Chapter 13 Broadband Network Management Wired and Optical

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Chapter 13 Broadband Network Management: Wired and Optical Access Networks Last modified: 07/04/2018 Network Management: Principles and Practice © Mani Subramanian 2010 1

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Objectives • (Wired) Broadband access networks • Cable or HFC (hybrid fiber cable) network • ADSL (asymmetrical digital subscriber line) network • PON (passive optical network) • Cable access network • Popular in North American continents • “Triple play” ( Voice, vedio, Data services together) service can be provided • ADSL • Predominant throughout the rest of the world • Uses conventional telephone local loop medium • Broadband voice and data services • Adopts IETF and DSL forum standards • VDSL 2 for performance improvement of broadband service • PON deployment configurations • Ethernet-based PON, EPON Network Management: Principles and Practice © Mani Subramanian 2010 2

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Broadband Access Networks Notes • Access network is the network between WAN( backbone network) and home network(customer premises) • Four access network technologies : Three customer types: enterprise customers by optical link, service provider (cable operator, telephone company, multiple system operator (MSO), etc. ) via a gateway, and residential and small business office via wired (Passive Optical Network) or wireless • OC-n an extension of WAN for enterprise Network Management: Principles and Practice © Mani Subramanian 2010 3

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Broadband Access Technologies Notes • Cable popular in North America: Networks based on Hybrid Fiber Coaxial (HFC) / Cable Modem (CM) • ADSL more extensively deployed elsewhere in the world • Wireless: • Fixed: MMDS, LMDS, and Wi. Max • Mobile: CDMA, GPRS • Passive Optical Network (PON) on fiber medium Network Management: Principles and Practice © Mani Subramanian 2010 4

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Cable Modem Technology Notes Network Management: Principles and Practice © Mani Subramanian 2010 5

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Cable Modem Technology • CM technology is also called as HFC and is based on Cable TV or CATV technology. • The signal is brought to a fiber node via a pair of optical fibers and then distributed via a coaxial cable to the customer premises • Head end: • Signals from multiple sources multiplexed • Frequency conversion for local signal ( Electrical to optical conversion ) • Traffic Flow: a pair of optical fibers • Downstream (forward path signal): Head end to NIU • Upstream (reverse path signal): NIU to head end • Network interface device (NID) / unit (NIU): Demarcation point between customer network and service provider networks, The analog signal is split at the NIU, TV signal directed to TV and data to the CM. • Cable modem: separates the digitally modulated analog carrier signal to Ethernet and voice-over-IP • From the headend to fiber node, oneway fiber is used. ( so 2 pairs are needed for up and down ) • From fiber node to NIU, Coaxial cable is used, it can carry signals in two way, so a two way amplifier introduced to carry signals to long distance. Network Management: Principles and Practice © Mani Subramanian 2010 6

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Comparative Speeds Table 13. 1 Comparative Data Transmission Speeds Notes • The broadband cable access system with the CM can process data at a much faster rate than a conventional telephone modem or integrated services digital network (ISDN). • A typical comparative data transmission rate to transmit a single 500 kilobytes message is shown in Table 13. 1 Network Management: Principles and Practice © Mani Subramanian 2010 7

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Cable Access Network Technology • HFC Technology Hybrid fiber-coaxial (HFC) is a telecommunications industry term for a broadband network that combines optical fiber and coaxial cable • It is based on • 1. Transmission Mode and medium • Downstream: Time Division Multiplexing (TDM) broadcast mode • Upstream: Time Division Multiple Access ( TDMA) / Synchronous Code Division Multiple Access (S- CDMA ) • 2 CM at customer premises • 3. CMTS ( Cable Modem Termination System) at the head end • 4. 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 2010 8

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Cable Access Network Technology Notes • Time-division multiplexing (TDM) is a method of putting multiple data streams in a single signal by separating the signal into many segments, each having a very short duration. • Each individual data stream is reassembled at the receiving end based on the timing. • Time division multiple access (TDMA) is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. • The users transmit in rapid succession, one after the other, each using its own time slot. • This allows multiple stations to share the same transmission medium (e. g. radio frequency channel) while using only a part of its channel capacity. • Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. • CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. • This allows several users to share a band of frequencies. • To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme (where each transmitter is assigned a code). Network Management: Principles and Practice © Mani Subramanian 2010 9

