Lecture 2

Agenda

1. QUIZ 2. HOMEWORK LAST CLASS 3. HOMEWORK NEXT CLASS 4. dBs, NYQUIST & SHANNON 5. NOISE 6. TRANSISSION LINES 7. FIBER 8. ISDN 9. DSL10. Cable Modems11. LANS & MANS

Homework Last Week

Engineering GroupNetwork Planning and Design

Operations GroupNOC

Network Operations

I & M GroupNetwork Installation

and Maintenance

Network

Fault TT

Installation

Performance & Traffic Data

New Technology

ManagementDecision

Users

TT Restoration

Configuration Data

InternetCentralManager

Centralized Architecture

CentralDatabase

Homework Centralized Arch

Engineering GroupNetwork Planning and Design

Operations GroupNOC

Network Operations

I & M GroupNetwork Installation

and Maintenance

Network

Fault TT

Installation

Performance & Traffic DataLatency, Capacity & Avail-ability summaries

New Technology

ManagementDecision

Users

TT Restoration

Configuration Data

Accounting Management Data Security Management Data

Internet

NetworkManagementServer

Hierarchial Architecture

DBMS

NetworkManagementClient

NetworkManagementClient

NetworkManagementClient

Internet

ReplicationComm

Distributed Architecture

DBMSDBMSDBMS

DBMS

Physical/Data Link/Network/ Layers?

Response time of a transaction:RT = (i) N(i) S(i)

N(i) = Number of times service i is needed S(i) = Time needed for completion of service i

Server i utilization:U(i) = A(i) S(i)

A(i) = Arrival rate of requests for service i

Queue length at server i:

Q(i) = U

Ui

i

()

()1

Homework-P 1 of 3

A company has a corporate network which consists of fiveEthernet LANs connected to a mainframe through 56 KBpslines. Each LAN has about 20 workstations which generate one message per second. Each message is 1000 bytes (8bits per byte). Most workstations interact with each other on their LANs with only 20% of the messages being sent to themainframe. The messages sent to the mainframe access a corporate database which services 50 I/O per second. Howmuch of a congestion problem exists on the LAN, the WAN and the mainframe database.

Homework P 2 of 3

An Advise To The Lovelorn database operates on a T-1 line.The average input is 1000 bytes of questions. The average output has 1Million bytes of answers. Database processing time averages 3 seconds. What is the total response time if you assume 8 bits per byte.

Homework P 3 of 3

Ping ns1.bangla.net. How many packets were lost?What was the response time?Now do a trace rout and see how many hops it takes to get to get to ns1.bangla.net.

Decibells & Logarithms

Converting watts to dB (or milliwatts to dBm): 10 log10 1000 watts = 30 dBw

Converting dB to watts (or dBm to milliwatts):30 dBw = log-1, or log-1 (3) or 10 raised

to the 3rd power = 103 = 1000 watts

35 dBw = 103.5 = 3162.3 watts

Note: There’s a point between the 3 & 5.

Decibells & Logarithms

dBW Watts -3 .5 0 1 3 2 6 4 9 8 10 10 20 100 30 1000 40 10000

Physical Layer

Nyquist1. Nyquist: The maximum practical data rate (samples) per channel.

Max R = 2 H log2 V

Logarithmic function to the base 2: For each # V, log V = the exponent to which 2 must be raised to produce V. Then if V = 16, the log2 of V = 4. If V = 2, the log2 of V = 1.

Then what is the maximum practical data rate for BPSK signal on a line with a bandwidth of 3000 Hz?

What is the maximum practical data rate for a QPSK signal on a line with a bandwidth of 3000 Hz?

Shannon

Shannon: The maximum theoretical data rate per channel.

Max R = CBW x log2 (1 + S/N)

[CBW = H in Nyquist Theorem]

Then what is the maximum practical data rate for signal with a 30 dB S/N on a line with a bandwidth of 3000 Hz?

Noise

T = SNT = System Noise Temperature

No = Noise Density = kT, where k is Boltzmann’s Constant (-228.6 dBw)

N = Noise Power = kTB, where B is bandwidth.

Transmission Lines

We understand transmission lines by oversimplifying them:a. Lump all resistances into a single large resistance.b. Lump all inductances into a single large inductance.c. Lump all capacitances into a single large capacitance.d. Lump all conductance (leakage) into a single large conductance.e. Assume perfectly uniform construction and perfect symmetry so it looks exactly the same from both ends.f. Lump all of the above into a simple impedance network and assume stability.

Transmission Lines

. Transmission Line Impedance:

Zo = LC = Induc ce

Capaci ce

tan

tan =E

Ii

i = IncidentVoltage

IncidentCurrent

Transmission Lines

Impedance mismatches (impedance of load does not equalimpedance of the line) result in a standing wave ratio (how muchenergy is reflected back to the transmitter).

