Physical Layer Overview

Network CoE Training

Continuation with Physical Layer

Network CoE Training

Layered Model (Layer n talks to Layer n)

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Application

Application

Transport

Transport

Network

Network

Data Link

Data Link

Physical

Physical

OSI Model

Layer 7

Application

HTTP, FTP, IMAP

Layer 6

Presentation

asn.1, ASCII

Layer 5

Session

3-way handshake (TCP), Graceful close (TCP) iSCSI for SANs

Layer 4

Transport

TCP, UDP

Layer 3

Network

IPv4, IPv6, ICMP, BGP, OSPF

Layer 2

Data Link

Ethernet 802.3, 802.11

Layer 1

Physical

Fiber,Cat5, Modems, SONET, ADSL

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Course Outline

 Basics of Optical Fiber  Interfaces ƒ WAN Interfaces ƒ LAN Interfaces  Media Testing instruments  Modems

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Basics of Optical Fiber

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Fiber as transmission medium

 Core – thin g glass center of the fiber where light g travels.  Cladding – outer optical material surrounding the core  Buffer Coating – plastic coating that protects the fiber.

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Applications of Optical Fiber

 Telecommunications

 Local Area Networks

 Cable TV

 Optical Fiber Sensors

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Advantages of Optical Fiber over Copper

 Higher Information f Carrying Capacity  Less Signal Degradation  Less Expensive in terms of maintenance  Carries to longer distance without signal boosters  Thinner & Light Weight

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Type of Optical Fibers

 Single-mode fibers – used to transmit one signal per fiber (used in telephone and cable TV). They have small cores (around 9 microns in diameter) and transmit infra-red light from laser.

 Multi-mode fibers – used to transmit many signals per fiber (used in computer networks). They have larger cores (around 62.5 microns in diameter) and transmit infra-red infra red light from LED. LED

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Single Mode vs. Multimode

Single mode

Multi Mode

High transmission speed

Less transmission speed

Carries data to larger distances

Carries data to lesser distances

Less attenuation

More attenuation

Less distortion

Higher distortion

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Fiber physical transport technologies

 OC-3 ƒ A fiber optic line capable of 155 megabits per second (155,000K).

 OC-48 OC 48 ƒ A fiber optic line capable of 2400 megabits per second (2,400,000K).

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How Does Optical Fibre Transmit Light??

 Total Internal Reflection:

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Interfaces

Interfaces

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Interfaces

 WAN Interfaces

 LAN Interfaces

ƒ

V.24

ƒ RJ-45

ƒ

V.35

ƒ RJ-11

ƒ

X.21

ƒ

G.703

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ƒ BNC Connector C t

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WAN Interfaces

WAN Interfaces

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V. 24

 A ITU-T standard that defines the interchange circuits between DTE and DCE.  V.24 is a specification for single-ended communications that includes the definition of connector pin allocations. allocations  It is used together with V.28 to define a specification for serial asynchronous or synchronous communications.

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V.35

 Commonly used for synchronous communication  Commonly used for 56kbps and 64kbps data rates.  It is typically used between a modem and a multiplexor.

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X.21

 X.21 is a digital signaling interface recommended by ITU-T that includes specifications for DTE/DCE physical interface elements,

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G.703

¾ G.703 is a ITU-T standard for transmitting voice or data over digital carriers such as T1 and E1.

¾ G.703 G 703 service is typically used for interconnecting data communications equipment such as bridges, routers, and multiplexers.

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LAN Interfaces

LAN Interfaces f

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Registered Jack

 RJ-45 ƒ Registered jack (RJ) is a standardized physical interface for connecting telecommunications equipment (commonly, a LAN or computer p networking g equipment.

 RJ 11 ƒ RJ-11 is the standard connector utilized on 2-pair (4-wire) telephone wiring. HCL Confidential

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BNC Connector

 The BNC (Bayonet Neill-Concelman) connector is a very common type of RF connector used for terminating coaxial cable.

 They are used on both on cable interconnections and network cards

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Media Testing Instruments

Media Testing Instruments

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Pentascanner

 It tests following: g ƒ Wiremap test is used to identify physical errors of the installation; proper pin termination at each end, shorts between any two or more wires continuity to the remote end wires, end, split pairs pairs, crossed pairs, pairs reversed pairs, and any other mis-wiring.

