring complexity
 Increased Packet
Delay
A-IX
B-IX (Major Peer)
10 GigE
2 x 1 GigE
1 GigE
Trunk

Internet Data Center
 High Performance Server with Gigabit NIC
Gigabit-over-Copper NIC is expected to dominate
high-end servers
 Up-link
1 GigE Trunks? No!
 10 GigE brings out:
• Better Load Balancing
• Faster Response Time
• Easier to Manage
• Easier to Implement
• Ultimately, Lower TCO1 GigE
10 GigE
L4 Switch
Switch/Router
100 M

High Speed Campus Network
ISP A
ISP B
10 GigE
Ring
100Base-FX
Up to 40Km
POS OC-3c
1 GigE
100 M
Mission
Critical
High-End
Servers
PCs
High-End
Servers

WireLess
Local Area Network

Uses
 Key drivers are mobility and
accessibility
 Easily change work locations in the
office
 Internet access at airports, cafes,
conferences, etc.

Benefits
 Increased productivity
Improved collaboration
No need to reconnect to the network
Ability to work in more areas
 Reduced costs
No need to wire hard-to-reach areas

Standards
 IEEE 802.11
 IEEE 802.11b
 IEEE 802.11a
 IEEE 802.11e
 Hiper LAN/2

802.11
 Published in June 1997
 2.4GHz operating frequency
 1 to 2 Mbps throughput
 Can choose between frequency hopping
or direct sequence spread modulation

802.11b
 Published in late 1999 as supplement to
802.11
 Still operates in 2.4GHz band
 Data rates can be as high as 11 Mbps
 Only direct sequence modulation is
specified
 Most widely deployed today

802.11a
 Also published in late 1999 as a supplement
to 802.11
 Operates in 5GHz band (less RF interference
than 2.4GHz range)
 Users Orthogonal Frequency Division
Multiplexing (OFDM)
 Supports data rates up to 54 Mbps
 Currently no products available, expected in
fourth quarter

802.11e
 Currently under development
 Working to improve security issues
 Extensions to MAC layer, longer keys,
and key management systems
 Adds 128-bit AES encryption

HiperLAN/2
 Development led by the European
Telecommunications Standards Institute
(ETSI)
 Operates in the 5 GHz range, uses OFDM
technology, and support data rates over
50Mbps like 802.11a

Functionality
 Basic Configuration
 WLAN Communication
 WLAN Packet Structure

Basic Configuration

802.11 Communication
 CSMA/CA (Carrier Sense Multiple
Access/Collision Avoidance) instead of
Collision Detection
 WLAN adapter cannot send and receive
traffic at the same time on the same
channel
 Four-Way Handshake

Four-Way Handshake
Source Destination

OSI Reference Model: Phy
 Network Oper. System
 Network Layer
 Guarantees delivery data
 Drivers
 LLC Layer
 send/receive data
 LAN Controller
 MAC Layer
 data into/out frame
 MODEM
 Physical Layer
 frame into/out phy frame
Physical Layer
IEEE: MAC Layer
IEEE: LLC Layer
Network Layer

Wireless LAN Technologies
Infrared
Spread
Spectrum
Narrow Band
Direct
Sequence
Frequency
Hopping
Wireless LAN technologies
(overview)

(Infrared)
 low power infrared light as the carrier
 No license required
 Very restricted mobility, limited coverage
 high data rate (10 Mbps, 16 Mbps)
 Line-of-Sight Infrared
no objects in the path between two stations
 Diffuse Infrared
uses reflections to set-up wireless link

(Narrow Band)
 Dedicated band (18 GHz)
 License required
 ISM band (915 MHz, 2.4 GHz, 5.8 GHz)
 unlicensed (special modulation)
 extremely low output power i.e. limited coverage
 high data rate (up to 10 Mbps) on short distance
 Europe - DECT band (1.8 GHz)
 based on voice standard

• 915 MHz only in the Americas (region 2)
• 2.4 GHz for global availability (region 1,2,3)
1 2 3 4 6 8 10 20 30 40 60 100
GHz
1
2
3
ISM Frequency Allocations
Worldwide

