MJ11/0704 1

Session 11Broadband Management

Adapted from Network Management: Principles and Practice © Mani Subramanian 2000 and solely used for Network Management course at Universitas Bina Nusantara

MJ11/0704 2

Broadband Access Networks

Cable ModemNetwork

HFC

Cable Modem

XDSL Mode

m

TelephoneLoop

CM Head End Central

Office

DSLNetwork

MJ11/0704 3

Access Technologies

BroadbandAccess

Technology

xDSL WirelessHFC

HDSLADSL VDSLTelephony-

ReturnTwo-Way

MMDSISM LMDS

SatelliteCommunication

Telephony-Return

Two-Way

One-Way

Two-Way

MJ11/0704 4

Access Technologies

• Hybrid fiber coaxial technology plant / cable modem at customer premises

• Telephony return is one-way, downstream (forward direction) cable, upstream (reverse direction) telephone• Two-way downstream at high frequency band and upstream at low frequency band

• Carries voice, video and data

• Upstream bandwidth requirements less compared to downstream bandwidth

MJ11/0704 5

Access Technologies

• xDSL: Digital subscriber line technology

• Asymmetric DSL (ADSL)• High-speed DSL (HDSL)• Very-high speed DSL (VDSL)

• Uses existing local loop telephone facilities

MJ11/0704 6

HFC Network

HeadEnd

FiberNode

CableModem

2-WAYCOAX

NIU Network Interface Unit

Fiber

CableModem

WAN

ISP

Satellite

NIU

NIU

FiberNode

Ethernet

Workstation

TV Monitor

Amplifier

MJ11/0704 7

HFC Network

• Fiber - 2 one-way transmission• Coaxial - 2-way transmission• 2-way amplifiers• Fiber node: optical - RF conversion•Head end:

• Signals from multiple sources multiplexed• Frequency conversion for local signal

• Network interface device (NID) / unit (NIU) Demarcation point between customer network and service provider networks• Cable modem: RF Ethernet, analog telephony, and video

MJ11/0704 8

HFC Technology

• Broadband LAN• Asymmetric bandwidth allocation for 2-way communication• RF spread-spectrum that carries multiple signals over HFC• RF spectrum allocation to carry multimedia services - voice, video and data

10-12

MJ11/0704 9

Broadband LAN

CableModem A

CableModem B

CableModem C

HeadEnd

Upstream Signal5 - 42 MHz

Downstream Signal50 - 860 MHz Termination

Termination

MJ11/0704 10

Cable Modem

• HFC uses tree topology• Downstream in broadcast mode• Upstream transmission by cable modem coordinated by head end• Data over cable service specifications (DOCSIS) for cable modem ensures interoperability• One-way cable modem uses telco-return

MJ11/0704 11

Cable Modem Termination System

• Equipment at the head end• All cable modems terminated on the head end• Gateway to the external network• Multiplexes and demultiplexes signals• Frequency converts upstream to downstream signals• Can be designed either as a bridge or router

MJ11/0704 12

HFC Plant

• Multiple fiber pairs run from head end to fiber node; each pair carries 2 one-way signals• Head end converts all (telephony, digital video, data, and analog video) signals to optical carrier to transmit on the fiber• Houses are connected from fiber node via coaxial cables• Coaxial cable are in tree topology and carries 2-way signal• Amplifiers on the coaxial cable have 2-way amplifiers that amplify the signals in both directions• “Drop from coaxial cable to NID (also called NIU) - called “Tap-to-TV” in CATV

MJ11/0704 13

RF Spectrum

Upstream(Reverse)5-42 MHz

GuardBand

42-54 MHz

Downstream (Forward)54-750 MHz

AnalogVideo

54-550 MHz

DigitalVideo

560-700 MHz

DigitalData Services550-560 MHz

Telephony700-750 MHz

Upstream (Reverse)5-42 MHz

DigitalVideo Control

6-8 MHz

DigitalData Services

10-25 MHz

Telephony25-40 MHz

MJ11/0704 14

DOCS Reference Architecture

HeadEnd

CableModem

SubscriberPC

1HFC LinkWAN

Cable Modem DataTermination System

(CMTS)

Switch / Router

Servers

Operations Support System/Element Manager

2

3

Co

mb

ine

r Transmitter

Receiver

Fiber

Security & AccessController

5

Sp

litter&

Filte

rMod

Demod

Term

Telco Return

4

Video

Data

6

6

6

The architecture shows two-way (HFC link) and one-way (HFC link & telco return).

