Transcript Chapter 10

Chapter 10
Chapter 10
Broadband Network Management:
Access Networks
Network Management: Principles and Practice
© Mani Subramanian 2000
10-1
Chapter 10
Broadband Access Networks
Cable Modem
Cable
Customer
Modem
Network
HFC
Network
Telephone
Loop
Cable
Modem
Head End
xDSL
Modem
DSL
Customer
Network
Central
Office
Equipment
SDH / SONET
WAN
Router/
ATM Switch
Business
Router/
Customers ATM Switch
OC-n /
STS-n
Link
Satellite Communication
and/or Telephone Loop
Wireless
& Telephone
Loop
Wireless
Customer
Network
Figure 10.1 Broadband Access Networks
Notes
• Three categories of customer base:
• Corporate or enterprise
• Service providers
• Residence or SOHO
Network Management: Principles and Practice
© Mani Subramanian 2000
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Chapter 10
Broadband Access Networks
Cable Modem
Cable
Customer
Modem
Network
HFC
Network
Telephone
Loop
Cable
Modem
Head End
xDSL
Modem
DSL
Customer
Network
Central
Office
Equipment
SDH / SONET
WAN
Router/
ATM Switch
Business
Router/
Customers ATM Switch
OC-n /
STS-n
Link
Satellite Communication
and/or Telephone Loop
Wireless
& Telephone
Loop
Wireless
Customer
Network
Figure 10.1 Broadband Access Networks
Notes
• Five types of access networks
• OC-n / STS-n link
• Gateway to service providers (not shown)
• HFC / Cable modem
• DSL
• Wireless
• Fixed wireless
• Satellite communication
Network Management: Principles and Practice
© Mani Subramanian 2000
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Chapter 10
Access Technologies
Broadband
Access
Technology
HFC
TelephonyReturn
xDSL
TwoWay
ADSL
HDSL
Satellite
Communication
Wireless
VDSL
ISM
MMDS
OneWay
LMDS
TelephonyReturn
TwoWay
TwoWay
Figure 10.2 Broadband Access Technologies
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-4
Chapter 10
Access Technologies
Broadband
Access
Technology
HFC
TelephonyReturn
xDSL
TwoWay
ADSL
HDSL
Satellite
Communication
Wireless
VDSL
ISM
MMDS
OneWay
LMDS
TelephonyReturn
TwoWay
TwoWay
Notes
• 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
Network Management: Principles and Practice
© Mani Subramanian 2000
10-5
Chapter 10
Access Technologies
Broadband
Access
Technology
HFC
TelephonyReturn
xDSL
TwoWay
ADSL
HDSL
Satellite
Communication
Wireless
VDSL
ISM
MMDS
OneWay
LMDS
TelephonyReturn
TwoWay
TwoWay
Notes
• xDSL: Digital subscriber line technology
• Asymmetric DSL (ADSL)
• High-speed DSL (HDSL)
• Very-high speed DSL (VDSL)
• Uses existing local loop telephone facilities
Network Management: Principles and Practice
© Mani Subramanian 2000
10-6
Chapter 10
Access Technologies
Broadband
Access
Technology
HFC
TelephonyReturn
xDSL
TwoWay
ADSL
HDSL
Satellite
Communication
Wireless
VDSL
ISM
MMDS
OneWay
LMDS
TelephonyReturn
TwoWay
TwoWay
Notes
• Wireless: Terrestrial fixed wireless systems
• Instructional scientific and medical (ISM):
902 - 928 MHz (0.5 mile) and
2400 - 2483 MHz (15 miles)
• Multichannel multipoint distribution service
(MMDS) 2500 - 2686 MHz (35 miles)
• Local multipoint distribution service
27,500 - 28,350 MHz and 31,000 - 31,300 MHz
(3 miles)
Network Management: Principles and Practice
© Mani Subramanian 2000
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Chapter 10
Access Technologies
Broadband
Access
Technology
HFC
TelephonyReturn
xDSL
TwoWay
ADSL
HDSL
Satellite
Communication
Wireless
VDSL
ISM
MMDS
OneWay
LMDS
TelephonyReturn
TwoWay
TwoWay
Notes
• Satellite communication
• Telephony return is one-way, downstream
wireless, upstream telephone
• Two-way downstream and upstream wireless
Network Management: Principles and Practice
© Mani Subramanian 2000
10-8
Chapter 10
HFC Network
Ethernet
Cable
Modem
NIU
Satellite
WAN
Head
