Network Working Group G. Bernstein
Internet Draft Grotto Networking
Intended status: Informational Y. Lee
Expires: April 2010 Huawei
Ben Mack-Crane
Huawei
October 7, 2009
WSON Signal Characteristics and Network Element Compatibility
Constraints for GMPLS
draft-bernstein-ccamp-wson-compatibility-01.txt
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Abstract
While the current GMPLS WSON framework can deal with many types of
wavelength switching systems there is a desire to extend the control
plane to networks that include a combination of transparent optical
and hybrid electro optical systems such as OEO switches,
regenerators, and wavelength converters. Such networks are frequently
referred to as translucent optical networks in the literature. Some
of the systems use in such networks can be limited to processing WSON
signals with specific characteristics or attributes. In addition,
some of the network elements may be able to perform important
optional processing functions such as regeneration on a signal and
would need to be provisioned as part of optical path establishment.
This document provides a WSON signal definition and attributes
characterization based on ITU-T interface and signal class standards
and describes the signal compatibility constraints of this extended
set of network elements. The signal characterization, network element
compatibility constraints and enhanced provisioning support enable
GMPLS routing and signaling to control these devices and PCE to
compute optical light-paths subject to signal compatibility
attributes.
Table of Contents
1. Introduction...................................................3
2. Describing Optical Signals in WSONs............................3
2.1. Optical Interfaces........................................4
2.2. Optical Tributary Signals.................................4
2.3. WSON Signal Characteristics...............................5
3. Electro-Optical Systems........................................6
3.1. Regenerators..............................................6
3.2. OEO Switches..............................................9
3.3. Wavelength Converters.....................................9
4. Characterizing WSON Network Elements..........................10
4.1. Input Constraints........................................10
4.2. Output Constraints.......................................11
4.3. Processing Capabilities..................................11
5. Networking Scenarios and the Control Plane....................12
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5.1. Fixed Regeneration Points................................12
5.2. Shared Regeneration Pools................................13
5.3. Reconfigurable Regenerators..............................13
5.4. Relation to Translucent Networks.........................13
6. Implications for GMPLS and PCE................................14
6.1. Link and Network Element Extensions for GMPLS Routing....14
6.2. Implications for GMPLS Signaling.........................15
6.3. PCEP Extensions..........................................16
7. Security Considerations.......................................17
8. IANA Considerations...........................................17
9. Acknowledgments...............................................17
10. References...................................................18
10.1. Normative References....................................18
10.2. Informative References..................................19
Author's Addresses...............................................19
Intellectual Property Statement..................................20
Disclaimer of Validity...........................................20
1. Introduction
The current GMPLS WSON formalism can deal with many types of
wavelength switching systems. However, there is an implicit
assumption that all signals used in a WSON are compatible with all
network elements. This arises in practice for a number of reasons (a)
in some WSONs only one class of signal is used throughout the
network, or (b) only "relatively" transparent network elements are
utilized in the WSON. Assumption (a) limits the inherent flexibility
that carriers seek from a WSON and assumption (b) leaves out very
common optical network elements including regenerators, OEO switches,
and wavelength converters.
Therefore there is a requirement to extend the GMPLS control plane to
allow both multiple WSON signal types and common hybrid electro
optical systems. In the following we characterize WSON signals in
line with ITU-T standards, and add attributes describing signal
compatibility constraints to WSON network elements. This way the
control plane signaling and path computation functions can ensure
"signal" compatibility between source, sink and any links or network
elements as part of the path selection process, and configure devices
appropriately via signaling as part of the connection provisioning
process.
2. Describing Optical Signals in WSONs
As we will later see the new network elements that we wish to
incorporate within the GMPLS control plane(OEO switches,
regenerators, and wavelength converters) can impose constraints on
the types of signals they can "process". Hence to enable the use of a
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larger set of network elements the first step is to more precisely
define and characterize our "optical signal".
2.1. Optical Interfaces
In wavelength switched optical networks (WSONs) our fundamental unit
of switching is intuitively that of a "wavelength". The transmitters
and receivers in these networks will deal with one wavelength at a
time, while the switching systems themselves can deal with multiple
wavelengths at a time. Hence we are generally concerned with
multichannel dense wavelength division multiplexing (DWDM) networks
with single channel interfaces. Interfaces of this type are defined
in ITU-T recommendations [G.698.1] and [G.698.1]. Key non-impairment
related parameters defined in [G.698.1] and [G.698.2] are:
(a) Minimum Channel Spacing (GHz)
(b) Bit-rate/Line coding (modulation) of optical tributary signals
(c) Minimum and Maximum central frequency
We see that (a) and (c) above are related to properties of the link
and have been modeled in [Otani], [WSON-FRAME], [WSON-Info] and (b)
is related to the "signal".
