inf5050 introduction to optical...

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INF5050 Introduction to optical networking

[email protected]

[email protected]

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Background

•  M.Sc. Physics/electronics UIO. •  Ph.D. Telecommunication NTNU •  10 years at Telenor R&D optical network •  Adjunct associate professor at NTNU •  Founder of TransPacket AS

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Scope of lecture

•  Give an introduction to optical networking •  Highlight main motivation for optical

networks •  Point to the hottest research topics

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Historic Internet traffic trends

1

1) Prediction made in 2000; the last years have not been that fast

What do you think will make the traffic grow in the future?

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Strong growth of mobile and Internet

•  Video and mobile traffic 2014 to 2019: 6X/10X

•  Video and mobile have strict quality demands to the network

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Propagation through fibre •  Lightpulses are reflected in the core when

hitting the cladding => approximately zero loss

Andreas Kimsås, Optiske Nett

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19. desember 2013

Transmission capacity in optical fiber (lab)

7

D.J. Richardson et al., Nature Photonics, v. 7 p. 354, 2013

100Tbit/s

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19. desember 2013

Transmission capacity in optical fiber (lab)

8

D.J. Richardson et al., Nature Photonics, v. 7 p. 354, 2013

Multicore fibre is next? Current record is: Pb/s HOT research!

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Fibre-cables are spanning the world

Source: RAMPART

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UNINETT "network:"Optical "

TRANSPORT"network"Example"

What is Metro?"And Access?

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What is a long distance?

•  100 m? •  10 Km? •  100 Km? •  1000 Km?

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What is a long distance?

•  100 m? – LAN

•  10 Km? – Access network

•  100 km? – Metro network

•  1000 Km? – Transport network – E.g. subsea-cables

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Access trends Fibre

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Paper for student presentation

•  “PON in Adolescence: From TDMA to WDM-PON”, Grobe, Klaus et al.; IEEE Applications & Practice: Topics in optical communications, January 2008, Pages: 26-34

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Fibre-optical transmission system

Transmitter (Laser+

modulator)

Receiver (photodiode +

aplifier Fibre

Attenuation: Some light being absorbed

Dispersion:

Time Time

Pulse Spreading

Illustration: Lucent Technologies

Light of speed wavelength dependent

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Wavelength division multiplexing

•  Enables large capacity increase in optical fibers •  Makes optical networking possible/interresting

Earlier 11 11

11 1111 1144 44

11

22

33

44

11

22

33

44

Tidligere utbygging

RegeneratorTerminalFiber

Før: 1 kanal pr fiber

Optisk forsterker

MultiplekserDemultiplekser

2,5 Gb/s =30000

Opptil20 000 000

WDM: 4-128 kanaler

pr fiberNåværende utbygging

Wavelength Divis ion Multiplexing(WDM), mangedobler kapas itet i fiber

Electronic/electrooptical

Now

Optical amplifier

WDM: 4-128 channels pr fiber

1 channel pr fiber

Up to

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Course WDM •  Cheap technology with limited capacity and distance •  Typically maximum 16 channels and no amplifiers

0

0,1

0,2

0,3

0,4

0,5

1200 1300 1400 1500 1600

Wavelength (nm)

Loss

(dB

/km

)

2 dB/km G.652 G.652C

1271-1451 nm 1471-1611 nm

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16 channel CWDM using two multiplexers for two different bands

18

EXT

EXT

C1 – (8+1) C1– (8+1)

C1 – 8L C1 – 8L

1471 1491 1511 1531 1551 1571 1591 1611

1471 1491 1511 1531 1551 1571 1591 1611

1271 1291 1311 1331 1351 1371 1431 1451

1271 1291 1311 1331 1351 1371 1431 1451

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Long distance optical system

•  Attenuation must be compensated – Regeneration – Attenuation

•  Dispersion must be compensated – Dispersion compensation employing fibre – Electronic compensation

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fibre-optical transmission at longer distances

Transmitter (Laser+

modulator)


aplifier Fibre

Must be compensated in long distance transmission:

Attenuation: Some light being absorbed

Dispersion:

Time Time

Pulse Spreading


Light of speed wavelength dependent

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Long distance fibre-optical transmission

Transmitter (Laser+

modulator)


amplifier) Fibre

To be compensated:

Dispersion:

Time Time

Pulse Spreading


Speed of light is wavelength dependent

EDFA

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Available wavelength range depends on amplifier technology

0

0,1

0,2

0,3

0,4

0,5

1200 1300 1400 1500 1600

Wavelength (nm)

Loss

(dB/

km)

EDFA C - band

1530-1562

EDFA L - band

1570-1600

ALTERNATIVE AMPLIFIER TECHNLOGIES: RAMAN AND SOA

PDFA 1300 nm

Commercially available Still subject to research

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Erbium Doped Fiber Amplifier (EDFA)

•  Widely deployed in optical networks

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Dispersion Compensating Fibre (DCF)

•  Negative dispersion compared to transmission fibre

•  Much higher dispersion/km => Shorter fibre than transmission fibre required for achieving zero dispersion

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Long distance fibre-optical transmission

Transmitter (Laser+

modulator)

Receiver (fotodiode +

amplifier) Long Fibre

Compensation of amplitude and dispersion

EDFA DCF

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Fibre optical transmission system

Receiver Optical fibre Single modus

Electric input data

Laser & modulator

Amplifier or

regenerator Optical fibre Single modus

Electric output data

Wavelength Division Multiplexing (WDM) transmission system: Add lasers & modulators + receivers

Time Division Multiplexing = TDM

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100 Gb/s per channel fibre optical transmission system

Receiver Optical fibre Single modus

Electric input data

Laser & modulator

Amplifier or

regenerator Optical fibre Single modus

Electric output data

Polarisation multiplexing: Doubles capacity

PBS

PBS Combine!

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ISP

Mobile

Optical networks

Metro Routers/optical switches

Core Optical switches/routers

Access Ethernet switches

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Mobile

Wavelength services

Metro Routers/optical switches



ISP

Wavelength !service!

Wavelength !service!

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Network element functionality (1)

•  70 % of traffic is through-passing in typical node => Should be able to avoid processing of this traffic.

•  Simple optical network element –  Static Optical Add-Drop Multiplexer

(here: ring network): ●  Fixed wavelengths

dropped and added at each node.

●  Not reconfigurable (inaccessible to control system).

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Network element functionality (2)

•  Traffic bypassing intermediate IP routers => Less load on routers (can be smaller and cheaper)

•  In meshed networks: Used to directly connect node pairs with high traffic between them.

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Reconfigurable (R-)OADM •  A flexible add-drop function •  Use cross-connect for some wavelength/

wavebands

Not single wavelength!

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Networking requirements

Wanted: High capacity optical layer network with the following requirements:

•  Support high utilization of resources •  Support high granularity •  Support quality needed for strict real-time

services •  Support variable length packets

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Optical Packet switching •  More complicated in the optical domain:

–  Higher speeds needed in switches –  Not (currently) available technology for optical

processing of headers etc. –  The payload information is switched optically –  Optical buffering is difficult!

OXC Controller

Node Controller (e.g., MPLS)

Delay <= header length+ processing time

Header processor

To OXC-control

Skiller header og nyttelast

DMUX’er WDM signal

Optiske buffere

Optisk krysskopler

MUX’er signaler til WDM signal

Optical crossconnect (with or without wavelength conversion)

Optical buffers (to handle contention on output)

Mux of signals to a WDM signal

Separates header and payload

Demux of WDM signals

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•  Wavelength and OTN services have a high production cost –  Occupies a physical wavelength or TDM channel

resource in the network –  Wavelengths/TDM channels are limited resources –  Wavelengths/TDM channels occupies resources end-to-

end – no intermediate additional aggregation possible •  Ethernet or VPN service preferred as compromise

–  Lower production cost (oversubscription/statistical multiplexing)

–  Does not offer transparency and performance (especially latency) as for wavelengths and OTN channels

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Carrier pain

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Mobile

Virtual wavelength service

Metro Routers/optical sw‹itches



ISP

Fusion

ISP

Virtual!wavelength !services!

Virtual!wavelength !service!

