Explain with neat diagram simple link using SONET devices.

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Write Short Note on: SONET Hardware.

Mumbai University > Electronics Engineering > Sem 8 > Advanced Networking Technologies

Marks: 10M, 5M

Year: May 14, Dec 14, Dec 15, May 15, May 12, May 13, May 11

1 Answer
  1. Figure shows simple link using SONET devices. SONET transmission relies on three basic devices: STS multiplexers/demultiplexer, add/drop multiplexers, 2. A number of incoming electronics signals are fed in to STS multiplexer where they are combined in to a single optical signal.
  2. The optical signal is transmitted to a regenerator where it is recreated without the noise it has picked up in transit.
  3. The regenerated signals from a number of sources are then fed into ADM.
  4. The ADM recognizes these signals if necessary and sends them out as directed by information in data frames.
  5. These re-multiplexed signals are sent to another generator and from there to the receiving STS demultiplexer where they are returned to a format usable by receiving links.
  6. SONET hardware distinctions are possibly most difficult aspect of SONET
  7. The most common equipment term used is the SONET terminal
  8. The word terminal or terminal adapter is used to represent SONET multiplexers, DXC and even a switch.
  9. There is a DXC/OXC interface or a terminal adapter to lower speed interfaces and protocols and these devices are combined through SONET terminal as a switch.
  • STS Multiplexers/Demultiplexer: STS multiplexers/demultiplexer mark the beginning point and end point of a SONET link. They provide the interfacing between the electrical tributary network and optical network. An STS Multiplexer multiplexes signals from multiple electrical sources and creates the corresponding optical signal. An STS Demultiplexer optical signal into corresponding electrical signals.
  • Regenerators: Regenerators extend the length of the link. A regenerator is a repeater that receives optical signal demodulates it into corresponding electrical signal, regenerates electrical signal and finally modulates it back into corresponding optical signal. A SONET regenerator may replace some of the header information with new information.
  • Add/Drop Multiplexer: Add/Drop Multiplexer allows insertion and extraction of signals. An add/drop multiplexer can add optical signal coming from different sources into a given path r can remove a desired signal from a path and redirect it without demultiplexing the entire signal. Instead of relying on timing and bit positions, add/drop multiplexers use header information such has addresses and pointers to identify individual streams.
  • Terminal: A terminal is a device that uses services of SONET network. For example, in the internet a terminal can be a router that needs to send packets to another router at the other side of SONET network.

enter image description here

SONET STS Signal OC Bitrate Mbps SDH signal
STS1 OC1 51.84 STM 0
STS2 OC3 155.52 STM 1
STS 12 OC12 622.08 STM 4
STS 48 OC 12 2488.32 STM 16
STS 192 OC 192 9953.28 STM 64


  • Advantages of SONET

    • Reduced network complexity and cost through SADM and SDXC capabilities
    • Capability to build optical interconnect between carriers
    • Efficiency management of bandwidth at the physical layer
    • Standard optical interface and restoration over electrical systems
    • Smart OAM&P features with uniformity
  • Disadvantages of SONET

    • Complex and costly SONET equipment’s
    • High percentage of SONET protocol overhead
    • Fibre laying unutilized in a ring architecture waiting on a failure
  • Applications of SONET

    • SONET can be used for ISDN, B-ISDN, ATM cells, cable TV networks
    • Can be used which provide bandwidth on demand
    • Can be used to replace T-1 and T-3 lines.
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