re: superluminals; if a tree falls in the forest, does it carry data?; Optical Network Magazine
Hello Bernard, Thread,
BL, thanks for once again pointing me to:
Superluminal Motion: Fact or Fiction?
By Ryan Frewin, Renee George, Deborah Paulson
lal.cs.byu.edu
I don't recall exactly why, but I was drawn to this paper the other day, but was distracted by something. I suppose that if I want to keep up with the new direction that this thread is taking, I'd better do some boning up and digest this and other papers like it. As to such capabilities as actually carrying information, that in itself presents one of those if a tree falls in the forest kinds of problems, doesn't it? <g>
On a related note, since we're talking about sources of optical information, today I received the second quarterly issue of Optical Networks Magazine, put out by SPIE. I'm only now nearing the completion of the first quarterly edition, but I've seen enough as of this time to wholeheartedly recommend it to anyone who is interested in next generation optical networking platforms.
optical-networks.com
The following link points to abstracts of each of the articles in this month's issue, from:
optical-networks.com
You may notice some familiar arguments, immediately in the first abstract below, and as you read throughout the remaining ones, some of which we've had here and elsewhere in SI over the past two years. Enjoy.
FAC
---------begin abstracts:
Abstracts from Issue 2 (April 2000)
How Many Wavelengths Do We Really Need? A
Study of the Performance Limits of Packet Over
Wavelengths
Joe Bannister
Joe Touch
Alan Willner
University of Southern California
Stephen Suryaputra
Nortel Networks
Abstract
Coupling Internet protocol (IP) routers with
wavelength-selective optical crossconnects makes it
possible to extend the existing Internet infrastructure to
a wavelength-division-multiplexing optical network.
Because optical wavelength routing is transparent to IP,
one can achieve very high throughput and low delay
when packets are made to bypass the IP forwarding
process by being switched directly through the optical
crossconnect. We study the performance of a specific
instantiation of this approach, which we call packet over
wavelengths (POW). We present the POW architecture
in detail and discuss its salient features. Realistic
simulations of the POW that use actual packet traces in
a well-known Internet backbone network reveal the level
of performance that can be expected from POW under
various options. Specifically, we evaluate the fraction of
packets that are switched through the crossconnect as
a function of the number of wavelengths and the degree
of flow aggregation that can be achieved. Our study,
conducted in the context of the very-high bandwidth
network service (vBNS) Internet backbone, suggests
that as few as four wavelengths combined with a high
degree of traffic aggregation can carry more than 98%
of IP packets in the streamlined switched mode. In
cases where it is not possible to aggregate traffic, the
deployment of wavelength-merging technology would
increase the fraction of IP packets carried in streamlined
switched mode by up to 52%.
Benefits of wavelength conversion in optical
ring-based networks
Dominique Marcenac
pp.7, B61-MH, BT Adastral Park Martlesham Heath,
Ipswich IP5 3RE, UK
Abstract
The impact of wavelength conversion in optical rings is
studied for a number of different types of traffic. When
the traffic forecasts are very accurate, wavelength
conversion is found to offer little benefit in terms of
network capacity. However, when the traffic is
unpredictable, or when the rate of churn is high,
wavelength conversion could become desirable.
Choices, Features and Issues in Optical Burst
Switching
C. Qiao
M. Yoo
Departments of CSE and EE University at Buffalo (SUNY)
Buffalo, NY 14260, USA
Abstract
In this article, we first explore design choices in
burst-switching and describe a new variation that is
especially suitable for optical WDM networks. We then
identify main features of optical burst switching (OBS),
discuss major differences and similarities between OBS
and optical circuit- and packet-switching, and address
important QoS related performance issues in OBS.
Lambda-Labeling: A Framework for
IP-Over-WDM Using MPLS
Nasir Ghani
Nokia Research Center Burlington, MA, 01801, USA
Abstract
The rapid pace of developments in both layer two/three
networking and optical technologies are inevitably
bringing the two domains closer together. In recent
years there has been a lot of interest in carrying IP over
WDM networks in an efficient manner. The benefits here
include larger bandwidth capacities, better network
scalability, and more efficient operation. However, the
current work in this area has essentially focused on
defining a lower protocol layer for WDM networks to
provide "circuit-switched" services to multiple
higher-layer protocols (IP, ATM, even SONET/SDH). This
introduces yet another network-level "access-layer"
between the IP layer and raw fiber and poses increased
network management and operations costs. As improved
optical networking devices get cheaper and more
commonly available, it is likely that a closer interworking
will be more beneficial. Furthermore, as developments in
the optical packet switching arena emerge, additional
features will have to be designed to augment the
current circuit-provisioning approaches being developed.
