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Internet Engineering Task Force (IETF) Y. Lee, Ed.
Request for Comments: 8780 Samsung Electronics
Category: Standards Track R. Casellas, Ed.
ISSN: 2070-1721 CTTC
July 2020
The Path Computation Element Communication Protocol (PCEP) Extension for
Wavelength Switched Optical Network (WSON) Routing and Wavelength
Assignment (RWA)
Abstract
This document provides Path Computation Element Communication
Protocol (PCEP) extensions for the support of Routing and Wavelength
Assignment (RWA) in Wavelength Switched Optical Networks (WSONs).
Path provisioning in WSONs requires an RWA process. From a path
computation perspective, wavelength assignment is the process of
determining which wavelength can be used on each hop of a path and
forms an additional routing constraint to optical path computation.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8780.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction
2. Terminology
3. Requirements Language
4. Encoding of an RWA Path Request
4.1. Wavelength Assignment (WA) Object
4.2. Wavelength Selection TLV
4.3. Wavelength Restriction TLV
4.3.1. Link Identifier Field
4.3.2. Wavelength Constraint Field
4.4. Signal Processing Capability Restrictions
4.4.1. Signal Processing Exclusion
4.4.2. Signal Processing Inclusion
5. Encoding of an RWA Path Reply
5.1. Wavelength Allocation TLV
5.2. Error Indicator
5.3. NO-PATH Indicator
6. Manageability Considerations
6.1. Control of Function and Policy
6.2. Liveness Detection and Monitoring
6.3. Verifying Correct Operation
6.4. Requirements on Other Protocols and Functional Components
6.5. Impact on Network Operation
7. Security Considerations
8. IANA Considerations
8.1. New PCEP Object: Wavelength Assignment Object
8.2. WA Object Flag Field
8.3. New PCEP TLV: Wavelength Selection TLV
8.4. New PCEP TLV: Wavelength Restriction TLV
8.5. Wavelength Restriction TLV Action Values
8.6. New PCEP TLV: Wavelength Allocation TLV
8.7. Wavelength Allocation TLV Flag Field
8.8. New PCEP TLV: Optical Interface Class List TLV
8.9. New PCEP TLV: Client Signal Information TLV
8.10. New Bit Flag for NO-PATH-VECTOR TLV
8.11. New Error-Types and Error-Values
8.12. New Subobjects for the Exclude Route Object
8.13. New Subobjects for the Include Route Object
8.14. Request for Updated Note for LMP TE Link Object Class Type
9. References
9.1. Normative References
9.2. Informative References
Acknowledgments
Contributors
Authors' Addresses
1. Introduction
[RFC5440] specifies the Path Computation Element Communication
Protocol (PCEP) for communications between a Path Computation Client
(PCC) and a PCE, or between two PCEs. Such interactions include Path
Computation Requests (PCReqs) and Path Computation Replies (PCReps)
as well as notifications of specific states related to the use of a
PCE in the context of Multiprotocol Label Switching (MPLS) and
Generalized MPLS (GMPLS) Traffic Engineering (TE).
A PCC is said to be any network component that makes such a request
and may be, for instance, an optical switching element within a
Wavelength Division Multiplexing (WDM) network. The PCE, itself, can
be located anywhere within the network and may be within an optical
switching element, a Network Management System (NMS), or an
Operational Support System (OSS), or it may be an independent network
server.
This document provides the PCEP extensions for the support of Routing
and Wavelength Assignment (RWA) in Wavelength Switched Optical
Networks (WSONs) based on the requirements specified in [RFC6163] and
[RFC7449].
WSON refers to WDM-based optical networks in which switching is
performed selectively based on the wavelength of an optical signal.
The devices used in WSONs that are able to switch signals based on
signal wavelength are known as Lambda Switch Capable (LSC). WSONs
can be transparent or translucent. A transparent optical network is
made up of optical devices that can switch but not convert from one
wavelength to another, all within the optical domain. On the other
hand, translucent networks include 3R regenerators (reamplification,
reshaping, and retiming) that are sparsely placed. The main function
of the 3R regenerators is to convert one optical wavelength to
another.
An LSC Label Switched Path (LSP) may span one or several transparent
segments, which are delimited by 3R regenerators typically with
electronic regenerator and optional wavelength conversion. Each
transparent segment or path in WSON is referred to as an optical
path. An optical path may span multiple fiber links, and the path
should be assigned the same wavelength for each link. In a case, the
optical path is said to satisfy the wavelength-continuity constraint.
Figure 1 illustrates the relationship between an LSC LSP and
transparent segments (optical paths).
+---+ +-----+ +-----+ +-----+ +-----+
| |I1 | | | | | | I2| |
| |o------| |-------[(3R) ]------| |--------o| |
| | | | | | | | | |
+---+ +-----+ +-----+ +-----+ +-----+
(X LSC) (LSC LSC) (LSC LSC) (LSC X)
<-------> <-------> <-----> <------->
<-----------------------><---------------------->
Transparent Segment Transparent Segment
<------------------------------------------------->
LSC LSP
Figure 1: Illustration of an LSC LSP and Transparent Segments
Note that two transparent segments within a WSON LSP do not need to
operate on the same wavelength (due to wavelength conversion
capabilities). Two optical channels that share a common fiber link
cannot be assigned the same wavelength; otherwise, the two signals
would interfere with each other. Note that advanced additional
multiplexing techniques such as polarization-based multiplexing are
not addressed in this document since the physical-layer aspects are
not currently standardized. Therefore, assigning the proper
wavelength on a path is an essential requirement in the optical path
computation process.
