WAN and Remote Access Technologies

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24 Οκτ 2013 (πριν από 4 χρόνια και 19 μέρες)

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WAN and Remote
Access Technologies

Chapter 7

Topics


WAN Technologies:


Internet Access Technologies


Remote Access Protocols and services


Connections to servers

Remote Access Connection Configuration
Requirements


Two basic components:


A

remote computer and


A

remote access system on the network


Hardware Requirements


Modem


Configuring an Internal Modem


Understand IRQ,

I/O, and COM ports

Modems

Modulator/demodulator

Converts analog signal into digital data

Compatible with telephone system

V Dot Standards

ITU
Standard

Speed

V.32

9,600 bps synchronous; 4,800 bps asynchronous

V.32 bis

14.4 Kbps synchronous and asynchronous

V.34

28.8 Kbps

V.34 bis

33.6 Kbps

V.42

57.6 Kbps; specifies standards for error checking

V.42 bis

57.6 Kbps; specifies standards for compression

V.90

56 Kbps upstream; 33.6 Kbps downstream because
downstream data is modulated

Know

your available resources


Open Com ports


Open DMA channels


The UART type


Software Requirements

Resource Settings for COM1

I/O Address

IRQ

IRQ
, DMA and I/O Addresses

IRQ Assignments

0

=

System Timer

1

=

Keyboard

2

=

Cascade to IRQ 9

3

=

COM 2 & 4

4

=

COM 1 & 3

5

=

LPT 2

6

=

Floppy
-
Drive Controller

7

=

LPT 1

8

=

Real Time Clock

9

=

Cascade from IRQ 2

10

=

Available

11

=

Available

12

=

PS/2 Mouse

13

=

Math Coprocessor

14

=

Primary Hard
-
Drive Controller

15

=

Secondary Controller

DMA Assignments

0

=

free

1

=

free

2

=

Floppy Drive

3

=

LPT 1

4

=

Secondary DMA Controller

5

=

free

6

=

free

7

=

free

I/O Memory Addresses

COM 1

=

3F8h

COM 2

=

2F8h

COM 3

=

3E8h

COM 4

=

2E8h

LPT 1


=

378h

LPT 2


=

278h

Primary IDE

=

1F0h

Secondary IDE

=

170h

Floppy Drive

=

3F0h

Network Adapter

=

300
-

310

NetTech Solutions

POTS


POTS has many advantages,
including:


It is inexpensive to set up. Almost every
home in the United
States and Canada
has or can have a telephone
connection.


There are no LAN cabling costs.


Connections are available in many
countries throughout the world.

Remote Networking

Established connection mechanism

Network resources

PSTN

PSTN

o
r

PTOS

Modem

Modem

Remote
computer

Remote

access server

Remote Networking

Supports mobile or distant users

Controls amount of network that is
available

Provides network services

Email

File and print services

Database services

Remote Access Networking



Server provides security



All traffic from remote node passes through server

Remote

access server

PSTN

or

POTS

Modem

Modem

Remote
node

Remote Control Networking

Host client

Remote client

Host client should be a
dedicated machine

RAS Servers


Windows servers


Routing and Remote Access Services
(RRAS)


Available for Windows NT 4.0, Windows
2000 Server, Windows XP Professional,
and Windows Server 2003


Can use existing user accounts


Third
-
party servers


Perle


Citrix


Patton


Need to synchronize user accounts

Network Protocols


Transmission Control
Protocol/Internet Protocol (TCP/IP)


Internet Packet
eXchange

(IPX)


Point
-
to
-
Point Protocol (PPP)


Point
-
to
-
Point
Tunneling

Protocol
(PPTP)


Layer 2
Tunneling

Protocol (L2TP)

Public and Switched


Public:

for a fee, anyone can lease
the use of the network, without the
need to run cabling.


Switched
explains how the phone
system works.

Terms:


CO:

Central Office.


Demarc
:

Point

of control between


the user and the Telco.


Local Loop:

Region between the CO


and the
Demarc
.

Leased Data Lines

Telco network

Leased data lines

ISDN

ISDN adapter

ISDN switch

Subscriber

Telco

Packet

data network

Switched

data network

Private

line network

TA

NTU


Terminal Adapter


Network Termination Unit

ISDN Channels

B

B channel = Data

D channel = Change and control

BRI =

B

D

64K

64K

16K

23
B
ch
.

PRI =

D

64Kx23

64K


BRI has two B channels and one D channel.


Maximized throughput of 128Kbps


DSL

DSL modem

PSTN

Multiplexer

Customer

Telco

Local loop

phone line

Voice

Digital

DSL Hardware

Local

loop

Voice

DSL

splitter


DSL Modem

Customer
premises

Telco

PSTN

DSLAM

Digital

DSL

Data

Voice

DSL
network

Splitter

Cable Internet Access

Cable TV feed

TV signal

Cable modem

ISP

Frame Relay

Frame Relay

Bearer Services

(FRBS)

DCE

Customer
network

DTE

Clean carrier networks

Less error checking required

CSU/DSU

Frame Relay Access
Device (FRAD)

ES

ES

ES

ES

Another Frame Relay


Uses:


PVC Permanent


SVC Switched


CIR:


Committed

Information Rate


Up to 1.544Mbps

Virtual Circuits

Logical

connections

Permanent virtual circuits:

Provider network always on

Switched virtual circuits: Provider

network connects when needed

PVCs

DLCI=40

40 to 16

CIR=56 Kbps

Telco network is
always on.