(Spread Spectrum)
 Unlicensed usage (ISM band)
 No line of sight requirement (indoor)
 High link reliability
 Built-in transmission security
 Two techniques used:
 Direct Sequence
 Frequency Hopping
Standard Radio
Transmission
Spread Spectrum
Transmission
Frequency Spectrum (MHz)
2400 2500
PowerPower
FrequencyFrequency
88 103 2400
FM Band

Module contents
 Technologies overview
 Spread Spectrum
Direct Sequence
Frequency Hopping
 Modulation
DBPSK/DQPSK
CCK

Multiple Access Methods
Multiple users share the available spectrum
FREQUENCY
TIME
User 3
User 2
User 1
• Multiple users share
the same frequency
channel sequentially
• Time slot sequence
repeats over and over
TDMA
TIME
FREQUENCY
CODE
CDMA
also known as “Spread Spectrum”
User 3
User 2
User 1
• Channel is “spread” over wide frequency
band
• Many users share the same frequency
band at the same time
• Each user is assigned a unique “code”
to identify and separate
them
FREQUENCY
TIME
FDMA
1 2 3
Each user assigned a
different frequency -
like ordinary radio

Spread Spectrum Technologies
DS vs. FH
 Direct Sequence
 Each symbol is transmitted over
multiple frequencies at the same time
 Very efficient (no overhead)
 Higher speed than FH at comparable
distances
 System capacity (multiple channels)
higher than FH
 Frequency Hopping
 Sequential use of multiple frequencies
 Hop sequence and rate will vary
 “End hop waste time”
COMPLETE WAVEBAND ALLOCATED
Time
Time

 Spreading: Information signal (I.e. a “symbol”) is multiplied by a
unique, high rate digital code which stretches (spreads) its
bandwidth before transmission.
 Code bits are called “Chips”.
 Sequence is called “Barker Code”
Source and
Channel
Coding
RF
Modulator
Code
Generator
X
Multiplier
Code Bits (Chips)
Digital Signal (Bits)
Frequency
Spectrum
f
“Spread” Frequency
Spectrum
f
Direct Sequence transmitter

 At the receiver, the spread signal is multiplied again by a
synchronized replica of the same code, and is “de-spread”
and recovered
 The outcome of the process is the original “symbol”
RF
Demodulator
Channel
and
Source
Decoding
Code
Generator
X
Multiplied
Code Bits (Chips)
De-Spread
Signal
f
“Spread” Frequency
Spectrum
f
Digital Signal (Bits)
Direct Sequence receiver

VIRTUAL PRIVATE NETWORKS
(VPN)

Traditional Connectivity

What is VPN?
 Virtual Private Network is a type of private
network that uses public telecommunication,
such as the Internet, instead of leased lines to
communicate.
 Became popular as more employees worked
in remote locations.
 Terminologies to understand how VPNs work.

Private Networks vs. Virtual Private Networks
 Employees can access the network (Intranet) from remote
locations.
 Secured networks.
 The Internet is used as the backbone for VPNs
 Saves cost tremendously from reduction of equipment and
maintenance costs.
 Scalability

Remote Access Virtual Private Network

Four Protocols used in VPN
 PPTP -- Point-to-Point Tunneling
Protocol
 L2TP -- Layer 2 Tunneling Protocol
 IPsec -- Internet Protocol Security
 SOCKS – is not used as much as the
ones above

VPN Encapsulation of Packets

Types of Implementations
What does “implementation” mean in
VPNs?
3 types
Intranet – Within an organization
Extranet – Outside an organization
Remote Access – Employee to Business

Virtual Private Networks (VPN)
Basic Architecture

Device Types
What it means
3 types
Hardware
Firewall
Software

Device Types: Hardware
 Usually a VPN type of router
Pros
• Highest network throughput
• Plug and Play
• Dual-purpose
Cons
• Cost
• Lack of flexibility

Device Types: Firewall
 More security?
Pros
• “Harden” Operating System
• Tri-purpose
• Cost-effective
Cons
• Still relatively costly

Device Types: Software
 Ideal for 2 end points not in same org.
 Great when different firewalls
implemented
Pros
• Flexible
• Low relative cost
Cons
• Lack of efficiency
• More labor training
required
• Lower productivity;
higher labor costs

 Eliminating the need for expensive long-
distance leased lines
 Reducing the long-distance telephone
charges for remote access.
 Transferring the support burden to the
service providers
 Operational costs
Advantages: Cost Savings