2.2. Optical Tributary Signals
The optical interface specifications [G.698.1], [G.698.2], and
[G.959.1] all use the concept of an Optical Tributary Signal which is
defined as "a single channel signal that is placed within an optical
channel for transport across the optical network". Note the use of
the qualifier "tributary" to indicate that this is a single channel
entity and not a multichannel optical signal. This is our candidate
terminology for the entity that we will be controlling in our GMPLS
extensions for WSONs.
There are a currently a number of different "flavors" of optical
tributary signals, known as "optical tributary signal classes". These
are currently characterized by a modulation format and bit rate range
[G.959.1]:
(a) optical tributary signal class NRZ 1.25G
(b) optical tributary signal class NRZ 2.5G
(c) optical tributary signal class NRZ 10G
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(d) optical tributary signal class NRZ 40G
(e) optical tributary signal class RZ 40G
Note that with advances in technology more optical tributary signal
classes may be added and that this is currently an active area for
deployment and standardization. In particular at the 40G rate there
are a number of non-standardized advanced modulation formats that
have seen significant deployment including Differential Phase Shift
Keying (DPSK) and Phase Shaped Binary Transmission (PSBT)[Winzer06].
Note that according to [G.698.2] it is important to fully specify the
bit rate of the optical tributary signal:
"When an optical system uses one of these codes, therefore, it is
necessary to specify both the application code and also the exact bit
rate of the system. In other words, there is no requirement for
equipment compliant with one of these codes to operate over the
complete range of bit rates specified for its optical tributary
signal class."
Hence we see that modulation format (optical tributary signal class)
and bit rate are key in characterizing the optical tributary signal.
2.3. WSON Signal Characteristics
We refer an optical tributary signal defined in ITU-T G.698.1 and .2
to as the signal in this document. This is an "entity" that can be
put on an optical communications channel formed from links and
network elements in a WSON. This corresponds to the "lambda" LSP in
GMPLS. For signal compatibility purposes we will be interested in the
following signal characteristics:
List 1. WSON Signal Characteristics
1. Optical tributary signal class (modulation format).
2. FEC: whether forward error correction is used in the digital stream
and what type of error correcting code is used
3. Center frequency (wavelength)
4. Bit rate
5. G-PID: General Protocol Identifier for the information format
The first three items on this list can change as a WSON signal
traverses a network with regenerators, OEO switches, or wavelength
converters. An ability to control wavelength conversion already
exists in GMPLS.
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Bit rate and GPID would not change since they describe the encoded
bit stream. A set of G-PID values are already defined for lambda
switching in [RFC3471] and [RFC4328].
Note that a number of "pre-standard" or proprietary modulation
formats and FEC codes are commonly used in WSONs. For some digital
bit streams the presence of FEC can be detected, e.g., in [G.707]
this is indicated in the signal itself via the FEC status indication
(FSI) byte, while in [G.709] this can be inferred from whether the
FEC field of the OTUk is all zeros or not.
3. Electro-Optical Systems
This section describes how Electro-Optical Systems (e.g., OEO
switches, wavelength converters, and regenerators) interact with the
WSON signal characteristics defined in List 1 in Section 2.3. OEO
switches, wavelength converters and regenerators all share a similar
property: they can be more or less "transparent" to an "optical
signal" depending on their functionality and/or implementation.
Regenerators have been fairly well characterized in this regard so we
start by describing their properties.
3.1. Regenerators
The various approaches to regeneration are discussed in ITU-T G.872
Annex A [G.872]. They map a number of functions into the so-called
1R, 2R and 3R categories of regenerators as summarized in Table 1
below:
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Table 1 Regenerator functionality mapped to general regenerator
classes from [G.872].
---------------------------------------------------------------------
1R | 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 single-
| channel 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. Noise suppression.
+-----------------------------------------------------------------
| 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. Complete regeneration of the
| pulse shape including clock recovery and retiming within
| required jitter limits.