When a switching node has the ability to perform wavelength
conversion, the wavelength-continuity constraint can be relaxed, and
an LSP may use different wavelengths on different links along its
route from origin to destination. It is, however, to be noted that
wavelength converters may be limited due to their relatively high
cost, while the number of WDM channels that can be supported in a
fiber is also limited. As a WSON can be composed of network nodes
that cannot perform wavelength conversion, nodes with limited
wavelength conversion, and nodes with full wavelength conversion
abilities, wavelength assignment is an additional routing constraint
to be considered in all optical path computation.
For example (see Figure 1), within a translucent WSON, an LSC LSP may
be established between interfaces I1 and I2, spanning two transparent
segments (optical paths) where the wavelength continuity constraint
applies (i.e., the same unique wavelength must be assigned to the LSP
at each TE link of the segment). If the LSC LSP induced a Forwarding
Adjacency / TE link, the switching capabilities of the TE link would
be (X X), where X refers to the switching capability of I1 and I2.
For example, X can be Packet Switch Capable (PSC), Time-Division
Multiplexing (TDM), etc.
This document aligns with [RFC8779] for generic properties such as
label, label set, and label assignment, noting that a wavelength is a
type of label. Wavelength restrictions and constraints are also
formulated in terms of labels per [RFC7579].
The optical modulation properties, which are also referred to as
signal compatibility, are already considered in the signaling in
[RFC7581] and [RFC7688]. In order to improve the signal quality and
limit some optical effects, several advanced modulation processing
capabilities are used by the mechanisms specified in this document.
These modulation capabilities not only contribute to optical signal
quality checks but also constrain the selection of sender and
receiver, as they should have matching signal processing
capabilities. This document includes signal compatibility
constraints as part of RWA path computation. That is, the signal
processing capabilities (e.g., modulation and Forward Error
Correction (FEC)) indicated by means of the Optical Interface Class
(OIC) must be compatible between the sender and the receiver of the
optical path across all optical elements.
This document, however, does not address optical impairments as part
of RWA path computation. See [RFC6566] for the framework for optical
impairments.
2. Terminology
This document uses the terminology defined in [RFC4655] and
[RFC5440].
3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
4. Encoding of an RWA Path Request
Figure 2 shows one typical PCE-based implementation, which is
referred to as the Combined Process (R&WA). With this architecture,
the two processes of routing and wavelength assignment are accessed
via a single PCE. This architecture is the base architecture
specified in [RFC6163], and the PCEP extensions that are specified in
this document are based on this architecture.
+----------------------------+
+-----+ | +-------+ +--+ |
| | | |Routing| |WA| |
| PCC |<----->| +-------+ +--+ |
| | | |
+-----+ | PCE |
+----------------------------+
Figure 2: Combined Process (R&WA) Architecture
4.1. Wavelength Assignment (WA) Object
Wavelength allocation can be performed by the PCE by means of:
(a) Explicit Label Control [RFC3471] where the PCE allocates which
label to use for each interface/node along the path. The
allocated labels MAY appear after an interface route subobject.
(b) A Label Set where the PCE provides a range of potential labels
to be allocated by each node along the path.
Option (b) allows distributed label allocation (performed during
signaling) to complete wavelength assignment.
Additionally, given a range of potential labels to allocate, a PCReq
SHOULD convey the heuristic or mechanism used for the allocation.
Per [RFC5440], the format of a PCReq message after incorporating the
Wavelength Assignment (WA) object is as follows:
<PCReq Message> ::= <Common Header>
[<svec-list>]
<request-list>
Where:
<request-list>::=<request>[<request-list>]
<request>::= <RP>
<END-POINTS>
<WA>
[other optional objects...]
If the WA object is present in the request, it MUST be encoded after
the END-POINTS object as defined in [RFC8779]. The WA object is
mandatory in this document. Orderings for the other optional objects
are irrelevant.
For the WA object, the Object-Class is 42, and the Object-Type is 1.
The format of the WA object body is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: WA Object
Reserved (16 bits): Reserved for future use and SHOULD be zeroed and
ignored on receipt.
Flags field (16 bits): One flag bit is allocated as follows:
M (1 bit): Wavelength Allocation Mode. The M bit is used to
indicate the mode of wavelength assignment. When the M bit is
set to 1, this indicates that the label assigned by the PCE
must be explicit. That is, the selected way to convey the
allocated wavelength is by means of Explicit Label Control for
each hop of a computed LSP. Otherwise (M bit is set to 0), the
label assigned by the PCE need not be explicit (i.e., it can be
suggested in the form of Label Set objects in the corresponding
response, to allow distributed WA. If M is 0, the PCE MUST
return a Label Set Field as described in Section 2.6 of
[RFC7579] in the response. See Section 5 of this document for
the encoding discussion of a Label Set Field in a PCRep
message.
All unused flags SHOULD be zeroed. IANA has created a new
registry to manage the Flags field of the WA object.
TLVs (variable): In the TLVs field, the following two TLVs are
defined. At least one TLV MUST be present.
