Optical Transport Networks - TREND · Optical Transport Networks: operator’s requirements and ICT...

TELECOM ITALIA GROUP

Torino, July 2nd, 2013

Optical Transport Networks:

Operator’s requirements and

ICT DISCUS concepts

Marco Schiano

Telecom Italia, Transport Innovation

Felipe Jimenez Arribas

Telefonica I+D GCTO, Core Network Evolution group

Summary

► Core and metro networks requirements from operator’s

perspective

► Core networks design and implementation examples

► The DISCUS flat architecture

► Core networks evolution and next generation technologies


Optical Transport Networks: operator’s requirements and ICT DISCUS concepts

3 Marco Schiano, Transport Innovation © Telecom Italia SpA 2013, all rights reserved

Summary


perspective



► Core networks evolution and next generation

technologies



Business impact of network characteristics

► Optical transmission and switching: high capacity

► Wide variety of services: traffic grooming and client i/f

► High reliability services: protection and restoration

schemes

► ≥ 100 G efficient transmission: few regenerators

► Optimized design of Photonic, OTN and IP layer

► Scalability and modularity: pay as you grow

► Low power consumption and footprint

► Reliable equipment

► Effective OAM: end to end manageable services

Revenues

Costs

Capex

Opex




Traffic and power consumption

5



TEF Power consumption/Co2 emissions in 2012

6



Power consumption distribution

7



Energy costs projection

8



TEF Identified measures for 2015 target

(30% power reduction)

9



Current networks are based on intensive power-consuming technologies

that rely on electronic switching matrices.

A reduction in the no. of OEO conversions on the E2E data path is

essential. Several approaches have been considered:

Optical switching within the core (mesh) by routing “wavelengths”.

Data-network simplification, fewer levels and less electronic switching.

Potential IP/MPLS offloading at OTN layer (fewer OEO conversions) or even

at pure “channel layer” (no OEO conversion at skipped nodes).

OEO conversion

10



OEO conversion: core network evolution

Currently OTN offloading IP offloading

IP/MPLS

SDH

OTN

(sub-)

WDM

mesh

IP/MPLS

SDH

OTN

(sub-)

WDM

mesh

IP/MPLS

SDH

OTN

(sub-)

WDM

mesh

Three steps are envisaged in the core network evolution:

Assume two connections: A B and A C

IP hops at intermediate

nodes OEO conversion

+ packet processing.

High IP-router port count.

A B

C A B

C A B

C

EOE conversion at

intermediate nodes.

Transponders at each

node.

All-optical, elastic (sub-)

routing from source to

destination nodes in a

transparent way.

11



SDH

ETH

MPL

S

IP

WDM

OTN

OEO conversion: metro network evolution

WDM ring WDM photonic mesh

• OEO conversion + transponders at each node

• OTN/SDH processing at each transport node

• IP-router high port count + packet processing at each IP node

saving by removing the SDH layer

less proc. w/ OTN offloading

photonic switching

12



ETH

MPL

S

IP

WDM

OTN






saving by leaving out the SDH layer

less proc. w/ OTN offloading

photonic switching less OEO conv. w/ IP offloading

less OEO conv. w/ IP offload.

13



OTN

WDM Sub-

ETH

MPL

S

IP

WDM

OTN







less OEO conv. w/ IP offloading


WDM ring Sub- tech ring

Sub- tech ring

14



OTN

WDM Sub-

ETH

MPL

S

IP


WDM photonic mesh






WDM ring Sub- tech ring

Sub- tech ring

Sub-

• New approaches like “optical packet/burst switching” where a (virtual) distributed Ethernet

switch spans a network region, no OEO is performed at intermediate (real) switches and every

optical transponder can be shared to reach every possible destination.

OBS, OPST, TSON...

15




Summary


perspective




technologies




Telecom Italia new Photonic Backbone motivations

► To cope with a remarkable traffic increase

► from the domestic networks (especially the IP backbone)

► from International networks

► from the emerging wholesale market

► To decrease costs (both CAPEX and OPEX)

► To enhance reliability for critical services

► To reorganize the transport backbone into a single

easily manageable platform, switching over multiple

legacy DWDM systems




The domestic client networks IP backbone

architecture

OPB: Optical

Packet Backbone

M I

PD

TS BS

BO

TO

GE

FI

PA

RM

NA

BA

SV

AL

BG CO

VR VE

BZ

MO RI

PI

AN

PG

PE

CA

TA

CZ

CT

NL

M I

PD

TS BS

BO

TO

GE

FI

PA

RM

NA

BA

SV

AL

BG CO

VR VE

BZ

MO RI

PI

AN

PG

PE

CA

TA

CZ

CT

NL

TO

AL

VR

VE

RM 2 RM 1

MI 1 MI 2

RM 2

CT

PA

RM 1 RM 1 RM 2

VR

VE

MI 1 MI 2

BO

PC

RM 1 RM 2

SS

CA

SS BA

TA

BO

PI FI

PC

RM 1 RM 2

P

E

A

N P

G

R

M

1

X

► CRS 1 Tera-routers in the core

► 10 Gbit/s POS interfaces for all

links

► 40 Gbit/s POS interfaces in the core

► ASON meshed network

► SDH cross-connects and

DWDM links

► Control Plane, centralized

routing

► 2.5 Gbit/s SDH ring architecture

► Today used for structured VC4

services

► Excellent reliability (MS-SPRing)