Transmission Line Standing Wave Ratio:

SWR = E

Emax

min = I

Imax

min = Z

Zmax

min

Transmission Line Connector Distortion

Normal Power Level: - 120 dBmProblem Power Level +/- 10 dB

Linear Non-Linear

Fiber Optics

Attenuation: Light loss due to both scattering and absorption.

Absorption: The amount of light loss due to its conversion to heat.

Scattering: The disappearance of light due to its leaving the core of of a fiber.

Chromatic dispersion: The tendency of a fiber to cause slightly differing wavelengths of emitted light to travel through the fiber at different speeds.

(See Handout)

Integrated Services Digital Network (ISDN) Standard

1. A major TELCO attempt to integrate voice and non-voice services.2. Integrated multiple channels interleaved with time division multiplexing.

A - 4 KHz analog telephone channelB - 64 Kbps digital PCM channel for voice or dataC - 8 or 16 Kbps digital channelD - 16 Kbps digital channel for out of band signallingE - 64 Kbps channel for internal ISDN signallingH - 384, 1536, or 1920 Kbps digital channel

Basic Rate = 2B + 1D (the nominal 128 frequently used in homes)Primary Rate = 23 B + 1D

Integrated Services Digital Network (ISDN) Standard

TE 1 ISDN Terminal

TE 1 ISDN Telephone

Non-ISDN Terminal

TA

S

S

S

R

ISDN PBX

NT1 ISDNExchange

T U

R, S, T & U are CCITT defined reference PointsTA is terminal adapter

Digital Subscriber Line (DSL) Standard

Drivers:• ISDN didn’t capture significant market share for TELCOs• Higher speed applications require new technologies• Users want to stay connected longer• High cost of converting infrastructure• Telephone lines weren’t designed to provide simultaneous digital and analog services• Competition from satellite (e.g., DirectTV/Direct PC) & cable industry

Digital Subscriber Line (DSL) Standard Services

Type DSL SpeedAsymmetric DSL 1.5 to 8 Mbps to user

16 to 640 Kbps to networkHigh-data-rate DSL 1.544 Mbps to and from userSingle-line DSL 768 Kbps full duplex on a pairRate-adaptive DSL 1.5 to 8 Mbps to user

16 to 640 Kbps to network(can adjust speeds)

Consumer DSL 1 Mbps to user16 to 128 Kbps to network(does not include splitter)

ISDN DSL Basic ISDN rateVery-high-data-rate DSL 13 to 52 Mbps to user

1.5 to 6 Mbps to network

DSL Rates (using 24 gauge wire)

Connection Max Data Rate Distance LimitADSL 1.5-8 Mbps downstream 12-18 K feet

Up to 1.544 Mbps upstream

HDSL T1 - 1.544 Mbps (4 wire) 12,000 feet

IDSL 144 Kbps (symmetric) 18,000 feet (36 w rptr)

SDSL T1 - 1.544 Mbps (2 wire) 11,000 feet

VDSL 13-52 Mbps downstream 1-4.5 K feet 1.5-2.3 Mbps upstream Up to 34 Mbps Symmetric

R-ADSL 1.5-8 Mbps downstream 12-18 K feet Up to 1.544 Mbps upstream

DSL Network Configuration

Asymmetric DSL

Characteristics • Uses frequency division multiplex occupying spectrum above voice• Principal modulation scheme is Discrete multitone (DMT), a quadrature amplitude modulation coding technique developed by Bell Labs (ANSI T1.413 standard)• Can be mapped into higher layer protocol mechanisms that can include IP frames or ATM cells• Can interface to Simple Network Management Protocol (SNMP) for operations, administration and management

0-4 KHz 25KHz 200KHz 1.1MHz

To Network To User

Cable Modem DSL Access

Cable Modem Access

0

10

20

30

40

50

Mill

ion

Lin

es

1998 1999 2000 2001 2002 2003 2004

DSL Market

DSL Roll-Out

TeleChoice

1999 2000 2001 2002 2003 2004 2005

50

40

30

20

10

0

Mil

lion

s of

Lin

es

Simplified xDSL Architecture

PSTN

Fast Packet

Internet

Local Loop

Splitter

Voice Switch

DSLAM

ISPRouter

The transparent network …

Ideally, the network is transparenttransparent — the end user simply wants to get information to or from a remote location

Applicatione-business

Content ProviderEnterprise Host

End UserBusiness orResidential

…isn’t really so transparent

But today’s reality is that the transparent network is a complex value chaincomplex value chain of individual networks

NSPNSPNSPNSPNSPNSPNSPNSP

LECLECLECLEC

NAPNAPNAPNAP

BackboneBackboneBackboneBackbone

BackboneBackboneBackboneBackbone

BackboneBackboneBackboneBackbone

BackboneBackboneBackboneBackboneTransportTransportTransportTransport TransportTransportTransportTransport