MJ11/0704 15

CMTS Components

Cable Modem DataTermination System

(CMTS)

Switch / Router

Servers

Operations Support System/Element Manager

2

3

Co

mb

iner Transmitter

Receiver

Fiber

Security & AccessController

5

Sp

litter&

Filter

Mod

Demod

Term

Video

Data

6

6

MJ11/0704 16

CMTS Components

• Switch / router routes the traffic between cable modems and to the external network. It interfaces to CMTS via the terminator (term).

• Modulator (mod) and demodulator (demod) transform digital data from and to analog format.

• Combiner and splitter and filter perform the complimentary functions of mux’ing and demuxing.

• Transmitter converts the RF signals to optical carrier; receiver down-converts the optical signal.

• Servers handle the applications and databases.• Security is managed by the security and access

controller.• OSS and element manager perform network and service

management.

MJ11/0704 17

• Three groups of interfaces:• Data interfaces

• Cable modem to CPE (1)• CMTS-NSI (2)

• Operations support systems and telco-return• OSS (3)• Telco-return (4)

• RF and security• DOCS security system (5)• RF interface (6)

CMTS Components

MJ11/0704 18

HFC Management Challenges

• More complex than either computer network or telecommunication network

• Involves both physical and data layers• Multiple physical facilities• Legacy cable system• Multimedia service• RF spectrum management• Service and business management important for

MSOs and customer• Shared media impacts security and bandwidth• Security and privacy of home network

MJ11/0704 19

HFC Protocol Architecture

SNMP

TCP / UDP

Modem ApplicationsSNMP Agent

IP

ATMLink

HFCLink

EthernetLink

EthernetLink

HFCLink

SNMP, FTP,HTTP, ETC

TCP / UDP

Applications

IP

Cable ModemHead End

SDH

SNMP, FTP,HTTP, ETC

TCP / UDP

Applications,SNMP Manager

IP

• Head end has both NM applications and manager• Cable modems have SNMP agents• NMS can be regionalized; then, head ends could behave as RMONs

MJ11/0704 20

HFC / CM Management

• Cable modem management

• CMTS management

• HFC link management

• RF spectrum management

MJ11/0704 21

CM Management MIBs

docsDev (69)system (1)

mib-2(internet.2.1)

transmission (10)interfaces (2)

ifMIB (31)

docsIfMib (127) docsTrCmMIB (128)

MJ11/0704 22

CM Management MIBs

• Three categories of MIBs• Standard MIBs:

• system, interfaces, ifMIB•CM and CMTS interfaces

• docIfMIB .. RF Interfaces in CM and CMTS, base line privacy and QoS• docsTrCmMIB .. telephony-return interface

•CM and CMTS objects•docsDevMIB

MJ11/0704 23

DOCS Interface MIB

docsQosMIB (6)

docsFlowToClassTable (6)

docsBpiMIB (5)

docsSidToClassTable (5)docsQosIpPktClassTable (1)

docsIfMIB(127)

docsIfMIBObjects (1)docsIfNotification (2)

docsIfConformance(3)

docsIfBaseObjects(1) docsIfCmtsObjects (3)

docsIfCmObjects (2)

docsBpiMIBObjects(1)

docsBpiNotification(2)

docsBpiConformance(3)

transmission(mib-2 10)

docsQosEthPktClassTable (2)

docsQosFlowTable (4)docsQosServiceClassGroup (3)

docsQosMIBObjects(6)

MJ11/0704 24

RF MAC Interface

Network Layer

RF MAC Layer

Downstream1 Upstream1 Upstream2

RF Physical Layer

• Multiple RF channels upstream and downstream• Layered structure• Specified using RFC 1573 ifMIB

MJ11/0704 25

DOCS Cable Device MIB

Entity OID DescriptiondocsDevMIBObjects docsDev 1 Objects of the cable

modem and CMTS devicedocsDevBase docsDevMIBObjects 1 Extends MIB-II System

Group with objectsneeded for cable devicesystem management

docsDevNmAccessTable docsDevMIBObjects 2 Defines the minimumlevel of SNMP accesssecurity

docsDevSoftware docsDevMIBObjects 3 Provides information fornetwork-downloadablesoftware upgrades

docsDevServer docsDevMIBObjects 4 Provides informationabout the progress of theinteraction with variousprovisioning servers

docsDevEvent docsDevMIBObjects 5 Provides control andlogging for eventreporting

docsDevFilter docsDevMIBObjects 6 Configures filters at linklayer and IP layer forbridged data traffic

docsDevCpe docsDevMIBObjects 7 CPE IP management andanti-spoofing group oncable modems

