network training present

@2006 - 2007 All rights Created by Mr. Sopon Tumchota Contact at.. [email protected]

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


Basic Network Understanding … THE ISO’s OSI REFERENCE MODEL …

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



THE ISO’s OSI REFERENCE MODEL …

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


Basic Network Understanding … THE ISO’s OSI REFERENCE MODEL …

Application

Presentation

Session

Transport

Network

Data Link

Physical Options from CCITT, IEEE etc.

802-2 (LLC)

9314-2

FDDI

802-3CSMA/CD

802-4Token-Bus

802-5Token-Ring

7776X.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


Basic Network Understanding … 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)


Basic Network Understanding … 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

CCCC


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

LOCAL AREA 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

LOCAL AREA NETWORK


SAMPLE TOKEN RING LANs

Server1Server2

Server3

B

B

B

HU

B

HU

B

Ring 1Ring 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 dualcounter 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

LOCAL AREA 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

WW

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

LOCAL AREA 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.)

LOCAL AREA NETWORK

Ethernet Fast Ethernet


SAMPLE 100Base-T LANs

ETHERNET SWITCH

WW WK WW WKWW WK

Fast Ethernet SwitchHost A

100Mb

Host B

100Mb100 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.

Cabling System Structure

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


Network Cabling System Concept. Cabling System Structure

Horizontal Cabling System



Cabling System

Structure

Backbone Cabling

System



Cabling System StructureWork 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


Network Cabling System Concept. 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 ComputerNetwork 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 19930

10

20

30

40

50

60

70

80

90

100

1983 1986 1990 1993

YEAR

Year of Introduction

MIP

S

286 386486

PentiumIntel 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 95Intel 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 usersSERV.

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 ofBroadcast control

Security

Performance

Network management


Understanding Virtual LANs


Construction Basics

Using an Ethernet port-switching hub.

ServerS1

ServerS2

0 1

2 3 4 5 6 7

C1C2 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..

ServerS1

ServerS2

0 1

2 3 4 5 6 7

C1C2 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 vLANn

n

= Port n= MAC address


MAC-BASED SWITCHING

Moving stations when using a layer-2 vLANnn

= 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

nI

= 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

serverI

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 withthe Sponsor Group

Call for Interest and then,Study Group Formed

Project Authorization Requestto NesCom

Working Group Formed

Standards must be completedwithin 4 Years as of the PARapproval

Standards Review by RevCombefore the Sponsor Ballot

IEEE

IEEE-SA

Standards Board IEEE 802Sponsor Group

IEEE 802.3Working Group

IEEE 802.3aeTask Force

RevCom* NesCom**

Start Here!

End Here!

* Review Committee** New Standard Committee


10 GigE Standards Time Table

Study Group Formed (HSSG*)

802.3aeFormed

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 LANMMF 850nm Serial 25, 65, 300m

10GBase-SW WAN

10GBase-LR LANSMF

1310nm

Serial10km

10GBase-LW WAN

10GBase-ER LANSMF

1550nm

Serial40km

10GBase-EW WAN

10GBase-LX4 LANMMF 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

Reco

ncilia

tion

PCS

PM

A

XG

MII

WIS

(Optio

n)

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 GigERing

100Base-FXUp 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 ControllerMAC 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

InfraredSpread

SpectrumNarrow Band

Direct Sequence

FrequencyHopping

Wireless LAN technologies (overview)


Wireless LAN technologies (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


Wireless LAN technologies (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


Wireless LAN technologies (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 MethodsMultiple 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

Spread Spectrum Technologies 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)

Spread Spectrum Technologies 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

ComputerNetworking 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

http://www.globetrotting.com/tcpip/classa.htm


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

Class A 0 Network Host Host Host

Class B 1 0 Network Network Host Host

Class C 1 1 0 Network Network Network Host

Class D 1 1 1 0 Multicast Address Multicast Address Multicast Address Multicast Address

Class E 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

ServiceFASTLA

NE

S C I T E C

F5voice data packet bandwidth manager

Network

Control

Terminal

Ethernet LAN NET_A

N11

FASTL

ANE

S C I T E C


Ethernet LAN NET_B

N23

FASTL

ANE

S C I T E C


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

123.4.4.5123.4.4.4

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

IPv6Background


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)



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 mediaWhen 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)


Multiplexers

Telcom networks divided into 2 types:

Access network: attach to clients

Core network: connects access networks to each

other, provide services

Client/access interface: UNI (User/network

interface)

Access/core interface: SN (Service node interface)

or:

# NNI: Network-to-Network Interface


Network Terminology


Multiplexers

Maximizing bandwidth requires:# Multiplexing: combining information channels

# De-multiplexing: recovering original signals

3 basic techniques:# FDM, TDM and CDM

3 ways can be combined:# FDM and TDM

# Time-division Duplex:time slots alternate signal directionRequires guard tone to compensate for propagation

delay


Multiplexers

Multiplexing:

Channel bank: combine analog voice

signals using FDM (analog) or TDM (digital)

Multiplexer: device that combines digital

channels into a single TDM channel

FDM


Multiplexers

Remember: if multiplexer determines rate and time

of processing: synchronous

Statistical multiplexing

Inverse multiplexing

T-1/E-1 Carrier

Original form:

# Channel bank multiplexing (24/31 voice to 24/31, 64Kbps

PCM)

