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Advances of WAN Technologies


Some companies carry IP, ATM, frame relay and Gigabit Ethernet on a SONET ... expensive re-cabling and can tremendously reduce the cost of network upgrades. ... – PowerPoint PPT presentation

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Title: Advances of WAN Technologies

Advances of WAN Technologies
  • Zhangxi Lin
  • ISQS 6341

  • Not dead yet
  • Some companies carry IP, ATM, frame relay and
    Gigabit Ethernet on a SONET transport structure
  • Main beef against SONET End users can't scale up
    gradually to get--and pay for--just what they
    need. Another annoyance is that it traditionally
    took weeks and a couple of truck rolls to add to
    any customer's capacity.
  • There is a way to provision bandwidth over SONET
    in seconds, and at increments of just 1.5 Mbps.
  • The mistake most competitive carriers made is
    strictly focusing on customer touch--having
    facilities in the ground--rather than on the
    profit per megabit. Value-added voice--that's
    high revenue. Video is high revenue
  • - May 29, 2001

  • A SONET ring provides point-to-point connections
    between routers. IP packets must, therefore, map
    to a point-to-point link, for which the most
    popular solution is using the Point-to-Point
    Protocol (PPP), defined by the IETF in RFC 1661.
  • (the technology in 1997)

IP over DWDM
  • IP over DWDM is the concept of transmitting raw
    IP packets over an optical layer, using DWDM for
    its capacity and other operations.
  • This new technical solution can increase the
    capacity of existing networks without the need
    for expensive re-cabling and can tremendously
    reduce the cost of network upgrades. This creates
    a vision of an all-optical network where all
    management is carried out in the photonic layer.
  • Transmitting IP directly over DWDM holds the key
    to the bandwidth glut and opens the frontier of
    terabit Internets.
  • http//

DWDM (Dense wavelength division multiplexing)
  • A technology that puts data from different
    sources together on an optical fiber, with each
    signal carried on its own separate light
  • Up to 80 (and theoretically more) separate
    wavelengths or channel of data can be
    multiplexing into a lightstream transmitted on a
    single optical fiber. In a system with each
    channel carrying 2.5 Gbps (billion bits per
    second), up to 200 billion bits can be delivered
    a second by the optical fiber.
  • Sometimes called wave division multiplexing
    (WDM). Since each channel is demultiplexed at the
    end of the transmission back into the original
    source, different data formats being transmitted
    at different data rates can be transmitted
    together. Specifically, Internet (IP) data,
    Synchronous Optical Network data, and
    asynchronous transfer mode data can all be
    traveling at the same time within the optical
  • Promises to solve the "fiber exhaust" problem and
    is expected to be the central technology in the
    all-optical networks of the future.
  • Replaces time-division multiplexing
    (Time-Division Multiplexing) as the most
    effective optical transmission method. Although
    TDM is the primary approach in today's networks,
    DWDM systems were tested and deployed in late
    1998 and 1999.

DWDM The Solution for the next generation
Internet (NGI)
  • If one million families decide they want to see
    video on Web sites and sample the new emerging
    video applications, then network transmission
    rates of terabits (trillions of bits per second
    Tbps) are required. With a transmission rate of
    one Tbps, it is possible to transmit 20 million
    simultaneous 2-way phone calls or transmit the
    text from 300 yearsworth of daily newspapers per
  • For some applications the time sensitivity is so
    important that minimum delay is the overriding
    factor for all protocol and equipment design
    decisions. So, there is a need for Burst mode
    optical data switching.
  • Many transmission protocols require that data
    packets traverse the network only after a circuit
    has been established. For some applications, such
    as periodic transmission of sensor data, this may
    be an unnecessary overhead to impose.

