12-wide area networking

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Wide Area Networking

WAN Concepts

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At the end of this lesson we will be able to

– Categorize WAN technology types and properties

Network+2009 – Objective 2.5

What we will cover

• WAN Concepts

– What is a WAN

– WAN Terminology

– Types of WANs

– WAN Media

– WAN bandwidth

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What is a WAN

Use Service Provider

Wider reach than LAN, up to global

Usually lower speed that LAN (exceptions)

WAN CONCEPTS

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WAN Terminology

Provider Network

DSU/CSU

Central Office ( CO ) Demarc

Local Loop Customer Premises Equipment ( CPE )

What are the types of WANs

Dedicated Synchronous serial

Packet-switched

Service Provider

Synchronous serial

Telco Circuit-switched

Asynchronous serial, ISDN

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WAN Media

Copper Cables

Fibre Optic

Cables

Wireless

WAN Bandwidth varies widely depending on the Service

56Kbps (Dial-up)

1.544 Mbps (T1)

44.736 Mbps (T3)

9.953Gbps (OC-192 )

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Review

WAN Concepts What is a WAN

WAN Terminology

Types of WANs

WAN Media

WAN bandwidth

SOHO WAN Services

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– Categorize SOHO WAN Services technology types and properties


What we will cover

• SOHO WAN Services

• POTS

• ISDN

• DSL

• Cable

• Satellite

• Wireless

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SMALL OFFICE HOME OFFICE (SOHO) WAN SERVICES

Public Switched Telephone Network (PSTN)

• Also Known as Plain Old Telephone Service (POTS)

Telco

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WAN using POTS

Modem Modem

Analog Analog

Telco

Integrated Services Digital Network (ISDN)

ISDN

Basic Rate Interface (BRI)

Primary Rate Interface (PRI)

All Digital Voice and Data Service

Over POTS Copper Lines

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ISDN Basic Rate Interface

Two 64 Kbps “B” (Bearer) Channels

One 16 Kbps “D” (Signaling)

Channel ISDN BRI

WAN Using ISDN BRI

NT-1 NT-1 Telco

Digital

NT-1 => Network Termination 1

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DIGITAL SUBSCRIBER LINE

What Is a DSL?

• Uses high transmission frequencies (up to 1 MHz)

• Technology for delivering high bandwidth over regular copper lines

• Connection between subscriber and CO

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DSL Connections

SOHO

ISP

Central Office

Low pass filters DSL

Modem

Maximum distance of 5,460m (18,000 feet)

DSLAM

Class 4 or 5 Switch

Internet

PSTN

How Does DSL Work?

• Downstream and upstream transmission

• Symmetrical and asymmetrical services

• Multiple xDSL variations

• Delivers data and voice signals simultaneously and transparently

• Provides an always-on data connection

• Bandwidth varies with distance

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DSL Variants

• DSL variants differ in:

– Nature - relationship between downstream and upstream rates

– Maximum data rate

– Line coding technology

– Data and voice support

– Maximum distance

DSL Variants Characteristics

DSL

Technology Nature

Max. Data

Rate (Down /

Up) [bps]

Data and

POTS

ADSL Asymmetric 8 M / 1 M Yes

VDSL

Symmetric

or

Asymmetric

52 M / 13 M Yes

IDSL Symmetric 144 k / 144 k No

SDSL Symmetric 768 k / 768 k No

HDSL Symmetric 2 M / 2 M No

G.SHDSL Symmetric 2.3 M / 2.3 M No

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Factors Affecting DSL maximum distance and speed

• Signal attenuation

• Line Condition

– Bridge tap

– Load coil

– Wire gauge

– Impedance mismatch

• Crosstalk and Interference

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DSL Distance Limitations

DSL Technology Max. Data Rate

(Down / Up) [bps] Max. Distance

[feet / km]

ADSL 8 M / 1 M 18,000 / 5.5

VDSL 52 M / 13 M 4,500 / 1.4

IDSL 144 k / 144 k 18,000 / 5.5

SDSL 768 k / 768 k 22,000 / 6.7

G.SHDSL 2.3 M / 2.3 M 28,000 / 8.5

• Maximum data rate and distance assume no impairments.

• Maximum data rate is achieved at shortest distance.

• Maximum distance is achieved at lowest data rate.

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CABLE SYSTEM

What is a Cable System?