Wavelength Selection TLV: The type of this TLV is 8, and it has a
fixed length of 32 bits. This TLV indicates the wavelength
selection. See Section 4.2 for details.
Wavelength Restriction TLV: The type of this TLV is 9, and it has
a variable length. This TLV indicates wavelength restrictions.
See Section 4.3 for details.
4.2. Wavelength Selection TLV
The Wavelength Selection TLV is used to indicate the wavelength
selection constraint in regard to the order of wavelength assignment
to be returned by the PCE. This TLV is only applied when the M bit
is set in the WA object specified in Section 4.1. This TLV MUST NOT
be used when the M bit is cleared.
The encoding of this TLV is specified as the WavelengthSelection sub-
TLV in Section 4.2.2 of [RFC7689]. IANA has allocated a new TLV type
for the Wavelength Selection TLV (Type 8).
4.3. Wavelength Restriction TLV
For any request that contains a wavelength assignment, the requester
(PCC) MUST specify a restriction on the wavelengths to be used. This
restriction is to be interpreted by the PCE as a constraint on the
tuning ability of the origination laser transmitter or on any other
maintenance-related constraints. Note that if the LSC LSP spans
different segments, the PCE must have mechanisms to know the
tunability restrictions of the involved wavelength converters/
regenerators, e.g., by means of the Traffic Engineering Database
(TED) via either IGP or NMS. Even if the PCE knows the tunability of
the transmitter, the PCC must be able to apply additional constraints
to the request.
The format of the Wavelength Restriction TLV is as follows:
<Wavelength Restriction> ::=
(<Action> <Count> <Reserved>
<Link Identifiers> <Wavelength Constraint>)...
Where:
<Link Identifiers> ::= <Link Identifier> [<Link Identifiers>]
See Section 4.3.1 for the encoding of the Link Identifier field.
These fields (i.e., <Action>, <Link Identifiers>, and <Wavelength
Constraint>, etc.) MAY appear together more than once to be able to
specify multiple actions and their restrictions.
IANA has allocated a new TLV type for the Wavelength Restriction TLV
(Type 9).
The TLV data is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action | Count | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifiers |
// . . . //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Wavelength Constraint |
// . . . . //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ . . . . ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action | Count | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifiers |
// . . . //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Wavelength Constraint |
// . . . . //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Wavelength Restriction TLV Encoding
Action (8 bits):
0: Inclusive List. Indicates that one or more link identifiers
are included in the Link Set. Each identifies a separate link
that is part of the set.
1: Inclusive Range. Indicates that the Link Set defines a range
of links. It contains two link identifiers. The first
identifier indicates the start of the range (inclusive). The
second identifier indicates the end of the range (inclusive).
All links with numeric values between the bounds are considered
to be part of the set. A value of zero in either position
indicates that there is no bound on the corresponding portion
of the range.
2-255: Unassigned.
IANA has created a new registry to manage the Action values of the
Wavelength Restriction TLV.
If a PCE receives an unrecognized Action value, the PCE MUST send
a PCEP Error (PCErr) message with a PCEP-ERROR object with Error-
Type=27 and an Error-value=3. See Section 5.2 for details.
Note that "links" are assumed to be bidirectional.
Count (8 bits):
The number of the link identifiers.
Note that a PCC MAY add a Wavelength restriction that applies to
all links by setting the Count field to zero and specifying just a
set of wavelengths.
Note that all link identifiers in the same list MUST be of the
same type.
Reserved (16 bits):
Reserved for future use and SHOULD be zeroed and ignored on
receipt.
Link Identifiers:
Identifies each link ID for which restriction is applied. The
length is dependent on the link format and the Count field. See
Section 4.3.1 for encoding of the Link Identifier field.
Wavelength Constraint:
See Section 4.3.2 for the encoding of the Wavelength Constraint
field.
Various encoding errors are possible with this TLV (e.g., not exactly
two link identifiers with the range case, unknown identifier types,
no matching link for a given identifier, etc.). To indicate errors
associated with this encoding, a PCEP speaker MUST send a PCErr
message with Error-Type=27 and Error-value=3. See Section 5.2 for
details.
4.3.1. Link Identifier Field
The Link Identifier field can be an IPv4 [RFC3630], IPv6 [RFC5329],
or unnumbered interface ID [RFC4203].
<Link Identifier> ::=
<IPv4 Address> | <IPv6 Address> | <Unnumbered IF ID>
The encoding of each case is as follows.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 1 | Reserved (24 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: IPv4 Address Field
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 | Reserved (24 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: IPv6 Address Field
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 3 | Reserved (24 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Node ID (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Unnumbered Interface ID Address Field
Type (8 bits): Indicates the type of the link identifier.
Reserved (24 bits): Reserved for future use and SHOULD be zeroed and
ignored on receipt.
Link Identifier: When the Type field is 1, a 4-byte IPv4 address is
encoded; when the Type field is 2, a 16-byte IPv6 address is
encoded; and when the Type field is 3, a tuple of a 4-byte TE node
ID and a 4-byte interface ID is encoded.
The Type field is extensible and matches the "TE_LINK Object Class
type name space (Value 11)" registry created for the Link Management
Protocol (LMP) [RFC4204] (see [LMP-PARAM]). IANA has added an
introductory note before the aforementioned registry stating that the
values have additional usage for the Link Identifier Type field. See
Section 8.14.