 Flexibility of growth
 Efficiency with broadband technology
Advantages: Scalability

VPNs require an in-depth understanding of
public network security issues and proper
deployment of precautions
Availability and performance depends on factors
largely outside of their control
Immature standards
VPNs need to accommodate protocols other than
IP and existing internal network technology
Disadvantages

Applications: Site-to-Site VPNs
Large-scale encryption between multiple
fixed sites such as remote offices and
central offices
Network traffic is sent over the branch
office Internet connection
This saves the company hardware and
management expenses

Site-to-Site VPNs

Applications: Remote Access
 Encrypted connections between mobile or
remote users and their corporate networks
 Remote user can make a local call to an ISP, as
opposed to a long distance call to the corporate
remote access server.
 Ideal for a telecommuter or mobile sales people.
 VPN allows mobile workers & telecommuters to
take advantage of broadband connectivity.
i.e. DSL, Cable

Chapter 5
Computer
Networking Protocol

Contents
 Sample Network Protocol
 TCP/IP v4
 TCP/IP v6

 AppleTalk
 DECnet Phase IV
 DECnet Phase V
 Novell IPX/SPX
 TCP/IP
 Net BIOS
 XEROX XNS
 SNA
 X.25
 Frame Relay
 HDLC
 SDLC
Sample Network Protocol

TCP/IP Protocol
(IPv4)

 The Transmission Control Protocol / Internet
Protocol
 Best of all Inter-Networking protocol
 Developed in 1970
 More 300 hardware/software vendor product
 Protocol follows four layer
Network Access Layer
Internet Layer
Host-Host Layer
Process/Application Layer
TCP/IP Protocol

OSI: Open System Internetworking Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI
File, print, message, database, and application services
Data encryption, compression, and data translation services
Dialog control
End to end connection
Routing
Framing, CRC
Physical topology

DoD: Department of Defense Model
 TCP/IP was created by the department of
Defense
 It was intended initially for military use
 TCP/IP became a standard for the internet as
well as LANs
 It consists of four layers

DoD Reference Model
Process/Applications
Host-to-Host
Internet
Network Access
DoD
Telnet, FTP, LDP, SMNP, TFTP, SMTP, NFS, X Windows
TCP, UDP
ICMP,BootP,ARP, RARP,IP
Ethernet, Fast Ethernet, Token Ring, FDDI

OSI and TCP/IP
Process/Applications
Host-to-Host
Internet
Network Access
DoD
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI
 TCP/IP is a condensed version of the OSI model

 Controls access to locally LAN or WAN
 Network specific and multiple
implementation the internet
Network Access Layer

 Routing and Switching of data through
the communication network
 Forwarding a data on the network
address of the destination
 Fragmentation and Reassembly of the
data
Internet Layer

 Provide virtual circuit service between
end user application
 Responsible for end to end connection
between host process
 Error control and detecting missing
information
 Flow control that fast sender with slower
receiver
 Connection control
Host-Host Layer

 Provide TCP/IP Application:
FTP ; File Transfer Protocol
Telnet; Terminal Emulation Protocol
SMTP; Simple Mail Transfer Protocol
SNMP; Simple Network Management
Protocol
etc.
Process/Application Layer

IP Addresses
 Every host must be configured with a pre-assigned IP address
 DHCP can be used to automate IP assignment
 IP has: a network address and host or node address
 IP addresses are 32-bits long
 It’s divided into 4 section each a byte long and separated by a dot ( not flat )
 IP could be noted: Dotted-decimal, Binary or Hexadecimal
 IP uses Three levels of addressing: network, subnet and host
 It's similar to phone numbers: Area code, prefix and final segment

IP Addresses (continued)
 IP differentiates networks with their size
 IP ranks three main classes: Class A, Class B and Class C
 IP mandates the leading bits section of the address for each different
network class
 There are additional classes, Class D and Class E
 IP addresses are assigned by the InterNIC
 Class A: (126 Networks, 16,777,214 nodes) link
 Class B: (16,384networks,65,534 nodes)
 Class C:(2,097,157 networks 254 nodes