# Octet multiplexed to 1.544 /2 Mbps over 4 wires


Multiplexers

T-1/E-1:

# DS-1 is the speed designator

# Components

PBX to CSU to repeaters to CO

2-pair copper wire

AMI signaling

Max 50 miles (jitter)

Repeaters at 3000ft from CO and customer premises

6000ft. From repeater-repeater


Multiplexers

1st stage of multiplexing:

Convert voice/modem to digital pulse

# PCM (sampling) 64Kbs base 125uS sample

# 24 channel PCM (DS-1): (24) 8-bit samples each

125uS

# Compress-LPF-sample (PAM)-A/D(PCM)-mix with 23

more-convert binary to AMI at 1.544 Mbps

# 24-channel frame uses 1st bit of every frame for frame

(odd) and Multiframe (even) alignment

Multiframe is 12 frames


Multiplexers

PDH multiplexing: Plesiochronous digital hierarchy: (still in common use)

# Plesio = almost, close

# Synchronous multiplexers:Tributaries that have the same frequency AND each

are synchronized to a common clock

# Plesiochronous multiplexers:Tributaries have same nominal frequency and no

common clock

Drawback: no easy way to demultiplex channels (add/drop) between major points


Multiplexers

PDH multiplexing: Plesiochronous Digital

Hierarchy:

# 24 DS-0’s multiplexed=DS-1 (24 channels):

First order multiplexing

# (4) DS-1’s multiplexed=DS-2 (96 channels):

2nd order multiplexing

# (7) DS-2’s multiplexed=DS-3 (672 channels):

3rd order multiplexing

# (6) DS-3’s multiplexed=DS-4 (4032 channels)

4th order multiplexing


xDSL Technology

What is the xDSL

Is the Digital Subscriber line

xDSL are dedicated, point-to-point, public network

Multiple forms of data, voice, and video

Carried over twisted-pair copper wire

Supporting high-speed Internet/intranet access

xDSL are - ADSL, R-ADSL, HDSL, SDSL, and VDSL


xDSL Technology

Is the ADSL ? Is Asymmetric Digital Subscriber Line

It allows more bandwidth downstream

Than upstream from the subscriber

Always on access (which eliminates call setup)

Users of applications download much more information than they send.

Downstream, supports between 1.5 and 8 Mbps

Upstream, is between 640 Kbps and 1.54 Mbps

Provide 1.54 Mbps transmission up to 5.5Km over one-wire pair.

Optimal of 6 to 8 Mbps of 3 to 3.6 Km on 24 AWG wire.


xDSL Technology

Is the R-ADSL

Is Rate-Adaptive Digital Subscriber Line

Operates within the same rates as ADSL

Dynamically to varying lengths and

qualities of twisted-pair local access lines.


xDSL Technology

Is the HDSL

Is High Bit-Rate Digital Subscriber Line

HDSL technology is symmetric

Providing same bandwidth upstream&

downstream

Speed 1.544 Mbps over two pairs

Speed 2.048 Mbps over three pairs

HDSL’s 3.5 to 4.5 Km operating distance


xDSL Technology

Is the SDSL

Is Single-Line Digital Subscriber Line

Like HDSL, SDSL supports symmetrical

Single copper-pair wire

Maximum operating range of 3 km.


xDSL Technology

Is the VDSL

Is Very High Bit-Rate Digital Subscriber Line

Technology is the fastest xDSL

Supporting a downstream rate of 13 to 52 Mbps

Upstream rate of 1.5 to 2.3 Mbps

Single copper-pair wire

Operating distance is only 1,000 to 4,500 feet


xDSL Technology


Public Switched Telephone Network (PSTN)

Originally designed for telephone service

Also called plain old telephone service (POTS)

Dial-up connection uses a PSTN or other line to

access a remote server via modems at both the source

and destination

PSTN includes:

Central offices

Long-distance carriers

Points of presence

Subscriber wiring &

equipment

Demarcation point

Local loops


Public Switched Telephone Network (PSTN)

FIGURE - Typical PSTN connection to the Internet


Public Switched Telephone Network

Central office

Lines

Voice digitization

Numbering

Services


Telephone Set

Transmitter

Analog signal

Receiver

Sidetone

Switchhook

On-hook and off-hook

Dialing

Rotary dial

Dual-Tone-Multi-Frequency (DTMF)

Ringing

Call setup time


Central Office EquipmentManual switching

Electromechanical switching

Electronic switching# Reliable

# One total failure in 40 years

# Quite & efficient

# Less Labor costs with higher skill levels

FunctionsAT & T dynamic non hierarchical routing (DNHR)

# direct, redundancy, and alternate routing

# Maximum 4 toll office


Central Office Hierarchy

Class 5: local central office

Tandem office

Class 4: toll center

Class 3: primary center

Class 2: sectional center

Class 1 regional center


Lines

Local loop (pair of copper wires: tip and ring)

Drop wire

Distribution cable

Feeder cable

Trunk

Copper wire

Coaxial cable

Microwave radio

Fiber optic cable

Internet line usage problem


Voice Digitization Bandwidth

DS-0 with 64,000 bits/sec

T-1 with 24 Ds-0

Adaptive differential pulse code

modulation (ADPCM)

