Increasing traffic volumes in the Internet put strict requirements to the architecture
of optical core networks. The exploding number of Internet users, and
massive increase in Internet content consumption forces carriers to constantly
upgrade and transform their core networks in order to cope with the traffic
growth. The choice of both physical components and transport protocols in
the core network is crucial in order to provide satisfactorily performance.
Data traffic in the core network consists of a wide variety of protocols.
OTN is a digital wrapper technology, responsible for encapsulating existing
frames of data, regardless of native protocol, and adding additional overhead
for addressing, OAM and error control. The wrapped signal is then
transported directly over wavelengths in the optical transport network. The
common OTN wrapper overhead makes it possible to monitor and control
the signals, regardless of the protocol type being transported.
OTN is standardized by the ITU through a series of recommendations,
the two most important being ITU-T G.709 - "Interfaces for the Optical
Transport Network", and ITU-T G.872 - "Architecture of the Optical Transport
Network". OTN uses a flexible TDM hierarchy in order to provide high
wavelength utilization. The TDM hierarchy makes it possible to perform
switching at various sub-wavelength bit rates in network nodes.
An introduction to OTN and an overview of recent progress in OTN
standardization is given in the thesis. An OTN switch which utilizes the
flexible multiplexing hierarchy of OTN is proposed, and its characteristics is
tested in a network scenario, comparing it to the packet switched alternative.
Simulation results reveal that OTN switching doesnt provide any performance
benefits compared to packet switching in the core network. OTN
switches do however provide bypass of intermediate IP routers, reducing the
requirements for router processing power in each network node. This reduces
overall cost, and improves network scalability.
An automatically reconfigurable OTN switch which rearranges link subcapacities
based on differences in output buffer queue lengths is also proposed
and simulated in the thesis. Simulation results show that the reconfigurable
OTN switch has better performance than both pure packet switching and
regular OTN switching in the network scenario.
Place, publisher, year, edition, pages
Institutt for telematikk , 2011. , 138 p.
ntnudaim:6183, MSTCNNS Master of Telematics - Communication Networks and Networked Services (2 year), Nett og tjenestekvalitet
IdentifiersURN: urn:nbn:no:ntnu:diva-14136Local ID: ntnudaim:6183OAI: oai:DiVA.org:ntnu-14136DiVA: diva2:447286
Bjørnstad, Steinar, Førsteamanuensis IIVeisllari, Raimena