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Cable Access Network DOCSIS: Data Over Cable Service Interface Specification. Figure 13. 4 Two-way Transmission in a Coaxial Cable Notes • Figure shows several CMs communicating with each other through Coaxial cable. • Single physical medium, 2 logical data streams • Downstream 6 MHz (North American) / 8 MHz (Europe, Asia) channels • Upstream Variable speed channels 160 kbps to 5. 2 Mbps • Downstream TDM broadcast mode • Upstream TDMA in DOCSIS 1. 0 and 1. 1 • Upstream S-CDMA in DOCSIS 2. 0 • CMs receive the signal in the downstream signal band transmit in the upstream signal band Network Management: Principles and Practice © Mani Subramanian 2010 10

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Cable Access Network Figure 13. 4 Two-way Transmission in a Coaxial Cable Notes • Tracing of cable modem B sending a message to CM A – The message first goes past CM A to the head end where it is converted to the downstream band frequency and retransmitted – CM modem A sees the message addressed to it coming from B in the downstream band picks it up – If the message is to be transmitted outside the CM access network , then the head end will act as a gateway or as a router Network Management: Principles and Practice © Mani Subramanian 2010 11

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Cable Modem • Cable modem modulates and demodulates the digital signal from the customer’s equipment, to RF signal that is carried on the cable. Cable Modem Termination System • All Cable modems terminate on a server called CMTS ( Cable Modem Termination System • It does routing and bridging functions outside and inside the network. Notes Network Management: Principles and Practice © Mani Subramanian 2010 12 12

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Digital-to-Analog Encoding Carrier • bit rate • symbol (baud) rate • number of levels n = 2 k; k. . number of bits per symbol • bit rate = symbol rate x k Notes • Telecommunication transmission terminology used in managing and evaluating modems: bit rate, baud rate, carrier frequency, and bandwidth. • bit rate: The bit rate is the number of bits per second that traverses the medium • symbol (baud) rate: . The baud rate is the signal units/symbols per second • number of levels n = 2 k; k. . number of bits per symbol; The input signal could also be quantized into multiple levels, for example, into four levels (2 pow 2). We would then need two bits to represent each signal unit (00, 01, 10, and 11). In this situation, the bit rate would be twice the baud rate. • bit rate = symbol rate x k Network Management: Principles and Practice © Mani Subramanian 2010 13

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Modulation Schemes • Basic modulation techniques • ASK (Amplitude Shift Keying) • FSK (Frequency Shift Keying) • PSK (Phase Shift Keying) • Cable technology uses • QPSK (Quadrature Phase Shift Keying) • QAM (Quadrature Amplitude Modulation) Notes • Quadrature phase shift keying • Four levels ( 00, 01, 10, 11) • Relatively insensitive to noise • Used for low-band upstream • 8 MHz channel: 8 x 2=16 Mbps • 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 • 8 MHz channel 8 x 4=32 Mbps Network Management: Principles and Practice © Mani Subramanian 2010 14

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Digital Subscriber Line Access Network Management: Principles and Practice © Mani Subramanian 2010 15

Chapter 13 Broadband Network Management: Wired and Optical Access Networks DSL Access Technology • Why is DSL attractive? • The main motivating factor to employ x. DSL (x digital subscriber line) for access technology in multimedia services is the pre-existence of local loop facilities to most households. • Shannon limit of data rate is 30, 000 bps (3 -KHz, 30 d. B S/N channel) • Shannon’s fundamental limitation of data rate that is prevalent in an analog modem can be overcome by direct digital transmission. This is the basic concept behind x. DSL technology, • Digital transmission over loop (DSL) improves data rate • 8 -15 Mbps downstream • 0. 8 -1. 5 Mbps upstream • Limit on distance: max to 18, 000 feet (5486. 4 m) Network Management: Principles and Practice © Mani Subramanian 2010 16