Fusion

Fusion

Fusion

Fusion

ISP Fusion ISP

Virtual!wavelength !services!

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D B

GST lightpath from A→D

Underutilized circuit (wavelength): FUSION fills it!

Incoming GST packets destined for node D

Time between packets is unused L

–  Pure WDM system (circuit) gives low channel utilization

–  For 270 Mb/s video on a 1 Gbps, 70 % of capacity is wasted

OpMiGua switch will insert lower quality (Internet) traffic in voids

Transit traffic passes through on optical layer with minimum or no processing

B

C

C

Packet Switch

D

Input Queue Output Queue A C

D

C D

D

D

C

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•  Fusion Packet optical networking Add-Drop Muxponder ‒  2 x 10 Gigabit Ethernet line-interfaces ‒  10 x 1 Gigabit Ethernet client-interfaces

•  10 Gigabit Ethernet wavelength or circuit •  Sub-wavelength switching: Gigabit Ethernet Packet or

circuit paths •  Optional passive or active optical module

–  CWDM, DWDM, OADM

TransPacket H1 – the first fusion product

GbE 10GbE Optional optical module

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•  Typical scenario –  Invest at 50% fill rate –  10 - 30% utilization

•  TransPacket H1 –  Intelligent Traffic Injection –  Exploit capacity without

affecting existing traffic –  Monetize on idle capacity –  Postpone capacity upgrade 0

10 Gb/s

Utilized capacity

Available capacity

Vacant fiber-bandwidth can be utilized

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Example Trondheim-Oslo field trial Utilize network capacity

•  10G Virtual wavelength •  600 km transmission of 10 Gb/s Ethernet •  More capacity: Intelligent Traffic Injection (ITI)

UNINETT Router Trondheim

TransPacket H1 TransPacket H1

Transport/Metro network

UNINETT Router Oslo

Nokia Siemens WDM system

Extra capacity Extra capacity

Fibre 600 Km

WDM WDM

10 Gb/s 10 Gb/s

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Results Trondheim-Oslo – stress test •  Green: Traffic during World championship cross-

country skiing, Trondheim-Oslo both directions •  Blue: Added SM traffic

–  1- 6 Gb/s of added traffic

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Controlling the optical network

•  Network management system (NMS) working across vendors and network layers is required

•  Setup and tear down of wavelengths according to capacity needs

OADM OADM

OADM

OADM OADM

NMS

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Controlling across network layers

•  Applications triggers resource usage on servers •  Server communication triggers network capacity

needs •  IP- routers requires capacity from the optical network •  Optical network must deliver resources on demand

from upper layers

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Controlling across network layers

•  Applications triggers resource usage on servers •  Server communication triggers network capacity

needs •  IP- routers requires capacity from the optical network •  Optical network must deliver resources on demand

from upper layers

Software defined networks (SDN)?

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SDN: The new hype and research area

Software Defined Networking Can it be combined with optical

networking?

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SDN goals (carrier view)

•  Centralized control of network resources •  Control across network layers •  Control independent of equipment vendor

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SDN Logical Architecture

Centralized intelligence and network state knowledge to configure the devices

Applications see the network as a single, logical switch controlled via abstracted API

Enterprises and carriers gain vendor-independent control over the entire network from a single logical point, which greatly simplifies the network design and operation.

Simplified network devices do not need to process all routing/switching protocols

Example application: Load balancing

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Specialized Packet Forwarding Hardware

Feature Feature





Operating System

Operating System

Operating System

Operating System

Operating System

Network Operating System

Feature Feature

Feature Feature

Feature Feature

Feature Feature

Feature Feature

The OpenFlow Network Innovation

Source: S.Seetharaman, OpenFlow/SDN tutorial, OFC/NFOEC 2012

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Network Operating System

Feature Feature

The OpenFlow Network Innovation

Source: S.Seetharaman, OpenFlow/SDN tutorial, OFC/NFOEC 2012

OpenFlow

OpenFlow

OpenFlow

OpenFlow

OpenFlow

1. Open interface to hardware

3. Well-defined open API 2. At least one good operating system Extensible, possibly open-source

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SDN Multidomain control: Much more than openflow

