Overview of ITU-T standards for
optical systems for terrestrial
transport networks
G.Bruno1, A. Percelsi2, F.Cavaliere1
1
Ericsson, 2 Telecom Italia Lab
14°Convegno
14 Convegno Nazionale delle Tecnologie Fotoniche, Firenze, 16 May 2012
Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Outline
• ITU-T standardization activities in Optical Transport
• Transversely Compatible Systems
• Enabling Optical Transparent Domains
• Future-proofing Spectral Usage via the Flexible Grid
• Conclusions
G.Bruno, A. Percelsi, F.Cavaliere
2
Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
ITU-T standardization activity in Optical Transport
Optical Technologies: cables, components, methods
Major projects in SG15:
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Access Network Transport
Q1, 2, 4a, 4b, 4c
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Optical Technologies
Q5, 6, 7, 8, 16, 17, 18
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Optical Transport Networks
Q3, 9, 10, 11, 12, 13, 14, 15
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source: ITU-T
Access Network
Collection, Consolidation &
Grooming of Access Traffic
Metro Core
Interconnect of Collector POPs
with the Long Haul Optical Network
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Transversely Compatible Systems – G.959.1/G.693
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“transversely-compatible interfaces”, “no line amplifiers”
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applications for 2.5/10/25/40G “optical tributary signal classes”
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example of implementations in XFP, XFP+, QSFP+, CFP form factors
Multichannel
IrDI
Single-channel
IrDI
IrDI
transmitting
equipment
MPI-S
MPI-R
Single-channel optical path
IrDI
receiving
equipment
G.959.1(09)_F5-2
IrDI
transmitting
equipment
MPI-SM
Main optical path
MPI-RM
IrDI
receiving
equipment
G.959.1(09)_F5-1
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Transversely Compatible Systems (G.698.x series)
Passive, “metro” amplified and “seeded WDM” applications
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May lead to the elimination of transponders
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The “black link” concept for G.698.1 and G.698.2:
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G.698.{1,2}: up to 10G and 50GHz applications
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40G specification is ongoing in G.698.2
source: P. Anslow, OFC 2007
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Transversely Compatible Systems – seeded WDM
►
Reference diagram
RS for signals
going Rx1
Tx1
SS for signal
MPI-SM
Rx2
Tx2
going 
for signals
going OD
/OM
Rx1
Tx1
RS OD
/OM
MPI-RM
Rx2
Tx2
SS 
for signals
going 
RxN
TxN
Head-end
RS Seed
source
RxN
TxN
SS 
Black link
Tail-end
source: ITU-T G.698.3
►
Application: 1.25G over about 40km of G.652 fibre
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100 GHz (tail- to head-end) / 97.15 GHz spacing (head- to tail-end)
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Enabling Optical Transparent Domains – G.680
Domains of optical transparency large enough to ensure that all the
potential routes of the backbone network could be realized all optically
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adapted from R. Clemente, ECOC 2010
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Enabling Optical Transparent Domains – G.680
G.680 defines a "degradation function" of optical network elements
making up an optical network:
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►
the case where line segments are from different vendors is under study
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Enabling Optical Transparent Domains – G.rmon
G.rmon (under development) defines
MD-ROADM as a network element:
to provide (remotely) routing wavelengths
from any optical line to another one
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to provide (remotely) add and drop for any
wavelength to/from any optical line
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to provide colourless, directionless,
contentionless A/D
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to provide hitless degree upgrade/downgrade
to provide hitless optical channels
provisioning
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to support optical restoration
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Future-proofing Spectral Usage via the Flexible Grid
Frequency grids are defined in G.694.1 to support DWDM applications:
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12.5, 25, 50 and 100 GHz spacings, 193.1 THz common to all grids
The flexible grid (example):
source: ITU-T G.694.1
allows a mixed bit-rates/modulation formats transmission system to
allocate frequency slots with different widths
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allows better exploitation of the spectrum
G.Bruno, A. Percelsi, F.Cavaliere
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Fotonica 2012, paper A3.2
Overview of ITU-T Standards for Optical Systems for Terrestrial Transport Networks
Conclusions
In the last 5 years Q6 and Q7 have produced or updated 16 ITU-T
recommendations related to the optical transport physical layer
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Quick process: 18 months from inception to approval for the new
G.698.3 and less than one year for the revision of G.694.1
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10 recommendations and a Supplement are currently under active
working in the field of transversal compatibility of interfaces,
monitoring, network design engineering and other topics
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We thank Peter Stassar and Pete Anslow for the useful discussion
G.Bruno, A. Percelsi, F.Cavaliere
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THANK YOU!