Need half of bandwidth for PCM

Used for voice compression with less

quality


Telephone Numbering

9 geographic zones in the entire world

Composition

Access code, carrier’s code,

Zone and country code

Area/city code

Exchange code

Subscriber code


Telephone Services - I

Types of calls

Local calling

Long distance calls

International calls

Operator services


Telephone Services - II

Calling card calls

Discounted calls

800 or 888 service

Geographic: interstate, intrastate,

international (Universal International

Freephone Numbering -UIFN)

Call direction: in, out, or both

900 service


Telephone Services - III

Software defined network (SDN)

Foreign exchange (FX) lines

Integrated Services Digital Network (ISDN)

Selection criteria for telephone service

Time

Duration

Number

Location Usage pattern

Usage pattern (busy hour)

1-5% (Blocking) grade service level


Dialup/ISDN Technology

Is ISDN

Integrated Services Digital Network (ISDN)

ISDN the digitization of the telephone

network

Permits voice, data, text, graphics, music,

video, and other

Is the Dialup Digital Network.



ISDN Devices

Terminal adapters (TAs),

Network termination (NT)



ISDN Service Type

ISDN Basic Rate Interface (BRI)

# Offers two B channels and one D channel

(2B+D).

# BRI B-channel service operates at 64 kbps

# BRI D-channel service operates at 16 kbps

ISDN Primary Rate Interface (PRI)

# 30 B channels plus one 64-kbps D channel

# Total interface rate of 2.048 Mbps.


Digital Data Networks

Digital lease at n x 64 Kbps

Dedicated High Speed access to internet

On-line transactions

Audio/Video - conferencing

Virtual Private Network (VPN)

Internetworking (connection Local Area

Networks - LANs)



DDN FeatureVery high reliability and data security

Fully-managed network service

Predetermined flat rate charging

Customer manageable VPN

Single point of contact

Guaranteed Quality of Service (Qos)

Burst Excess (BE) opportunity

Multi service platform

Wide range of service portfolio

High-speed access



LAN

Customer

Corporate Head Office

Copper

Lines

Router

Customer

Branch Office

ETC

Public Data Network

Customer

Branch Office

Copper

Lines

Router

LAN

DTU

LAN

Copper

Lines

Router

DTU

WAN

Cloud (LL

Service)



ETC

Public Data Network

Customer

Branch Office

Copper

Lines

DTU

Router

LANDTU

Router

LAN

ISP

INTERNET

Customer

Branch Office

WAN

(Frame Relay)

Copper Lines

DTU

Router

LAN



Customer

Branch Office

NON ISDN Telephone

ISDN

Switch

NT1

ETC

Digital Data Network

ISDN PRI

ISDN TERMINALISDN BRI

INTERNET

ISP

Customer Head Office

NT1

LAN

TA

NT1

ISDN Telephone

WAN

(ISDN SERVICE) TA


Frame-Relay Technology

IntroductionFrame Relay is a high-performance WAN protocol

Operates at the physical and data link layers of OSI

Is Packet-switched networks

Two techniques are packet-switching technology# Variable-length packets

# Statistical multiplexing

Frame Relay is a Layer 2 protocol suite

By CCITT Standard



Frame Relay Devices

Frame Relay WAN following two categories

# Data terminal equipment (DTE)

# Data circuit-terminating equipment (DCE)

DTE generally are

# personal computers, routers, and bridges

DCE are carrier-owned internetworking

# DCE equipment is to provide clocking

# Switching services in a network



Frame Relay Components

Frame Relay Virtual Circuits

# Switched Virtual Circuits

# Permanent Virtual Circuits

Data-Link Connection Identifier



Frame Relay Local Management Interface

Local Management Interface (LMI)

Is set of enhancements to Frame Relay

specification

LMI addressing extension gives Frame

Relay data-link connection identifier (DLCI)

values

synchronization Frame Relay DTE and DCE


ATM Switching


Background

ITU uses the words “Transfer Mode” to describe a technique that covers the aspects of transmission, multiplexing, and switching of information signals.

The Asynchronous Transfer Mode (ATM) is the ground on which Broadband ISDN (B-ISDN) is built.

ATM is used in the implementation of many networks worldwide for the transport of voice, data, and video information signals (multimedia).

Key concepts: Traffic-type prioritization

Statistical multiplexing


Defining ATM

ATM is a specific Packet Oriented Transfer Modebased on Asynchronous Time Division Multiplexingwith fixed length packets called Cells.

Each ATM cell is 53 bytes consisting of a Header and an Information Field (5 +48 bytes respectively).

The information field is carried transparently through the network (no processing or error check).

The header is used to identify cells belonging to the same virtual channel and to perform the appropriate routing.