MJ11/0704 26

Link & Spectrum Management

• HFC Link Management• Signal strength critical• Requires continuous monitoring of amplifiers using transponders (CheetahNet)• Legacy system requires proxy server

• RF Spectrum Management• Allocation of spectrum for services - upstream and downstream• Frequency agility management

MJ11/0704 27

DSL Access Technology

• Why is DSL attractive? • Shannon limit of data rate is 30,000 bps

(3-KHz, 30 dB S/N channel)• Digital transmission over loop (DSL) improves

data rate• T1/DS1 (1.544Mbps) 18,000 feet• T2/DS2 (6.312 Mbps) 12,000 feet

MJ11/0704 28

DSL Limitations

• Loop conditions with no direct copper to the house • Loaded coils in loop (used to increase analog

distance) cannot carry digital signal• Modern subdivisions have fiber to the

neighborhood or curb with digital mux• Operating company inventory dated (administrative

issue)

MJ11/0704 29

xDSL Technologies

Copper Access Transmission Technologies [ADSL Forum]

Name Meaning Data rate Mode Cable ApplicationsModem Voice Band

Modems1200 bps to28,800 bps

Duplex 2-pair Low data ratedatacommunications

ISDN IntegratedServices DigitalNetwork

160 kbps Duplex ISDN serviceVoice and datacommunications

HDSL High data rateDigitalSubscriber Line

1.544 Mbps2.048 Mbps

DuplexDuplex

2-pair T1/E1 serviceFeeder plant,WAN, LANaccess, serveraccess

SDSL Single lineDigitalSubscriber Line

1.544 Mbps2.048 Mbps

DuplexDuplex

1-pair Same as HDSLplus premisesaccess forsymmetricservices

ADSL AsymmetricDigitalSubscriber Line

1.5 to 9 Mbps16 to 640 kbps

DownUp

1-pair Internet access,video demand,simplex video,LAN access,interactivemultimedia

VDSL Very high datarate DigitalSubscriber Line

13 to 52 Mbps1.5 to 2.3Mbps

DownUp

2-pair Same as ADSLplus HDTV

MJ11/0704 30

ADSL Network

• ADSL .. Asymmetric Digital Subscriber Line• ATU-C ADSL transmission unit - central office• ATU-C ADSL transmission unit - remote/residence• Splitter separates voice and data

ATU-CBroadbandNetwork Splitter Splitter ATU-R

ADSL Loop

Voice Voice

MJ11/0704 31

ADSL Spectrum Allocation

FDM

Frequency

POTS

Upstream Downstream

1.1 MHz4 KHz 25 KHz 200 KHz

With Guard Band

MJ11/0704 32

Echo Cancellation

Frequency

POTS

Upstream Downstream

1.1 MHz4 KHz 25 KHz 200 KHz

• Echo cancellation separates upstream and downstream signals• Increases (low-frequency) upstream bandwidth

ADSL Spectrum Allocation

With Echo Cancellation

MJ11/0704 33

Modulation Schemes

• Carrierless amplitude phase (CAP) modulation • Discrete multiTone modulation (DMT): 4kHz tones• Both CAP and DMT are QAM-based• DMT outperforms CAP

• 4-to-1 downstream throughput• 10-to-1 upstream throughput• Rate adaptive•On-going active monitoring• Maximum loop variation coverage• Standard and hence interoperability

MJ11/0704 34

ADSL Network

TEISDN

ServiceSystems

BroadbandNetwork

NarrowbandNetwork

AccessNode ATU-C ATU-R

PDN

SMSettop

SMPC I/O

TETV

TEPC

SMISDN

PublicNetwork

PremisesNetwork

PrivateNetwork

STM

ATM

ATM

Transport Modes

ADSL Access Network

ADSL ADSL

OSOS

ATM STM

PacketNetwork

Packet

Packet

ADSL Asynchronous Digital Subscriber Line

ATM Asynchronous Transfer Mode

STM Synchronous Transfer Mode

TE Terminal Equipment

OS Operations System

PDN Premises Distribution Network

SM Service Module

MJ11/0704 35

ADSL System Reference Model

NetworkManagement

T

ATU-R

AccessNode

ATU-C

ATU-C

ATU-C

ATU-C

BroadbandNetwork

NarrowbandNetwork

DigitalBroadcast

PSTN

PremisesDistribution

Network

T-SMU-C

POTS-C POTS-R

Loop

Splitter

Phone(s)

U-C2 U-R2VAVC U-R

T.E.

T.E.

T.E.

T.E.