4.3.2. Wavelength Constraint Field
The Wavelength Constraint field of the Wavelength Restriction TLV is
encoded as a Label Set Field as specified in Section 2.6 of [RFC7579]
with the base label encoded as a 32-bit LSC label, as defined in
[RFC6205]. The Label Set format is repeated here for convenience,
with the base label internal structure included. See [RFC6205] for a
description of Grid, Channel Spacing (C.S.), Identifier, and n, and
see [RFC7579] for the details of each action.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action| Num Labels | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Identifier | n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional fields as necessary per action |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Wavelength Constraint Field
Action (4 bits):
0: Inclusive List
1: Exclusive List
2: Inclusive Range
3: Exclusive Range
4: Bitmap Set
Num Labels (12 bits):
It is generally the number of labels. It has a specific meaning
depending on the action value.
Length (16 bits):
It is the length in bytes of the entire Wavelength Constraint
field.
Identifier (9 bits):
The Identifier is always set to 0. If PCC receives the value of
the identifier other than 0, it will ignore.
See Sections 2.6.1-2.6.3 of [RFC7579] for details on additional field
discussion for each action.
4.4. Signal Processing Capability Restrictions
Path computation for WSON includes the checking of signal processing
capabilities at each interface against requested capability; the PCE
MUST have mechanisms to know the signal processing capabilities at
each interface, e.g., by means of (TED) via either IGP or NMS.
Moreover, a PCC should be able to indicate additional restrictions to
signal processing compatibility, on either the endpoint or any given
link.
The supported signal processing capabilities considered in the RWA
Information Model [RFC7446] are:
* Optical Interface Class List
* Bit Rate
* Client Signal
The bit rate restriction is already expressed in the BANDWIDTH object
in [RFC8779].
In order to support the optical interface class information and the
client signal information, new TLVs are introduced as endpoint
restrictions in the END-POINTS type Generalized Endpoint:
* Client Signal Information TLV
* Optical Interface Class List TLV
The END-POINTS type Generalized Endpoint is extended as follows:
<endpoint-restriction> ::=
<LABEL-REQUEST> <label-restriction-list>
<label-restriction-list> ::= <label-restriction>
[<label-restriction-list>]
<label-restriction> ::= (<LABEL-SET>|
[<Wavelength Restriction>]
[<signal-compatibility-restriction>])
Where:
<signal-compatibility-restriction> ::=
[<Optical Interface Class List>] [<Client Signal Information>]
The Wavelength Restriction TLV is defined in Section 4.3.
A new Optical Interface Class List TLV (Type 11) is defined; the
encoding of the value part of this TLV is described in Section 4.1 of
[RFC7581].
A new Client Signal Information TLV (Type 12) is defined; the
encoding of the value part of this TLV is described in Section 4.2 of
[RFC7581].
4.4.1. Signal Processing Exclusion
The PCC/PCE should be able to exclude particular types of signal
processing along the path in order to handle client restriction or
multi-domain path computation. [RFC5521] defines how the Exclude
Route Object (XRO) subobject is used. In this document, we add two
new XRO Signal Processing Exclusion subobjects.
The first XRO subobject type (8) is the Optical Interface Class List,
which is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type=8 | Length | Reserved | Attribute |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optical Interface Class List //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Optical Interface Class List XRO Subobject
Refer to [RFC5521] for the definitions of X, Length, and Attribute.
Type (7 bits): The type of the Signaling Processing Exclusion field.
IANA has assigned value 8 for the Optical Interface Class List XRO
subobject type.
Reserved bits (8 bits): These are for future use and SHOULD be
zeroed and ignored on receipt.
Attribute (8 bits): [RFC5521] defines several Attribute values; the
only permitted Attribute values for this field are 0 (Interface)
or 1 (Node).
Optical Interface Class List: This field is encoded as described in
Section 4.1 of [RFC7581].
The second XRO subobject type (9) is the Client Signal Information,
which is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type=9 | Length | Reserved | Attribute |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Client Signal Information //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Client Signal Information XRO Subobject
Refer to [RFC5521] for the definitions of X, Length, and Attribute.
Type (7 bits): The type of the Signaling Processing Exclusion field.
IANA has assigned value 9 for the Client Signal Information XRO
subobject type.
Reserved bits (8 bits): These are for future use and SHOULD be
zeroed and ignored on receipt.
Attribute (8 bits): [RFC5521] defines several Attribute values; the
only permitted Attribute values for this field are 0 (Interface)
or 1 (Node).
Client Signal Information: This field is encoded as described in
Section 4.2 of [RFC7581].
The XRO needs to support the new Signaling Processing Exclusion XRO
subobject types:
8: Optical Interface Class List
9: Client Signal Information
4.4.2. Signal Processing Inclusion
Similar to the XRO subobject, the PCC/PCE should be able to include
particular types of signal processing along the path in order to
handle client restriction or multi-domain path computation.
[RFC5440] defines how the Include Route Object (IRO) subobject is
used. In this document, we add two new Signal Processing Inclusion
subobjects.