E-businessE-businessE-businessE-business

LECLECLECLEC

ConsumerResidentialBusiness

Applicatione-business

Content Provider

Applicatione-business

Content Provider

PSINetPSINetPSINetPSINet

AOLAOLAOLAOL

XYZXYZXYZXYZ

The Value Chain

ConsumerResidentialBusiness

Applicatione-business

Content Provider

SBCSBCSBCSBC

SprintSprintSprintSprint

GTEIGTEIGTEIGTEI

New EdgeNew EdgeNew EdgeNew Edge

UUNetUUNetUUNetUUNetWilliamsWilliamsWilliamsWilliams QwestQwestQwestQwest

eBayeBayeBayeBay

The players in this value chain have many names and may be linked in different configurations

GTEGTEGTEGTE

Applicatione-business

Content Provider

PSINetPSINetPSINetPSINet

AOLAOLAOLAOL

XYZXYZXYZXYZ

The Value ChainConsumerResidentialBusiness

Applicatione-business

Content Provider

Applicatione-business

Content Provider

SBCSBCSBCSBC

SprintSprintSprintSprint

GTEIGTEIGTEIGTEI

New EdgeNew EdgeNew EdgeNew Edge

UUNetUUNetUUNetUUNetWilliamsWilliamsWilliamsWilliams QwestQwestQwestQwest

eBayeBayeBayeBay

These value chains are held together by very thin threadsthin threads of linkages between legacy operations support systems (OSSs) and a lot of manual processesmanual processes

GTEGTEGTEGTE

Serving CO

Who Fixes The Network?

Hub office

DSLAM

ADM

DWDM

Internet

DWDM

ATMNetwork

VerizonILEC Verizon ILEC

Worldcom

VerizonAdvanced

Data Verizon Advanced Data

VerizonAdvanced

Data

AOL

AOL

ADM

ADM

ADM

LEC NAP LEC NAP

BackboneNAPNSPApplicatione-business

Content Provider

Providers Ask Two Pivotal Questions

Is the network service up Is the network service up

and running properly?and running properly?

If it’s not, where’s the If it’s not, where’s the problemproblem

and how do we fix itand how do we fix it??

LEC

The Answer...

Providers must tightly link their operations with their trading trading partnerspartners through integratedintegrated service assurance service assurance

NAP

NSP

Service Assurance Market

Test & Measurement

Test & Measurement

OperationsSupportSystems

OperationsSupportSystems

Service AssuranceService AssuranceService AssuranceService Assurance

• $3.5B* in 2000$8.4B* in 2004

• Growing at 25%

• Includes OSS software, services, and remote probes

• Key players: Spirent Communications, Telcordia, Lucent, Acterna (TTC/WWG), Micromuse

* RHK Estimates

Service Assurance Activities

Monitor SLAsMonitor SLAs

ReportReport

Allocate ResourcesAllocate Resources

Determine SLA ViolationsDetermine SLA Violations

TestTest

Isolate Root CauseIsolate Root Cause

Detect Alarms/EventsDetect Alarms/Events

Detect Performance/Traffic ProblemsDetect Performance/Traffic Problems

Decide RepairDecide Repair

Network “Communication” is Key

Need to provide service information within and between networks

LEC

NAP

NSP

Outsourcing Net Mgt

• IT Spending averages 3% of revenue & revenue is down• No outsourcer will meet all the needs of your business or agency• The annual cost of 9 networking and 6 help desk staffers averages $1.08 million (including benefits)• Four vendors investigated that cost approximately $350,000 to $500,000• Worth while thoughts:

• Double check special requests (what, who, when, where, how)• Lay-offs hurt you and the outsourcer• Willingness to accept fines or reimbursement is a big deal• Block & Level the SLA vs. the network

Outsourcing Net Mgt

PerformanceIT Net Mgt Service

iNOC Imonitor

HCL Technologies

iNOC Services

NetProactive Services Remote

Infrastructure Management

IT Bdgt Reduction 30% 4 5 3 1 Svce-level Mgt 30% 5 4.5 3 3

Other Costs 20% 5 4 4 3 Operations 10% 4 4 5 3 Reporting 10% 5 4 5 4 Total Score 100% 4.60 4.45 3.60 2.50

Grade A A- B- C-

Outsourcing Net Mgt

Company Name Service Name Svc Yrs Sales Per Yr EmployeesHCL Technologies iNOC Services 3 $336M 8748America

iNOC IMonitor 3 $4.8M 30

NetProactive Remote 4 $500K 28Services Infrastructure

Management

PerformanceIT PerformanceIT 6 $10M 100 Network MgtService