• CATV originally meant “community antenna television.” This form of transmission shared TV signals.

• Modern cable systems use fiber and coaxial cable for signal transmission.

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Sending Data over Cable

• Data service runs between Cable Modem (CM) and Cable Modem Termination system (CMTS).

• Users on a segment share upstream and downstream bandwidth.

Cable System Benefits

• Cable is cost-effective because “broadcast” architecture is cascaded to users.

• Cable supports different services:

– Analog video

– Digital video

– Voice

– Data

• Inexpensive high-speed Internet access enables the application of advanced SOHO and teleworker deployments.

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WIRELESS WAN SERVICES

Satellite – Provides Internet access to remote sites

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Cellular Data Services

• GSM, GRPS, EDGE, EDVO, and HSPDA

Industrial Cellular Modem

USB

PCMCIA

Cell Phone

Wi-Fi – 802.11x

Wi-Fi ISP Tower

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Worldwide Interoperability for Microwave Access (WiMAX – 802.16)

• Non-Line-of-Sight (NLoS) coverage

• 3 to 10 Kilometer Range

• Up to 5 Mbps

Bas

e A

nte

nn

a

Clie

nt

An

ten

na WiMAX USB adaptor

Stand-alone WiMAX modem

Point-to-Point Wireless

Provides line-of-sight communications between sites

Typical: 1.6km to 16km (1 to 10 miles)

Records: 304km, Italy, 5GHz; 276km, Venezuela, 2.4GHz

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Review

Small Office Home Office (SOHO) WAN Services

PSTN

• POTS

• ISDN BRI

• xDSL Cable modem

Wireless

• Wi-Fi

• WiMAX

• Cellular

• Satellite

• Point-to-Point

Enterprise WAN Technology

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– Categorize Enterprise WAN Services types and properties


What we will cover

• Enterprise WAN Services

– T and E Carrier TDM

– ISDN PRI

– MPLS

– ATM

– SDH / SONET / OC-x

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T and E carrier Time Division Multiplexing

DS0

0 1 2 21 22 23

0 1 2 29 30 31

T-carrier and E-Carrier Systems

T-carrier E-carrier

64 kbit/s (DS0) (Single channel) 64 kbit/s

1.544 Mbit/s (DS1) (24 channels) (T1) 2.048 Mbit/s (32 channels) (E1)

44.736 Mbit/s (DS3) (672 Ch.) (T3) 34.368 Mbit/s (512 Ch.) (E3)

274.176 Mbit/s (DS4) (4032 Ch.) 139.264 Mbit/s (2048 Ch.) (E4)

400.352 Mbit/s (DS5) (5760 Ch.) 565.148 Mbit/s (8192 Ch.) (E5)

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T1 ISDN Primary Rate Interface provides 23 Digital Channels

1

23

Twenty-Three 64 Kbps “B” (Bearer) Channels

One 64 Kbps “D” (Signaling)

Channel ISDN PRI

E1 ISDN Primary Rate Interface provides 30 Digital Channels

1

30

Thirty 64 Kbps “B” (Bearer)

Channels

Two Special Timeslots TS0 = Framing and Synchronization TS16 = Signaling

E1 ISDN PRI

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Frame relay – Connect sites using Virtual Circuits

Virtual

Circuits

(VC)

HQ

Branch3

Branch1

Branch2

VC 1 : HQ => Branch1



Asynchronous Transfer Mode (ATM)

• Fixed sized, 53 byte cell

• 5-byte header and 48-byte payload

• Transports real-time Voice, Video, and Data

• Used in SONET/SDH backbone of PSTNs

• Many ADSL implementations also use ATM

Header

5 Bytes

Payload

48 Bytes

ATM Cell – 48 bytes

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Multiprotocol Label Switching (MPLS)

• Data Packets are assigned labels

• Packet-forwarding decisions based solely on

labels

• Allows end-to-end virtual links, using any

protocol, over any medium

Terms used with Fibre Optic Multiplexing Protocols

Synchronous Optical Networking (SONET)

• Synchronous Transport Signal (STS), SONET Frame Format

• Optical Carrier (OC), SONET Optical Carrier Level

Synchronous Digital Hierarchy (SDH)

• Synchronous Transport Module (STM), SDH Frame Format

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SONET/SDH Designations and bandwidths

SONET Optical Carrier Level

SONET Frame Format

SDH level and Frame Format

Payload (Mbps)