The IRO needs to support the new IRO subobject types (8 and 9) for
the PCEP IRO object [RFC5440]:
8: Optical Interface Class List
9: Client Signal Information
The encoding of the Signal Processing Inclusion subobjects is similar
to the process in Section 4.4.1 where the 'X' field is replaced with
the 'L' field; all the other fields remain the same. The 'L' field
is described in [RFC3209].
5. Encoding of an RWA Path Reply
This section provides the encoding of an RWA Path Reply for a
wavelength allocation request as discussed in Section 4.
5.1. Wavelength Allocation TLV
Recall that wavelength allocation can be performed by the PCE by
means of:
(a) Explicit Label Control (ELC) where the PCE allocates which label
to use for each interface/node along the path.
(b) A Label Set where the PCE provides a range of potential labels
to be allocated by each node along the path.
Option (b) allows distributed label allocation (performed during
signaling) to complete wavelength allocation.
The type for the Wavelength Allocation TLV is 10 (see Section 8.4).
Note that this TLV is used for both (a) and (b) above. The TLV data
is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifier |
// . . . //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Allocated Wavelength(s) |
// . . . . //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Wavelength Allocation TLV Encoding
Reserved (16 bits): Reserved for future use.
Flags field (16 bits): One flag bit is allocated as follows:
M (1 bit): Wavelength Allocation Mode.
0: Indicates the allocation relies on the use of Label Sets.
1: Indicates the allocation is done using Explicit Label
Control.
IANA has created a new registry to manage the Flags field of the
Wavelength Allocation TLV.
Link Identifier: Identifies the interface to which the assignment
wavelength(s) is applied. See Section 4.3.1 for encoding of the
Link Identifier field.
Allocated Wavelength(s): Indicates the allocated wavelength(s) to be
associated with the link identifier. See Section 4.3.2 for
encoding details.
This TLV is carried in a PCRep message as an Attribute TLV [RFC5420]
in the Hop Attribute subobjects [RFC7570] in the Explicit Route
Object (ERO) [RFC5440].
5.2. Error Indicator
To indicate errors associated with the RWA request, a new Error-Type
27 (WSON RWA Error) and subsequent Error-values are defined as
follows for inclusion in the PCEP-ERROR object:
* Error-Type=27; Error-value=1: If a PCE receives an RWA request and
the PCE is not capable of processing the request due to
insufficient memory, the PCE MUST send a PCErr message with a
PCEP-ERROR object with Error-Type=27 and Error-value=1. The PCE
stops processing the request. The corresponding RWA request MUST
be canceled at the PCC.
* Error-Type=27; Error-value=2: If a PCE receives an RWA request and
the PCE is not capable of RWA computation, the PCE MUST send a
PCErr message with a PCEP-ERROR object with Error-Type=27 and
Error-value=2. The PCE stops processing the request. The
corresponding RWA computation MUST be canceled at the PCC.
* Error-Type=27; Error-value=3: If a PCE receives an RWA request and
there are syntactical encoding errors (e.g., not exactly two link
identifiers with the range case, unknown identifier types, no
matching link for a given identifier, unknown Action value, etc.),
the PCE MUST send a PCErr message with a PCEP-ERROR object with
Error-Type=27 and Error-value=3.
5.3. NO-PATH Indicator
To communicate the reason(s) for not being able to find RWA for the
path request, the NO-PATH object can be used in the corresponding
response. The format of the NO-PATH object body is defined in
[RFC5440]. The object may contain a NO-PATH-VECTOR TLV to provide
additional information about why a path computation has failed.
This document defines a new bit flag to be carried in the Flags field
in the NO-PATH-VECTOR TLV, which is carried in the NO-PATH object:
Bit 23: When set, the PCE indicates no feasible route was found that
meets all the constraints (e.g., wavelength restriction, signal
compatibility, etc.) associated with RWA.
6. Manageability Considerations
Manageability of WSON RWA with PCE must address the considerations in
the following subsections.
6.1. Control of Function and Policy
In addition to the parameters already listed in Section 8.1 of
[RFC5440], a PCEP implementation SHOULD allow configuration of the
following PCEP session parameters on a PCC:
* The ability to send a WSON RWA request.
In addition to the parameters already listed in Section 8.1 of
[RFC5440], a PCEP implementation SHOULD allow configuration of the
following PCEP session parameters on a PCE:
* The support for WSON RWA.
* A set of WSON-RWA-specific policies (authorized sender, request
rate limiter, etc).
These parameters may be configured as default parameters for any PCEP
session the PCEP speaker participates in, or they may apply to a
specific session with a given PCEP peer or a specific group of
sessions with a specific group of PCEP peers.
6.2. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements, aside from those already
listed in Section 8.3 of [RFC5440].
6.3. Verifying Correct Operation
Mechanisms defined in this document do not imply any new verification
requirements, aside from those already listed in Section 8.4 of
[RFC5440].
6.4. Requirements on Other Protocols and Functional Components
The PCEP Link-State mechanism [PCEP-LS] may be used to advertise WSON
RWA path computation capabilities to PCCs.
6.5. Impact on Network Operation
Mechanisms defined in this document do not imply any new network
operation requirements, aside from those already listed in
Section 8.6 of [RFC5440].
7. Security Considerations
The security considerations discussed in [RFC5440] are relevant for
this document; this document does not introduce any new security
issues. If an operator wishes to keep the information distributed by
WSON private, PCEPS (Usage of TLS to Provide a Secure Transport for
PCEP) [RFC8253] SHOULD be used.
