Optimizing Multi-Layered Networks Towards a Transparently

Optical Internet

Presenter: Moshe Zukerman Electronic Engineering Dept., City University of Hong Kong

Hong Kong SAR, PRC

Authors: Ron Addie, David Fatseas, Moshe Zukerman

Outline• The Current Internet

• Energy considerations

• Teletraffic implications

• Tecnology options

• Flow size dependent routing

• Conclusion

Outline• The Current Internet

• Background

• Circuit switching versus packet switching

• Optical Internet model and design options: OCS, OBS, OFS, fractional lambda, flow routing.

• Conclusion

• Mainly based on Packet switching.

• Layered approach - flexibility

• Packets - independent of applications

• Open Shortest Path First (OSPF) protocol

• Routers; Look up tables; no state information of connections (net-head approach).

• Hard to guarantee Quality of Service (QoS).

Current Internet

Current Internet – the success

• So far the Netheads have had the upper-hand.• IP dominates the desktop. • Users have voted with their feet - satisfied with service received because they get it at supermarket prices.• This is a “simple” observation that we can learn from.

Current Internet – the successWhy?

• Efficiency - Statistical multiplexing;

• Flexibility – new services are

designed to cope with the quality

(or lack thereof) provided by the

Internet (e.g. Skype).

The netheads have had the upper hand

This needs to be respected.

But where are we going from here?

ScalabilityQoS

Energy consumption (growth - energ. Improv. >> GNP)

Efficiency

Image: http://www.dotolearn.com/picturecards/printcards/coloring/largeimages/headache.htm

TrafficPrediction

and engineering

Technologychoices

Security

ReliabilityTopology

Dimensioning

Multi-domain

[1] R. S. Tucker, “Green Optical Communications - Part I: Energy Limitations in Transport”, To be published in IEEE Journal of Selected Topics in Quantum Electronics, Special Issue on Green Photonics.

Energy/bit/distance for various transatlantic transmission systems

[2] R. S. Tucker, “Green Optical Communications - Part II: Energy Limitations in Networks”, To be published in IEEE Journal of Selected Topics in Quantum Electronics, Special Issue on Green Photonics.

“business as usual”

[2] R. S. Tucker, “Green Optical Communications - Part II: Energy Limitations in Networks”, To be published in IEEE Journal of Selected Topics in Quantum Electronics, Special Issue on Green Photonics.

PIC = photonic integrated circuit

Towards all-optical Internet

• Packet Switching at the access is here to stay for many users.

• For the present and into the near future this means IP

• But for the core, optical bypass and Optical Circuit Switching (OPC) could be justified more and more based on cost and energy consumption considerations.

Towards All-Optical Internet (cont.)“Old” Electronic Internet:

Capacity expensive, buffering cheap

Introduction of DWDM makes capacity cheap

Future All-Optical Internet (?):

Link capacity plentiful, buffering painful (cost, power, space); wavelength conversion (for Optical Packet Switching) is costly.

A further case for CS

Services

• Emails, Sensor signals (mice)

• HD-IPTV, Virtual reality (elephants, whales)

• Others (kangaroos)

• Traffic engineering and network dimensioning implications

Size-based Routing

• mice – maybe aggregated together and sent using a permanent/semi-permanent path.

• HD-IPTV, virtual reality (elephants, whales)

– their size may justify setting up a path/light-path

– whales need to swim in an ocean (although there are not many big pipes)

Size-based Routing (cont.)

• Others (kangaroos) – may use the current shortest path routing.

• Size based routing provides:– Technology choice

– Traffic engineering

– Dimensioning

In a scalable way.

The Traffic model

The traffic for each end-to-end demand follows a Poisson Pareto burst process (PPBP) - Poisson arrival process of Pareto distributed bursts/flows.

Flow size distribution(Truncated Pareto)

.,1

,,1

,,0

t

t

tt

P( F > t ) =

Δ = Max flow size = Min flow size

= rate parameterThe case is included =Δ

Mean Bitrate (PPBP)

E[Bitrate] =

λ = Arrival rate of flows

.1

11

γγ

γγ

Δδ)(γ

Δδλγ

The Approach

• Layers – each layer - a technology (e.g. IP, ATM, WDM)

• Traffic model: Poisson arrivals of flows

• Each flow – Pareto distributed size

• In principle, each flow is routed on the least-cost path for this flow size in each layer (technology).

The Approach (continued)

• Lower layer costs less per bit – but modules are larger.

Some intuition:– Flocking – so relatively not many large links. – Elephants decide the permanent path and mice

use the scraps.

The Approach (continued)

• A new technology can be incorporated into this model by choosing a collection of cost parameters for traffic delivery.

• Traffic stream is split between layers according to flow sizes.

• Traffic stream is split between alternative routes according to flow sizes.

The Approach (continued)

• So we have here aggregation of flows and splitting of flows in routing and in layers.

• All the aggregated traffic that needs to use a link in layer n may require (delegation) a path in layer n-1.

=> link at n => traffic at n-1.

The Approach (continued)

• The traffic is consistent in routing – the mean is maintained consistent – no traffic is lost – or added.

• For simplicity and scalability merging of many Pareto models is modeled by a single Pareto model. (Peak and mean are fitted – lower bound is adjusted.)

The Approach (continued)

• Fixed-point iterations are used to obtain the capacity required for each layer.

• The convergence criterion is the sum of the capacity differences between two iterations (absolute values) of each link/layer < small value.

• For simplicity and scalability, merging of many Pareto models is modeled by a single Pareto model. (Peak and mean are fitted – lower bound is adjusted.)

• In the current implementation, there are 4 types of flow sizes separated by

NETML Demo

http://www.sci.usq.edu.au/staff/addie/netmldemo3/netmldemo3.htm

Thank You!