Carrying international traffic through Italy

MedNautilus

Telecom Italia Sparkle

Pan-European

Backbone

► Traffic originated in far and middle east is

conveyed to Sicily by submarine systems

► It has to be delivered to northern Italy

where the Telecom Italia Sparkle Pan

European Backbone PoPs are located




Opportunities of new photonic technologies

Transparent

Optical Tunnel CP CP

CP

CP

CP

CP CP CP

Ultra Long-Haul

DWDM

Multi-degree

ROADM

► Fewer regenerators

► CAPEX savings

Enhanced

GMPLS

Control Plane

► End-to end provisioning

► OCh protection and restoration

► OPEX savings

Protected/

Restored

Path




The Photonic Backbone structure

► Network diameter: 2400-3100 km (working-protection paths)

► Maximum number of hops: 11

► Nodal degree: 25 (av. 3.1)

► Technology:

► 44 switching nodes based on

ROADMs

► 71 ULH DWDM systems with 80 lambdas

► G.655 and G.652 fibers

► 10 and 40 Gbit/s OCh

► Ready for 100 G transmission

1000 km

500 km

Tentative scheme

of the new Backbone




Preliminary network dimensioning

► Traffic load rough forecast in 2013:

► 542 OCh (mixed 10 and 40 Gbit/s)

► 100 OCh are used for traffic protection

► Maximum number of hops: 9

► Maximum OCh length: 1600 km

► 6 Tbit/s total capacity

► No serious issues of lambda congestion at least with 2013

traffic estimates

► A double fully disjoint protection path is not available for

all OCh due to cable topology limitations




Energy savings and other operational benefits

► Compared to transport on point-to-point DWDM systems,

energy savings range between 20 and 30%

► Energy saving is mainly due to the regenerator number

reduction, while ROADMs power consumption is very low

► Other important benefits are:

► Remarkable spare parts reduction (due to fewer regenerators);

► ~40% circuit creation cost reduction;

► Opportunity of relocating the circuits of legacy networks on the new

backbone simplifying the transport in the backbone




Summary


perspective




technologies



Today’s networks vs. DISCUS architecture

Long reach

WDM/TDM

PON access

~100 node

all-optical

core

Access nodes

replaced by passive

optics + optical

amplifiers

Inner / outer core

hierarchy scrapped

No backhaul /

metro network

All nodes both

access and core

One electronic

layer at Access

core boundary

DISCUS Optical Network Architecture Today’s Electronics Centric Architecture

Inner Core PoPs

Outer Core PoPs

Metro PoPs

Access PoPs with WDM

Access PoPs

Electronic conversion

when crossing layer

Multiple hierarchical layers

+ Large number of opto-electronic conversions

+ Large routing/ switching nodes

+ High customer port count

= High cost and high power consumption

= Limited scalability

One hierarchical layer

+ Flat core

+ LR-PON

= Minimum opto-electronic conversions

= Minimum router/switch size & customer port count

= Low cost and low power consumption

= Scalable network


► DISCUS is an end to end network architecture design for the next generation super fast broadband networks

► It is the sum of the parts; access/metro network, switching/routing nodes and core network that make it a

winning solution - not simply the individual parts.



Access and core architecture




WMSAN

W

E

MSAN

Cu FMSAN

ODF

Cable Chamber

MDF

Large Local Exchange with Copper MSAN, Fibre MSAN

& WDM MSAN

Small Local Exchange with Copper MSAN

only (no fibre customers)‏

MSAN

Cu FMSAN

ODF

Cable Chamber

MDF

Medium Local Exchange with Copper MSAN & Fibre

MSAN

MSAN

Cu

ODF

Cable Chamber

MDF

Cable Chamber Cable Chamber Cable Chamber

Access nodes (Local Exchange) evolution

Access nodes in LR-PON optical network architecture

4x4

ONT Management

Power

LR-PON optical card 1st Generation

LR-PON optical card 2nd Generation DWDM

4x4

ONT

Management

Power

Spare fibre ports

for future upgrade




LR-PON = LE/CO & metro network bypass

NTE

ONT DP

Old Local

Exchange

Site

Cabinet

ONT NTE

4x4

OLT

Tx

Rx

OLT

Working Metro-node

Stand-by Metro-node

ONTs fitted with DWDM

bandpass blocking filter

from day one

Tx

Rx

Initial LR-PON assumed to use a single wavelength

and two fibre working in the long reach section from

exchange site to metro-node

Optical

Amplifiers




Evolution of LR-PON - by WDM upgrade

NTE

ONT DP

Exchange

Site

Cabinet

ONT NTE

4x4 Spare fibres for future

technology upgrade e.g.

