PowerPoint Presentation - Optical Network Control OverviewGreg
Bernstein
[email protected] Grotto Networking
Young Lee
[email protected]
Huawei
draft-bernstein-wson-impairment-info-00.txt
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Introduction
Impairments in optical networks can be accounted for in a number of
ways as discussed in the Impairment Framework draft . This draft
provides an information model for path validation in optical
networks utilizing approximate computations.
The definitions, characteristics and usage of the optical
parameters that form this model are based on ITU-T recommendation
G.680.
This impairment related model is intentionally compatible with the
impairment free model of reference [RWA-Info].
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Optical Signal to Noise Ratio (OSNR)
Residual Dispersion (CD)
Channel Ripple
System Transients
Channel Uniformity
The impact is dependent upon the signal type and rate
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Apply to the network element (NE) as a whole
Get one parameter of each particular type in this category per
NE
Vary on a per port basis
Get one parameter of each particular type in this category per NE
port. Not all parameters different so smart encoding can save
“space”.
Vary based on port to port pairs
Get one parameter of each particular type in this category per
(ingress port, egress port) pair. Not all parameters different so
smart encoding can save “space”.
These categories are inferred from ITU-T G.680 and are useful for
control plane purposes and don’t change G.680.
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Channel extinction (dB, Min)
Channel gain (dB, Max, Min)
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Input reflectance (dB, Max) (with amplifiers)
Output reflectance (dB, Max) (with amplifiers)
Maximum reflectance tolerable at input (dB, Min)
Maximum reflectance tolerable at output (dB, Min)
Maximum total output power (dBm, Max)
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Ripple (dB, Max)
Differential group delay (ps, Max)
Polarization dependent loss (dB, Max)
Reflectance (passive component) (dB, Max)
Reconfigure time/Switching time (ms, Max, Min)
Channel uniformity (dB, Max)
Transient duration (ms, Max)
Multichannel gain-change difference (inter-channel gain-change
difference) (dB, Max)
Multichannel gain tilt (inter-channel gain-change ratio)(dB,
Max)
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Cascade formulas given in sections 9 and 10 of G.680
Example Optical SNR:
Where to Pin,i are the channel powers in dBm at the inputs to the
ONEs or amplifiers on the relevant path through the network; and
NFi are the noise factors of the amplifiers or ONEs on the relevant
path through the network.
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Issues
Not all parameters are necessarily used in all situations. Should
default values be explicitly specified in draft?
Transmitter and Receiver characteristics are not specified in G.680
but in other ITU-T recommendations. Should these be including in
info model? Connection request?
Not all impairments are included in G.680 – Our approach is to
begin with what G.680 has defined.
Compact Encodings are possible when per port or port-to-port
parameters repeat. Define encodings here or another document?
32-bit floating point for all parameters for simplicity?