8. IANA Considerations
IANA maintains a registry of PCEP parameters. IANA has made
allocations from the subregistries as described in the following
sections.
8.1. New PCEP Object: Wavelength Assignment Object
As described in Section 4.1, a new PCEP object is defined to carry
wavelength-assignment-related constraints. IANA has allocated the
following in the "PCEP Objects" subregistry [PCEP-NUMBERS]:
+====================+======+==========================+===========+
| Object-Class Value | Name | Object-Type | Reference |
+====================+======+==========================+===========+
| 42 | WA | 0: Reserved | RFC 8780 |
+--------------------+------+--------------------------+-----------+
| | | 1: Wavelength Assignment | RFC 8780 |
+--------------------+------+--------------------------+-----------+
Table 1
8.2. WA Object Flag Field
As described in Section 4.1, IANA has created the "WA Object Flag
Field" subregistry under the "Path Computation Element Protocol
(PCEP) Numbers" registry [PCEP-NUMBERS] to manage the Flags field of
the WA object. New values are to be assigned by Standards Action
[RFC8126]. Each bit should be tracked with the following qualities:
* Bit number (counting from bit 0 as the most significant bit)
* Capability description
* Defining RFC
The initial contents of this registry are shown below. One bit has
been allocated for the flag defined in this document:
+======+============================+===========+
| Bit | Description | Reference |
+======+============================+===========+
| 0-14 | Unassigned | |
+------+----------------------------+-----------+
| 15 | Wavelength Allocation Mode | RFC 8780 |
+------+----------------------------+-----------+
Table 2
8.3. New PCEP TLV: Wavelength Selection TLV
In Section 4.2, a new PCEP TLV is defined to indicate wavelength
selection constraints. IANA has made the following allocation in the
"PCEP TLV Type Indicators" subregistry [PCEP-NUMBERS]:
+=======+======================+===========+
| Value | Description | Reference |
+=======+======================+===========+
| 8 | Wavelength Selection | RFC 8780 |
+-------+----------------------+-----------+
Table 3
8.4. New PCEP TLV: Wavelength Restriction TLV
In Section 4.3, a new PCEP TLV is defined to indicate wavelength
restrictions. IANA has made the following allocation in the "PCEP
TLV Type Indicators" subregistry [PCEP-NUMBERS]:
+=======+========================+===========+
| Value | Description | Reference |
+=======+========================+===========+
| 9 | Wavelength Restriction | RFC 8780 |
+-------+------------------------+-----------+
Table 4
8.5. Wavelength Restriction TLV Action Values
As described in Section 4.3, IANA has created the new "Wavelength
Restriction TLV Action Values" subregistry under the "Path
Computation Element Protocol (PCEP) Numbers" registry [PCEP-NUMBERS]
to manage the Action values of the Action field of the Wavelength
Restriction TLV. New values are assigned by Standards Action
[RFC8126]. Each value should be tracked with the following
qualities:
* Value
* Meaning
* Defining RFC
The initial contents of this registry are shown below:
+=======+=================+===========+
| Value | Meaning | Reference |
+=======+=================+===========+
| 0 | Inclusive List | RFC 8780 |
+-------+-----------------+-----------+
| 1 | Inclusive Range | RFC 8780 |
+-------+-----------------+-----------+
| 2-255 | Unassigned | |
+-------+-----------------+-----------+
Table 5
8.6. New PCEP TLV: Wavelength Allocation TLV
In Section 5.1, a new PCEP TLV is defined to indicate the allocation
of the wavelength(s) by the PCE in response to a request by the PCC.
IANA has made the following allocation in "PCEP TLV Type Indicators"
subregistry [PCEP-NUMBERS]:
+=======+=======================+===========+
| Value | Description | Reference |
+=======+=======================+===========+
| 10 | Wavelength Allocation | RFC 8780 |
+-------+-----------------------+-----------+
Table 6
8.7. Wavelength Allocation TLV Flag Field
As described in Section 5.1, IANA has created a new "Wavelength
Allocation TLV Flag Field" subregistry under the "Path Computation
Element Protocol (PCEP) Numbers" registry [PCEP-NUMBERS] to manage
the Flags field of the Wavelength Allocation TLV. New values are to
be assigned by Standards Action [RFC8126]. Each bit should be
tracked with the following qualities:
* Bit number (counting from bit 0 as the most significant bit)
* Capability description
* Defining RFC
One bit is defined for the flag defined in this document. The
initial contents of this registry are shown below:
+======+============================+===========+
| Bit | Description | Reference |
+======+============================+===========+
| 0-14 | Unassigned | |
+------+----------------------------+-----------+
| 15 | Wavelength Allocation Mode | RFC 8780 |
+------+----------------------------+-----------+
Table 7
8.8. New PCEP TLV: Optical Interface Class List TLV
In Section 4.4, a new PCEP TLV is defined to indicate the Optical
Interface Class List. IANA has made the following allocation in the
"PCEP TLV Type Indicators" subregistry [PCEP-NUMBERS]:
+=======+==============================+===========+
| Value | Description | Reference |
+=======+==============================+===========+
| 11 | Optical Interface Class List | RFC 8780 |
+-------+------------------------------+-----------+
Table 8
8.9. New PCEP TLV: Client Signal Information TLV
In Section 4.4, a new PCEP TLV is defined to indicate the Client
Signal Information. IANA has made the following allocation in the
"PCEP TLV Type Indicators" subregistry [PCEP-NUMBERS]:
+=======+===========================+===========+
| Value | Description | Reference |
+=======+===========================+===========+
| 12 | Client Signal Information | RFC 8780 |
+-------+---------------------------+-----------+
Table 9
8.10. New Bit Flag for NO-PATH-VECTOR TLV
In Section 5.3, a new bit flag is defined to be carried in the Flags
field in the NO-PATH-VECTOR TLV, which is carried in the NO-PATH
object. This flag, when set, indicates that no feasible route was
found that meets all the RWA constraints (e.g., wavelength
restriction, signal compatibility, etc.) associated with an RWA path
computation request.