coherent LR-PON

OLT

Working Metro-node

Stand-by Metro-node

Tx

Rx

Tx

Rx

OLT

Tx

Rx

Tx

Rx

Bandwidth upgrade is simple addition of OLT cards at the metro-node and

ONU equipped to receive the new wavelengths.

When tuneable receivers are installed at the ONU full wavelength flexibility

is enabled.

Other wavelengths can carry high bandwidth point to point links direct to

the core at 10 to 100+ Gb/s.




Fully flexible optical core node structure




UK With All Exchanges UK with~100 nodes

Simplification of country network (UK example)

Source BT




Simplification of country network (Ireland example)

Ireland with all 1100 exchange buildings Ireland with 18 nodes




Power consumption benefits

User power BAU v LR-PON + flat corePower per user: BAU v LR-PON + flat core

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20

Sustained user bandwidth (Mb/s)

Po

wer

per

user

(Watt

s)

BAU Watts per B'band fixednetwork user

LR-PON + flat optical core

Comparison of relative

power consumption against

user sustained bandwidth.

BAU case versus LR-PON

plus flat optical core.

LR-PON case power

consumption is dominated

by access power (ONU)

consumption.

BAU quickly becomes

dominated by core network

power consumption as user

bandwidth rise.




DISCUS evolvable & sustainable network

► Remains economically viable ► as demand and services evolve

► and supports a range of business and ownership models

► Low power consumption ► “Green” network solutions

► Can scale to meet service growth requirements

► particularly those enabled by FTTP

► Access bandwidth scales indefinitely up to limits of fibre technology

► Can adopt new technologies

► while co-existing with previous generations

► re-use installed physical infrastructure

► Efficiently use network resources

► e.g. spectrum, bandwidth, infrastructure (cables & fibre), equipment and components, man-power, processing power, space, storage etc.

► Major reduction in electronic equipment per unit of user bandwidth

► Reduced number of nodes, interface ports, OEO conversions, and line cards

► Cost per unit bandwidth needs to fall almost inline with bandwidth growth





Summary


perspective




technologies



Optical networks at a turning point

ESSIAMBRE et al.,

JLT, 2010

Recent record experiments

New disruptive Photonics

• MIMO on multimode fibers

• Multicore fibers

• Photon’s Orbital Angular

Momentum

• …

Today’s Photonics

with

enhanced capacity

Mid term

Long term

More efficient use

of optical bandwidth

Optical bandwidth

broadening

2012 ~2020 ~2030




Towards more efficient wideband optical networks

More efficient

use of optical

bandwidth

► Optical superchannels

► Configurable transponders

► Flexible optical grid

Optical

bandwidth

broadening

► Raman amplification

Enabling Technologies

Ne

xt

ge

ne

rati

on

ph

oto

nic

b

ac

kb

on

es




Nyquist DWDM and superchannels

► OCh can be closely spaced and managed as

superchannels

► Nyquist DWDM channel spacing limit is the baud rate Optical

Frequency

Po

we

r S

pe

ctr

um

Channel spacing Df

Superchannel

BOSCO et al.,

JLT 2011

► System reach is limited by non linear

crosstalk (FWM-like impairment model)

► The narrower the channel spacing the

higher the spectral efficiency and the

shorter the system reach

G.652

G.655

Paper OTh3A.3, Poggiolini et al., "Ultra-

Long-Haul Transmission of 16x112 Gb/s

Spectrally-Engineered DAC-Generated

Nyquist-WDM PM-16QAM Channels with

1.05x(Symbol-Rate) Frequency Spacing"

100 G

50 G

150 G

200 G




Spectral Efficiency versus Reach tradeoff

► For a given modulation format Reach

can vary by 70% for Df in the range

27.7 ÷ 50 GHz

► About the same variation is observed

for Spectral Efficiency

BOSCO et al., JLT 2011

► Spectral Efficiency by Reach product (EDFA,

G.652)

► 33.3 GHz provides the highest SE∙R product

for almost all considered modulation formats

50

40 33

31 30

29

27.7

Channel spacing (GHz)

G.655

Span loss 25 dB

EDFA NF 5 dB

27.75 Gsymbol/s

50 G

100 G 150 G

200 G




Next generation transponders

► No dramatic change in

symbol rate

► Configurable modulation

format: DP-BPSK, DP-QPSK,

DP-8QAM, DP-16QAM

► Electrical spectral shaping:

DSP and DAC in the

transmitter

► Optical carrier tunability on a

flexible grid scheme

► Soft Decision FEC: > 10 dB

coding gain

Optical

Frequency

Po

we

r S

pe

ctr

um

Baud Rate

Spectral shaping

DAC

DAC

DAC

DAC

DS

P

Optical

modulator

Optical

modulator

Laser PC

ADC

ADC

ADC

ADC

DS

P

Laser PS

90°

Hyb

rid

90°

Hyb

rid




Raman amplification

► Wideband 100 nm Raman systems

already demonstrated

► 3÷6 dB OSNR reduction compared to

EDFA

► Approximately reach doubling

compared to EDFA

Pe

r P

ola

riza

tio

n S

pe

ctr

al E

ffic

ien

cy

Puc et al., ECOC 2005

► Systems with Raman approach Shannon

limit Spectral Efficiency

► Optimized constellation and coding

► 16 bit/s/Hz spectral efficiency with

1000 km reach (dual polarization)

1518 nm 1620 nm

ESSIAMBRE et al., JLT 2010

Sir

Chandrasekhara

Raman

1930 Nobel Prize




Network evolution scenarios

Today’s WSON Scenario 1 Scenario 2 Scenario 3

(SE limit)

Channel spacing

[GHz]

50 33.3 33.3 33.3

Amplification EDFA EDFA RAMAN RAMAN

Optical

Bandwidth [nm]

32 32 100 100

N. of DWDM

channels

80 120 360 360

Transponders’

bit rate [Gbit/s]

40 100 100 150 100 200 400

Transponder’s

reach [km]

3000 2000 1800 700 3600 700 <1000

Modulation

format

(dual pol.)

BPSK QPSK QPSK 8QAM QPSK 16QAM Optimized

constellation

and coding




Kaleidon backbone as a benchmark

► 44 ROADM nodes

► 71 DWDM ULH links (80 )

► Network diameter: 2400-3100 km (working-protection)

► Max. n. of hops: 11

► Nodal degree: 25 (average 3.1)

► G.655 and G.652 fibers

► 40 and 100 Gbit/s OCh

k a i ode nk a i ode n




Traffic composition and growth estimate

► Traffic baseline: 10 Tbit/s

► IP: 4.7 Tbit/s

► OTN: 5.1 Tbit/s

► wholesale: 0.2 Tbit/s

► IP is assumed to grow faster than other traffic

► Percentage over total traffic ranges from 48 to 80%

► 50% of IP traffic is protected




Traffic routing and network dimensioning

► Two options in network dimensioning:

► Maximum node degree 8

► (1x9 WSS, 8 line ports, 2 add-drop ports)

► Maximum node degree 16

► (1x20 WSS, 16 line ports, 5 add-drop ports)

(1x9 WSS)

A/D

A/D

7

(1x20 WSS)

A/D

A/D

15

A/D

A/D

A/D

► Minimum distance routing metric

► Traffic demand provisioning in order of decreasing length to minimize

blocking

► Regenerators reduction by modulation formats fitting demand length




Kaleidon scalability analysis

EDFA

Df=50 GHz

40/100

Gbit/s

EDFA

Df=33 GHz

150 Gbit/s

Raman

Df=33 GHz

100/200

Gbit/s

Raman

Df=33 GHz

400

Gbit/s

Total Photonic Layer traffic including IP protection




Conclusions

► A fourfold traffic increase can be supported by next

generation photonic backbones if 100 nm Raman

amplification is used together with 33 GHz grid and 100-

200 Gbit/s configurable transponders

► The scalability bound set by Shannon limit is still 4 times

higher than the capacity of these advanced backbones

► For the Kaleidon photonic backbone there is a limited

waste of optical bandwidth when a fixed 33 GHz spacing

is used instead of a flexible grid




References

► R-J. Essiambre et al., “Capacity Limits of Optical Fiber Networks”, JOURNAL

OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO. 4, FEBRUARY 15, 2010, pp. 662-

701.

► G. Bosco et al., “On the Performance of Nyquist-WDM Terabit Superchannels

Based on PM-BPSK, PM-QPSK, PM-8QAM or PM-16QAM Subcarriers”,

JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 29, NO. 1, JANUARY 1, 2011,

pp. 53-61.

► G. Bosco et al., “Performance Limits of Nyquist-WDM and CO-OFDM in High

Speed PM-QPSK Systems”, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL.

22, NO. 15, AUGUST 1, 2010, pp. 1129-1131..

► A. Puc, et al., “Ultra-wideband 10.7 Gb/s NRZ terrestrial transmission

beyond 3000 km using all-Raman amplifiers”, proceedings ECOC 2005, pp.

17-18.


Optical Transport Networks - TREND · Optical Transport Networks: operator’s requirements and ICT...

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