Transmission Bandwidth Efficiency

h =Number of information bytes

Number of information bytes + number of overhead bytes

The transmission bandwidth efficiency is determined as:

48 48 444555

100

paddingHeader Field

Information Field

Information


Numerical Example

X Number of useful information bytes to transmit

L Information size of the packet in bytes

H Header size of the packet in bytes

For an information packet length of 100 bytes:

is rounded up to next integer HL

L

X

X

h

L

X

628931.0

5483

100

h


Another Example

HL

L

h

480.90566

48 5h



4800

0.90566100 48 5

h


ATM Transmission Bandwith Efficiency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 200 400 600 800 1000

Information Bytes

Eff

icie

nc

y

ATM Cell Efficiency


ATM Switching Networks

ATM Standard

User-to-Network Interface (UNI) 2.0

UNI 3.0

UNI 3.1

UNI 4.0

Public-Network Node Interface (P-NNI)

LAN Emulation (LANE)

Multiprotocol over ATM


ATM Switching Networks ATM Physical Interface Rates



ATM Devices and Network Environment

ATM Devices



ATM Devices and Network Environment

ATM Network Interfaces


Communication Path

OSI Reference Model

Application

Presentation

Session

Transport

Network

Data Link

Physical

Application

Presentation

Session

Transport

Network

Data Link

PhysicalBits

F A C Data Unit ( I Field ) FCS F

AP DataPH

Data UnitSH

Data UnitTH

Data UnitNH

AP DataAH

AP DataAP “X” AP “Y”


B-ISDN Protocol Reference Model (PRM)

Physical Layer

ATM Layer

Adaptation Layer

Higher Layers Higher Layers

Management Plane

Lay

er Man

agem

ent

Control Plane User Plane


The ATM Protocol Stack

Physical Layer

ATM Layer

ATM Adaptation Layer

ITU-T Rec. I.150, I.361, I.362, and I.363.


Physical Layer

(e.g. SDH)

SDH: Synchronous Digital Hierarchy

ATM: Asynchronous Transfer Mode

AAL: ATM Adaptation Layer

CS: Convergence Sublayer

SAR: Segmentation and Reassembly Sublayer

SSCS: Service Specific Convergence Sublayer

CPCS: Common Part Convergence Sublayer

ATM Relationship to OSI Model

Data Link Layer

(AAL & ATM)

Network Layer

(Client)

ATM

AAL SAR

CS CPCS

SSCS


ATM Network Interfaces

CA UNI UNINNI

NNI NNI

B

UNI

UNI: User-Network Interface

NNI: Network-Node Interface


Virtual Channels & Paths

Virtual Channel Connections (VCCs) are the basic switching units between end users on the network.

VCCs are also used for control signalling and network management functions.

Each VCC is capable of carrying a variable-rate full-duplex flow of cells.

VCCs between the same two points along a network are grouped into virtual path connections (VPCs).

VPCs are in turn multiplexed along a physical medium.


Transmission Path

VP

VP

VP

VC

VC

VC

VP

VP

VP

VC

VC

VC

VC,VP, and Transmission Path


VCC Structure

VCC

VP Link VP LinkVP Link

VP Switch VP Switch

VPC VPC

VC Switch

User 1 User 2


VP Switch

Virtual Path Switching

VCI 1

VCI 2

VCI 5

VCI 6

VCI 3

VCI 4

VPI 1

VPI 2

VPI 3

VPI 4

VPI 5

VPI 6VCI 1

VCI 2

VCI 5

VCI 6

VCI 3

VCI 4

VCI: Virtual Channel Identifier

VP: Virtual Path

VPI: Virtual Path Identifier


VC/VP Switching

VP Switch

VCI 1

VCI 2 VCI 3

VCI 4

VC Switch

VCI 1

VCI 2

VPI 1

VPI 4 VPI 5

VPI 2

VPI 3

VCI 1

VCI 2


ATM Service Categories

Constant Bit Rate (CBR)

Variable Bit rate Real time (rt-VBR)

Variable Bit Rate non-real time (nrt-VBR)

Available Bit Rate (ABR)

Unspecified Bit Rate (UBR)

The concept of dynamic bandwidth allocation


The ATM Physical Layer

Transmission Conversion

( TC )

Physical Medium

( PM )

PHY

ATM

AAL


Physical Layer Functions

Physical Medium (PM):Bit transmission capability, including bit alignment,

Line coding, Scrambling/descrambling, and

If necessary, electrical/optical conversion

Transmission Convergence (TC):Generation and recovery of transmission frames,

Transmission frame adaptation,

Cell delineation,

HEC sequence generation, and

Cell rate decoupling


PM Standards

Physical media standardised by the ATM

Forum include SDH/SONET, PDH, FDDI,

and xDSL.

The transmission media include twisted

pair, coaxial, multi-mode and single-

mode fibre.

ITU-T standards SDH (G.707, G.708,

G.709) and PDH (G.703).


The ATM Layer

Physical Layer

ATM Layer


The functional characteristics of the ATM layer is included in ITU-T Rec. I.150.

The detailed specification is in ITU-T Rec. I.361.


ATM Layer Functions

The characteristic features of the ATM layer

are independent of the physical medium.

The ATM layer performs the following

functions:

Cell Multiplexing

Cell Demultiplexing

VPI and VCI Translation

Cell Header Generation and Extraction

Generic Flow Control (GFC) at UNI


ATM Cell Structure

Information Field

48 octets

Header

5 octets

8 7 6 5 4 3 2 1

1

.

5

6

.

.

.

53

ATM Cell

53 octets

Bit

Octets are sent to line in an increasing order (i.e. octet 1, 2, ... etc.)

Within an octet, the bits

are sent in a decreasing

order starting with bit 8.