IP Addresses (continued)
Bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
ClassA 0 Network Host Host Host
ClassB 1 0 Network Network Host Host
ClassC 1 1 0 Network Network Network Host
ClassD 1 1 1 0 MulticastAddress MulticastAddress MulticastAddress MulticastAddress
ClassE 1 1 1 1 0 Reserved Reserved Reserved Reserved

Invalid IP addresses
 0,255 and 127 can’t be used in the first byte of the
network address
0: means this network
255: broadcast
127: loop back
 0,255 are invalid node Ids
0: this network
255 broadcast

IP Host names
 It’s an alias assigned to computer
 Multiple names can be assigned to the same host
 As the number of nodes grew on the internet, the flat
database became harder to manage
 DNS divides the name space into smaller partitions: Domains
 Name management can be delegated to organizations on the
internet
 The top level domains are: arpa, int, edu,gov, mil, net, org,
com
 FQDN fully qualified domain names: ftp.apple.com

Subnet Masking
 Sub-netting is used to divide a network to smaller subnets
 Physical layers protocols impose limitations on the number
of nodes on network segments
 Having all the nodes on the same network imposes use of the
same technology (EX: Ethernet or Token Rings)
 Networks that have Nodes across wide geographical area can
also be a problem
 TCP/IP supports breaking a network to smaller subnets
 Bits are borrowed from node ID to subnet the network
 The number of subnets is 2^n - 2 where n is the number of
bits borrowed

Routing

Routing (continued)
 There are two types of routers: static and dynamic
 Dynamic routers build and update routing tables
automatically
 Dynamic routers use RIP routing Information protocol
 Static routers can only communicate with networks
directly connected to their interface
 Entries have to be manually put in routing tables

Sample TCPIP Network
Carrier
Service
FASTLA
NE
SC IT EC
F5
voice data packet bandwidth manager
Network
Control
Terminal
Ethernet LAN NET_A
N11
FASTL
ANE
SC IT EC
F5
Ethernet LAN NET_B
N23
FASTL
ANE
SC IT EC
F5
Ethernet LAN NET_C
N20
126.10.10.1
126.10.10.2
126.10.10.3
122.8.8.6
122.8.8.7
122.8.8.8
122.8.8.11122.8.8.10122.8.8.8
123.4.4.10
123.4.4.5
123.4.4.4
123.4.4.3123.4.4.2123.4.4.1
121.10.10.3
121.10.10.6121.10.10.5121.10.10.4

Examples of TCP/IP applications
 FTP
 Allows file transfer
 Uses telnet to let client logon to server
 Telnet
 Terminal emulation
 allows clients to appear as virtual terminals to remote hosts
 SNMP
 Used to collect and manipulate information about devices on the network
 Also used to monitor networks
 SNMP clients send trap messages to management stations
 SMTP
 Used to queue and deliver mail messages
 NFS
 Allows two different file systems on the network to share files

TCP/IP Protocol
IPv6
Background

Why a New IP?
only compelling reason: more addresses!
for billions of new devices,
e.g., cell phones, PDAs, appliances, cars,
etc.
for billions of new users,
e.g., in China, India, etc.
for “always-on” access technologies,
e.g., xDSL, cable, Ethernet-to-the-home, etc.

IPv4 Address Space Left?
 ~ half the IPv4 space is unallocated
if size of Internet is doubling each year,
does this mean only one year’s worth?!
 no, because today we deny unique IPv4
addresses to most new hosts
we make them use methods like NAT, PPP, etc.
to share addresses
 but new types of applications and new types
of access need unique addresses!

Why Are NATs?
 they won’t work for large numbers of
“servers”, i.e., devices that are “called”
by others (e.g., IP phones)
 they inhibit deployment of new
applications and services
 they compromise the performance,
robustness, security, and
manageability of the Internet

Summary of Main IPv6 Benefits
 expanded addressing capabilities
 server-less auto-configuration (“plug-n-play”)
and reconfiguration
 more efficient and robust mobility
mechanisms
 built-in, strong IP-layer encryption and
authentication
 streamlined header format and flow
identification
 improved support for options / extensions

IPv6 Standard Protocol
 The 4 billion addresses available in IPv4
 Working on IPv6 since the early 1990s
 Expanded addressing from 32-bit to 128-bit
 Addresses are n:n:n:n:n:n:n:n n = 4 digit
 Hexadecimal integer, 16 ¥ 8 = 128 address