End
Fiber
Fiber
Node
2-WAY
COAX
Amplifier
NIU
ISP
Cable
Modem
NIU Network Interface Unit
TV Monitor
Workstation
Notes
• Fiber - 2 one-way transmission
• Coaxial - 2-way transmission
• 2-way amplifiers
• Fiber node: optical - RF conversion
Network Management: Principles and Practice
© Mani Subramanian 2000
10-9
Chapter 10
HFC Network
Ethernet
Cable
Modem
NIU
Satellite
WAN
Head
End
Fiber
Fiber
Node
2-WAY
COAX
Amplifier
NIU
ISP
Cable
Modem
NIU Network Interface Unit
TV Monitor
Workstation
Notes
• 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
Network Management: Principles and Practice
© Mani Subramanian 2000
10-10
Chapter 10
Comparative Speeds
(Source: Cable Labs)
Telephone Modem 28.8 kbps
ISDN 64 kbps
Cable Modem 10 Mbps
6 - 8 minutes
1 -1.5 minutes
Approximately 1 second
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-11
Chapter 10
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
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-12
Chapter 10
Broadband LAN
Downstream Signal
50 - 860 MHz
Head
End
Cable
Modem A
Cable
Modem B
Termination
Cable
Modem C
Upstream Signal
5 - 42 MHz
Termination
Figure 10.4 Broadband LAN
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-13
Chapter 10
Digital-to-Analog Encoding
Digital
Modulated analog
Modem
Digital
Modem
carrier
1
0
time
frequency
1
0
time
Channel
bandwidth
Figure 10.5 Digital-to-Analog Encoding
• bit rate
• symbol rate
• number of levels n = 2k
• bit rate = symbol rate x k
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-14
Chapter 10
Modulation Schemes
• Amplitude shift keying
• Frequency shift keying
• Phase shift keying
• Quadrature phase shift keying
• Four levels ( 00, 01. 10, 11)
• Relatively insensitive to noise
• Used for low-band upstream
• Quadrature amplitude modulation (not 4-levels)
• Combination of AM and PM
• 16-QAM = 8 PM x 2 AM or 4 PM x 4 AM
• Used for higher-band downstream
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-15
Chapter 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
Toshiba
RCA DCM105
Cisco
LANcity
Motorola
Upstream
2.56 Msym/sec
10 Mbps
10 Mbps
10 Mbps
10 Mbps
Downstream
5.36 Msym/sec
38 Mbps
38 Mbps
10 Mbps
40 Mbps
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-16
Chapter 10
Functions of 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
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-17
Chapter 10
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
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
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Chapter 10
RF Spectrum
Upstream
(Reverse)
5-42 MHz
Guard
Band
42-54 MHz
Downstream (Forward)
54-750 MHz
Analog
Video
54-550 MHz
Digital
Data Services
550-560 MHz
Digital
Video
560-700 MHz
Telephony
700-750 MHz
Upstream (Reverse)
5-42 MHz
Digital
Video Control
6-8 MHz
Digital
Data Services
10-25 MHz
Telephony
25-40 MHz
Figure 10.6 An Example of RF Frequency Assignment
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-19
Chapter 10
DOCS Reference Architecture
Telco Return
4
Head
End
WAN
HFC Link
6
Cable Modem Data
Termination System
(CMTS)
Mod
Switch / Router
2
Term
6
Subscriber
PC
Transmitter
Fiber
3
5
Splitter&
Filter
6
Servers
INTERFACES:
1 CMCI
2 CMTS-NSI
3 DOCS-OSSI
4 CMTRI
5 DOCSS
6 RFI
1
Data
Demod
Operations Support System/
Element Manager
Combiner
Video
Cable
Modem
Receiver
Security & Access
Controller
Cable Modem to CPE Interface
CMTS Network Side Interface
Data Over Cable Services Operations Support System Interface
Cable Modem to Telco Return Interface
Data Over Cable Security System
Cable Modem to RF Interface
Source: CableLabs
Notes
• The architecture shows two-way (HFC link)
and one-way (HFC link & telco return).