MSB


UNI Cell Header

HEC

CLPPTVCI

VCI

VCIVPI

VPIGFC

CLP Cell loss priority

GFC Generic flow control

HEC Header error control

NNI Network-node interface

PT Payload type

VCI Virtual channel identifier

VPI Virtual path identifier

UNI User-network interface


NNI Cell Header

HEC

CLPPTVCI

VCI

VCIVPI

VPI

CLP Cell loss priority

HEC Header error control

NNI Network-node interface

PT Payload type

VCI Virtual channel identifier

VPI Virtual path identifier

UNI User-network interface


VPI / VCI

Virtual Path Identifier / Virtual Channel

Identifier

Local only to each link

Will change as cell passes through switch

Index into lookup tables setup at

connection time


Payload Type

3 bits

bit 1

0 = user cell

1 = management cell

bit 3 in user cells

signalling bit

used to signal end of datagram in AAL5


Cell Loss Priority

1 bit

Switch must drop CLP=1 cells before

CLP=0 cells

Can be set by network

non-conforming cells

Can be set by application

lower priority cells


Header Error Control

Cyclic Redundancy Check

Calculated over 4 byte cell header

Can correct single bit and detect large

class of multiple bit errors

Recalculated at each hop in the ATM

network


The ATM Adaptation Layer

Physical Layer

ATM Layer


The functions the ATM Adaptation Layer are specified in ITU-T Rec. I.362 and I.363

(the latter is more detailed).


AAL General Functions

Adaptation of the ATM layer services to the higher protocol layers.

Mapping of the user services / control / management PDUs into the information field of ATM cells of a VC and vice versa.

Exchange of information between peer AAL entities.

Consists of two sublayers, SAR (segmentation & reassembly) and CS (conversion sublayer).

Different types of AAL to suit particular traffic: AAL 1, AAL 2, AAL 3/4, AAL 5


Connection

-lessConnection Oriented

VariableConstant

Not requiredRequired

AAL Service Classifications

Class DClass CClass BClass A

Connection mode

Bit rate

Timing relation

between source and

destination


Examples of Service Classes

Class A

circuit emulation (e.g. 2MB, 34MB data links),

digitised voice, or constant bit rate (CBR) video.

Class B

variable bit rate (VBR) video and audio.

Class C

connection-oriented data transfer.

Class D

connectionless data transfer.


AAL Architecture

ATM: Asynchronous Transfer Mode

AAL: ATM Adaptation Layer

CS: Convergence Sublayer

SAR: Segmentation and Reassembly Sublayer

SSCS: Service Specific Convergence Sublayer

CPCS: Common Part Convergence Sublayer

Physical Layer

ATM Layer

SAR

CPCS

SSCSCS

AAL


Functions Performed by AAL

Segmentation and reassembly of user information,

Handling of cell delay variation,

Handling of cell payload assembly delay,

Handling of lost and misinserted cells,

Source clock frequency recovery at the receiver,

Recovery of the source data structure at the receiver,

Monitoring of AAL-PCI for bit errors as well as handling those errors, and

Monitoring of the user information field for bit errors and possible corrective actions.


SAR Sublayer

At the transmitting side,

segmentation of the higher layer PDUs for insertion into the ATM cells information fields.

At the receiving side,

reassembly of the ATM cells information fields into higher layer PDUs.

The information field of an ATM cell being 48 octets.


User Data O/P User Data I/P

Segmentation

Reassembly

Transmit Side Receive Side

User Application

AAL

ATM Layer

Physical Layer

ATM

PHY


Conversion Sublayer

CS is service dependent that interfaces

with the the higher layer via a special

Service Access Point (SAP).

Different SAPs for higher layers can be

derived using different combinations of

SAR and CS.


AAL

ATM

PHY

User Application

SAP

Service Access Point

CSSAR


ATM Forum Contact

Worldwide Headquarters

2570 West El Camino Real, Suite 304

Mountain View, CA 94040-1313

+1.650.949.6700 Phone

+1.650.949.6705 Fax

Europe Office

Av. De Tervueren 402

1150 Brussels, Belguim

+32.2.761.66.77 Phone

+32.2.761.66.79 Fax

Asia-Pacific Office

Hamamatsucho Suzuki Building 3F

1-2-11, Hamamatsucho, Minato-ku

Tokyo 105-0013, Japan

+81.3.3438.3694 Phone

+81.3.3438.3698 Fax

Web site

www.atmforum.com


SDH/SONET Switching Networks

SDH & SONET

What is SDH/SONET ?

# Standard interface developed for the public network

# Multiplexing standard for optical fiber transmission

SONET = Synchronous Optical Network

# Refers to the system used within the U.S. and Canada

SDH = Synchronous Digital Hierarchy

# International community term (ITU-T recommendtions)



SDH goalsGoals

# Make it possible for different carrier to interwork

# Unify the U.S., European and Japanese digital system

# Provide a way to multiplex multiple digital signal togethers

# Provide support for operations, administration, and maintenace

Characteristics# Use single master clock to synchronize

# Bit stream can be a added or extracted directly

# Basic transmission rate = 155.52 Mbps



Synchronous Digital Hierarchy of

Layer Model



Container (C-n)

Is provided for each signal to be transport.

Virtual Container (VC-n)

Is made up from the thus container formed

together.

Tributary Unit (TU-n)

Addition a pointer indicating signal for VC-n.

Administrative Unit (AU-n)

Turn collection together into a VC and plus section

overhead for transport.


