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					Why Choose Optical Fibre Instead of Copper

Russell Ellis PhD
Corning Optical Fiber
Senior Applications Engineer
12:15pm March 8, 2006
Why Choose Optical Fibre Over Copper Cables?

  •   Higher Bandwidth
  •   System Performance

  •   Installation Considerations
       – Ease of optical fibre
       – Complexity of copper cables

  •   Network Cost Modeling
       – UTP and Fibre Networks

  •   Fibre Specifications
       – Laser Optimized Fibre
       – Transceivers

  •   Fibre Costing Modeling
       – MMF vs SMF

  •   Summary
Higher Bandwidth
                                                  Copper                   50/125
                                                  Cable                    Multimode fibre (850 nm)
                                      One generation of MMF outlived
                                           4 generations of UTP
      Bandwidth (



                                                                                      CAT 7
                                                                           CAT 6
                              1                      CAT 5      CAT 5e
                                          CAT 3

                                   1985       1990       1995       1999       2002     2005-6

 Evolution of relative bandwidth-reach ( performance of copper cabling
                 vs 50/125 multimode fibre optical fibre over time
System Performance

 Reach capability of fibre vs copper cables at 1Gb/s and 10 Gb/s
                 Optical fibre
System Cabling

                 Copper Cable
                         CAT 7                                                           1Gb/s
                         CAT 6                                                           10 Gb/s

                         CAT 5e

                                  0         200        400        600         800       1000       1200
                                                     System Reach (meters)

                                 Note: MMF link distances are quoted for 850 nm operating wavelengths
Installation Considerations

• Despite the complex nature of optical fibre
  technology, Laser Optimized fibres are easy to
  work with…
Optical fibre cables are easier to install…
• Smaller size and consequently lighter weight cables are more
  practical and easier to route in confined spaces
• A typical duplex fibre cable is up to 40% smaller than a CAT-6 (UTP)
• A typical 24F optical fibre cable is roughly the same size as a CAT-7
    – For approximately the same diameter a 24F OM-3 cable can support
      12x more bandwidth, > 240 Gb/s (Duplex) and able to reach up to 300m
    – Optical cable design is not restricted to fibre type

    Duplex Fibre     CAT-6               CAT-7           12x Duplex Fibre
     (2 Fibres)      (UTP)               (STP)            (24 fibre cable)

• Technical Hurdles
  – 2.5 Gb/s per twisted pair across 500 MHz frequency
     • CAT6 legacy cable tested to 250 MHz
  – Digital signal processing (DSP) for internal noise
     • eliminate the effects of cross-talk between pairs of cable and
       the effects of signal reflections
  - EMI Noise Ingress
  - Heat Dissipation (8-10W/port)
  - Reduced Blade Density
     - 6-8 ports per blade (copper)
     - 16-18 ports per blade (optical)
10GBASE-T Cable Noise
   10GBASE-T – Alien Cross Talk
• Main electrical parameter limiting
  10 Gigabit Ethernet performance over
  copper UTP cable
   – Cannot be corrected with electronics
   – 20dB suppression required over 100m
   – Cable and patchcord separation
   – Wider port separation on patch panel
• Cable electrical Specifications defined by
  IEEE and passed to TIA for adoption into
  augmented CAT6e.
   – CAT6e only UTP cable with alien
     cross-talk guidance
   – Not backward compatible to other
 10GBASE-T – Alien Cross Talk

• PSANEXT measured in controlled
   – Six around one configuration
   – No reliable field measurement
     capability to date
• Interoperability issues with pre
  Standard cable solutions
   –   Larger cable
   –   Larger jack
   –   Larger plug
   –   Reduced port density on patch panels
        • 1U – 24 ports
Installation: Cable routing considerations

• The dielectric nature of optical fibre
  cables and EMI immunity enables
  increased flexibility                      Optical Fibre cables can be
• Copper UTP cables generate and are         densely routed In channels
  sensitive to EMI
• At high data rates UTP cables
  generate more RF interference
• To avoid alien cross-talk problems
  UTP cables are required to be
  separated or S-routed in channels
• Coupled with the larger diameter this
  can choke channels and ducting
  areas and reduce the airflow needed
  for cooling in Data Centre applications

                                            UTP cables require spacing to
                                             reduce cross talk penalties
Fibre connectivity trends