OC-1 STS-1 STM-0 50

OC-3 STS-3 STM-1 150

OC-12 STS-12 STM-4 601

OC-24 STS-24 – 1,202

OC-48 STS-48 STM-16 2,405

OC-192 STS-192 STM-64 9,621

OC-768 STS-768 STM-256 38,486

Choosing a WAN Service

• Availability

• Price

• Speed

• Reliability

• Delay and Jitter

• Symmetric/Asymmetric

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Review

Enterprise WAN Services E-1/T-1

ISDN PRI

Frame relay

ATM

MPLS

SDH/SONET/OC-x

Choosing a WAN Service

Network Address Translation

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In this lesson we will cover:

• Given a scenario, evaluate the proper use of the following addressing technologies and addressing schemes

Network+ 2009 – 1.4

Agenda

Addressing Technologies Public and Private Addresses Network Address Translation

Port Address Translation Static NAT Dynamic NAT Destination NAT (DNAT) SNAT

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WHAT ARE PRIVATE IP ADDRESSES?

Private IP Addresses for use within an organization

Private IP Addresses Ranges

From To

10.0.0.0 10.255.255.255 10.0.0.0/8

172.16.0.0 172.31.255.255 172.16.0.0/12

192.168.0.0 192.168.255.255 192.168.0.0/16

RFC 1918

Within organizations ONLY!

NOT on the Internet

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PUBLIC IP ADDRESSES

Public IP Addresses must be Globally Unique

• Obtain Public IP Address from ISP

or

• Internet Corporation for Assigned Names and Numbers (ICANN)

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Internet Corporation for Assigned Names and Numbers

• Non-profit corporation

• Responsibility for IP Address Space Allocation

ICANN Delegates to Regional Internet Registries

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If Private addresses cannot work on the Internet, that how can they communicate?

Network Address Translation

NAT SA:

Private IP Address

DA:

Public IP Address

SA:

Public IP Address

DA:

Public IP Address

Changed

UnChanged

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Outside Inside

NAT – Network Address Translation

SA

10.0.0.1 SA

171.68.50.80

Inside Local IPv4 Address

Inside Global IPv4 Address

10.0.0.1 171.68.50.80

10.0.0.2 171.68.50.81

10.0.0.1

10.0.0.2

NAT Table

Benefits of NAT

Conserves Public IP Addresses

Prevents Renumbering

Improves Security

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Inside

SA:SP

10.0.0.1:1501

10.0.0.1

10.0.0.2 10.0.0.3

10.0.0.2

SA:SP

10.0.0.2:1501

Outside

SA:SP

171.68.50.80:1501

SA:SP

171.68.50.80:1502

Port Address Translation

Inside Local Source Address & Port

Inside Global Source Address & Port

10.0.0.1:1501 171.68.50.80:1501

10.0.0.2:1501 171.68.50.80:1502

10.0.0.3:1502 171.68.50.80:1503

NAT Table

Static NAT – Static One-to-One Mapping of Private to Public address

Outside Inside

SA

10.0.0.3 SA

171.68.50.82

Inside Address Translated Address

10.0.0.3 171.68.50.82

10.0.0.3

NAT Table

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Dynamic NAT – Maps Private address to one of a Pool of Public IP addresses

Outside Inside

SA

10.0.0.1 SA

171.68.50.80

Inside Address Translated Address

10.0.0.2 171.68.50.80

10.0.0.3 171.68.50.82

10.0.0.4 172.68.50.81

10.0.0.2

10.0.0.3

NAT Table

SA

10.0.0.2 SA

171.68.50.82

SNAT – Acronym can mean many things

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Source NAT - counterpart of Destination NAT (DNAT)

Secure NAT (Microsoft)

Stateful NAT (Cisco)

Softwires NAT (IETF)

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Destination Network Address Translation (DNAT)

Used to publish a service located in a private network on a publicly accessible IP address

For example, you want public access to your web server but you want it to be located in your internal private address space.

Destination Network Address Translation (DNAT)

Outside Inside

DA

10.0.0.2 DA

171.68.50.80

10.0.0.2

NAT Table

Destination Address Translated Address

171.68.50.80 10.0.0.2

www

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Summary

• Private IP Addresses

• Pubic IP Addresses

• Network Address Translation

• Port Address Translation

• Static NAT, SNAT, DNAT

12-wide area networking

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