DLCI=60

60 to 18

CIR=1.54 Mbps

DLCI=16

DLCI=20

DLCI=18

network1

network2

network3

network4

network5

SVCs

Telco network is normally off;
connections are switched on
when needed.

network1

network2

network3

network4

network5

The T
-
Carrier System

T
-
Carrier circuit

T1: 24 channels

T3: 672 channels

T
-
Carrier System



Fractional T uses only part of a T service

ATM

Fast 155 Mbps to 622 Mbps

Support data, voice, and video

53
-
byte cell

Built in quality of service

PVC or SVC

ATM

Endpoints

Data

Voice

Video

Public ATM network

Private ATM LAN

ATM switch

ATM Data

ATM Frame

Header

Payload

5 bytes

48 bytes

53 bytes

ATM Virtual Paths

1
2
3
4

Transmission

Path A

5
6
7
8

VP1

VP2

VC

SONET


Synchronous data transport
over fiber optic cable


Excellent bandwidth


Built
-
in fault recovery


Speeds up to 2.48
Gbps


OC and STS specifications


Self
-
healing dual
-
fiber ring

Optical Carrier (OC) System

OC
Specification

Number of
Channels

Data Rate

OC 1

810

51.84 Mbps

OC 3

2,430

155.52 Mbps

OC 9

7,290

466.56 Mbps

OC 12

9,720

622.08 Mbps

OC 18

14,580

933.12 Mbps

OC 24

19,440

1.244 Mbps

OC 36

26,160

1.866 Mbps

OC 48

2.488Gbps

OC 192

155,520

9.95 Mbps

SONET

Synchronous Optical
NETwork

Excellent bandwidth management

Built
-
in fault recovery

High bandwidth = 51.84 Mbps to 70
Gbps

Often used as a backbone for frame relay
and ATM

SONET Network Components

Broadband backbone network

Regional network

Integrated management

Collector ring

LAN

Routes between

regional networks

Joins multiple

collector rings

DCS to place customer’s
signal on ring

SONET Collector Ring

LAN

LAN

ATM

T
-
1

OC
-
3

SONET Regional Ring

Collector ring

Collector ring

OC
-
12

OC
-
3

OC
-
3

Pass through data

Drop
data

Add
data

Add/Drop
Mux

Fiber Distributed Data
Interface (
FDDI)

One ring carries data

One ring carries
control signals

FDDI Connectivity

DAS

SAS


Nodes are connected to the FDDI network
in one of two ways:


Dual attached stations (DAS)


Single attached station (SAS)

FDDI Failure Recovery

Auto
-
reconfiguration

Isolation

Remote Access Protocols


A remote access protocol manages the
connection between a remote computer
and a remote access server.


They include:


Serial Line Internet Protocol (SLIP)


Point
-
to
-
Point Protocol (PPP) and Point
-
to
-
Point Protocol over Ethernet (
PPPoE
)


Point
-
to
-
Point
Tunneling

Protocol (PPTP)


Layer 2
Tunneling

Protocol (L2TP)


Remote Access Services (RAS)


Remote Desktop Protocol (RDP)

Serial Line Internet Protocol (SLIP)


In 1984, students at the University of
California, Berkeley, developed SLIP
for UNIX as a way to transmit
TCP/IP over serial connections
(such as modem connections over
POTS).


SLIP does not support encrypted
passwords and therefore transmits
passwords in clear text, which is not
secure at all.


PPP


PPP is used to implement TCP/IP; it
is the protocol that establishes a
connection over point
-
to
-
point links
(for example, dial
-
up and dedicated
leased lines).


PPP uses the Link Control Protocol
(LCP) to communicate between PPP
client and host.


PPP uses LCP between client and
Host.

Configure

PPP in Vista

226
-
1234

Richard

************

RMFRED

PPPoE


This allows the authentication
methods of PPP to be used over
Ethernet and high
-
speed Internet
connections so individual users can
be authenticated for Internet access
over a shared medium like Ethernet
or DSL.

Point
-
to
-
Point
Tunneling

Protocol (PPTP)


PPTP is the Microsoft
-
created
protocol based on PPP.


It is used to create virtual
connections across the Internet using
TCP/IP and PPP so that two
networks can use the Internet as
their WAN link and yet retain private
network security.


PPTP is both simple and secure.

Configure

PPTP in Vista

209.89.29.40

Richard

***********

RMFRED

Layer 2
Tunneling

Protocol (L2TP)


Published in 1999 as proposed
standard
RFC 2661
, L2TP has its
origins primarily in two older
tunneling

protocols for PPP: Cisco's
Layer 2 Forwarding (L2F) and
Microsoft's
Point
-
to
-
Point
Tunneling

Protocol

(PPTP).

Tunneling

Carrier protocol (IP)
moves the data

ISP

Passenger protocol
enters the network

Passenger protocol
leaves the network

IP data

unencapsulated

IP data

encapsulated

Tunnel Types

ISP

Voluntary tunnel from end to end

ISP

Compulsory tunnel between routers
through public network

VPN in Windows 2003

Home

209.89.29.40

Remote Access Services (RAS)


RAS is used in smaller NT 4.0
networks where a dedicated dial
-
up
router is not practical or possible.


Windows 2000, however, comes with
the ability to share outbound
connections. This is set up with
Windows 2000’s RRAS utility.


Remote Desktop Protocol (RDP)


The Remote Desktop Protocol (RDP)
is very similar to the Independent
Computing Architecture (ICA)
protocol used by Citrix products.


It requires port 3389 to be open.


You can start RDP from the RUN line
using the
MSTSC

command.

Summary


Summary and


Exam

Essentials on page 309


Review Questions on page 310