• Pre-terminated solutions – 75% faster
  installations than traditional cabling
• Attractive for high port density applications
  such as data centres
• Coded connector and patch-panel
  increase security
• Modular component design – facilitates
  moves, adds and changes
                                                  • Pre-terminated cable
• Small-form-factor products (LC, MT-RJ,          • 72F Small diameter cable
                                                  • 6 MTP terminations
  MTP, ribbon cable) – reduce space
  needed under floor, overhead and in
Post Network Cabling Installation On-Site
Testing and Certification
• MMF for Premises Networks
   – Factory Measured BW, Attn
     etc.                                                                           Post Installation Testing
                                                                                    For copper cables & fibre
   – MMF & SMF: Insertion loss

                                     # Individual certification tests
     measurement, even for 10Gb/s
                                                                        14    Optical Fibre

• Copper cables increasingly                                            12    Copper Cable

  more complex to work with                                             10

   – Requiring a number of tests                                        8

   – UTP sensitive to EMI and                                           6
     cross-talk issues                                                  4
   – Automated test equipment can                                       2
     reduce time
   – Copper data more difficult to                                           1980     1992    1995     2002     2006
     interpret if one or more test
     criteria not met                                                                          Year
     Optical Fibre vs Copper Cables in Premises
     Application Space
   • >99% Copper                                                                                       Riser
   • 10/100/1000 Mb/s                                                                       • 80% MMF/20% Copper
                                                                                            • 25% 1Gb/s
                                                                                            • 75% 100 Mb/s

                                                                                            • 95% fibre
                                                                                            • and increasing
      Data Centers                                                                          • 50% 1Gb/s
• 50% fibre and increasing                                                                  • 50% 100Mb/s
• 1, 2, 4 and 10 Gb/s        Source: Corning Optical Fibre/Corning Cable Systems Analysis   • single-mode fibre for long
• Fibre is winning, MMF is                                                                    distance
Installation Summary

• Optical fibre is increasingly easier to install and test
• Field installable connectors offer flexibility and pre-
  terminated solutions are faster and easier to work with
• Optical fibres offer an easier upgrade path
   – Overlay optical cables have no interference or operational
     impact on existing copper or fibre infrastructure
   – OM-3 grade multimode can theoretically support up to 40Gb/s
     100Gb/s using parallel optics
• Copper cables are becoming more difficult to install
  and test
• UTP cables at high data rates require spacing to
  reduce cross-talk effects
   – Increased spacing at the connector reduces port density
• STP copper cables require grounding – increased
  complexity and testing requirements
Cost breakdown passive/interface
Optical Fibre Networks

                                                 Typical Component Cost
• Electronic systems costs                             Breakdown
• Transceiver selection/cost                 Transceivers             Fibre Optic Cable
  important                                          24%                      1%
    – Depends on fibre type                                                                Jumpers,
• Cable infrastructure cost is                                                            Connectors
                                                                                             < 1%
    – Longest life cycle                                                           Patch Panel, Rack
                                                                                         < 1%
    – Dictates current and future
      bandwidth capacity                          Fixed Cost
    – System Reach Capability
    – Big bearing on operating costs
    – Flexibility                            Switch Electronics 74%
    – Upgrade options
                                  Source: Corning Optical Fiber/Corning Cable Systems Analysis
Copper Cable Interfaces

• Shorter reach of copper solutions require greater number of
  telecommunication or equipment rooms (TR/ER) in larger buildings
    – Typically one TR/ER per floor in multi-storey building
• Whilst copper cables are cheaper than optical fibre cables, longer
  reach capability of fibre can reduce other associated costs
• Copper interfaces >1Gb/s increasing require signal processing to
  recover transmission quality
    –   Increased complexity
    –   Higher signal attenuation of copper at high frequencies
    –   May result in higher power consumption
    –   Higher burden on cooling equipment
    –   Port density may be affected
Cost Modelling Private Networks

• Cost model analysis of 3 different network topologies for PNs using
  fibre and copper structured cabling;

• Hierarchical Star Network Design
    – UTP copper used in horizontal cabling
    – Fibre used in the riser/vertical cabling only
• Centralized Fibre Network
    – Fibre rich network
    – Fibre-To-The Desk (FTTD) type architecture
• Fibre-To-The-Enclosure (FTTE) Network
  (low & high density designs)
    – Fibre “home runs” to smaller telecom enclosures on each floor of the
    – UTP copper cable connection to the User
Premises Network Topologies

Hierarchical Star Network

Cat 6 Patch                         Cat 6 Cabling

Fibre patch
                        Telecom Room (TR)

                                             8th Floor

                            1st – 7th Floor (typical)

                                            Core Switch
                                            1000BaseSX B/B
              Patch Panel                   1000 BaseTX
                                            Server Ports     Main
                                                             Equipment room