Chapter 13 Broadband Network Management: Wired and Optical Access Networks x. DSL Technologies Table 13. 8 DSL Technologies Name Meaning Max Data Rate* Mode Cable Applications ADSL / ADSL 2+ Asymmetric Digital Subscriber Line 7/12/24 Mbps 0. 8/1/1 Mbps Down Up 1 -pair Most common type SHDSL Symmetric High data rate DSL 5. 6 Mbps Duplex 2 -pair Business Connections VDSL 1 Km Very high data rate Digital Subscriber Line 55 Mbps 15 Mbps Down Up 2 -pair Triple Play (No Qo. S) VDSL 2 - Long Reach 3 Km Very high data rate Digital Subscriber Line 55 Mbps 30 Mbps Down Up 2 -pair Triple Play VDSL Short Reach 500 m Very high data rate Digital Subscriber Line 100 Mbps Down Up 2 -pair Triple Play * Max Data Rate as per Broadband Forum Notes Network Management: Principles and Practice © Mani Subramanian 2010 17

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL Network Notes • ADSL. . Asymmetric Digital Subscriber Line • ATU-C ADSL transmission unit - central office • Converts the data and video signal from the broadband network to an analog signal • ATU-R ADSL transmission unit - remote/residence • ATU is also called the ADSL modem • Splitter separates voice and data • At the central office, combines the plain old telephone service (POTS) voice signal and the broadband signal • There are modems available that embed the splitter • ADSL-Lite a. k. a. GLite Network Management: Principles and Practice © Mani Subramanian 2010 18

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL Spectrum Allocation with Guard Band (Frequency Division Multiplexing: FDM) Figure 13. 16 ADSL Spectrum Allocationd (FDM) Notes • POTS. . Plain old telephone service – Always allocated the baseband of 4 KHz and separated from the broadband signal by a guard band – There are two schemes for separating the upstream and downstream signals – 1. FDM ( refer figure above) – 2. Echo cancellation ( next slide) Network Management: Principles and Practice © Mani Subramanian 2010 19

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL Spectrum Allocation with Echo Cancellation Figure 13. 16 ADSL Spectrum Allocation (Echo Cancellation) Notes • Echo cancellation separates upstream and downstream signals – Echo suppression and echo cancellation are methods in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. • Increases (low-frequency) upstream bandwidth Network Management: Principles and Practice © Mani Subramanian 2010 20

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Modulation Schemes • Carrierless amplitude phase (CAP) modulation • Discrete Multi. Tone modulation (DMT): 4 k. Hz tones • Both CAP and DMT are QAM-based • DMT outperforms CAP • Higher downstream throughput > 4 times • Higher upstream throughput > 10 • Rate adaptive • Ongoing active monitoring • Maximum loop variation coverage • Standard and hence interoperability • However more complex and costly Notes Network Management: Principles and Practice © Mani Subramanian 2010 21

Chapter 13 Broadband Network Management: Wired and Optical Access Networks DSL / Broadband Forum • ADSL (now Broadband) Forum is an industry consortium formed to • Achieve interoperability • Accelerate DSL implementation • Address end-to-end system operation • Security • Management • 3 sets of complementary standards adopted • ITU-T standards • G. 992. x • G. 997. x • T 1 -413 (ANSI) • Forum Standards • Technical reports TR-xxx • IETF standards • RFC xxxx Notes Network Management: Principles and Practice © Mani Subramanian 2010 22

Chapter 13 Broadband Network Management: Wired and Optical Access Networks VDSL Network Figure 13. 17 VDSL Access Network Notes • Used in FTTN configuration • Asymmetric band allocation (similar to ADSL) Fiber to the node (FTTN) is one of several options for providing cable telecommunications services to multiple destinations. Fiber to the node helps to provide broadband connection and other data services through a common network box, which is often called a node. Fiber to the node may also be called fiber to the neighborhood. • Fiber carries multiple channels to ONU • Channels demultiplexed at Optical Network Unit (ONU) and carried to customer premises on multiple twisted pairs • Shorter distance of multiple twisted pairs • Higher data rate - 55. 2 Mbps downstream and 2. 3 Mbps upstream Network Management: Principles and Practice © Mani Subramanian 2010 23