Network Management: Principles and Practice
© Mani Subramanian 2000
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Chapter 10
CMTS Components
Cable Modem Data
Termination System
(CMTS)
Mod
Switch / Router
2
Term
6
Transmitter
Fiber
Data
6
Servers
3
5
Splitter&
Filter
Demod
Operations Support System/
Element Manager
Combiner
Video
Receiver
Security & Access
Controller
Notes
• 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 demux’ing.
• 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.
Network Management: Principles and Practice
© Mani Subramanian 2000
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Chapter 10
DOCS Interfaces
Telco Return
4
Head
End
WAN
HFC Link
6
Cable Modem Data
Termination System
(CMTS)
Mod
Switch / Router
2
Term
6
1
Subscriber
PC
Transmitter
Fiber
Data
6
Servers
3
5
Splitter&
Filter
Demod
Operations Support System/
Element Manager
Combiner
Video
Cable
Modem
Receiver
Security & Access
Controller
Notes
• 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)
Network Management: Principles and Practice
© Mani Subramanian 2000
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Chapter 10
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
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-23
Chapter 10
HFC Protocol Architecture
Head End
SONET
Cable Modem
Subscriber PC
Applications,
SNMP Manager
Modem Applications
SNMP Agent
Applications
SNMP, FTP,
HTTP, ETC
SNMP
SNMP, FTP,
HTTP, ETC
TCP / UDP
TCP / UDP
TCP / UDP
IP
IP
IP
ATM
Link
HFC
Link
HFC
Link
Ethernet
Link
Ethernet
Link
Figure 10.8 Protocol Layer Architecture in HFC System
Notes
• Head end has both NM applications and manager
• Cable modems have SNMP agents
• NMS can be regionalized; then, head ends could
behave as RMONs
Network Management: Principles and Practice
© Mani Subramanian 2000
10-24
Chapter 10
HFC / CM Management
• Cable modem management
• CMTS management
• HFC link management
• RF spectrum management
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-25
Chapter 10
CM Management MIBs
mib-2
(internet.2.1)
system (1)
interfaces (2)
docsDev (69)
transmission (10)
ifMIB (31)
docsIfMib (127)
docsTrCmMIB (128)
Figure 10.9 Cable Modem Management MIBs
Notes
• 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
Network Management: Principles and Practice
© Mani Subramanian 2000
10-26
Chapter 10
DOCS Documentation
tr-docs-ossiw08-961016
sp-ossi-i02-990113
sp-ossi-rfi-i03-990113
draft-ietf-ipcdn-interface-mib-03.txt,
January 1998
sp-ossi-bpi-i01-980331.pdf
draft-ietf-ipcdn-cable-device-mib-07.txt,
February 20, 1999
draft-ietf-ipcdn-mcns-bpi-mib-00.txt,
January 17, 1999
draft-ietf-ipcdn-rf-interface-mib-07.txt,
February 17, 1999
draft-ietf-ipcdn-tri-mib-00.txt, July 30,
1998
draft-ietf-ipcdn-qos-mib-00.txt, August
7, 1998
SP-CMCI-I02-980317, 03/17/98
SP-NSI-I01, 07/22/96
SP-OSSI-BPI-I01-980331
SP-CMTRI-I01-970804
SP-RSMI-I01-980204
SP-BPI-I02-990319
SP-SSI-I01-970506
SP-RFIv1-I01-990311
OSSI Framework
OSSI Specification Overview
OSSI RF Interface Specification
MCNS Interface MIB
OSSI Baseline Privacy Interface MIB
DOCSIS Cable Device MIB
Baseline Privacy MIB
DOCSIS RF Interface MIB
Telephony-return interface MIB for
Cable Modems and CMTS
DOCSIS Quality of Service MIB
Cable Modem to Customer Premises
equipment Interface (CMCI)
Specification
Cable Modem Termination system network side Interface specification
Operations Support system Interface
specification Baseline Privacy Interface
MIB
Cable Modem Telephony return
Interface Specification
Removable Security Module Interface
Specification - Interim
Baseline Privacy Interface
Specification
Security System Specification
RF Interface Specification