--------------------------------------------------------------------
From the previous table we can see that 1R regenerators are generally
independent of signal modulation format (also known as line coding),
but may work over a limited range of wavelength/frequencies. We see
that 2R regenerators are generally applicable to a single digital
stream and are dependent upon modulation format (line coding) and to
a lesser extent are limited to a range of bit rates (but not a
specific bit rate). Finally, 3R regenerators apply to a single
channel, are dependent upon the modulation format and generally
sensitive to the bit rate of digital signal, i.e., either are
designed to only handle a specific bit rate or need to be programmed
to accept and regenerate a specific bit rate. In all these types of
regenerators the digital bit stream contained within the optical or
electrical signal is not modified.
However, in the most common usage of regenerators the digital bit
stream may be slightly modified for performance monitoring and fault
management purposes. SONET, SDH and G.709 all have a digital signal
"envelope" designed to be used between "regenerators" (in this case
3R regenerators). In SONET this is known as the "section" signal, in
SDH this is known as the "regenerator section" signal, in G.709 this
is known as an OTUk (Optical Channel Transport Unit-k). These
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signals reserve a portion of their frame structure (known as
overhead) for use by regenerators. The nature of this overhead is
summarized in Table 2.
Table 2. SONET, SDH, and G.709 regenerator related overhead.
+-----------------------------------------------------------------+
|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) | | |
+-----------------------------------------------------------------+
In the previous table we see support for frame alignment, signal
identification, and FEC. What this table also shows by its omission
is that no switching or multiplexing occurs at this layer. This is a
significant simplification for the control plane since control plane
standards require a multi-layer approach when there are multiple
switching layers, but not for "layering" to provide the management
functions of Table 2. That is, many existing technologies covered by
GMPLS contain extra management related layers that are essentially
ignored by the control plane (though not by the management plane!).
Hence, the approach here is to include regenerators and other devices
at the WSON layer unless they provide higher layer switching and then
a multi-layer or multi-region approach [RFC5212] is called for.
However, this can result in regenerators having a dependence on the
client signal type.
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Hence we see that depending upon the regenerator technology we may
have the following constraints imposed by a regenerator device:
Table 3. Regenerator Compatibility Constraints
+--------------------------------------------------------+
| Constraints | 1R | 2R | 3R |
+--------------------------------------------------------+
| Limited Wavelength Range | x | x | x |
+--------------------------------------------------------+
| Modulation Type Restriction | | x | x |
+--------------------------------------------------------+
| Bit Rate Range Restriction | | x | x |
+--------------------------------------------------------+
| Exact Bit Rate Restriction | | | x |
+--------------------------------------------------------+
| Client Signal Dependence | | | x |
+--------------------------------------------------------+
Note that Limited Wavelength Range constraint is already modeled in
GMPLS for WSON and that Modulation Type Restriction constraint
includes FEC.
3.2. OEO Switches
A common place where optical-to-electrical-to-optical (OEO)
processing may take place is in WSON switches that utilize (or
contain) regenerators. A vendor may add regenerators to a switching
system for a number of reasons. One obvious reason is to restore
signal quality either before or after optical processing (switching).
Another reason may be to convert the signal to an electronic form for
switching then reconverting to an optical signal prior to egress from
the switch. In this later case the regeneration is applied to adapt
the signal to the switch fabric regardless of whether or not it is
needed from a signal quality perspective.
In either case these optical switches have essentially the same
compatibility constraints as those we described for regenerators in
Table 3.
3.3. Wavelength Converters
In [WSON-FRAME] the motivation for utilizing wavelength converters
was discussed. In essence a wavelength converter would take one or
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more optical channels on specific wavelengths and convert them to
corresponding new specific wavelengths. Currently all optical
wavelength converters exist but have not been widely deployed, hence
the majority of wavelength converters are based on demodulation to an
electrical signal and then re-modulation onto a new optical carrier,
i.e., an OEO process. This process is very similar to that used for a
regenerator except that the output optical wavelength will be
different from the input optical wavelength. Hence in general
wavelength converters have signal processing restrictions that are
essentially the same as those we described for regenerators in Table
3 with perhaps an additional input frequency range restriction and
output frequency range restriction. By additional we mean more
restrictive than the range of the WDM link. Such a restriction has
already been modeled in [WSON-Frame] and [WSON-Info].
4. Characterizing WSON Network Elements
In this section we characterize WSON network elements by the three
key functional components: Input constraints, Output constraints and
Processing Capabilities.