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL Network 5 Transport Modes • Synchronous transport mode (STM) • Bit synchronous transmission (T 1/E 1) • 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 Network Management: Principles and Practice © Mani Subramanian 2010 24

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL System Reference Model Network Management: Principles and Practice © Mani Subramanian 2010 25

Chapter 13 Broadband Network Management: Wired and Optical Access Networks 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 Network Management: Principles and Practice © Mani Subramanian 2010 26

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL Channeling Schemes Downstream bearer channels ATU-C Duplex bearer channels Fast channel ATU-C ATU-R Interleaved channel Figure 13. 20 ADSL Channeling Notes • Transport bearer channels • Seven AS downstream channels (in simplex) - multiples (1 -, 2 -, 3 - or 4 -) T 1 rate of 1. 536 Mbps (North America, 24 channels at 64 Kbps) or E 1 rate of 2. 048 Mbps (Europe, 32 channels at 64 Kbps, with 2 for signaling and controlling) • Three LS duplex channels for downstream and upstream - 160, 384, and 576 Kbps • Buffering scheme • Fast channel: uses fast buffers for real-time data • Interleaved channel: used for non-real-time data (digital data channel) • Both fast and interleaved channels carried on the same physical channel Network Management: Principles and Practice © Mani Subramanian 2010 27

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Management Reference Model Notes Same as fig 13. 19, but includes additional components for switching and physical layer functions Network Management: Principles and Practice © Mani Subramanian 2010 28

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Management Elements • Management of ADSL network involves 5 elements • 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 in the previous slide • Management of physical layer involves: • Physical channel • Fast channel for RT • Interleaved channel for NRT • Management of type of line encoding • DMT: most efficient • CAP Network Management: Principles and Practice © Mani Subramanian 2010 29

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Signal Power and Data Rate Management 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 (but remains a that level afterwards) (2), and dynamic (3) • Goal: reduce power to decrease the energy consumption while increasing the data rate Network Management: Principles and Practice © Mani Subramanian 2010 30

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Configuration Mgmt Parameters Table 13. 10 ADSL Configuration Management Parameters 31

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Fault Management Table 13. 11 ADSL Fault Management Parameters 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 T 1. 413 • Noise margin threshold alarms • Rate change due to noise margin Network Management: Principles and Practice © Mani Subramanian 2010 32

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Performance Management Table 13. 12 ADSL Performance Management Parameters Notes • Line attenuation • Noise margin • Output power • Data rate • Data integrity check • Interleave channel delay • Error statistics Network Management: Principles and Practice © Mani Subramanian 2010 33

Chapter 13 Broadband Network Management: Wired and Optical Access Networks 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 Network Management: Principles and Practice © Mani Subramanian 2010 34

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Configuration Profile: Mode I - Dynamic • The access node can have hundred of (ADSL transmission unit - central office ) ATU-Cs (see Figure 13. 19) • Impractical to provision all the parameters for each ATU-C individually • There are two MIB tables to address this issue: one for configuration profile ({ADSLMib. Objects 14} which contains information shown in Table 13. 10) and another for the performance profile • Each ADSL line interface (1 to x) shares the configuration profiles (1 to n) Network Management: Principles and Practice © Mani Subramanian 2010 35

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Configuration Profile: Mode II - Static • Each ADSL line interface (1 to x) has a static configuration profile • Note that the alarm profile can be structured in a manner similar to the configuration profile (dynamic and static) • Use of adsl. Line. Alarm. Profile. Table {adsl. Mib. Objects 15} Network Management: Principles and Practice © Mani Subramanian 2010 36

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL 2 and ADSL 2+ • Rate and reach Improvements • ADSL Speed Downstream/Upstream 1/. 256 Mbps • ADSL 2 Standard G. 992. 3 July 2002 • ADSL 2 Lite Standard G. 992. 4 July 2002 • Speed Downstream/Upstream 12/1 Mbps • ADSL 2+ Standard G. 992. 5 January 2003 • Speed Downstream/Upstream 24/2 Mbps • Other Major Enhancements • Diagnostics • Power enhancements • Rate adaptation • Bonding for higher data rates • Channelization and Channelized Voice-over DSL (CVo. DSL) • Additional Benefits • Improved interoperability • Fast startup • All-Digital Mode • Support of packet-based services Network Management: Principles and Practice © Mani Subramanian 2010 37