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-27
Chapter 10
DOCS Interface MIB
transmission
(mib-2 10)
docsIfMIB
(127)
docsIfMIBObjects (1)
docsIfNotification (2)
docsBpiMIB (5)
docsIfConformance
(3)
docsIfBaseObjects(1)
docsQosMIB (6)
docsIfCmtsObjects (3)
docsIfCmObjects (2)
docsBpiMIBObjects
(1)
docsBpiConformance
(3)
docsBpiNotification
(2)
docsQosMIBObjects
(6)
docsQosIpPktClassTable (1)
docsQosEthPktClassTable (2)
docsQosServiceClassGroup (3)
docsFlowToClassTable (6)
docsSidToClassTable (5)
docsQosFlowTable (4)
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-28
Chapter 10
RF MAC Interface
Network Layer
RF MAC Layer
Downstream1
Upstream1
Upstream2
RF Physical Layer
Figure 10.11 RF MAC Interface
Notes
• Multiple RF channels upstream and downstream
• Layered structure
• Specified using RFC 1573 ifMIB
Network Management: Principles and Practice
© Mani Subramanian 2000
10-29
Chapter 10
DOCS Cable Device MIB
Entity
docsDevMIBObjects
OID
docsDev 1
docsDevBase
docsDevMIBObjects 1
docsDevNmAccessTable
docsDevMIBObjects 2
docsDevSoftware
docsDevMIBObjects 3
docsDevServer
docsDevMIBObjects 4
docsDevEvent
docsDevMIBObjects 5
docsDevFilter
docsDevMIBObjects 6
docsDevCpe
docsDevMIBObjects 7
Description
Objects of the cable
modem and CMTS device
Extends MIB-II System
Group with objects
needed for cable device
system management
Defines the minimum
level of SNMP access
security
Provides information for
network-downloadable
software upgrades
Provides information
about the progress of the
interaction with various
provisioning servers
Provides control and
logging for event
reporting
Configures filters at link
layer and IP layer for
bridged data traffic
CPE IP management and
anti-spoofing group on
cable modems
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-30
Chapter 10
HFC Failure Models
Failure Probability
Window
(Modem voltage)
Smooth
(Connector loss)
Sharp
(Signal/Noise)
Event Index
Network Management: Principles and Practice
© Mani Subramanian 2000
10-31
Chapter 10
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
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-32
Chapter 10
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
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-33
Chapter 10
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)
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-34
Chapter 10
xDSL Technologies
Copper Access Transmission Technologies [ADSL Forum]
Name
Meaning
Modem Voice Band
Modems
Data rate
1200 bps to
28,800 bps
Mode
Duplex
ISDN
Integrated
Services Digital
Network
High data rate
Digital
Subscriber Line
160 kbps
Duplex
1.544 Mbps
2.048 Mbps
Duplex
Duplex
2-pair
SDSL
Single line
Digital
Subscriber Line
1.544 Mbps
2.048 Mbps
Duplex
Duplex
1-pair
ADSL
Asymmetric
Digital
Subscriber Line
1.5 to 9 Mbps
16 to 640 kbps
Down
Up
1-pair
VDSL
Very high data
rate Digital
Subscriber Line
13 to 52 Mbps
1.5 to 2.3
Mbps
Down
Up
2-pair
HDSL
Cable
2-pair
Applications
Low data rate
data
communications
ISDN service
Voice and data
communications
T1/E1 service
Feeder plant,
WAN, LAN
access, server
access
Same as HDSL
plus premises
access for
symmetric
services
Internet access,
video demand,
simplex video,
LAN access,
interactive
multimedia
Same as ADSL
plus HDTV
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-35
Chapter 10
ADSL Network
Broadband
Network
ATU-C
Splitter
Voice
ADSL
Loop
Splitter
ATU-R
Voice
Figure 10.13 ADSL Access Network
Notes
• ADSL .. Asymmetric Digital Subscriber Line
• ATU-C ADSL transmission unit - central office
• ATU-C ADSL transmission unit - remote/residence
• Splitter separates voice and data