introduced two QoS classes (Fig.1D) in the COP call definition (Fig.1C, trafficParams). Each QoS class defines a certain packet loss rate (PLR) for OPS domains, and a certain OSNR for OCS domains, for a given bandwidth request. The SDN orchestrator will translate the high level QoS classes into the necessary parameters in the calls sent to the different SDN controllers. Fig.2A shows the message exchange between the different involved computing and network elements in order to jointly provide interconnected VMs with QoS. The provisioning of the VMs is requested to each responsible cloud controller, while the VM interconnection is requested to the SDN orchestrator with an E2E call (ID: 1) including a QoS class. The SDN orchestrator computes the E2E path and requests the necessary calls (IDs: 10, 11, 12, 13) to the different SDN Controllers. Fig.2B shows the wireshark captures at the integrated cloud and network orchestrator and at the SDN orchestrator. Per-domain / E2E service recovery with QoS Fig.3A shows three conducted experiments for QoS recovery: in an OPS domain (scenario A), in an OCS domain (scenarios B, C) and finally E2E QoS recovery (scenario D). Per-domain QoS recovery through adaptive route control in the OPS network. Fig. 3B shows the experimental setup of the OPS domain in NICT premises in Japan. The OPS nodes used are optical packet and circuit integrated nodes4, including one SOA-based 4 × 4 optical packet switch (4 × 4 OPS). In the control plane, an OF-based SDN controller is used to control the OPS nodes. Four OPS nodes with optical packet counters are used, including OF agents and OPS transmitters and receivers. The OF agent periodically reads and provides to SDN controller

the optical packet count information that is measured. In this use case, two E2E transport connections are setup involving the OPS domain, flow1 with a packet occupancy rate of 10% and flow2 with a packet occupancy rate of 2%. In this case, the PLR for flow1 measured by a tester is around 4%. When we increase the packet occupancy rate of flow2 from 2% to 6%, the optical packet counter of OPS node 4 reaches the pre-defined threshold indicating packet congestion. Fig. 3C shows the measured packet counts of Node 4. With the increase of the packet occupancy rate, packet count at OPS node 4 is finally smaller than 17000, corresponding to the pre-defined packet count threshold. The OF agent attached to OPS node 4 detects packet congestion and sends an alarm message to the SDN controller. The SDN controller receives the alarm and then issues the route adaption for the switching table of node 2, aiming at improving the PLR. After the route control, the obtained PLR for flow1 measured by the traffic tester is reduced from around 4% to 0.1%. Route adaptation is announced to SDN orchestrator by means of COP notification mechanism (using websocket). QoS recovery in an OCS domain. For same BER performance, the required OSNR value will relax when a signal with a lower order modulation format is used5. Fig.3E shows the tested OSNR vs. BER curve for our 28Gbaud PM-QPSK and PM-16QAM transmitters. QPSK requires an OSNR value less than that of 16QAM about 9dB at HD-FEC threshold (3.8E-3). Moreover, OSNR monitoring of a circuit flow can detect the OSNR degradation for optical links. The receiver-side error-vector-magnitude (EVM) based OSNR monitor provides in-band OSNR monitoring without deploying new hardware6. With monitoring information, the COP can

Fig. 1: A) Proposed LIGHTNESS-STRAUSS scenario; B) Abstracted network/cloud scenario; C) Call example, D) QoS classes

A)

B)

C)D)

Fig. 2: A) VM connectivity provisioning workflow; B) Wireshark capture.

A) B)

Ecoc 2015 - ID: 1061

R. Vilalta et.al. ECOC 2015: First experimental demonstration of distributed cloud and heterogeneous network orchestration with a common Transport API for E2E service provisioning and recovery with QoS

Control Orchestration Protocol (COP) for communication with controllers for each domain and vendor.

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Summary •  Optical fibres are the ultimate transmission

medium – Long range, Terabit capacity now, petabit in

research •  Optical networking enables switching of

high bitrate wavelengths •  A common control and management of the

network layers is required – Preferably standardized – working across

vendors •  Is SDN the solution?

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inf5050 introduction to optical...

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