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Pentascanner tests continued (1)…

 Propagation Delay The Propagation Delay test tests for the time it takes for the signal to be sent from one end and received by the other end. This time is measured in milliseconds nanoseconds and picoseconds milliseconds, picoseconds.  Cable Length The Cable Length test verifies that the cable from the transmitter to receiver does not exceed the maximum recommended distance of 100 meters in a 10/100/1000baseT[X] network.  Insertion or Attenuation loss Losses occuring due to characteristics of the media

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Pentascanner tests continued (2)…

 Return Loss Return Loss is the measurement of the amount of signal that is reflected back toward the transmitter. The reflection of the signal is caused by the variations of impedance in the connectors and cable and is usually attributed to a poorly terminated wire  Near-End Crosstalk (NEXT) Near-End Crosstalk (NEXT) is an error condition that describes the occurrence of a signal from one wire pair radiating to and interfering with the signal of another wire pair.

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BERT

 BERT or Bit Error Rate Tester is a testing method for digital communication circuits that uses pre-determined patterns of a sequence of logical ones or zeros.

 A BERT Tester consists of a test pattern generator and a receiver that can be set to the same pattern. Based on the response to the sent bit stream, error rate t is i calculated. l l t d

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OTDR

 An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber

 An OTDR injects a series of optical pulses into the fiber under test test. It also extracts, from the same end of the fiber, light that is scattered and reflected back from points in the fiber where the index of refraction changes h

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OTDR Continued…

 The strength of the return pulses is measured and integrated as a function of time, and is plotted as a function of fiber length.  An OTDR may be used for estimating the fiber's length and overall attenuation including splice and mated attenuation, mated-connector connector losses. losses It may also be used to locate faults, such as breaks.

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Modems

Modems

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MODEM

 Modem (from modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information.  The most familiar example is a modem that turns the digital 1s and 0s of a personal computer into sounds that can be transmitted over the telephone lines of Plain Old Telephone Systems (POTS), and once received on the other side side, converts those 1s and 0s back into a form used by a USB USB, Serial, or Network connection.

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Modem LED indicators

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ASM i52 Modem

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ASM i52 Modem

 PWR (green) –

Power

 DATA (yellow) –

Transmit data (except E1 or T1 interface)

 SYNC A/B (green/red) –

Sync status of DSL line

 E1 or T1 SYNC ( (red) d) –

L Loss ofE1 fE1 or T1 sync (E1 or T1interface T1i t f

only)  AIS (yellow) –

“All 1s” string is received (E1 or T1

interface only)  ALM (red) –

Alarm enters the buffer

 TST (red) –

Test in progress

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Connectivity using Modem

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RAD HTU-E1 Termination Units

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Multiplexers

 A multiplexer or MUX is a device that performs multiplexing i.e. selects one of many analog l or digital di it l input i t signals i l and d outputs t t that th t into i t a single i l line. li  An electronic multiplexer makes it possible for several signals to share one expensive device or other resource, for example one Analog to Digital converter or one communication line line, instead of having one device per input signal signal.  A multiplexer can be considered as a multiple-input, single-output switch

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De-multiplexer

 A demultiplexer (or demux) is a device taking a single input signal and selecting one of many data-output-lines.  A multiplexer is often used with a complementary demultiplexer on the receiving end.  A demultiplexer works as a single-input, multiple-output switch

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Integrated Services Digital Network

1. Integrated g Services Digital g Network. A digital g p phone service capable p of speeds from 64 K to 128 K. 2. Provides two data channels, each with its own phone number, making simultaneous voice and data possible. 3. Services offered by ISDN: 1. Digital Telephone and Fax -with a facility to identify the calling subscriber number and other facilities. 2. Data Transmission at 64 Kbps with ISDN controller card 3 Video Conferencing at 128 Kbps 3. 4. Video Conferencing at 384 Kbps (Possible with 3 ISDN lines)

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Types of ISDN Accesses There are two types of "accesses" (connections) for ISDN: ƒ Basic Rate Interface (BRI): 2B+D 2 Channels of 64 Kbps for Speech And Data. 1 Channel of 16 Kbps for Signaling ƒ Primary Rate Interface (PRI): 30 B+D 30 Channels of 64 Kbps for speech and data. 1 Channel Ch l off 64 Kbps Kb for f signaling. i li

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Leased Lines  To transmit data between computer and electronic information devices, different vendors provide data communication services to its subscribers. It offers a choice of high, medium and low speed leased data circuits as well as dial-up lines. 

Bandwidth is available on demand in most of the cities. Managed leased Line Network (MLLN) offers flexibility of providing circuits with speeds of n x 64 Kbps up to 2 Mbps which is useful for internet leased lines and international principle Leased Lines (IPLCs).

 Leased circuits are provided to subscribers for internal communication between their offices/factories at various sites within a city/town or different cities/town on point to point basis, or on a network basis interconnecting the various sites.

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SONET And SDH

 Synchronous optical networking (SONET) and Synchronous Digital Hierarchy (SDH), are two closely related multiplexing protocols for transferring multiple digital bit streams using lasers or light-emitting diodes ((LEDs)) over the same optical p fiber.