WSON Network Element
+-----------------------+
WSON Signal | | | | WSON Signal
| | | |
---------------> | | | | ----------------->
| | | |
+-----------------------+
<-----> <-------> <----->
Input Processing Output
Figure 1 WSON Network Element
4.1. Input Constraints
Section 3 discussed the basic properties regenerators, OEO switches
and wavelength converters from these we have the following possible
types of input constraints and properties:
1. Acceptable Modulation formats
2. Client Signal (GPID) restrictions
3. Bit Rate restrictions
4. FEC coding restrictions
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5. Configurability: (a) none, (b) self-configuring, (c) required
We can represent these constraints via simple lists. Note that the
device may need to be "provisioned" via signaling or some other means
to accept signals with some attributes versus others. In other cases
the devices maybe relatively transparent to some attributes, e.g.,
such as a 2R regenerator to bit rate. Finally, some devices maybe
able to auto-detect some attributes and configure themselves, e.g., a
3R regenerator with bit rate detection mechanisms and flexible phase
locking circuitry. To account for these different cases we've added
item 5, which describes the devices configurability.
Note that such input constraints also apply to the final destination,
sink or termination, of the WSON signal.
4.2. Output Constraints
None of the network elements considered here modifies either the bit
rate or the basic type of the client signal. However, they may modify
the modulation format or the FEC code. Typically we'd see the
following types of output constraints:
1. Output modulation is the same as input modulation (default)
2. A limited set of output modulations is available
3. Output FEC is the same as input FEC code (default)
4. A limited set of output FEC codes is available
Note that in cases (2) and (4) above, where there is more than one
choice in the output modulation or FEC code then the network element
will need to be configured on a per LSP basis as to which choice to
use.
4.3. Processing Capabilities
A general WSON network element (NE) can perform a number of signal
processing functions including:
(A) Regeneration (possibly different types)
(B) Fault and Performance Monitoring
(C) Wavelength Conversion
(D) Switching
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Items (C) and (D) are already covered in GMPLS and [WSON-Frame].
An NE may or may not have the ability to perform regeneration (of the
one of the types previously discussed). In addition some nodes may
have limited regeneration capability, i.e., a shared pool, which may
be applied to selected signals traversing the NE. Hence to describe
the regeneration capability of a link or node we have at a minimum:
1. Regeneration capability: (a)fixed, (b) selective, (c) none
2. Regeneration type: 1R, 2R, 3R
3. Regeneration pool properties for the case of selective
regeneration (ingress & egress restrictions, availability)
Note that the properties of shared regenerator pools would be
essentially the same at that of wavelength converter pools modeled in
[WSON-Frame].
Item (B), fault and performance monitoring, is typically outside the
scope of the control plane. However, when the operations are to be
performed on an LSP basis or as part of an LSP then the control plane
can be of assistance in their configuration. Per LSP, per node, fault
and performance monitoring examples include setting up a "section
trace" (a regenerator overhead identifier) between two nodes, or
intermediate optical performance monitoring at selected nodes along a
path.
5. Networking Scenarios and the Control Plane
In the following we look at various networking scenarios involving
regenerators, OEO switches and wavelength converters. We group these
scenarios roughly by type and number of extensions to the GMPLS
control plane that would be required.
5.1. Fixed Regeneration Points
In the simplest networking scenario involving regenerators, the
regeneration is associated with a WDM link or entire node and is not
optional, i.e., all signals traversing the link or node will be
regenerated. This includes OEO switches since they provide
regeneration on every port.
There maybe input constraints and output constraints on the
regenerators. Hence the path selection process will need to know from
an IGP or other means the regenerator constraints so that it can
choose a compatible path. For impairment aware routing and wavelength
assignment (IA-RWA) the path selection process will also need to know
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which links/nodes provide regeneration. Even for "regular" RWA, this
regeneration information is useful since wavelength converters
typically perform regeneration and the wavelength continuity
constraint can be relaxed at such a point.
Signaling does not need to be enhanced to include this scenario since
there are no reconfigurable regenerator options on input, output or
with respect to processing.
5.2. Shared Regeneration Pools
In this scenario there are nodes with shared regenerator pools within
the network in addition to fixed regenerators of the previous
scenario. These regenerators are shared within a node and their
application to a signal is optional. There are no reconfigurable
options on either input or output. The only processing option is to
"regenerate" a particular signal or not.
Regenerator information in this case is used in path computation to
select a path that ensures signal compatibility and IA-RWA criteria.
To setup an LSP that utilizes a regenerator from a node with a shared
regenerator pool we need to be able to indicate that regeneration is
to take place at that particular node along the signal path. Such a
capability currently does not exist in GMPLS signaling.