Network Management: Principles and Practice
© Mani Subramanian 2000
10-36
Chapter 10
ADSL Spectrum Allocation
with Guard Band
FDM
Upstream
POTS
4 KHz
25 KHz
Downstream
200 KHz
Frequency
1.1 MHz
Notes
• POTS .. Plain old telephone service
Network Management: Principles and Practice
© Mani Subramanian 2000
10-37
Chapter 10
ADSL Spectrum Allocation
with Echo Cancellation
Echo Cancellation
Upstream
POTS
4 KHz 25 KHz
Downstream
200 KHz
Frequency
1.1 MHz
Notes
• Echo cancellation separates upstream and
downstream signals
• Increases (low-frequency) upstream bandwidth
Network Management: Principles and Practice
© Mani Subramanian 2000
10-38
Chapter 10
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
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-39
Chapter 10
ADSL Forum
TR-001
TR-005
TR-006
TR-014
TR-015
TR-016
ADSL Forum System Reference Model
ADSL Network Element Management System
SNMP-based ADSL LINE MIB; see also draftietf-adslmib-adsllinemib-09.txt
DMT Line Code Specific MIB
CAP Line Code Specific MIB
CMIP-based Network Management Framework
• ADSL Forum is an industry consortium to
• achieve interoperability
• accelerate implementation
• address end-to-end system operation
• security
• management
• Physical layer standard T1-413 (ANSI)
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-40
Chapter 10
VDSL Network
Central
Office
Fiber
Optical
Network
Unit
VDSL
Twisted
Pair
VDSL
Home
Network
Notes
• Used in FTTN configuration
• Asymmetric band allocation (similar to ADSL)
• Fiber carries multiple channels to ONU
• Channels demultiplexed at ONU and carried to
customer premises on multiple twisted pairs
• Shorter distance of twisted pairs permission of
higher data rate - 55.2 Mbps downstream and
2.3 Mbps upstream
Network Management: Principles and Practice
© Mani Subramanian 2000
10-41
Chapter 10
ADSL Network
Private
Network
Public
Network
Premises
Network
ADSL Access Network
OS
Service
Systems
On-line Services
Internet Access
LAN Access
Interactive Video
Video Conf
OS
Broadband
Network
Narrowband
Network
Access
Node
Packet
Network
ATU-C
ATU-R
ADSL
LLLLL
L
ADSL
PDN
SM
Settop
TE(s)
TV
SM
PC I/O
TE(s)
PC
SM
ISDN
TE(s)
ISDN
STM
Packet
ATM
STM
ATM
Packet
ATM
Transport Modes
ADSL
ATM
STM
TE
OS
PDN
SM
Asynchronous Digital Subscriber Line
Asynchronous Transfer Mode
Synchronous Transfer Mode
Terminal Equipment
Operations System
Premises Distribution Network
Service Module
Figure 10.16 Overall Network and ADSL
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-42
Chapter 10
Transport Modes
• Synchronous transport mode (STM)
• Bit synchronous transmission ( T1/E1)
• End-to-end packet mode
• Used for SOHO (IP packets)
• ATM / STM
• ATM WAN (Public network) and
STM access network
• ATM / Packet
• ATM WAN and packet access network (IP)
• End-to-end ATM
Notes
Network Management: Principles and Practice
© Mani Subramanian 2000
10-43
Chapter 10
ADSL System Reference Model
VC
U-C2 U-C
VA
T-SM
T
B
Splitter
Digital
Broadcast
ATU-C
Broadband
Network
ATU-C
Narrowband
Network
ATU-C
Network
Management
U-R U-R2
ATU-C
T.E.
Loop
ATU-R
T.E.
T.E.
POTS-C
PSTN
POTS-R
Phone(s)
Access
Node
Interfaces:
B
Auxiliary data input such as a satellite feed to Service Module (TE)
POTS-C Interface between PSTN and POTS splitter at network end
POTS-R Interface between phones and POTS splitter at premises end
T
Interface between Premises Distribution Network and Service Modules
T/SM Interface between ATU-R and Premises Distribution Network
U-C Interface between Loop and ATU-C (analog)
U-C2 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
VA
Logical interface between ATU-C and Access Node
VC
Interface between Access Node and network
T.E.
