• norsk
    • English
  • English 
    • norsk
    • English
  • Login
View Item 
  •   Home
  • Fakultet for informasjonsteknologi og elektroteknikk (IE)
  • Institutt for informasjonssikkerhet og kommunikasjonsteknologi
  • View Item
  •   Home
  • Fakultet for informasjonsteknologi og elektroteknikk (IE)
  • Institutt for informasjonssikkerhet og kommunikasjonsteknologi
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Performance and Control of Integrated Hybrid Optical Networks

Veisllari, Raimena
Doctoral thesis
View/Open
Fulltext not avialable (Locked)
URI
http://hdl.handle.net/11250/2432171
Date
2016
Metadata
Show full item record
Collections
  • Institutt for informasjonssikkerhet og kommunikasjonsteknologi [1601]
Abstract
In the last two decades optical technologies have progressed both in terms of

network layer functionality and coverage: evolving from transmission to switching,

and disseminating in all network segments. The catalyst is, in part, the need to

meet the bandwidth demands of an exponentially increasing amount of traffic

conveyed through all networks. In this context, optics are attractive with the high

bandwidth-distance product, low processing overhead, and low environmental

footprint. At the same time, innovations in ICT and the penetration of Internet

have not only affected the amount of generated data traffic but also created an

extensive range of applications with as extensive quality of service requirements,

from bandwidth hungry to time critical services. A competitive market challenges

carriers to deliver these services effectively at a low cost. Thus it is essential to

maximize the utilization efficiency of network resources and offer a wide variety of

differentiated services, i.e. be able to support the quality of service (QoS) needed by

the most demanding applications.

It is in this context that the integrated hybrid optical network (IHON) is propositioned

as an attractive solution for next generation optical networks. It enables

networks with high throughput efficiency of packet switching and strict service

guarantees of circuit switching. The unique property of IHON is that it combines

advantages from the best of both worlds, i.e. circuit and packet switching, in a

fully integrated manner, at the link level. Each switching paradigm marks one

class of quality of service, which can then be segregated further within the class.

The circuit-switching performance characteristics are preserved by the guaranteed

service transport (GST) class: fixed end-to-end delay, theoretically no packet delay

variation and no packet loss. This equips carriers with a premiumquality service,

e.g. as legacy technologies like time-division multiplexing and leased line. High

resource utilization is gained from the statistically multiplexed (SM) service class of

packet switching traffic. This empowers a flexible, cost-efficient and future proof

network that can serve current and future classes of services and maximize resource

function.

This PhD thesis builds upon previous work on IHON node architectures, pro posed and studied at theDepartment of Telematics, NTNU, and the commercialized

IHON architecture from TransPacket, Fusion H1. The first architecture is the OpticalMigration

Capable with service guarantees (OpMiGua). It was presented by S.

Bjornstad in 2003 and further studied in the PhD work of A. Kimsas in 2011. It is

the basis for the two other architectures that build upon its principle of multiplexing

circuit and packet traffic on the same wavelength links in a time interleaved

method. The second architecture, the three level integrated hybrid optical network

(3LiHON) architecture, proposed by N. Stol in 2010, enhances OpMiGua by adding

a real-time packet service. The third architecture, the commercial Fusion node

from Transpacket, implements the OpMiGua principle in Ethernet-based networks.

These three architectures are the basis throughout this work and the termIHON

was introduced to denote all architectures which implement the integrated principle.

Note that, in the IHON context, the circuit traffic is also packet traffic which is

switched in the network as in circuit-switching.

The research objectives are categorized into studies and enhancements of the

data plane mechanisms and control planes for IHON. The OpMiGua architecture is

considered throughout all the publishedwork, while 3LiHON and Fusion on specific

works. Part I presents the reasons behind hybrid optical networks, an overview

on related work, and the edge that integrated hybrids have on this category. The

contributions are then presented into two categories: data plane and control plane

studies for IHON.