IPV6
Addressing & Routing

Text Representation of Addresses
“preferred” form:
1080:0:FF:0:8:800:200C:417A
compressed form: FF01:0:0:0:0:0:0:43
becomes FF01::43
IPv4-compatible: 0:0:0:0:0:0:13.1.68.3
or ::13.1.68.3

Address Types
unicast (one-to-one)
- global
- link-local
- site-local
- IPv4-compatible
multicast (one-to-many)
anycast (one-to-nearest)
reserved

 Unicast
Unicast is a communication between a single host
and a single receiver

 Multicast
 Multicast is communication between a
single host and multiple receivers

 Anycast
 Anycast is a communication between a single sender and a
list of addresses

Chapter 6
Data Transmission
System

Contents
 Data Transmission Equipment
Modem (Mod-De Modulation)
MUX (Multiplexer De-Multiplexer)
xDSL (Digital Sub-Scriber Line)
 PSTN (Public Switching Telephone Networks)
 ISDN (Integrate Service Digital Networks)
 Frame Relay Networks
 ATM (Asynchronous Transfer Mode)
 SDH/SONET (Synchronous Optical Networks)

Data Transmission Equipment
 Modem

 Modem Type
Analog Modem
# Asynchronous
# Synchronous
Digital Modem
# Synchronous

Access Via ISPs
 Consumers and businesses typically gain Internet access via ISPs.
Many ISPs provide a variety of connection interfaces including:
 Dial-in modem connections
 ISDN
 Cable modems
 T/E-n and fractional T/E-n
 Wireless service providers (WSPs) provide wireless Internet access for
users with wireless modems, smart phones, and Web-enabled PDAs, or
handheld computers
 Despite increasing use of DSL and cable modems, dial-in access over
voice-grade analog circuits is the most common form of Internet access
for consumers
 Point-to-point (PPP) protocol is the most widely used protocol over dial-
up connections

Character Encoding
 Encoding is one of the first requirements of a data
communication network
 Character encoding involves the conversion of
human-readable characters to corresponding fixed-
length series of bits
 Bits can be represented as discrete signals and
therefore can be easily transmitted or received over
communication media
 When bits are represented as discrete signals, such as
different voltage levels, they are in a digital format

Data Codes
 Several character encoding schemes are widely used
in data communication systems including:
 ASCII (American Standard Code for Information Interchange)
 EBCDIC (Extended Binary-Coded Decimal Interchange Code)
 Unicode (aka ISO 10646)
 Touch-tone telephone code
 As illustrated in, these vary in the number of bits used
to represent each character as well as the total
number of characters that can be represented

Transmitting Encoded Data
 The bits that represent encoded characters can be transmitted
simultaneously (parallel transmission) or one at time (serial
transmission) – see Figure 6-2
 Serial transmission is more widely used than parallel transmission
for data communication
 Parallel transmission is used for communication between
components within a computer
 In serial transmission, encoded characters can either be
transmitted one at a time (asynchronous transmission) or in
blocks (synchronous transmission) – see Figure 6-5
 Figure 6-4 illustrates asynchronous transmission of a single
character.
 UART provides the interface between parallel transmission within
the computer and serial transmission ports. It also plays a key role
in formatting encoded characters for asynchronous transmission

Figure 6-2

Figure 6-4

Figure 6-5

Data Flow
 Data communication networks, including modem-to-
modem communications, must have some
mechanism for control over the flow of data between
senders and receivers
 Three elementary kinds of data flow are:
 Simplex
 Half-duplex
 Full-duplex
 These are illustrated in Figures 6-6 and 6-7
 Most modems in use today support both full- and half-
duplex communication

Figure 6-7

Interfaces and Interface Standards
 There are two major classes of data communication equipment:
 Data communication equipment (DCE): this includes modems,
media, switches, routers, satellite transponders, etc.)
 Data terminating equipment (DTE): this includes terminals, servers,
workstations, printers, etc.)
 The physical interface is the manner in these two classes are
joined together (see Figure 6-8)
 A wide range of interface standards exist including
 RS-232-C
 RS-422, RS-423, RS-449
 A variety of ISO and ITU interfaces
 USB and FireWire