Network Elements

Nonstandard, Functional NamesTM: Terminal MuxADM: Add-Drop MuxDCC: Digital Cross Connect

(Wideband and Broadband)MN: Matched NodeD+R: Drop and Repeat

ADMTMDS1s

DS1s

MN MN

MNDCC

D+R

D+R

D+RMN


Topology Building Blocks

DCC

ADM

ADM

ADM

DCC

ADM

ADM

ADM 2 Fiber RingEach Line IsFull Duplex

DCC

ADM

ADM

ADM 4 Fiber RingEach Line IsFull Duplex

DCC

ADM

ADM

ADM

Uni- vs. Bi-Directional

All Traffic Runs Clockwise, vs Either Way


Technology Relationships

Synchronous Digital Hierarchy (SDH)

International Diffs - Terms, OH Fields

Rates: STS-N -> STM-N/3 For N>=3

SDL Proposal

Fix HDLC For High Speed Use

Pt-Pt Links Without SONET Overhead

WDM/DWDM:

More Capacity - Optical Routing For Redundancy

No Access To Lower-Level (I.e. DS1 Signals)


References

Telcordia (Bellcore) GR-253-CORE

ANSI T1.105 and T1.106

ITU-T G.707 and G.783

SONET, Walter J. Goralski, McGraw-Hill

Series on Computer Communications

RFC-1619 and Successor http://search.ietf.org/internet-drafts/draft-ietf-pppext-pppoversonet-update-

04.txt


Chapter 7

Computer Networking

Design Concept


Contents

Networking Design Structure

Option of Networking Design

Communication Noise System


Overview of Planning

Overview of planning and design

guidelines.

Understanding Basic Internetworking

Devices

Identifying & Selecting Internetworking

Capabilities


Devices


Understanding Basic Internetworking Devices



Capabilities



Capabilities

Choosing Internetworking Reliability

Options

Redundant Links Versus Meshed

Topologies

Redundant Power Systems

Fault-Tolerant Media Implementations

Backup Hardware



Capabilities


Identifying and Selecting Internetworking

Devices

Hubs (concentrators)

Bridges

Switches (Layer 2 or Layer 3)

Fast-Ethernet

Gigabit or ATM

Router


Sample Networking Design


Communication

Noise System


Noise Types

Thermal Noise

Inter-modulation Noise

Crosstalk Noise

Impulse Noise


Noise Types

Thermal noise

Results from thermal agitation of electrons in

a conductor.

It cannot be eliminated,

Depends on the…

temperature,

bandwidth,

uniformly distributed across the frequency

spectrum


Noise Types

Inter-modulation noise

Results when different frequencies same transmission media

Unwanted signals often appear at frequencies

Differences of the two frequencies


Noise Types

Crosstalk noise

Results from unwanted coupling between signal paths.

Hearing another conversation (faintly) on a telephone connection


Noise Types

Impulse noise

Electrical Power Surge,

Short lived disturbances Signaling,

Arrester lightning,


Chapter 8

Computer Network

Management System


Contents

Introduction to Network Management

Overview of NM Protocol

ICMP – PING

SGMP

HEMS

CMOT (CMIP over TCP/IP)

SNMP SNMP v1, v2 and V3


Introduction to

Network Management


Session coverage

Network Management Requirements

Entities in Network Management

Architecture issues in NM

Sample applications


Why NM?

Multitude of Network elements

Heterogeneity of Network elements

Geographical spread of network

Managing network applications


Using NM for

Network fault monitoring

Performance monitoring

Network accounting

Load and usage statistics

Network Provisioning

Configuration management


Network Elements

Virtually everything that can be connected to

network or can be interfaced with the system

Routers

LAN/WAN Switches

Modems

Printers

Servers

Applications


OSI Functional Areas

Fault Management

Accounting Management

Configuration Management

Security Management

Performance Management


NM reports

No: of links up/down on a specific router

Amount of throughput for a given link

No: of mails pending for delivery with mail server

No: of process running on the server

Routing table in the core router

And much more………..


How…?

Using an Open standard and

extensible protocol

Using a standard and extensible way

information base to store and retrieve

information


Throughput

Packet loss

Time Delay

Link Up/Down

Service running

No: of request

Information Base

Node Info.

No: of links

Link address

Devices attached

Static Information

Dynamic Information

Statistical Information


Management strategies

Distributed system – Split up the

network and run different management

systems

Centralized – Most applications run on

one machine

Hierarchical – A combination of both

centralized and distributed.


NM Entities

Monitoring Appln

Manager Function

Monitoring Appln

Manager Function

Agent function

Managed Objects

Agent function

Managed Objects

Monitoring Agent


NM Entities

Managed objects – Represents the resources and the information base contained

Agent function – Application that gathers monitors and gathers information about managed objects

Manager function – Provides monitoring and analysis of network resources

Monitoring agent – Generates summaries and statistical analysis. Part of Manager


Entities Interaction

Pull information from the devices

Push information to Manager

Trade-off analysis

Protocol overhead in pull and push

Computational and processing overhead at nodes

Robustness to network conditions

Response to changing network conditions


Overview

of

NM Protocols


Evolution

ICMP – PING

SGMP

HEMS

CMOT (CMIP over TCP/IP)

SNMP SNMP v1, v2 and V3


NM Standards

IETF Standards (Operations and

Management)

ISO Standard (CMIP)