IANA has made the following allocation for this new bit flag in the
"NO-PATH-VECTOR TLV Flag Field" subregistry [PCEP-NUMBERS]:
+=====+========================+===========+
| Bit | Description | Reference |
+=====+========================+===========+
| 23 | No RWA constraints met | RFC 8780 |
+-----+------------------------+-----------+
Table 10
8.11. New Error-Types and Error-Values
In Section 5.2, new PCEP error codes are defined for WSON RWA errors.
IANA has made the following allocations in the "PCEP-ERROR Object
Error Types and Values" subregistry [PCEP-NUMBERS]:
+============+================+========================+===========+
| Error-Type | Meaning | Error-value | Reference |
+============+================+========================+===========+
| 27 | WSON RWA error | 0: Unassigned | RFC 8780 |
+------------+----------------+------------------------+-----------+
| | | 1: Insufficient memory | RFC 8780 |
+------------+----------------+------------------------+-----------+
| | | 2: RWA computation not | RFC 8780 |
| | | supported | |
+------------+----------------+------------------------+-----------+
| | | 3: Syntactical | RFC 8780 |
| | | encoding error | |
+------------+----------------+------------------------+-----------+
| | | 4-255: Unassigned | RFC 8780 |
+------------+----------------+------------------------+-----------+
Table 11
8.12. New Subobjects for the Exclude Route Object
The "Path Computation Element Protocol (PCEP) Numbers" registry
contains a subregistry titled "XRO Subobjects" [PCEP-NUMBERS]. Per
Section 4.4.1, IANA has added the following subobjects that can be
carried in the XRO:
+=======+==============================+===========+
| Value | Description | Reference |
+=======+==============================+===========+
| 8 | Optical Interface Class List | RFC 8780 |
+-------+------------------------------+-----------+
| 9 | Client Signal Information | RFC 8780 |
+-------+------------------------------+-----------+
Table 12
8.13. New Subobjects for the Include Route Object
The "Path Computation Element Protocol (PCEP) Numbers" registry
contains a subregistry titled "IRO Subobjects" [PCEP-NUMBERS]. Per
Section 4.4.2, IANA has added the following subobjects that can be
carried in the IRO:
+=======+==============================+===========+
| Value | Description | Reference |
+=======+==============================+===========+
| 8 | Optical Interface Class List | RFC 8780 |
+-------+------------------------------+-----------+
| 9 | Client Signal Information | RFC 8780 |
+-------+------------------------------+-----------+
Table 13
8.14. Request for Updated Note for LMP TE Link Object Class Type
The "TE_LINK Object Class type name space (Value 11)" registry was
created for the Link Management Protocol (LMP) [RFC4204]. As
discussed in Section 4.3.1, IANA has added the following note at the
top of the "TE_LINK Object Class type name space (Value 11)" registry
[LMP-PARAM]:
These values have additional usage for the Link Identifier Type
field.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
[RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed.,
"Traffic Engineering Extensions to OSPF Version 3",
RFC 5329, DOI 10.17487/RFC5329, September 2008,
<https://www.rfc-editor.org/info/rfc5329>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC6205] Otani, T., Ed. and D. Li, Ed., "Generalized Labels for
Lambda-Switch-Capable (LSC) Label Switching Routers",
RFC 6205, DOI 10.17487/RFC6205, March 2011,
<https://www.rfc-editor.org/info/rfc6205>.
[RFC7570] Margaria, C., Ed., Martinelli, G., Balls, S., and B.
Wright, "Label Switched Path (LSP) Attribute in the
Explicit Route Object (ERO)", RFC 7570,
DOI 10.17487/RFC7570, July 2015,
<https://www.rfc-editor.org/info/rfc7570>.
[RFC7579] Bernstein, G., Ed., Lee, Y., Ed., Li, D., Imajuku, W., and
J. Han, "General Network Element Constraint Encoding for
GMPLS-Controlled Networks", RFC 7579,
DOI 10.17487/RFC7579, June 2015,
<https://www.rfc-editor.org/info/rfc7579>.
[RFC7581] Bernstein, G., Ed., Lee, Y., Ed., Li, D., Imajuku, W., and
J. Han, "Routing and Wavelength Assignment Information
Encoding for Wavelength Switched Optical Networks",
RFC 7581, DOI 10.17487/RFC7581, June 2015,
<https://www.rfc-editor.org/info/rfc7581>.