                                            Main Floor
   Premises Network Topologies

   Centralized Fibre Network (FTTD)

Splice/connect                      Fibre Cables                             W/S with NIC
 (not required                                                                    +
   if <90m)                                                                     Media
                     Telecom Room (TR)
                     (smaller – rack/wall enclosure)

                                             8th Floor
       High fibre
       count riser
                           1st – 7th Floor (typical)

                                           Core Switch
Patch Panel                                1000BaseSX B/B
Workgroup                                  1000 BaseTX
Switches                                   Server Ports     Main
                                                            Equipment room

                                            Main Floor
     Premises Network Topologies

     Fibre-To-The Enclosure Network

                              Optical Fibre        Patch Panel

Fibre Cables
(no splice or
Interconnect                                       Patch Panel
                                               8th Floor

                                 1st – 7th Floor (typical)

                                          Core Switch
                                          1000BaseSX B/B
                Patch Panel               1000 BaseTX
                                          Server Ports           Main
                                                                 Equipment room

                                              Main Floor
Comparative Network Costs
• 8 Floor Building PN
• 54 Ports/floor                                       Calculated Network Installation Costs
• Copper cable:                                          Desk Hardware                          Cabling and
   – Cat 6 UTP and 1000BaseTX                            ER Install & Running Costs
                                                         ER Cabling & Equipment
                                                                                                Labour costs
• Optical Fibre
   – 50/125 (OM-2) Fibre                $ 300K

   – 1000BaseSX Transceivers            $ 250K

                                        $ 200K
   – Hierarchical Star Network
       • UTP Horiz./MMF Riser           $ 150K
       • ER costs > 50% total
                                        $ 100K
   – Centralized Fibre Network
       • Cabling & Switch electronics    $ 50K
         >50% cost
   – FTTE (High Density)                    0
                                                 Hierarchical    Centralized     FTTE          FTTE
       • Lowest Cost                                 Star          Fibre         (HD)          (LD)
   – FTTE (Low Density)                           Network         Network        Network       Network
       • Cabling & Switch electronics
         >50% cost                                  Source: Corning Optical Fiber/FOLS Interactive Cost Model
10Gb/s Operating Costs
Optical vs. Copper
    Fiber                          Copper

    ~2W      Power Consumption     ~8-15W

            Cooling Requirements

              Transceiver Size

      $       Data Center Area      $$$$
Cost Modelling Summary

• Significant cost differences in between copper and
  optical fibre components
• Fibre based networks can cost less than copper based
  networks when designed around the intrinsic
  advantages of fibre
• Higher associated costs of active equipment for copper
   –   Equipment Rooms Costs
   –   Higher Power Consumption
   –   Increased Cooling
   –   Other system/operating costs, UPS, etc.
• Optical fibre cables have a longer life cycle than copper
  Standard Optical Fibre Types for Premises
                                         OFL Bandwidth
 Optical fibre            Fibre                                   Bandwidth                 Data
 Classification           Type                                        Rate/Applications
                                          (850 / 1300)
                       62.5/125                                                         10 - 100Mb/s,
     OM-1*                                  200 / 5001              ≥ 2202
                      (or 50/125)                                                          1Gb/s*
                        50/125                                                          10 - 100Mb/s,
     OM-2*                                  500 / 5001              ≥ 5102
                     (or 62.5/125)                                                         1Gb/s*
                                                                                        10 - 100Mb/s,
      OM-3               50/125            1500 / 5001              20003
                                                                                          1, 10Gb/s
    “OM-3+”              50/125                  -                  47003,4                ≥ 10Gb/s
                         G.652                                                             Typically
      OS-1                                       -                “unlimited”
                     (single-mode)                                                         > 1Gb/s
 *Laser Optimized fibre types recommended
Notes regarding BW measurements:
1 As predicted by OFL BW, per IEC 60793-1-41, for legacy and LED-based systems (typically up to 100Mb/s)
2 As predicted by RML BW, per IEC 60793-1-41 for intermediate performance laser-based systems typ. Up to 1Gb/s
3 As predicted by minEMBc, per IEC 60793-1-49, for high performance laser-based systems up to 10Gb/s
4 550m link distance achievable with cabled fibre attenuation ≤ 3.0dB/km and 1.0dB total connector loss
Laser Optimized multimode fibres can
assure high performance with Lasers

        Light Sources                   Bandwidth Measurement
                                           OFL (Overfilled-Launch)
                                    • Designed to predict performance of low-
                                      speed LEDs, not lasers
                                    • Power distributed in 100% of the fibre
                                      core, like LEDs
  (Typically 10 and 100 Mb/s)       • Perturbations in index profile undetected