5.3. Reconfigurable Regenerators
In this scenario we have regenerators that require configuration
prior to use on an optical signal. We discussed previously that this
could be due to a regenerator that must be configured to accept
signals with different characteristics, for regenerators with a
selection of output attributes, or for regenerators with additional
optional processing capabilities.
As in the previous scenarios we will need information concerning
regenerator properties for selection of compatible paths and for IA-
RWA computations. In addition during LSP setup we need to be able
configure regenerator options at a particular node along the path.
Such a capability currently does not exist in GMPLS signaling.
5.4. Relation to Translucent Networks
In the literature networks that contain both transparent network
elements such as reconfigurable optical add drop multiplexers
(ROADMs) and electro-optical network elements such regenerators or
OEO switches are frequently referred to as Translucent optical
networks [Trans07]. Earlier work suggesting GMPLS extensions for
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translucent optical networks can be found in [Yang05] while a more
comprehensive evaluation of differing GMPLS control plane approaches
to translucent networks can be found in [Sambo09].
Three main types of translucent optical networks have been discussed:
1. Transparent "islands" surrounded by regenerators. This is
frequently seen when transitioning from a metro optical sub-
network to a long haul optical sub-network.
2. Mostly transparent networks with a limited number of OEO
("opaque") nodes strategically placed. This takes advantage of the
inherent regeneration capabilities of OEO switches. In the
planning of such networks one has to determine the optimal
placement of the OEO switches [Sen08].
3. Mostly transparent networks with a limited number of optical
switching nodes with "shared regenerator pools" that can be
optionally applied to signals passing through these switches.
These switches are sometimes called translucent nodes.
All three of these types of translucent networks fit within either
the networking scenarios of sections 5.1. and 5.2. above. And hence,
can be accommodated by the GMPLS extensions suggested in this
document.
6. Implications for GMPLS and PCE
6.1. Link and Network Element Extensions for GMPLS Routing
Other drafts [WSON-FRAME],[WSON-Info] provide NE models that include
switching asymmetry and port wavelength constraints here we add
parameters to our existing node and link models to take into account
input constraints, output constraints, and the signal processing
capabilities of a NE.
Input Constraints:
1. 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. [configuration type]
2. Acceptable FEC codes [configuration type]
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3. 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.
4. Acceptable G-PID list: A list of G-PIDs corresponding to the
"client" digital streams that is compatible with this device.
Note that since the bit rate of the signal does not change over the
LSP. We can make this an LSP parameter and hence this information
would be available for any NE that needs to use it for configuration.
Hence we do not need "configuration type" for the NE with respect to
bit rate.
Output Constraints:
1. Output modulation: (a)same as input, (b) list of available types
2. FEC options: (a) same as input, (b) list of available codes
Processing Capabilities:
1. Regeneration: (a) 1R, (b) 2R, (c) 3R, (d)list of selectable
regeneration types
2. Fault and Performance Monitoring (a)GPID particular capabilities
TBD, (b) optical performance monitoring capabilities TBD.
Note that such parameters could be specified on an (a) Network
element wide basis, (b) a per port basis, (c) on a per regenerator
basis. Typically such information has been on a per port basis,
e.g., the GMPLS interface switching capability descriptor [RFC4202].
However, in [WSON-FRAME] we give examples of shared wavelength
converters within a switching system, and hence this would be on a
subsystem basis. The exact form would be defined in the [WSON-Info]
and [WSON-Encoding] drafts.
6.2. Implications for GMPLS Signaling
We saw in section 2.3. that a WSON signal at any point along its path
can be characterized by the (a) modulation format, (b) FEC, (c)
wavelength, (d)bit rate, and (d)G-PID.
Currently G-PID, wavelength (via labels), and bit rate (via bandwidth
encoding) are supported in [RFC3471] and [RFC3473]. These RFCs can
accommodate the wavelength changing at any node along the LSP and can
provide explicit control of wavelength converters.
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In the fixed regeneration point scenario (section 5.1. ) no
enhancements are required to signaling since there are no additional
configuration options for the LSP at a node.
In the case of shared regeneration pools (section 5.2. ) we need to
be able to indicate to a node that it should perform regeneration on
a particular signal. Viewed another way, for an LSP we want to
specify that certain nodes along the path perform regeneration. Such
a capability currently does not exist in GMPLS signaling.
The case of configurable regenerators (section 5.3. ) is very similar
to the previous except that now there are potentially many more items
that we may want to configure on a per node basis for an LSP.