[RFC7688] Lee, Y., Ed. and G. Bernstein, Ed., "GMPLS OSPF
Enhancement for Signal and Network Element Compatibility
for Wavelength Switched Optical Networks", RFC 7688,
DOI 10.17487/RFC7688, November 2015,
<https://www.rfc-editor.org/info/rfc7688>.
[RFC7689] Bernstein, G., Ed., Xu, S., Lee, Y., Ed., Martinelli, G.,
and H. Harai, "Signaling Extensions for Wavelength
Switched Optical Networks", RFC 7689,
DOI 10.17487/RFC7689, November 2015,
<https://www.rfc-editor.org/info/rfc7689>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8779] Margaria, C., Ed., Gonzalez de Dios, O., Ed., and F.
Zhang, Ed., "Path Computation Element Communication
Protocol (PCEP) Extensions for GMPLS", RFC 8779,
DOI 10.17487/RFC8779, July 2020,
<https://www.rfc-editor.org/info/rfc8779>.
9.2. Informative References
[LMP-PARAM]
IANA, "Link Management Protocol (LMP) Parameters",
<https://www.iana.org/assignments/lmp-parameters/>.
[PCEP-LS] Lee, Y., Zheng, H., Ceccarelli, D., Wang, W., Park, P.,
and B. Yoon, "PCEP Extension for Distribution of Link-
State and TE information for Optical Networks", Work in
Progress, Internet-Draft, draft-lee-pce-pcep-ls-optical-
09, 9 March 2020, <https://tools.ietf.org/html/draft-lee-
pce-pcep-ls-optical-09>.
[PCEP-NUMBERS]
IANA, "Path Computation Element Protocol (PCEP) Numbers",
<https://www.iana.org/assignments/pcep/>.
[RFC3471] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description",
RFC 3471, DOI 10.17487/RFC3471, January 2003,
<https://www.rfc-editor.org/info/rfc3471>.
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<https://www.rfc-editor.org/info/rfc4203>.
[RFC4204] Lang, J., Ed., "Link Management Protocol (LMP)", RFC 4204,
DOI 10.17487/RFC4204, October 2005,
<https://www.rfc-editor.org/info/rfc4204>.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5420] Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
Ayyangar, "Encoding of Attributes for MPLS LSP
Establishment Using Resource Reservation Protocol Traffic
Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420,
February 2009, <https://www.rfc-editor.org/info/rfc5420>.
[RFC5521] Oki, E., Takeda, T., and A. Farrel, "Extensions to the
Path Computation Element Communication Protocol (PCEP) for
Route Exclusions", RFC 5521, DOI 10.17487/RFC5521, April
2009, <https://www.rfc-editor.org/info/rfc5521>.
[RFC6163] Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
"Framework for GMPLS and Path Computation Element (PCE)
Control of Wavelength Switched Optical Networks (WSONs)",
RFC 6163, DOI 10.17487/RFC6163, April 2011,
<https://www.rfc-editor.org/info/rfc6163>.
[RFC6566] Lee, Y., Ed., Bernstein, G., Ed., Li, D., and G.
Martinelli, "A Framework for the Control of Wavelength
Switched Optical Networks (WSONs) with Impairments",
RFC 6566, DOI 10.17487/RFC6566, March 2012,
<https://www.rfc-editor.org/info/rfc6566>.
[RFC7446] Lee, Y., Ed., Bernstein, G., Ed., Li, D., and W. Imajuku,
"Routing and Wavelength Assignment Information Model for
Wavelength Switched Optical Networks", RFC 7446,
DOI 10.17487/RFC7446, February 2015,
<https://www.rfc-editor.org/info/rfc7446>.
[RFC7449] Lee, Y., Ed., Bernstein, G., Ed., Martensson, J., Takeda,
T., Tsuritani, T., and O. Gonzalez de Dios, "Path
Computation Element Communication Protocol (PCEP)
Requirements for Wavelength Switched Optical Network
(WSON) Routing and Wavelength Assignment", RFC 7449,
DOI 10.17487/RFC7449, February 2015,
<https://www.rfc-editor.org/info/rfc7449>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Acknowledgments
The authors would like to thank Adrian Farrel, Julien Meuric, Dhruv
Dhody, and Benjamin Kaduk for many helpful comments that greatly
improved the contents of this document.
Contributors
Fatai Zhang
Huawei Technologies
Email: zhangfatai@huawei.com
Cyril Margaria
Nokia Siemens Networks
St. Martin Strasse 76
81541 Munich
Germany
Phone: +49 89 5159 16934
Email: cyril.margaria@nsn.com
Oscar Gonzalez de Dios
Telefonica Investigacion y Desarrollo
C/ Emilio Vargas 6
28043 Madrid
Spain
Phone: +34 91 3374013
Email: ogondio@tid.es
Greg Bernstein
Grotto Networking
Fremont, CA
United States of America
Phone: +1 510 573 2237
Email: gregb@grotto-networking.com
Authors' Addresses
Young Lee (editor)
Samsung Electronics
Email: younglee.tx@gmail.com
Ramon Casellas, Editor (editor)
CTTC
Carl Friedrich Gauss 7
PMT Ed B4 Av.
08860 Castelldefels Barcelona
Spain
Phone: +34 936452916
Email: ramon.casellas@cttc.es