Premises
Distribution
Network
TE
Terminal Equipment
POTS Plain Old Telephone Service
PSTN Public Switched Telephone Network
Figure 10.17 ADSL System Reference Model
Notes
(ADSL Forum)
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Chapter 10
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)
Notes
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Chapter 10
ADSL Channeling Schemes
Downstream bearer channels
ATU-R
ATU-C
Duplex bearer channels
Fast channel
ATU-C
ATU-R
Interleaved channel
Notes
• 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
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Chapter 10
Management Reference Model
T-R
V-C
T/S
Service
Module
Network Termination
Broadband
Network
PHY
Layer
Switch
Switch
ATU-C
ATU-R
PHY
Layer
Home
Network
U-C2
Service
Module
U-R2
High
Pass
Filter
PSTN
PSTN
Low
Pass
Filter
Splitter-C
High
Pass
Filter
Loop
U-C U-R
Low
Pass
Filter
POTS
Telephone Set
or
Voice-Band Modem
Splitter-R
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
Figure 10.18 ADSL Forum System Reference Model for Management
Notes
Network Management: Principles and Practice
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Chapter 10
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
Notes
• 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
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Chapter 10
Signal Power and Data Rate Mgmt
Reduce power
Maximum noise margin
Increase rate if noise margin > Upshift noise margin
Upshift noise margin
Steady state operation
Target noise margin
Steady state operation
Downshift noise margin
Decrease rate if noise margin < Downshift noise margin
Minimum noise margin
Increase power
Figure 10.19 Noise Margins
Notes
• 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)
Network Management: Principles and Practice
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Chapter 10
Configuration Mgmt Parameters
Parameter
ADSL Line type
ADSL Line coding
Target noise margin
Max. noise margin
Min. noise margin
Rate adaptation mode
Upshift noise margin
Min. time interval for upshift
rate adaptation
Downshift noise margin
Component Line
Description
ADSL Line N/A Five types: no channel, fast,
interleaved, either or both
ADSL Line N/A ADSL coding type
ATU-C/R Phy Noise margin under steady
-7)
state (BER=<10
ATU-C/R Phy Modem reduces power above
this threshold
ATU-C/R Phy Modem increases power below
this margin
ATU-C/R Phy Mode 1: Manual
Mode 2: Select at start-up
Mode 3: Dynamic
ATU-C/R Phy Threshold for modem increases
data rate
ATU-C/R Phy Time interval to upshift
ATU-C/R
Min. time interval for downshift
rate adaptation
Desired max. rate
Desired min. rate
Rate adaptation ratio
ATU-C/R
Max. interleave delay
ATU-C/R
Alarm thresholds
ATU-C/R
Rate up threshold
Rate down threshold
Vendor ID
Version No.
Serial No.
ATU-C/R
ATU-C/R
ATU-C/R
ATU-C/R
ATU-C/R
ATU-C/R
ATU-C/R
ATU-C/R
Phy Threshold for modem
decreases data rate
Phy Time interval to downshift
F/I Max rates for ATU-C/R
F/I Min. rates for ATU-C/R
Phy Distribution ratio between fast
and interleaved channels for
available excess bit rate
F/I Max. transmission delay
allowed by interleaving process
Phy 15-minute count threshold on
loss of signal, frame, poser and
error-seconds
F/I Rate-up change alarm
F/I Rate-down change alarm
Phy Vendor ID assigned by T1E1.4
Phy Vendor specific version
Phy Vendor specific Serial No.