                                         Laser-Based Measurements
                                     EMBc laser based BW technique with
                                      DMD (Differential Mode Delay)
                                     RML (Restricted Mode Launch) or
                                      Power distributed in a narrow region
                                     Simulates an actual laser launch
 (1, 2, 4, 8, 10 Gb/s and higher)
                                     More accurate indication of performance
                                      in high-speed laser-based systems
Legacy OFL bandwidth measurements
cannot predict laser performance


    Laser Bandwidth (

                                                                                                 OFL ~ Laser
                                                                                                 OFL > Laser
                               1500                                                              OFL < Laser



                                      0   500   1000         1500         2000     2500   3000
                                                 OFL Bandwidth (

                                                Source: TIA FO-2.2.1 Round Robin
   Comparison: Spectral Characteristics
    $                          60 nm           Typ. 1300nm

                                                             Higher Performance
Fabry-Perot          4 nm
                                                 1310 nm

                                   ~ 3-10 dB
  VCSEL             < 0.5 nm                     850 nm

                     0.1 nm                      1550,
 DFB laser                         > 30dB
  $$$$$                                          1310 nm
    Laser Optimized OM-3 Solution
    Lower-cost than LX (1300 nm)
Assumptions:                                                       Relative System Costs: 1 Gigabit over 300m
 • 300m, 24F count cable, 24F Passive                              Transceivers    Fibre Optic Cable            Passive Interconnect

   Interconnect (x2), 18x 1 Gb/s                              2    OM-2
   Transceivers                                                                   upgrade

                                             Relative Cost
                                                                   Lowest          cost to
System Solution Options:                                            cost          10Gb/s

•   OM-2 fibre with SX transceivers                           1


•   OM-3 fibre with SX transceivers


•   OM-2 fibre with LX transceivers
•   Single-mode fibre with LX transceivers
                                                                    OM-2           OM-3            OM-2                  OS1 (LX)

                                                                     Note: Figures based on Corning conservative estimates

               SX solution saves up to half the cost LX option
                      And OM-3 ≤ 5% overall cost increase
    OM-3 & OM3+ Lower-cost than SMF over
                                                                Relative System Cost: 10 Gb/s 300m
• 300m, 24F count cable, 24F                              1.4
  Interconnect hardware (x2),                             1.3        Passive Interconnect
  18x 10 Gb/s transceivers;                                          Optical fibre cable
                                                          1.2        Transceivers

                                          Relative Cost
System Solution Options:                                  1.1
•   OM-3 fibre cable with 850nm VCSELs                    1.0
•   OM-3+ fibre cable with 850nm
    VCSELs                                                0.9

•   Legacy OM-1 fibre cable with WWDM                     0.8
    10 GBASE LX-4 1300nm lasers                                             OM-3+
                                                                   OM-3                OM-1    Single-Mode
    and mode-conditioning patch-cords                             850 nm    850 nm    1300 nm    1300 nm
•   Single-mode fibre cable with 1300nm                         10GBaseSX 10GBaseSX 10GBaseLX4 10GBaseLR
    LR transceivers

                                                                   Note: Figures based on Corning conservative estimates
OM-3+ Fibre Enables Higher Insertion Loss
and Extra Operating Margin
                                  10Gb/s Serial Power Budgets (850nm)
                          Using standards complaint 10GBASE-SR Transceivers
                      7                  Extra                                                  Spare margin
  Power Budget (dB)

                      6                                                                         Other penalties
                      5                                             Higher                      ISI penalty
                      4                                              Over                       Total connector loss
                                                                    Longer                      Cable attenuation
                      2                 Channel                      550m
                            OM-3               OM-3+ (550m)              OM-3+ (550m )
                            fibre                  fibre                     Fibre
                          300 meters               300 meters               550 meters*
                                Power budget calculations based 10Gb/s IEEE model
                                Cable attenuation is 3.5 dB/km, total connector loss 1.5 dB
                                *Max cable attenuation 3.0 dB/km, 1.0 dB total connector loss
Benefits of Optical Fibre
•   Higher data rates and longer link lengths
•   Flexible, reliable networks with low latency
•   Unparalleled network security
•   Immune to EMI, RFI and cross-talk
•   Small lightweight cables – maximizes pathway and
    space utilization
•   Higher port density
•   Easier installation, handling and termination
•   Simplified field testing
•   Longer cable life cycle
•   Lower power consumption, less expensive to operate

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