Figure 6-8

RS-232-C
 EIA’s RS-232-C standard is arguably the most important physical
layer standard
 It is the most widely accepted standard for transferring encoded
characters across copper wires between a computer or terminal
and a modem
 RS-232-C uses voltage levels between –15 and +15 volts (see
Figure 6-9); negative voltages are used to represent 1 bits and
positive voltages are use to represent 0 bits
 This standard does not specify size or kind of connectors to be
used in the interface. It does define 25 signal leads (see Table 6-
4). 25-pin connectors and 9-pin connectors are most common,
but other kinds of connectors are sometimes used

Figure 6-9

Digital Data Transmission
 All communication media are capable of
transmitting data in either digital or analog
form.
 Voice-grade dial-up circuits are typically
analog, however, relative to analog
transmission, digital transmission has several
advantages:
Lower error rates
Higher transmission speeds
No digital-analog conversion
Security

Analog Transmission
 Data is represented in analog form when transmitted over analog
voice-grade dial-up circuits (see Figure 6-14)
 This is done by varying the amplitude, frequency, or phase of the
carrier signal (carrier wave) raised during the handshaking
process at the start of a communication session between two
modems
 During handshaking, the two modems raise a carrier signal and
agree on how it will be manipulated to represent 0 and 1 bits
 In some modulation schemes, more than one of the carrier signal’s
characteristics are simultaneously manipulated
 Modems (modulator/demodulators) are the devices used to
translate the digital signals transmitted by computers into
corresponding analog signals used to represent bits over analog
dial-up circuits (see Figure 6-13)

Figure 6-13

Figure 6-17
Figure 6-19

Figure 6-20

Phase Modulation
Figure 6-24

Bit Rates and Bandwidth
 The bandwidth of an analog channel is the difference
between the minimum and maximum frequencies it
can carry
 A voice-grade dial-up circuit can transmit frequencies
between 300 and 3400 Hz and thus has a bandwidth of 3100
Hz
 For digital circuits, bandwidth is a measure of the
amount of data that can be transmitted per unit. Bits
per second (bps) is the most widely used measure for
digital circuits
 Over time, bit rates (bps) have also become on of the
key measures of modem performance (e.g. a 56 Kbps
modem)
 However, modem bit rates are not necessarily an accurate
reflection of their data throughput rates

Baud Rate
 Baud rate is a measure of the number of discrete signals that can
be transmitted (or received) per unit of time
 A modem’s baud rate measures the number of signals that it is
capable of transmitting (or receiving) per second
 Baud rate represents the number of times per second that a modem
can modulate (or demodulate) the carrier signal to represent bits
 Although baud rate and bit rate are sometimes used
interchangeably to refer to modem data transfer speeds, these
are only identical when each signal transmitted (or received)
represents a signal bit
 A modem’s bit rate is typically higher than its baud rate because
each signal transmitted or received may represent a combination of
two or more bits

Dibits, Tribits, Quadbits, and QAM
 Dibits are a transmission mode in which each signal conveys
two bits of data
 With tribits, each carrier signal modulation represents a 3-bit
combination
 Quadbits is a transmission mode in which each signal
represents a 4-bit combination. Sixteen distinct carrier signal
modulations are required for quadbits
 Phase modulation is common on today’s modems because it
lends itself well to the implementation of dibits, tribits, and
quadbits (see Figure 6-27)
 Quadrature amplitude modulation (QAM) is widely used in
today’s modems. Many versions of QAM represent far more than
4-bits per baud

Figure 6-27

Modem Capabilities
 Modems differ in several dimensions including:
The type of medium they can be connected to
(copper-based, fiber-optic, wireless)
Speed
Connection options (such as support for call
waiting)
Support for voice-over-data
Data compression algorithms
Security features (such as password controls or
callback)
Error detection and recovery mechanisms

Modem Speed
 Over time, the evolution of modem standards has corresponded
with increases in modem speeds (see Table 6-6)
 In 2002, V.92 is the newest modem standard
 V.92 is backward compatible with V.90 but is capable of upstream
data rates of 48,000
 Like V.90, V.92 modems leverage PCM for downstream links
 A variety of factors contribute to modem speed and data
throughput including:
 Adaptive line probing
 Dynamic speed shifts
 Fallback capabilities
 Fallforword capabilities
 Data compression