Hence it is very desirable to design an integration
strategy which will seamlessly migrate towards possible
future trends. Here a novel IP standards-based
approach, termed "lambda-labeling" is presented for
direct IP-over-WDM integration. The scheme uses the IP
MPLS protocol and uses its label-switching concept to
provision wavelength-switched channels. Specifically,
optical network nodes are treated as IP MPLS devices
and label stacking is used at the edge of optical
subnetworks to aggregate smaller LSP's from electronic
MPLS nodes into larger (discrete) "lambda" LSP's
associated with optical lightpath channels. However,
since the intermediate core "optical" MPLS nodes cannot
perform any electronic label processing during data
transfer, only a subset of the label processing operations
can be replicated. By using the MPLS explicit-routing
capability, this framework can make use of the large
body of work already done in the optical arena on topics
such as wavelength channel routing and assignment,
wavelength conversion, and channel
restoration/protection. Furthermore, an MPLS-based
control framework is more amenable towards future
evolutions in optical networking. Keywords:
IP-over-WDM, MPLS, WDM networks, optical networks,
IP internetworking
CAD Tools in Optical Network Design
Don Montgomery
Rusty Brooks
Boston Communications Networks (BCN), Inc. Dallas,
Texas USA
Marco Tacca
Isabella Cerutti
Luca Valcarenghi
Center for Advanced Telecommunications Systems and
Services (CATSS) The University of Texas at Dallas
Richardson, Texas USA
Abstract
Dense wavelength division multiplexing (DWDM) optical
devices are enabling the advent of all-optical networks
and all-optical "islands" embedded in backbone networks.
Costs of these pioneering systems are high, functionality
is limited, and engineers need design tools to aid in the
design process itself, and in minimizing network devices
and management; and to maximize performance, both in
traffic metrics, and in delivery and reliability guarantees.
DWDM networks have unique characteristics which offer
unique design opportunities. Due to wavelength routing,
nodes which are topologically many hops away from
each other may be optical one-hop neighbors, linked by
a "lightpath." This differs from the SONET/SDH paradigm.
Questions of robustness and survivability are made
urgent by the impending widespread adoption of DWDM
networks. Just as importantly, design and configuration
of DWDM networks takes place in the context of existing
network infrastructure and protocols, making
compatibility a primary issue. The many interesting
problems in this new environment include finding ways to
deal with the huge increments of bandwidth available;
ways to best provide protection and survivability,
lightpath routing and wavelength assignment; how to
reduce and place optical crossconnect (OXC) ports,
wavelength-converters, amplifers, and other critical
resources; ways to carry IP and ATM directly on
wavelength channels; how to achieve high throughput in
concert with high connectivity; ways to implement
practical quality of service (QoS) guarantees; and how
to perform lightpath based network simulation and
performance modeling. Design tools for this emerging
all-optical networking environment will enable engineers
to achieve faster research/development/deployment
cycles, allow on-line network management, and, most
importantly, optimize critical network cost and
functionality relationships. After reviewing current
approaches, we demonstrate the design issues and
solutions in detail with a prototype tool, CATO (CAD Tool
for Optical Networks). Keywords: optical layer protection
and restoration, optical device placement and
configuration, DWDM network design, all-optical network
design, all-optical network simulation, all-optical network
optimization, wavelength multiplexed and routed
strategies, network modeling and performance issues.
Techniques and technologies towards all-optical
switching
A. Pattavina
M. Martinelli
G. Maier
P. Boffi
Politecnico di Milano/CoreCom, Milano (Italy)
Abstract
Progresses in transmission techniques have enabled the
building of a digital transmission infrastructure capable of
carrying an ever-increasing number of channels for the
provision of communication services. The deployment of
new switching techniques (progresses in switching
traditionally follow those in transmission), such as fast
packet switching, enabled the building of a networking
environment where the bandwidth could be used in a
flexible way, so as to bettermatch the service
characteristics. The need for more and more bandwidth
pushed the introduction of optical technologies in the
transmission world: point-to-point optical links carrying
digital flows on the order of Gbit/s are now a reality.
Again, switching technologies are trying to match the
progresses of transmission technologies: research and
experiments are being performed to figure out how
switching could be accomplished as well in the optical
domain. The state of the art of electronic switching
technology is reviewed and its evolution towards
all-optical switching is discussed in terms of problems
and perspectives within the frame of circuit-switching
versus packet-switching scenarios.
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