B

MJ11/0704 36

Interfaces

• An interface can have multiple physical connections • V interface

• VC interface between access node and external network and interfaces

• U interfaces - off the splitters; Will be eliminated with ADSL-Lite• POTS interfaces - low pass filter interfaces for POTS• T and B are customer premises network interfaces

• T between PDN and service modules• B auxiliary data input (e.g., satellite feed)

MJ11/0704 37

ADSL Channeling Schemes

• Transport bearer channels• Seven AS downstream channels - multiples (1-, 2-, 3- or 4-) T1 rate of 1.536 Mbps• Three LS duplex channels - 160. 384, and 576 Kbps

•Buffering scheme• Fast channel: uses fast buffers for real-time data• Interleaved channel: used for non-real-time data• Both fast and interleaved channels carried on the same physical channel

ATU-C ATU-RDownstream bearer channels

Duplex bearer channels

ATU-C ATU-RFast channel

Interleaved channel

MJ11/0704 38

Management Reference Model

Network Termination

Splitter-C

BroadbandNetwork

PHYLayer

SwitchATU-C

HighPassFilter

LowPassFilter

Splitter-R

HighPassFilter

LowPassFilter

HomeNetwork

PHYLayer

SwitchATU-R

ServiceModule

ServiceModule

LoopU-C U-R

PSTN PSTNTelephone Set

orVoice-Band Modem

POTS

T/ST-RV-C

U-C2U-R2

Interfaces: T-R Interface between ATU-R and Switching layers T/S Interface between ADSL Network Termination and customer installation or home network U-C Interface between Loop and ATU-C (analog) UC2 Interface between POTS splitter and ATU-C U-R Interface between Loop and ATU-R (analog) U-R2 Interface between POTS splitter and ATU-R V-C Logical interface between ATU-C and a digital network element such as one or more switching systems

MJ11/0704 39

Management Elements

• Management of elements done across V-interface:• Management communications protocol across V-interface• Management communications protocol across U-interfaces• Parameters and operations across ATU-C• Parameters and operations across ATU-R• ATU-R side of the T interface

• Note addition of physical layer and switching in the management architecture representation

• Management of physical layer involves:• Physical channel• Fast channel• Interleaved channel

• Management of type of line encoding• DMT• CAP

MJ11/0704 40

Signal Power and Data Rate Mgmt

Maximum noise margin

Upshift noise margin

Downshift noise margin

Minimum noise margin

Target noise margin

Reduce power

Increase power

Decrease rate if noise margin < Downshift noise margin

Increase rate if noise margin > Upshift noise margin

Steady state operation

Steady state operation

• Five levels of noise margin• Signal power controlled by noise margin• Data rate: Increase or decrease based on threshold margins• Data rate adaptation modes: Manual (1), automatic at start-up (2), and

dynamic (3)

MJ11/0704 41

Configuration Mgmt Parameters

Parameter Component Line Description

ADSL Line type ADSL Line N/A Five types: no channel, fast,interleaved, either or both

ADSL Line coding ADSL Line N/A ADSL coding type

Target noise margin ATU-C/R Phy Noise margin under steadystate (BER=<10 -7)

Max. noise margin ATU-C/R Phy Modem reduces power abovethis threshold

Min. noise margin ATU-C/R Phy Modem increases power belowthis margin

Rate adaptation mode ATU-C/R Phy Mode 1: ManualMode 2: Select at start-upMode 3: Dynamic

Upshift noise margin ATU-C/R Phy Threshold for modem increasesdata rate

Min. time interval for upshiftrate adaptation

ATU-C/R Phy Time interval to upshift

Downshift noise margin ATU-C/R Phy Threshold for modemdecreases data rate

Min. time interval for downshiftrate adaptation

ATU-C/R Phy Time interval to downshift

Desired max. rate ATU-C/R F/I Max rates for ATU-C/R

Desired min. rate ATU-C/R F/I Min. rates for ATU-C/R

Rate adaptation ratio ATU-C/R Phy Distribution ratio between fastand interleaved channels foravailable excess bit rate

Max. interleave delay ATU-C/R F/I Max. transmission delayallowed by interleaving process

Alarm thresholds ATU-C/R Phy 15-minute count threshold onloss of signal, frame, poser anderror-seconds

Rate up threshold ATU-C/R F/I Rate-up change alarm

Rate down threshold ATU-C/R F/I Rate-down change alarm

Vendor ID ATU-C/R Phy Vendor ID assigned by T1E1.4

Version No. ATU-C/R Phy Vendor specific version

Serial No. ATU-C/R Phy Vendor specific Serial No.

