Optical Burst Switching (OBS)

Definition

  • Optical Burst Switching (OBS) is an optical network technology that aims to improve the use of optical networks resources when compared to optical circuit switching (OCS).
  • OBS is implemented using Wavelength Division Multiplexing (WDM), a data transmission technology that transmits data in an optical fibre by establishing several channels, each channel corresponding to a specific light wavelength.
  • Optical Burst Switching is used in core networks, and viewed as a feasible compromise between the existing Optical Circuit Switching (OCS) and the yet not viable Optical Packet Switching (OPS).
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OBS network

  • Control and data information travel separately on different channels
  • Data coming from legacy networks are aggregated into a burst unit in edge node
  • The control packet is sent first in order to reserve the resources in intermediate nodes
  • The burst follows the control packet with some offset time, and it crosses the nodes remaining in the optical domain

OBS principles

  • Variable-length packets, named bursts
  • Asynchronous node operation
  • A strong separation between the control and data planes
    • control burst (with control information)transmitted on dedicated control channel andprocessed electronically
    • Data burst transmitted and switched all-optical way

 

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Edge Node

Consist of electronic router and OBS interface

Functions

  •  Electronic data buffering and processing
  •  Burst  Aggregation (BA), responsible for collecting data from legacy networks and building the burst unit
  • impact on the overall network operation by the control of the burst characteristics
  • in order to reduce the burst loss probabilities in the network the aggregation function can segmentate data bursts for the purpose of their partially dropping in core nodes when contention occurs
  • Setting up the pre-transmission offset time
  • in simple fixed offset scheme, the offset time is calculated as a sum of the total processing time at all the intermediate hops
  • offset time is one of the crucial OBS network parameter, since his incorrect estimation has impact on data lost
  • Sending the control packet
  • Sending the burst

Categorized in:

NETWORKING

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