Note that the techniques of [RFC5420] which allow for additional LSP
attributes and their recording in an RRO object could be extended to
allow for additional LSP attributes in an ERO. This could allow one
to indicate where optional 3R regeneration should take place along a
path, any modification of LSP attributes such as modulation format,
or any enhance processing such as performance monitoring.
6.3. PCEP Extensions
When requesting a path computation to PCE, the PCC should be able to
indicate the following:
o The GPID type of an LSP
o The signal attributes at the transmitter (at the source): (i)
modulation type; (ii) FEC type
o The signal attributes at the receiver (at the sink): (i)
modulation type; (ii) FEC type
The PCE should be able to respond to the PCC with the following:
o The conformity of the requested optical characteristics associated
with the resulting LSP with the source, sink and NE along the LSP.
o Additional LSP attributes modified along the path (e.g.,
modulation format change, etc.)
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7. Security Considerations
This document has no requirement for a change to the security models
within GMPLS and associated protocols. That is the OSPF-TE, RSVP-TE,
and PCEP [RFC5540] security models could be operated unchanged.
Furthermore the additional information distributed in order to extend
GMPLS capabilities to the additional network elements discussed in
this document represents a disclosure of network capabilities that an
operator may wish to keep private. Consideration should be given to
securing this information.
8. IANA Considerations
This document makes no request for IANA actions.
9. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
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10. References
10.1. Normative References
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)", RFC
4202, October 2005.
[RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, January 2006.
[G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM
applications: DWDM frequency grid", June, 2002.
[RFC5212] Shiomoto, K., Papadimitriou, D., Le Roux, JL., Vigoureux,
M., and D. Brungard, "Requirements for GMPLS-Based Multi-
Region and Multi-Layer Networks (MRN/MLN)", RFC 5212, July
2008.
[RFC5540] J.P. Vasseur and J.L. Le Roux (Editors), "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5540,
March 2009.
[WSON-FRAME] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
and PCE Control of Wavelength Switched Optical Networks
(WSON)", draft-ietf-ccamp-rwa-wson-framework-02.txt, March
2009.
[WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information for Wavelength Switched
Optical Networks", draft-bernstein-ccamp-wson-info-03.txt,
March, 2009.
[WSON-Encoding] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Encoding for Wavelength
Switched Optical networks", work in progress, draft-ietf-
ccamp-rwa-wson-encode-01.txt, March 2009.
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10.2. Informative References
[Otani] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, "Generalized
Labels for G.694 Lambda-Switching Capable Label Switching
Routers (LSR)", work in progress, draft-ietf-ccamp-gmpls-g-
694-lambda-labels-04.txt
[G.872] ITU-T Recommendation G.872, Architecture of optical
transport networks, November 2001.
[G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network
Physical Layer Interfaces, March 2006.
[Imp-Frame] G. Bernstein, Y. Lee, D. Li, G. Martinelli, "A Framework
for the Control and Measurement of Wavelength Switched
Optical Networks (WSON) with Impairments", Work in
Progress, draft-ietf-ccamp-wson-impairments-00.txt.
[Sambo09] N. Sambo, N. Andriolli, A. Giorgetti, L. Valcarenghi, I.
Cerutti, P. Castoldi, and F. Cugini, "GMPLS-controlled
dynamic translucent optical networks," Network, IEEE, vol.
23, 2009, pp. 34-40.
[Sen08] A. Sen, S. Murthy, and S. Bandyopadhyay, "On Sparse
Placement of Regenerator Nodes in Translucent Optical
Network," Global Telecommunications Conference, 2008. IEEE
GLOBECOM 2008. IEEE, 2008, pp. 1-6.
[Trans07] Gangxiang Shen and Rodney S. Tucker, "Translucent optical
networks: the way forward [Topics in Optical
Communications]," Communications Magazine, IEEE, vol. 45,
2007, pp. 48-54.
[Yang05] Xi Yang and B. Ramamurthy, "Dynamic routing in translucent
WDM optical networks: the intradomain case," Lightwave
Technology, Journal of, vol. 23, 2005, pp. 955-971.
Author's Addresses
Greg M. Bernstein
Grotto Networking
Fremont California, USA
Phone: (510) 573-2237
Email: gregb@grotto-networking.com
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Young Lee
Huawei Technologies
1700 Alma Drive, Suite 100
Plano, TX 75075
USA
Phone: (972) 509-5599 (x2240)
Email: ylee@huawei.com
T. Benjamin Mack-Crane
Huawei Technologies
Downers Grove, Illinois
Email: tmackcrane@huawei.com
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