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL 2 Rate and Reach Notes • Data rate increase of 50 kbps or increase of 600 feet reach achieved • Programmable overhead • ADSL 32 kbps • ADSL 2 4 -32 kbps • Higher coding gain from Reed-Solomon (RS) code Network Management: Principles and Practice © Mani Subramanian 2010 38

Chapter 13 Broadband Network Management: Wired and Optical Access Networks ADSL 2 Power Enhancement Notes • In ADSL 2 power saving is achieved by operating in 3 levels, high, low and medium • Savings in ATU-C and ATU-R • L 0 Full power – high data transfer Eg: file upload • L 2 Normal power – normal traffic • L 3 Sleep mode (user not on line) – no traffic Network Management: Principles and Practice © Mani Subramanian 2010 39

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Bonding for Higher Data Rates Notes • Bonds two or more UTP using ATM IMA (Inverse Multiplexing for ATM) • New sublayer between PHY and ATM Network Management: Principles and Practice © Mani Subramanian 2010 40

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Other ADSL 2 Enhancements • Diagnostics by use of enhanced transreceivers • Line noise • Loop attenuation • SNR (Signal-to-Noise ratio) • Improved interoperability due to initialization of state machine • Fast startup • Transmission of ADSL data in the voice bandwidth • Ethernet over ADSL 2 Notes Network Management: Principles and Practice © Mani Subramanian 2010 41

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Passive Optical Network Management: Principles and Practice © Mani Subramanian 2010 42

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Passive Optical Network • Fiber Medium • Can be implemented on copper • No active elements (regenerative repeaters, amplifiers, …) in the transmission medium • Passive elements in the fiber medium • Beam splitter – Lossy • is optical fiber tandem device with many input terminals and many output terminals • Wavelength Division Multiplexer (WDM) • multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i. e. , colors) of laser light. • This technique enables bidirectional communications over one strand of fiber, as well as multiplication of capacity. Notes Network Management: Principles and Practice © Mani Subramanian 2010 43

Chapter 13 Broadband Network Management: Wired and Optical Access Networks Generic PON Architecture Notes • Optical Line Termination (OLT) in central office • Optical Network Unit (ONU) in customer residence • Shared or dedicated optical path • 1 -way and 2 -way transmission using separate physical or optical wavelength (λ) path • Dedicated fiber (λ) vs. shared medium multiple (λ) • 3 deployment configurations • Dedicated fiber • EPON • WDM Network Management: Principles and Practice © Mani Subramanian 2010 44

Chapter 13 Broadband Network Management: Wired and Optical Access Networks PON Configurations: Dedicated Fiber Figure 13. 31(a) PON Configuration (Point-to Point PON) Notes • Dedicated fiber from OLT to each ONU • ONU function similar to ONU in cable access network • One-way in each fiber / Dual wavelength fiber for 2 -way • Expensive configuration Network Management: Principles and Practice © Mani Subramanian 2010 45

Chapter 13 Broadband Network Management: Wired and Optical Access Networks PON Configuration: EPON (Ethernet PON) Figure 13. 31(b) PON Configuration (EPON) Notes • Shared optical fiber from OLT to power splitter / combiner • Twisted pair or Cat-x cable from splitter / combiner to ONU • Modified Ethernet MAC protocol for EFM (Ethernet First Mile) • Downstream TDM and upstream TDMA • MIB specified only for EPON • Note that the link between OLT and the passive optical splitter-combiner uses Ethernet (EPON) or ATM (APON). APON is becoming obsolete Network Management: Principles and Practice © Mani Subramanian 2010 46

Chapter 13 Broadband Network Management: Wired and Optical Access Networks PON Configuration: WPON (WDM PON) Figure 13. 31(c) PON Configuration (WPON) Notes • Shared single fiber from Optical Line Termination (OLT) to Wavelength Division Multiplexer (WDM) • Multiple (λ), one to each Optical Network Unit (ONU) • DWDM (Dense WDM) special case of WDM Network Management: Principles and Practice © Mani Subramanian 2010 47