Optical Burst Switching (OBS)
- 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).
- 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
- 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
Consist of electronic router and OBS interface
- 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