IEEE Standard

OMG Standard for NM


TMN Process

OS1

OS2OSn

Data Communication Network

Xchange Tran Eq HFC EPAX Telephone

OS – Operations Systems


OSI - CMIP

GET

SET

CREATE

DELETE

NOTIFY


OSI

App. Service Elements (ASE) and protocols

Define service primitives, protocol and PDU for management operations

CMISE (Common Mgmt. Info. Service Element)Defines service elements used in communication

between service providers and users# Management Notification – reporting of an event

# Management Operation – define operation primitives


OSI

CMIP (Common Management Information Protocol)

Used by CMISE

Receives primitives from CMISE

Constructs Application PDU

Sends APDU to peer CMIP user


IP Management

SNMP Manager

UDP/IP

DLC Layer

SNMP Manager

UDP/IP

DLC Layer

Network or Internets

Management Process

Managed Resources

Managed Objects

SNMP Manager

SNMP Agent


SNMP Protocol

Application entities exchange messages using UDP datagrams

Supports other transport mechanisms also

Permitted access mode on variables are Read and Read Write

Messages are encoded using BER

Allows access to objects defined in MIB.


SNMP

Agent

UDP

IP Layer

DLC Layer

TCPSNMP

Agent

UDP

IP Layer

DLC Layer

TCP

SNMP

Agent

UDP

IP Layer

DLC Layer

TCP

MIB Store

Agent

SNMP

UDP

IPDLC Layer

Managing Process

Inter-network

Host System

RouterSwitch


Chapter 9

Computer Network

Security Concept


NETWORKSECURITY...


Security and its breaches…

Security a system is secure if it is

Security goals are achieved.

Components behaves as expected on it.

Breaches Interruption - System asset lost , unavailable or

unusable.

Interception - Unauthorized party gains access to asset.

Modification - Tampering with the asset.

Fabrication - counterfeit objects on computing system.


Security Goals and Vulnerabilities

Security Goals

Confidentiality - assets of a computing system accessible only by authorized user.Read only type of access like viewing, printing helps in privacy.

Integrity - modification only by authorized parties.

Precise, accurate, consistent assets.

Availability - assets are accessible to authorized parties.Timely response, fair allocation, fault tolerance, usability, controlled concurrency. (Denial of service attacks.)


The people involved…

Amateurs - fresh players of the game ,

disgruntled over a -ve work situation.

Crackers - breaking into unauthorized territory

without malicious intent.

Hackers - breaking into unauthorized territory

with malicious intent.

Career Criminals - people in the game for

money and have predefined targets.


Basic Encryption and Decryption

Encryption - process of encoding a message so that its meaning is not obvious.

Decryption - process of decoding the encrypted message.

Cryptography - Hidden writing, which conceals meaningful text.

Cryptanalyst - studies encryption and finds hidden messages.

Cryptanalysis attempt to break a single message. Recognize patterns in encrypted messages to break into

subproblems by straightforward decryption algorithm.

Find weakness in encryption algorithms.


Contd…

Encryption with Keys

Encryption DecryptionPlain Text Cipher Text Original Text

Encryption Key (Ke)

(Asymmetric Cryptosystem)

Decryption Key (Kd)

Encryption with Keys


Key

(Symmetric Cryptosystem)


Encryption


Encryption

Substitutions - one letter x-changed for other.

Monoalphabetic Ciphers.

# Caesar Cipher

Example: Plaintext:ABCDEFGHIJKLMNOPQRSTUVWXYZ

Cipher :DEFGHIJKLMNOPQRSTUVWXYZABC

Polyalphabetic Ciphers.

# Frequency distribution reflects the underlying letters.Table for Odd Positions

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A D G J M P S V Y B E H K N Q T W Z C F I L O R U XTable for Even Positions

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

N S X C H M R W B G L Q V A F K P U Z E J O T Y D ITable for Odd Positions


Contd…

Transposition - letters of message rearranged.GOAL - Diffusion

Example:

C1 C2 C3 C4 C5

C6 C7 C8 C9 C10

C11 C12 etc.

The resulting cipher text will be

C1 C2 C3 C4 C5

C6 C7 C8 C9 C10

C11 C12 etc.


Authentication in Distributed Systems

Kerberos

User

U

Kerberos

Server

Ticket Granting

Server

1. U’s Identity

Session key

SG

Ticket TG

2. Encrypted under

Password

Session

key SG

2. Encrypted under

KS-TGS Key

Initiating a Kerberos Session


Contd..

Obtaining a ticket to access a file

User

U

Ticket Granting

Server

1. Request to Access

File F

2.Encrypted under

TGS - F Key + SF

Ticket to File Server

to access File F + SF


Why Kerberos is not the perfect Answer?

Kerberos requires the availability of continuous

trusted “Ticket Granting Server ”.

Trusted relationship required between TGS and every

server.

Requires timely transactions.

Subverted workstation can save and later replay user

passwords.

Password guessing works.

Does not scale well.


Firewalls

Process that filters all traffic between a protected or “inside ” network and a less trustworthy or an

“outside” network.

Special form reference monitor.

That which is not expressly forbidden is permitted.

That which is expressly forbidden is not permitted.

Challenge of protecting a network with a firewall is determining the security policy that meets the need of the installation.


Types of Firewalls

Screening Router.

Address

192.19.33.0

Address

144.27.5.3

Address

100.24.4.0

Allow in only A.

Allow out only B , C.