MJ11/0704 42

Fault Management

Parameter Component Line DescriptionADSL Line status ADSL Line Phy Indicates operational and

various types of failures ofthe link

Alarms thresholds ATU-C/R Phy Generates alarms on failuresor crossing of thresholds

Unable to initialize ATU-R ATU-C/R Phy Initialization failure of ATU-Rfrom ATU-C

Rate change ATU-C/R Phy Event generation when ratechanges when crossing ofshift margins in bothupstream and downstream

• Failure indication of physical channel by NMS• Failure indication of logical channels• Failure indication of ATU-C/R• Self-test of ATU-C/R as per T1.413• Noise margin threshold alarms• Rate change due to noise margin

MJ11/0704 43

Performance Management

Parameter Component Line DescriptionLine attenuation ATU-C/R Phy Measured power loss in dB

from transmitter to receiverATU

Noise margin ATU-C/R Phy Noise margin in dB of theATU with respect to receivedsignal

Total output power ATU-C/R Phy Total output power from themodem

Max. attainable rate ATU-C/R Phy Max. currently attainabledata rate by the modem

Current rate ATU-C/R F/I Current transmit rate towhich the modem is adapted

Previous rate ATU-C/R F/I Rate of the modem beforethe last change

Channel data block length ATU-C/R F/I Data block on which CRCcheck is done

Interleave delay ATU-C/R F/I Transmit delay introducedby the interleaving process

Statistics ATU-C/R PhyF/I

15 minute / 1 day failurestatistics

• Line attenuation• Noise margin• Output power• Data rate• Data integrity check• Interleave channel delay• Error statistics

MJ11/0704 44

ADSL SNMP MIBadslForum

(1.3.6.1.4.1.xx)

adslMIB(1)

adslConformance (2)adslTraps (2)

adslLineTable (1)

adslAtucPhysTable (2)

adslAturPhysTable (3)

adslAtucChanTable (4)

adslAturChanTable (5)

adslLineAlarmConfProfileTable(15)adslLineConfProfileTable(14)

adslAturChanIntervalTable (13)

adslAtucChanIntervalTable(12)

adslAturChanPerfDataTable (11)adslAtucPerfDataTable (6)adslAtucChanPerfDataTable (10)adslAturPerfDataTable (7)

adslAturIntervalTable (9)adslAtucIntervalTable (8)

adslLCSMib (16)adslDMTMib (1) adslCAPMib (1)

adslLineMib(1)

adslMibObjects(1)

MJ11/0704 45

ADSL Interfaces Table

MIB Variable Physical Line (i) InterleavedChannel (j)

FastChannel (k)

ifDescr NORMAL NORMAL NORMALifType (IANA) 94 124 125ifSpeed ATU-C Line Tx

rateATU-C channelTx rate

ATU-C channelTx rate

ifPhyAddress NULL NULL NULLifAdminStatus NORMAL NORMAL NORMALifOperStatus NORMAL NORMAL NORMALifLastChange NORMAL NORMAL NORMALifLinkUpDownTrapEnable

NORMAL(default: Enable)

NORMAL(default: Enable)

NORMAL(default: Enable)

ifConnectPresent True False FalseifHighSpeed NULL NULL NULL

MJ11/0704 46

ADSL Profiles Management

• Configuration profile• Performance profile• Alarm profile• Traps

• Generic• Loss of frame• Loss of signal• Loss of power• Error-second threshold• Data rate change• Loss of link• ATU-C initialization failure

MJ11/0704 47

Configuration Profile: Mode I - Dynamic

ADSL Line Entry

Interleaved Chan

Fast Chan Entry

ADSL Line Entry

Interleaved Chan

Fast Chan Entry

ADSL Line Entry

Interleaved Chan

Fast Chan Entry

Profile-1

Profile-2

Profile-n

profileIndex

1

2

n

Configuration Profile TableifTableifIndex

i1

i2

ix

j1

k1

j2

k2

jx

kx

ADSL-Line

1

2

x

MJ11/0704 48

Configuration Profile:Mode II - Static

ADSL Line Entry

Interleaved Chan

Fast Chan Entry

ADSL Line Entry

Interleaved Chan

Fast Chan Entry

ADSL Line Entry

Interleaved Chan

Fast Chan Entry

Profile-i1

Profile-i2

Profile-in

profileIndex

i1

i2

ix

Configuration Profile Table

ifTableifIndex

i1

i2

ix

j1

k1

j2

k2

jx

kx

ADSL-Line

1

2

x