Multi-layer Stack
Disadvantages of Multi-layer Stack
  • The multi-layer stack has more problems than
  • Every layer now runs at its own speed. So, low
    speed devices cannot fill the wavelength
  • Increasing Bandwidth, due to this technological
    revolution, Core technologies are pushed to the
  • Functional overlap So many layers are doing the
    same thing, e.g. routing.
  • A failure affects many layers

IP and DWDM - A Winning Combination
  • The good news about optical networking is that it
    lets carriers deliver huge amounts of bandwidth.
    The bad news is that it's hard to get money out
    of those fat pipes. But now, with ATM and
    SONET/SDH out of the way revenue generating
    services (which were struggling till now) like IP
    virtual private networks (VPN) and voice over IP
    (VOIP) will gain direct access to DWDM resources,
    and will finally become practical.

Advantages of IP over DWDM
  • Less latency
  • Automatic provision
  • Unified bandwidth service
  • Improved QoS

  • Any pair of photonic transmission paths cannot
    use the sane wavelength on a shared fiber link.
    An algorithm needs to be devised which could
    route more than 1 line on the same wavelength.
  • There is limited address space arising from
    physical addressing i.e. there is a finite number
    of accessible wavelengths.

Multi-Protocol Lambda Switching (MPLambdaS)
  • Lambda switching is derived from Multi-Protocol
    Label Switching (MPLS). We can assume MPLambdaS
    to be just implementing Label Switching in the
    Optical domain.
  • A DWDM network (implementing Lambda switching) is
    analogical to an ATM network in the aspects of
    switching. ATM networks perform packet switching
    based on the virtual circuit number, while the
    optical channel layer performs switching based on
    the wavelength of the signal (or packet). Hence
    the name "Lambda Switching" is applied to the
    optical network.

The Way to All-Optical Network
  • DWDM is just the first step on the road to full
    optical networking and the realization of the
    optical layer. The concept of an All-optical
    network implies that the service provider will
    have optical access to traffic at various nodes
    in the network, much like the SONET layer for
    SONET traffic. Optical wavelength add/drop (OWAD)
    offers that capability, where wavelengths are
    added or dropped to or from a fiber, without
    requiring a SONET terminal. Combined with OWAD
    and DWDM, the optical cross-connect (OXC) will
    offer service providers the ability to create a
    flexible, high-capacity, efficient optical
    network with full optical bandwidth management.

  • The future holds many challenges to the
    All-optical networks. But, the commercial
    implementations for IP over DWDM are not far
    away. It provides the backbone to support
    existing and emerging technologies with almost
    limitless amounts of bandwidth capacity and opens
    the pathway to Terabit networking.
  • The trend of IP/DWDM solutions over the last few
    years seems to have taken an exponential growth.
    All-optical networking (not just point-to-point
    transport) enabled by Optical Cross-Connects,
    Optical programmable add/drop multiplexers, and
    Optical switches provides a unified
    infrastructure capable of meeting the
    telecommunications demands of today and tomorrow.
  • Transparently moving trillions of bits of
    information efficiently and cost effectively will
    enable service providers to maximize their
    embedded infrastructure and position themselves
    for the capacity demand of the future.

  • ATM tutorial at IEC proforum
    /atm_fund/index.htmlDescribes at length ATM
    technology, ATM classes of services High-speed
    local-area network (LAN) interconnection ATM
    standards, ATM multimedia applications in voice,
    video etc.
  • Sonet tutorial at IEC proforum
    ls/sonetThis Primer provides an introduction to
    the SONET standard, based on the latest
    information available from the Bellcore and
    International Telecommunications
    UnionTelecommunications Standardization Sector
    (ITUT) standards organizations.
  • DWDM tutorial at IEC proforum
    s/dwdmThis tutorial addresses the importance of
    scalable DWDM systems in enabling service
    providers to accommodate consumer demand for
    ever-increasing amounts of bandwidth.   
  • Talk by Dr.Raj Jain on IP over DWDM This
    streaming video lecture discusses a gamut of
    issues starting from the need for IP over DWDM to
    the requirements for creating an all optical
    networks based on Multi- protocol lambda