A

B

C


Contd …

Route Screening outside Addresses

Screening

Router

Subnet 100.50.25.x

100.50.25.1 100.50.25.2

100.50.25.x100.50.25.3


Contd …

Proxy Gateway Two headed piece of software.

runs pseudo applications.

Local Area Network

Remote Access

WWW AccessLogging

Remote File

Fetches

Address


Contd …

Guard sophisticated proxy firewall.

Receives PDU’s interprets them passes the through same or different PDU’s.

Screening

Router

Proxy

Firewall

Address


Comparisons of Firewall types

Screening Router1.Simplest.

2.Sees only address and

service protocol type.

3.Auditing difficult.

4.Screens based on

connection rules.

5.Complex addressing

rules can make

configuration tricky.

Proxy Gateway1.Somewhat complex.

2.Sees full text of

communication.

3.Can audit activity.

4.Screens based on

behavior of proxies.

5.Simple proxies can

substitute for complex

addressing rules

Guard1.Most Complex.

2.Sees full text of

communication.

3.Can audit activity.

4.Screens based on

interpretation of

message content.

5.Complex guard

functionality can

limit assurance.


Conclusions

Risks are involved in Computing.

Various techniques Encryption, Digital

Signatures, Firewalls, etc can be used

to provide security.

Web security is not a “Win” or “Loose”

there is just a degree to which it can be

realized.

No Solution is a complete solution !!!


Chapter 10

NOS (Network Operating System)


Contents

NOS Fundamentals

Clients

Server

Client – Server

Linux/Unix Server NOS


Why a NOS?

Network tools can be added to an operating

system

A key component of the way the system

A network may be viewed as a collection of

computers or as a collection of resources

A NOS to give transparent access to shared

resources


Networking Fundamentals

Network consists of:Servers – provides services

Clients – requests services

Peers – both requests and provides services

Types of networksServer-centric networks

Peer-to-peer networks



Network ServicesFile services

Print services

Message services

Applications services



Network Operating System (NOS)Two parts:

# System software that runs on the server

# Client software on each workstation

Examples# Banyan Vines

# Novell NetWare

# Microsoft LAN Manager

# LANtastic


Client model

What do clients want?

Simple, efficient access to shared resources

Data security (e.g. RAID)

Data integrity (e.g. clustering)

Often uses “directory services” idea

unified resource naming

hierarchical organisation of objects

Improves on “servers and terminals” structure


Peer-to-Peer model

Cheaper and simpler than client-server model

Supports basic file and printer sharing

May support other resource sharing

Some administration tools

Simple security measures

Good for connecting small numbers of

personal computers together


Review of Server Systems

Some common client-server systems

Novell Netware

Many of UNIX

Linux (very light-weight UNIX-like NOS)

Windows 2000 Server

Windows NT Server

Windows XP Server

Windows Server 2003



Novell NetwareFamous for NDS, the Network Directory Services

NDS is a global database of all network resources, hierarchically structured, searchable, secure and robust

Good for lower overheads on servers than Microsoft’s “Active Directory”

Good support for very thin clients

Netware was very well established in large organisations but seems to be losing market share to NT/Win2000 and to UNIX



UNIX was developed for

Platform independence

Inter-platform compatibility (but see below)

Network interoperability

Bell Labs, the parent company, was not allowed to

sell UNIX (US anti-monopoly laws)

Different groups developed new

About 20 incompatible versions now!



UNIX has been around on minicomputers and

mainframes since the early 70’s

It is a good server OS for networks with

Rich utility sets – client services, logging,

administration, security, backup, reliability

Enterprise-scale applications (e.g. RDB’s)



Windows NT/2000/XP/2003 Server

Relatively late entry into the corporate server

market

Seen as the least stable and least secure option by

many

Has some advantages – good performance in many

areas, excellent software support

Has a big chunk of the market


Review of Peer-to-Peer Systems

The common peer networking OS is Windows

Windows 3.11 for Workgroups (1992)Allowed mapped network drives

Allowed directory sharing

Windows 95 (1995)Partially 32-bit, so had protected memory – secure

Supported long file names, printer sharing

Could connect to Novell Netware



Windows 98 (1998)

Better support for Novell Netware

Support for Novell’s NDS – Network

Directory Services

Very limited server capabilities

Still almost no security measures

Last of the “Personal Operating Systems”



NT Workstation 4.0 (around 1996-1997)

More robust than Windows 9x

Relatively secure log-in procedure

Support for NTFS with built-in file-level security

and access logging

Different types of user (Administrators, Users,

Power Users etc.)

Robust pre-emptive multitasking



Windows 2000 (1998-2000)

Adds support for plug-and-play

Adds power management

Improves file system security and has more flexibility

in NTFS

Better support for peripherals than NT4

Windows XP (2001)

Ease of use (but poor compatibility with Win 9x)


Conclusion

We have seen

Why Network Operating Systems are key to modern

computer usage

Some Client-Server model concepts

Some Peer-to-Peer model concepts

Operating systems from the past and present with

networking support

A little of the history and development of the NOS


I Think are you fun,

for

Network learning, and

more in the future.

Good Luck…. See You

network training present

Education

sopon tumchota contact

capabilities of rs

eia standard

internetwork trainingwelcome

signalsthe prevalence

dnew version of rs

asynchronous transmission

timing draft