Download Optical Network Control Overview

WSON Signal Characteristics and Network
Element Compatibility Constraints for GMPLS
draft-bernstein-ccamp-wson-signal-00.txt
Greg Bernstein
Young Lee
Ben Mack-Crane
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[email protected]
Grotto Networking
[email protected]
Huawei
[email protected]
Huawei
75th IETF – Stockholm, Sweden, July 2009
WSON Signals and such…
• Tasks from San Francisco IETF
– Generalize WSON element information where
appropriate for possibly other technologies.
This was incorporated into the WSON RWA
info and encoding documents.
– Expand the WSON elements understood by the
control plane to include regenerators, OEO
switches, and wavelength converters.  That is
what this document addresses.
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75th IETF – Stockholm, Sweden, July 2009
Regenerators: Basics
• 1R
ITU-T Recommendation G.872 Definitions
– Equal amplification of all frequencies within the amplification
bandwidth. There is no restriction upon information formats.
– Amplification with different gain for frequencies within the
amplification bandwidth. This could be applied to both singlechannel and multi-channel systems.
– Dispersion compensation (phase distortion). This analogue process
can be applied in either single-channel or multi-channel systems.
• 2R (any or all 1R functions plus:)
– Digital reshaping (Schmitt Trigger function) with no clock
recovery. This is applicable to individual channels and can be used
for different bit rates but is not transparent to line coding
(modulation).
• 3R (any or all 1R and 2R functions plus:)
– Complete regeneration of the pulse shape including clock recovery
and retiming within required jitter limits.
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75th IETF – Stockholm, Sweden, July 2009
Regenerator: Management
+-----------------------------------------------------------------+
|Function
|
SONET/SDH
|
G.709 OTUk
|
|
|
Regenerator
|
|
|
|
Section
|
|
|------------------+----------------------+-----------------------|
|Signal
|
J0 (section
| Trail Trace
|
|Identifier
|
trace)
| Identifier (TTI)
|
|------------------+----------------------+-----------------------|
|Performance
|
BIP-8 (B1)
| BIP-8 (within SM)
|
|Monitoring
|
|
|
|------------------+----------------------+-----------------------|
|Management
|
D1-D3 bytes
| GCC0 (general
|
|Communications
|
| communications
|
|
|
| channel)
|
|------------------+----------------------+-----------------------|
|Fault Management |
A1, A2 framing | FAS (frame alignment |
|
|
bytes
| signal), BDI(backward|
|
|
| defect indication)BEI|
|
|
| (backward error
|
|
|
| indication)
|
+------------------+----------------------+-----------------------|
|Forward Error
|
P1,Q1 bytes
| OTUk FEC
|
|Correction (FEC) |
|
|
+-----------------------------------------------------------------+
– Many 3R type regenerators also process important management
overhead and hence can be particular to the digital signal format.
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75th IETF – Stockholm, Sweden, July 2009
Regenerator Compatibility Constraints
•
Limited wavelength range (1R)
–
•
•
•
•
Already modeled in GMPLS for WSON
Modulation type restriction (2R)
Bit rate range restriction (2R, 3R)
Exact bit rate restriction (3R)
Client signal dependence (“4R”)
These signal “compatibility” constraints may also
apply to OEO switches and to wavelength
converters.
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75th IETF – Stockholm, Sweden, July 2009
Optical Interfaces and Signals
• Optical Tributary Signal (G.959.1)
– "a single channel signal that is placed within an optical
channel for transport across the optical network"
– Different classes of optical tributary signals are defined
based on modulation (line coding) and bit rate range.
– From G.698.2 to fully specify an optical tributary signal
one must specify the exact bit rate.
• Single channel interfaces to DWDM networks
– ITU-T Recommendations G.698.1 & G.698.2
– Uses Optical Tributary Signal from G.959.1.
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75th IETF – Stockholm, Sweden, July 2009
Proposed WSON Signal & Parameters
•
Optical Tributary Signal (G.959.1, G.698.1, G.698.2)
–
–
–
–
–
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Optical tributary signal class: This relates to the specifics of
modulation format, and bit rate range. Could possibly change
along the path. For example when running through a 3R
regenerator a different output modulation format could be used.
Bit rate. This typically would not change since we are not
changing the digital bit stream in any end-to-end meaningful
way.
FEC: Indicates whether forward error correction is used in the
digital stream.
G-PID: General Protocol Identifier for the information format.
This would not change since this describes the encoded bit
stream. This is already present in GMPLS signaling. A set of GPID values are already defined for lambda switching in
[RFC3471], [RFC4328].
Center frequency (wavelength). Can change along path if there
are wavelength converters. This is already modeled via labels in
GMPLS.
75th IETF – Stockholm, Sweden, July 2009
Characterizing Network Elements
–
–
–
–
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Permitted optical tributary signal classes: A list of
optical tributary signal classes that can be processed
by this network element or carried over this link.
Acceptable Bit Rate Set: A list of specific bit rates or
bit rate ranges that the device can accommodate.
Coarse bit rate info is included with the optical
tributary signal class restrictions.
Acceptable G-PID list: A list of G-PIDs
corresponding to the "client" digital streams that are
compatible with this device.
Permitted optical frequencies. Already in WSON
GMPLS extensions.
75th IETF – Stockholm, Sweden, July 2009
Network Element Compatibility:
Digital Format
Source
GPID=SDH
R_A
R_B
OEO_G
R_C
GPID=
G.709
R_F
R_E
OEO_D
GPID=SDH,
G709
Connection request for an SDH formatted optical connection and
computed feasible paths based on network element compatibility.
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75th IETF – Stockholm, Sweden, July 2009
Client Signal Type Compatibility
Optical Subnet B
Regen bank
(SDH)
Regen bank
(SDH, G.709,
10GE)
Optical Subnet A
Two optical subnets interconnected by DWDM links with
regenerators. The regenerators for the different DWDM
links have differing capabilities to deal with client signal
types (G-PID).
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75th IETF – Stockholm, Sweden, July 2009
Modulation Compatibility
Metro subnets allow
optical tributary signal
classes: 10G NRZ and
40G NRZ
Metro Subnet B
Regen bank
Regenerators allow
optical tributary signal
classes: 10G NRZ and
40G NRZ, 40G RZ
Long Haul Subnet
Regen bank
Metro Subnet A
Regen bank
Long haul subnet allows
optical tributary signal
classes: 10G NRZ and
40G RZ
Metro Subnet C
Multi-subnet network where the various subnets work with different sets of
signal classes, i.e., the metro subnets work with 10G NRZ and 40G NRZ while
the long haul subnet works with 10G NRZ and 40G NRZ. The regenerators on
the DWDM links connecting the subnets can be used to perform modulation
format conversion between 40G NRZ and 40G RZ signals.
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75th IETF – Stockholm, Sweden, July 2009
Path Computation, PCE & Signaling
• New “optical compatibility” constraints
– Path computation can only choose paths
through elements that are “compatible” with the
particulars of the optical tributary signal.
• PCE requests
– Must include optical tributary signal
parameters.
• Signaling
– Should include optical tributary signal
parameters for configuration and validation.
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75th IETF – Stockholm, Sweden, July 2009
Possible Next Steps
• Add optical tributary signal notions to
WSON RWA Framework and related
documents
Or
• Keep this work as a separate draft in
parallel with WSON RWA Framework
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75th IETF – Stockholm, Sweden, July 2009