Table 6-6

Data Compression
 Modem data compression capabilities enable modems to have
data throughput rates greater than their maximum bit rates
 This is accomplished by substituting large strings of repeating
characters or bits with shorter codes
 The data compression process is illustrated in Figure 6-29
 Widely supported standards for data compression include (see
Table 6-7):
 V.42bis --- up to 4:1 compression using the Lempel Ziv algorithm
 MNP Class 5 --- supports 1.3:1 and 2:1 ratios (via Huffman encoding
and run-length encoding)
 MNP Class 7 – up to 3:1 compression
 V.44 --- capable of 20% to 100% improvements over V.42bis

Figure 6-29

Table 6-7

Error Detection and Recovery
 In order to ensure that data is not changed or lost
during transmission, error-detection and recovery
processes are standard aspects of modem operations
 The general process is as follows (see Figure 6-30)
 During handshaking, the modem pair determines the error
checking approach that will be used
 The sender sends the error-check along with the data
 The receiver calculates its own error-check on received data
and compares it to that transmitted by the sender
 If the receiver’s error-check matches the sender’s, no error is
detected; a mismatch indicates a transmission error
 Detected errors trigger error recovery mechanisms

Figure 6-30

Error Sources
 There are many sources of data
communication transmission errors including:
Signal attenuation
Impulse noise
Crosstalk
Echo
Phase jitter
Envelope delay distortion
White noise
Electromagnetic interference (EMI)

Error Impacts
 Errors cause bits to be changed (corrupted)
during transmission; without error-detection
mechanisms, erroneous data could be
received and used in application processing
 Figure 6-32 illustrates a transmission error
caused by noise
 Table 6-8 indicates that longer impulse noises
can corrupt multiple bits, especially as
transmission speed increases

Figure 6-32

Table 6-8

Error Prevention
 Error prevention approaches used in data
communications include:
Line conditioning
Adaptive protocols (such as adaptive line probing,
fallback, adaptive size packet assembly)
Shielding
Repeaters and amplifiers
Better equipment
Flow control
# RTS/CTS
# XON/OFF

Error Detection Approaches
 Error detection processes vary in complexity and
robustness. They include:
 Parity checking (see Table 6-9)
 Longitudinal redundancy checks (LRC) – see Table 6-10
 Checksums
 Cyclical redundancy checks (most widely used and robust)
# CRC-12
# CRC-16
# CRC-32
 Sequence checks
 Other approaches include check digits, hash totals, byte
counts, and character echoing

Table 6-9

Table 6-10

Error Recovery
 Automatic repeat request (ARQ) is the most widely used error-recovery
approach in data communications. In this approach, the receiver
requests retransmission if an error occurs. There are three major kinds
of ARQ:
 Discrete ARQ (aka stop-and-wait ARQ). Sender waits for an ACK or NAK
before transmitting another packet
 Continuous ARQ (aka go-back-N ARQ). Sender keeps transmitting until a
NAK is returned; sender retransmits that packet and all others after it
 Selective ARQ. Sender only retransmits packets with errors
 Forward error correction codes involve sending additional redundant
information with the data to enable receivers to correct some of the
errors they detect. Hamming code and Trellis Coded Modulation are
examples
 Error control/recovery standards include MNP Class 4, V.42, and LAP-M
(see Table 6-12)

Modem/Computer Communications
 One of the roles of communication software is to enable users to view
and modify modem settings (see Figure 6-33) such as:
 error control (see Figure 6-33a and Figure 6-33c)
 transmission speed (see Figure 6-33b)
 flow control (see Figure 6-33c)
 data compression (see Figure 6-33c)
 UART settings (see Figure 6-33d)
 Most communication software issues Hayes AT command set
instructions to modems
 When a user wants to establish a communication session over a dial-up
connection, communication software sends a setup string to the
modem.
 The setup string specifies what settings are to be used for
communicating with other modems and how the modem and
computer will interact.

Figure 6-33c

Special Purpose Modems
 A variety of special purpose modems are found in
data communication networks including:
 multiport modems
 short-haul modems
 modem eliminators
 fiber optic modems
 cable modems
 ISDN modems
 CSU/DSU

 Multiplexer De-Multiplexer (MUX)

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