 The method was developed to replace the Plesiochronous Digital Hierarchy (PDH) system t ffor ttransporting ti llarger amounts t off ttelephone l h calls ll and dd data t traffic over the same fiber wire without synchronization problems.

 SDH or SONET may be utilized to allow several Internet Service Providers to share the same optical fiber,

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Optical Signal Hierarchy

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Hierarchy

Data Rate

SONET

SDH

OCx

Level Zero

155.52

STS-3

STM1

OC-3

Level One

622.08

STS-12

STM4

OC-12

Level Two

2488.32 Mbit/s

STS-48

STM16

OC-48

Level Three

9953.28 Mbit/s

STS-192

STM64

OC-192

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Optical Carrier Rates

Optical Carrier

Data Rate

PayloadSONET (SPE)

User Data Rate

SONET

SDH

OC-1

51.84 Mbit/s

50.112 Mbit/s

49.536

STS-1

--

OC-3

155.52 Mbit/s

150.336 Mbit/s

148.608

STS-3

STM-1

OC-9

466.56 Mbit/s

451.044 Mbit/s

445.824

STS-9

STM-3

OC-12

622.08 Mbit/s

601.344 Mbit/s

594.824

STS-12

STM-4

OC-18

933.12 Mbit/s

902.088 Mbit/s

891.648

STS-18

STM-6

OC-24

1244.16 Mbit/s

1202.784 Mbit/s

1188.864

STS-24

STM-8

OC-36

1866.24 Mbit/s

1804.176 Mbit/s

1783.296

STS-36

STM-12

OC-48

2488.32 Mbit/s

2.4 Gbps

2377.728

STS-48

STM-16

OC-192

9953.28 Mbit/s

9.6 Gbps

9510.912

STS-192

STM-64

OC-768

40Gbit/s

-

-

STS-768

STM-256

OC-3072

160Gbit/s

-

-

STS-3072

STM-1024

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Telecom and Network Speeds: -

We see network speed terms (e.g. T1, DS0, OC-192) all over the place. l Here H are the th details: d t il Tx: North American Signal Hierarchy e.g. T1, T3 etc. E European Ex: E Signal Si l Hierarchy Hi h e.g. E1, E1 E3 etc. t Optical Carrier Hierarchy for SONET and SDH: e.g. OC-1, OC-192 etc. Includes STS-x and STM-x definitions.

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North America Network Speeds Remember: a DS0 is 64K or 64,000 bits per second. Hierarchy

Speed

Digital

Carrier

DS0's

Notes

Signal

First Level

1.544 Mbit/s

DS1

T-1

24

In ISDN PRI = 23B (user) + 1D (signaling) channels

Intermediate

3.152 Mbit/s

DS1C

-

48

-

Second Level

6.312 Mbit/s

DS2

T-2

96

4 x DS1

Thi d L Third Levell

44 736 Mbit/s 44.736 Mbi /

DS3

T 3 T-3

672

28 x DS1

Intermediate Level

139.264 Mbit/s

DS4NA

?

2016

3 x DS3 Highest designed in ANSI T1.107

Fourth Level

274.176 Mbit/s

DS4

T-4

4032

Replaced with OCx

Fifth Level

400.352 Mbit/s

DS5

T-5

5760

Replaced with OCx

Level

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European Network Speeds

Hierarchy

Speed

Carrier

DS0's

Notes

First Level

2.048 2 048 Mbit/s

E-1

32

In ISDN PRI = 30B (user) + 2D (signaling) channels

Second Level

8.448 Mbit/s

E-2

128

-

Third Level

34.368 Mbit/s

E-3

512

-

Fourth Level

139.264 Mbit/s

E-4

2048

-

Fifth Level

565.148 Mbit/s

E-5

8192

-

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Summary table for Bandwidths

Speed

DS0's

North

Europe

Japan

America

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64 Kbps

1

-

-

-

1.544 Mbit/s

24

T-1

-

J-1

2 048 Mbit/ 2.048 Mbit/s

32

-

E 1 E-1

-

6.312 Mbit/s

96

T-2

-

J-2

7.786 Mbit/s

120

-

-

J-2 (alt)

8.448 Mbit/s

128

-

E-2

-

32.064 Mbit/s

480

-

-

J-3

34.368 Mbit/s

512

-

E-3

-

44.736 Mbit/s

672

T-3

-

-

97 728 Mbit/s 97.728

1440

-

-

J-4

139.264 Mbit/s

2016

DS4NA

-

-

139.264 Mbit/s

2048

-

E4

-

274.176 Mbit/s

4032

T-4

-

-

400.352 Mbit/s

5760

T-5

-

-

565.148 Mbit/s

8192

-

E-5

J-5

49

Thank You!

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