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Chapter 10
Fault Management
Parameter
ADSL Line status
Component
ADSL Line
Line
Phy
Alarms thresholds
ATU-C/R
Phy
Unable to initialize ATU-R
ATU-C/R
Phy
Rate change
ATU-C/R
Phy
Description
Indicates operational and
various types of failures of
the link
Generates alarms on failures
or crossing of thresholds
Initialization failure of ATU-R
from ATU-C
Event generation when rate
changes when crossing of
shift margins in both
upstream and downstream
Notes
• 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
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Chapter 10
Performance Management
Parameter
Line attenuation
Component
ATU-C/R
Line
Phy
Noise margin
ATU-C/R
Phy
Total output power
ATU-C/R
Phy
Max. attainable rate
ATU-C/R
Phy
Current rate
ATU-C/R
F/I
Previous rate
ATU-C/R
F/I
Channel data block length
ATU-C/R
F/I
Interleave delay
ATU-C/R
F/I
Statistics
ATU-C/R
Phy
F/I
Description
Measured power loss in dB
from transmitter to receiver
ATU
Noise margin in dB of the
ATU with respect to received
signal
Total output power from the
modem
Max. currently attainable
data rate by the modem
Current transmit rate to
which the modem is adapted
Rate of the modem before
the last change
Data block on which CRC
check is done
Transmit delay introduced
by the interleaving process
15 minute / 1 day failure
statistics
Notes
• Line attenuation
• Noise margin
• Output power
• Data rate
• Data integrity check
• Interleave channel delay
• Error statistics
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Chapter 10
ADSL SNMP MIB
adslForum
(1.3.6.1.4.1.xx)
adslMIB
(1)
adslLineMib
(1)
adslTraps (2)
adslConformance (2)
adslMibObjects(1)
adslLineTable (1)
adslAtucPhysTable (2)
adslLineAlarmConfProfileTable(15
)
adslLineConfProfileTable(14)
adslAturChanIntervalTable (13)
adslAturPhysTable (3)
adslAtucChanTable (4)
adslAturChanTable (5)
adslAtucPerfDataTable (6)
adslAturPerfDataTable (7)
adslAtucIntervalTable (8)
adslAtucChanIntervalTable(12)
adslAturChanPerfDataTable (11)
adslAtucChanPerfDataTable (10)
adslAturIntervalTable (9)
adslLCSMib (16)
adslDMTMib (1)
adslCAPMib (1)
Figure 10.20 ADSL SNMP MIB
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Chapter 10
Proposed IF Types
Higher Layer IF
(e.g.: ATM)
Higher Layer IF
(e.g.: ATM)
Fast Channel IF
(ATU-C & ATU-R)
ifType = Fast (125)
ifIndex = k
Interleaved Channel IF
(ATU-C & ATU-R)
ifType = Interleaved (124)
ifIndex = j
Physical Line IF
(ATU-C & ATU-R)
ifType = ADSL (94)
ifIndex = i
Figure 10.21 Relationship between ADSL Entries
Notes
• Sub-layers handled by ifMIB
ifStackTable {ifMib.ifMIBObjects 2} (RFC 1573)
• Propose ifTypes
adslPhysIf ::= {transmission 94}
adslInterIf ::= {transmission 124}
adslFastIf ::= {transmission 125}
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Chapter 10
ADSL Interfaces Table
MIB Variable
Physical Line (i)
ifDescr
ifType (IANA)
ifSpeed
NORMAL
94
ATU-C Line Tx
rate
NULL
NORMAL
NORMAL
NORMAL
NORMAL
(default: Enable)
True
NULL
ifPhyAddress
ifAdminStatus
ifOperStatus
ifLastChange
ifLinkUpDownTrap
Enable
ifConnectPresent
ifHighSpeed
Interleaved
Channel (j)
NORMAL
124
ATU-C channel
Tx rate
NULL
NORMAL
NORMAL
NORMAL
NORMAL
(default: Enable)
False
NULL
Fast
Channel (k)
NORMAL
125
ATU-C channel
Tx rate
NULL
NORMAL
NORMAL
NORMAL
NORMAL
(default: Enable)
False
NULL
Notes
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Chapter 10
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
Notes
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Chapter 10
Configuration Profile:
Mode I - Dynamic
ADSL-Line
ifIndex
ifTable
1
i1
ADSL Line Entry
j1
Interleaved Chan
k1
Fast Chan Entry
i2
ADSL Line Entry
j2
Interleaved Chan
k2
Fast Chan Entry
ix
ADSL Line Entry
jx
Interleaved Chan
2
x
kx
profileIndex
Configuration
Profile Table
1
Profile-1
2
Profile-2
n
Profile-n
Fast Chan Entry
Figure 10.22 Use of Profiles in MODE-I (Dynamic)
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Chapter 10
Configuration Profile:
Mode II - Static
ADSL-Line
ifIndex
ifTable
1
i1
ADSL Line Entry
j1
Interleaved Chan
k1
Fast Chan Entry
i2
ADSL Line Entry
j2
Interleaved Chan
k2
Fast Chan Entry
ix
ADSL Line Entry
jx
Interleaved Chan
2
x
profileIndex
Configuration
Profile Table
i1
Profile-i1
i2
ix
Profile-i2
Profile-in
kx
Fast Chan Entry
Figure 10.23 Use of Profiles in MODE-II (Static)
Network Management: Principles and Practice
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