In the data plane, three mechanisms are investigated in line with the objective

ofmaximizing the wavelength utilization: a time-window scheduler with electronic

buffers, buffer management techniques, and rate-adaptive segmentation. In relation

to previous work on OpMiGua, there are two strategic different choices. First,

the SM traffic is buffered electronically, and second, the system under investigation

has only one output wavelength. The electronic buffering enables more involved

mechanisms, which are further investigated without the influence of thewavelength

contention resolution domain, thus focusing on fine tuning their performance. The

proposed schedulingmechanism monitors the gaps between GST packets through

the time-window and finds, in the buffer withmultiple queues, SMpackets of suitable

size that fit in the gaps. Results show that it efficiently increases the utilization

of the available capacity up to 90% total throughput without loss. The scheduler is

ever more important for the demanding case of the left over capacity for serving SM

being highly fragmented, i.e. GST is not burstified at the edge node before entering

the IHON domain but has the same packet length distribution as SM. Furthermore,

this packetized traffic pattern is an important case as it can describe the traffic

pattern of a time-sensitive class of service that could require a premium service

like GST; it is thoroughly investigated in this PhD work as compared to previous

studies where GST is mainly burstified. Results show that it is the worst scenario

for the SM performance as the system saturates at lower loads, e.g. 20% lower load

as compared to a short burst of ten GST packets. This is because the wavelength

blocking probability for the SM class increases when the GST traffic consists of

single packets because of the wavelength reservation to GST. Therefore, enhanced scheduling techniques in combination with buffer management techniques are

especially important for cases of high GST packet traffic load in order to increase the

resource utilization and make use of gaps shorter than the time-window. Moreover,

it motivates the investigation of queuemanagement schemes and proposing the

mechanism of adapting the segmentation of SM packets on the GST rate for limiting

the buffer overflow and SMdelay performance. Results from simulations show that

just by increasing the number of queues from one to four the wavelength utilization

increases by 5%; segmentation, performed only based on the probability that the

systemmight saturate to avoid over processing, reduces the SMpacket loss ratio

66% and keeps the SM delay close to the buffering bounds.

A highlight of this PhD work are the first experimental demonstrations of an

integrated hybrid optical network through the Fusion prototype nodes. Theoretical

and simulation results on the scheduling and buffer management techniques are

then compared to the implementation results, showing good compatibility and the

feasibility of the system. It is verified that GST is carried with no packet loss and

ultra-low delay and delay variation, enabling transport of the most time-demanding

services, like time-sensitive traffic and packet layer synchronization information.

Field-trials through metro and long-haul networks are also conducted with synthesized

traffic and also real production traffic, carried as GST in the carrier network

of UNINETT. The high throughput efficiency is demonstrated by adding SM traffic

on the common wavelength links, doubling the average link utilization without

affecting- and transparently to- GST. To stress the system to its maximum, measurements

are also performed during 24 hours and seven day periods, containing

high GST traffic load up to 0.8 and running the link into saturation. The amount

of SM traffic that is added ismonitored, resulting in a mean of 48% increase of the

link utilization. Strong dependence on time of day is observed, underlining the

importance of dimensioning IHON and load balancing/protection for SM, which

are areas outlined for further work. A simple analyticalmodel is proposed for the

leftover capacity. Its results are compared with the gathered experimental results,

showing that the model gives a lower bound on the maximumSM inserted in the

network as a function of the carried GST load. This theoretical estimate is offered

as a guideline when dimensioning the network. Furthermore, it quantifies the costefficiency

of IHON with the higher throughput efficiency as compared to parallel

hybrids.

The second part of this thesis investigates control plane solutions and their

compatibility with IHON. The specific requirements that IHON poses to the control

plane are defined and mapped to the current generalized multiprotocol label

switching (GMPLS) standards, showing that a fully compatible IHON control plane

is feasible. The control framework itself is integrated, i.e. it is considered that one

single GMPLS instance controls both packet-switched and circuit-switched virtual

network topologies. The framework requires no changes to the existing GMPLS

architecture; thus, it enables the addition of the GMPLS control plane as an added

functionality offered by the integrated hybrid networks. Furthermore, the recently

proposed software defined networking (SDN) paradigm is investigated both for its compatibility in controlling IHON and, more generally, for the scalability in optical

networks. This is the first work of this type and sheds light into possible issues

that might arise. Numerical results characterize the limitations in network dimensioning

when considering an SDN controller implementation in the presence of

different flow mixes in combination with the high bandwidth of the optical domain.

Employing flow aggregation and/or parallel distributed controllers is outlined as

potential solution to achieve SDN network scalability.
Publisher
NTNU
Series
Doctoral theses at NTNU;2016:254

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit
 

 

Browse

ArchiveCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsDocument TypesJournalsThis CollectionBy Issue DateAuthorsTitlesSubjectsDocument TypesJournals

My Account

Login

Statistics

View Usage Statistics

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit