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+Internet Engineering Task Force (IETF) X. Zhang
+Request for Comments: 8363 H. Zheng
+Category: Standards Track Huawei
+ISSN: 2070-1721 R. Casellas
+ CTTC
+ O. Gonzalez de Dios
+ Telefonica
+ D. Ceccarelli
+ Ericsson
+ May 2018
+
+
+ GMPLS OSPF-TE Extensions in Support of Flexi-Grid
+ Dense Wavelength Division Multiplexing (DWDM) Networks
+
+Abstract
+
+ The International Telecommunication Union Telecommunication
+ standardization sector (ITU-T) has extended its Recommendations
+ G.694.1 and G.872 to include a new Dense Wavelength Division
+ Multiplexing (DWDM) grid by defining channel spacings, a set of
+ nominal central frequencies, and the concept of the "frequency slot".
+ Corresponding techniques for data-plane connections are known as
+ "flexi-grid".
+
+ Based on the characteristics of flexi-grid defined in G.694.1 and in
+ RFCs 7698 and 7699, this document describes the Open Shortest Path
+ First - Traffic Engineering (OSPF-TE) extensions in support of GMPLS
+ control of networks that include devices that use the new flexible
+ optical grid.
+
+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/rfc8363.
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 1]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+Copyright Notice
+
+ Copyright (c) 2018 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2.1. Conventions Used in This Document . . . . . . . . . . . . 4
+ 3. Requirements for Flexi-Grid Routing . . . . . . . . . . . . . 4
+ 3.1. Available Frequency Ranges . . . . . . . . . . . . . . . 4
+ 3.2. Application Compliance Considerations . . . . . . . . . . 5
+ 3.3. Comparison with Fixed-Grid DWDM Links . . . . . . . . . . 6
+ 4. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 7
+ 4.1. Interface Switching Capability Descriptor (ISCD)
+ Extensions for Flexi-Grid . . . . . . . . . . . . . . . . 7
+ 4.1.1. Switching Capability Specific Information (SCSI) . . 8
+ 4.1.2. An SCSI Example . . . . . . . . . . . . . . . . . . . 10
+ 4.2. Extensions to the Port Label Restrictions Field . . . . . 11
+ 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
+ 5.1. New ISCD Switching Type . . . . . . . . . . . . . . . . . 13
+ 5.2. New SCSI Type . . . . . . . . . . . . . . . . . . . . . . 13
+ 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
+ 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
+ 7.1. Normative References . . . . . . . . . . . . . . . . . . 14
+ 7.2. Informative References . . . . . . . . . . . . . . . . . 15
+ Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 16
+ Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 16
+ Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
+
+
+
+
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 2]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+1. Introduction
+
+ [G.694.1] defines the Dense Wavelength Division Multiplexing (DWDM)
+ frequency grids for Wavelength Division Multiplexing (WDM)
+ applications. A frequency grid is a reference set of frequencies
+ used to denote allowed nominal central frequencies that may be used
+ for defining applications. The channel spacing is the frequency
+ spacing between two allowed nominal central frequencies. All of the
+ wavelengths on a fiber should use different central frequencies and
+ occupy a fixed bandwidth of frequency.
+
+ Fixed-grid channel spacing ranges from one of 12.5 GHz, 25 GHz, 50
+ GHz, or 100 GHz to integer multiples of 100 GHz. But [G.694.1] also
+ defines a "flexible grid", also known as "flexi-grid". The terms
+ "frequency slot" (i.e., the frequency range allocated to a specific
+ channel and unavailable to other channels within a flexible grid) and
+ "slot width" (i.e., the full width of a frequency slot in a flexible
+ grid) are used to define a flexible grid.
+
+ [RFC7698] defines a framework and the associated control-plane
+ requirements for the GMPLS-based control of flexi-grid DWDM networks.
+
+ [RFC6163] provides a framework for GMPLS and Path Computation Element
+ (PCE) control of Wavelength Switched Optical Networks (WSONs).
+ [RFC7688] defines the requirements and OSPF-TE extensions in support
+ of GMPLS control of a WSON.
+
+ [RFC7792] describes requirements and protocol extensions for
+ signaling to set up Label Switched Paths (LSPs) in networks that
+ support the flexi-grid. This document complements [RFC7792] by
+ describing the requirement and extensions for OSPF-TE routing in a
+ flexi-grid network.
+
+ This document complements the efforts to provide extensions to the
+ OSPF-TE protocol so as to support GMPLS control of flexi-grid
+ networks.
+
+2. Terminology
+
+ For terminology related to flexi-grid, please consult [RFC7698] and
+ [G.694.1].
+
+
+
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 3]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+2.1. Conventions Used in This Document
+
+ 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.
+
+3. Requirements for Flexi-Grid Routing
+
+ The architecture for establishing LSPs in a Spectrum Switched Optical
+ Network (SSON) is described in [RFC7698].
+
+ A flexi-grid LSP occupies one or multiple specific frequency slots.
+ The process of computing a route and the allocation of a frequency
+ slot is referred to as "RSA" (Routing and Spectrum Assignment).
+ [RFC7698] describes three types of architectural approaches to RSA:
+ combined RSA, separated RSA, and routing and distributed SA. The
+ first two approaches could be called "centralized SA" because the
+ spectrum (frequency slot) assignment is performed by a single entity
+ before the signaling procedure.
+
+ In the case of centralized SA, the assigned frequency slot is
+ specified in the RSVP-TE Path message during the signaling process.
+ In the case of routing and distributed SA, only the requested slot
+ width of the flexi-grid LSP is specified in the Path message,
+ allowing the involved network elements to select the frequency slot
+ to be used.
+
+ If the capability of switching or converting the whole optical
+ spectrum allocated to an optical spectrum LSP is not available at
+ nodes along the path of the LSP, the LSP is subject to the Optical
+ "Spectrum Continuity Constraint", as described in [RFC7698].
+
+ The remainder of this section states the additional extensions on the
+ routing protocols in a flexi-grid network.
+
+3.1. Available Frequency Ranges
+
+ In the case of flexi-grids, the central frequency steps from 193.1
+ THz with 6.25 GHz granularity. The calculation method of central
+ frequency and the frequency slot width of a frequency slot are
+ defined in [G.694.1], i.e., by using nominal central frequency n and
+ the slot width m.
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 4]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ On a DWDM link, the allocated or in-use frequency slots do not
+ overlap with each other. However, the border frequencies of two
+ frequency slots may be the same frequency, i.e., the upper bound of a
+ frequency slot and the lower bound of the directly adjacent frequency
+ slot are the same.
+
+ Frequency Slot 1 Frequency Slot 2
+ +-----------+-----------------------+
+ | | |
+ -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
+ ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--...
+ ------------ ------------------------
+ ^ ^
+ Central F = 193.1 THz Central F = 193.1375 THz
+ Slot width = 25 GHz Slot width = 50 GHz
+
+ Figure 1: Two Frequency Slots on a Link
+
+ Figure 1 shows two adjacent frequency slots on a link. The highest
+ frequency of frequency slot 1 denoted by n=2 is the lowest frequency
+ of slot 2. In this example, it means that the frequency range from
+ n=-2 to n=10 is unavailable to other flexi-grid LSPs. Available
+ central frequencies are advertised for m=1, which means that for an
+ available central frequency n, the frequency slot from central
+ frequency n-1 to central frequency n+1 is available.
+
+ Hence, in order to clearly show which frequency slots are available
+ and can be used for LSP establishment and which frequency slots are
+ unavailable, the availability of frequency slots is advertised by the
+ routing protocol for the flexi-grid DWDM links. A set of non-
+ overlapping available frequency ranges is disseminated in order to
+ allow efficient resource management of flexi-grid DWDM links and RSA
+ procedures, which are described in Section 4.8 of [RFC7698].
+
+3.2. Application Compliance Considerations
+
+ As described in [G.694.1], devices or applications that make use of
+ the flexi-grid may not be capable of supporting every possible slot
+ width or position (i.e., central frequency). In other words,
+ applications or implementations may be defined where only a subset of
+ the possible slot widths and positions are required to be supported.
+
+ For example, an application could be defined where the nominal
+ central frequency granularity is 12.5 GHz (by only requiring values
+ of n that are even) and the same application only requires slot
+ widths as a multiple of 25 GHz (by only requiring values of m that
+ are even).
+
+
+
+
+Zhang, et al. Standards Track [Page 5]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ Hence, in order to support all possible applications and
+ implementations, the following information SHOULD be advertised for a
+ flexi-grid DWDM link:
+
+ o Channel Spacing (C.S.): as defined in [RFC7699] for flexi-grid, is
+ set to 5 to denote 6.25 GHz.
+
+ o Central frequency granularity: a multiplier of C.S.
+
+ o Slot width granularity: a multiplier of 2*C.S.
+
+ o Slot width range: two multipliers of the slot width granularity,
+ each indicating the minimal and maximal slot width supported by a
+ port, respectively.
+
+ The combination of slot width range and slot width granularity can be
+ used to determine the slot widths set supported by a port.
+
+3.3. Comparison with Fixed-Grid DWDM Links
+
+ In the case of fixed-grid DWDM links, each wavelength has a
+ predefined central frequency. Each wavelength maps to a predefined
+ central frequency, and the usable frequency range is implicit by the
+ channel spacing. All the wavelengths on a DWDM link can be
+ identified with an identifier that mainly conveys its central
+ frequency as the label defined in [RFC6205]; the status of the
+ wavelengths (available or not) can be advertised through a routing
+ protocol.
+
+ Figure 2 shows a link that supports a fixed-grid with 50 GHz channel
+ spacing. The central frequencies of the wavelengths are predefined
+ by values of "n", and each wavelength occupies a fixed 50 GHz
+ frequency range as described in [G.694.1].
+
+ W(-2) | W(-1) | W(0) | W(1) | W(2) |
+ ...---------+-----------+-----------+-----------+-----------+----...
+ | 50 GHz | 50 GHz | 50 GHz | 50 GHz |
+
+ n=-2 n=-1 n=0 n=1 n=2
+ ...---+-----------+-----------+-----------+-----------+----------...
+ ^
+ Central F = 193.1 THz
+
+ Figure 2: A Link Supports Fixed Wavelengths
+ with 50 GHz Channel Spacing
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 6]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ Unlike the fixed-grid DWDM links, on a flexi-grid DWDM link, the slot
+ width of the frequency slot is flexible, as described in Section 3.1.
+ That is, the value of m in the following formula from [G.694.1] is
+ uncertain before a frequency slot is actually allocated for a flexi-
+ grid LSP.
+
+ Slot Width (in GHz) = 12.5GHz * m
+
+ For this reason, the available frequency slots (or ranges) are
+ advertised for a flexi-grid DWDM link instead of the specific
+ "wavelength" points that are sufficient for a fixed-grid link.
+ Moreover, this advertisement is represented by the combination of
+ central frequency granularity and slot width granularity.
+
+4. Extensions
+
+ The network-connectivity topology constructed by the links and/or
+ nodes and node capabilities are the same as for WSON, as described in
+ [RFC7698], and they can be advertised by the GMPLS routing protocols
+ using Opaque Link State Advertisements (LSAs) [RFC3630] in the case
+ of OSPF-TE [RFC4203] (refer to Section 6.2 of [RFC6163]). In the
+ flexi-grid case, the available frequency ranges, instead of the
+ specific "wavelengths", are advertised for the link. This section
+ defines the GMPLS OSPF-TE extensions in support of advertising the
+ available frequency ranges for flexi-grid DWDM links.
+
+4.1. Interface Switching Capability Descriptor (ISCD) Extensions for
+ Flexi-Grid
+
+ This section defines a new value for the Switching Capability field
+ of the ISCD with a value of 152 and type name Flexi-Grid-LSC.
+
+ Value Name
+ ----- --------------
+ 152 Flexi-Grid-LSC
+
+ Switching Capability and Encoding values MUST be used as follows:
+
+ Switching Capability = Flexi-Grid-LSC
+
+ Encoding Type = lambda (as defined in [RFC3471])
+
+ When the Switching Capability and Encoding fields are set to values
+ as stated above, the ISCD is interpreted as in [RFC4203] with the
+ optional inclusion of one or more Switching Capability Specific
+ Information (SCSI) sub-TLVs.
+
+
+
+
+
+Zhang, et al. Standards Track [Page 7]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ As the "Max LSP Bandwidth at priority x" (x from 0 to 7) fields in
+ the generic part of the ISCD [RFC4203] are not meaningful for flexi-
+ grid DWDM links, the values of these fields MUST be set to zero and
+ MUST be ignored. The SCSI as defined below provides the
+ corresponding information for flexi-grid DWDM links.
+
+4.1.1. Switching Capability Specific Information (SCSI)
+
+ [RFC8258] defines a Generalized SCSI for the ISCD. This document
+ defines the Frequency Availability Bitmap as a new type of the
+ Generalized SCSI TLV. The technology-specific part of the flexi-grid
+ ISCD includes the available frequency-spectrum resource as well as
+ the information regarding max slot widths per priority. The format
+ of this flexi-grid SCSI, the Frequency Availability Bitmap sub-TLV,
+ is depicted in the following figure:
+
+ 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 = 11 | Length |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Priority | Reserved |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ ~ Max Slot Width at Priority k | Unreserved Padding ~
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | C.S. | Starting n | No. of Effective Bits |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Bitmap ... ~
+ ~ ... | padding bits ~
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Type (16 bits): The type of this sub-TLV (11).
+
+ Length (16 bits): The length of the value field of this sub-TLV in
+ octets.
+
+ Priority (8 bits): A bitmap used to indicate which priorities are
+ being advertised. The bitmap is in ascending order, with the
+ leftmost bit representing priority level 0 (i.e., the highest) and
+ the rightmost bit representing priority level 7 (i.e., the lowest).
+ A bit is set (1) corresponding to each priority represented in the
+ sub-TLV and clear (0) for each priority not represented in the sub-
+ TLV. At least one priority level MUST be advertised. If only one
+ priority level is advertised, it MUST be at priority level 0.
+
+ Reserved: The Reserved field MUST be set to zero on transmission and
+ MUST be ignored on receipt.
+
+
+
+
+Zhang, et al. Standards Track [Page 8]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ Max Slot Width at Priority k (16 bits): This field indicates maximal
+ frequency slot width supported at a particular priority level, up to
+ 8. This field is set to max frequency slot width supported in the
+ unit of 2*C.S., for a particular priority level. One field MUST be
+ present for each bit set in the Priority field, and each present
+ field is ordered to match the Priority field. Fields MUST be present
+ for priority levels that are indicated in the Priority field.
+
+ Unreserved Padding (16 bits): The Padding field is used to ensure the
+ 32-bit alignment of Max Slot Width at Priority k. When k is an odd
+ number, the Unreserved Padding field MUST be included. When k is an
+ even number, the Unreserved Padding field MUST be omitted. This
+ field MUST be set to 0 and MUST be ignored on receipt.
+
+ C.S. (4 bits): As defined in [RFC7699]; it is currently set to 5.
+
+ Starting n (16 bits): As defined in [RFC7699]. This value denotes
+ the starting point of the nominal central frequency of the frequency
+ availability bitmap sub-TLV.
+
+ No. of Effective Bits (12 bits): Indicates the number of effective
+ bits in the Bitmap field.
+
+ Bitmap (variable): Indicates whether or not a basic frequency slot,
+ characterized by a nominal central frequency and a fixed m value of
+ 1, is available for flexi-grid LSP setup. The first nominal central
+ frequency is the value of starting n; subsequent nominal central
+ frequencies are implied by the position in the bitmap. Note that
+ setting to 1 indicates that the corresponding central frequency is
+ available for a flexi-grid LSP with m=1 and setting to 0 indicates
+ the corresponding central frequency is unavailable. Note that a
+ centralized SA process will need to extend this to high values of m
+ by checking a sufficiently large number of consecutive basic
+ frequency slots that are available.
+
+ padding bits (variable): Padded after the Bitmap to make it a
+ multiple of four bytes, if necessary. Padding bits MUST be set to 0
+ and MUST be ignored on receipt.
+
+ An example is provided in Section 4.1.2.
+
+
+
+
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 9]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+4.1.2. An SCSI Example
+
+ Figure 3 shows an example of the available frequency spectrum
+ resource of a flexi-grid DWDM link.
+
+ -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
+ ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--...
+ |--Available Frequency Range--|
+
+ Figure 3: Flexi-Grid DWDM Link Example
+
+ The symbol "+" represents the allowed nominal central frequency. The
+ symbol "--" represents a central frequency granularity of 6.25 GHz,
+ which is currently standardized in [G.694.1]. The number on the top
+ of the line represents the "n" in the frequency calculation formula
+ (193.1 + n * 0.00625). The nominal central frequency is 193.1 THz
+ when n equals zero.
+
+ In this example, it is assumed that the lowest nominal central
+ frequency supported is n=-9 and the highest is n=11. Note they
+ cannot be used as a nominal central frequency for setting up an LSP,
+ but merely as the way to express the supported frequency range.
+ Using the encoding defined in Section 4.1.1, the relevant fields to
+ express the frequency resource availability can be filled as below:
+
+ 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 = 11 | Length |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Priority | Reserved |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ ~ Max Slot Width at Priority k | Unreserved Padding ~
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 5 | Starting n (-9) | No. of Effec. Bits(21)|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |0|0|0|0|0|0|0|0|1|1|1|1|1|1|1|1|1|0|0|0|0| padding bits (0s) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ In the above example, the starting n is selected to be the lowest
+ nominal central frequency, i.e., -9. It is observed from the bitmap
+ that n=-1 to 7 can be used to set up LSPs. Note other starting n
+ values can be chosen to represent the bitmap; for example, the first
+ available nominal central frequency (a.k.a., the first available
+ basic frequency slot) can be chosen, and the SCSI will be expressed
+ as the following:
+
+
+
+
+
+Zhang, et al. Standards Track [Page 10]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ 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 = 11 | Length |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Priority | Reserved |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ ~ Max Slot Width at Priority k | Unreserved Padding ~
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 5 | Starting n (-1) | No. of Effec. Bits(9)|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |1|1|1|1|1|1|1|1|1| padding bits (0s) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ This encoding denotes that, other than the advertised available
+ nominal central frequencies, the other nominal central frequencies
+ within the whole frequency range supported by the link are not
+ available for flexi-grid LSP setup.
+
+ If an LSP with slot width m equal to 1 is set up using this link, say
+ using n=-1, then the SCSI information is updated to be the following:
+
+ 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 = 11 | Length |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Priority | Reserved |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ ~ Max Slot Width at Priority k | Unreserved Padding ~
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 5 | Starting n (-1) | No. of Effec. Bits(9)|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |0|0|1|1|1|1|1|1|1| padding bits (0s) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+4.2. Extensions to the Port Label Restrictions Field
+
+ As described in Section 3.2, a port that supports flexi-grid may
+ support only a restricted subset of the full flexible grid. The Port
+ Label Restrictions field is defined in [RFC7579]. It can be used to
+ describe the label restrictions on a port and is carried in the top-
+ level Link TLV as specified in [RFC7580]. A new restriction type,
+ the flexi-grid Restriction Type, is defined here to specify the
+ restrictions on a port to support flexi-grid.
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 11]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ 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
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | MatrixID | RstType = 5 | Switching Cap | Encoding |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | C.S. | C.F.G | S.W.G | Reserved |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Min Slot Width | Reserved |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+ MatrixID (8 bits): As defined in [RFC7579].
+
+ RstType (Restriction Type, 8 bits): Takes the value of 5 to indicate
+ the restrictions on a port to support flexi-grid.
+
+ Switching Cap (Switching Capability, 8 bits): As defined in
+ [RFC7579], MUST be consistent with the one specified in ISCD as
+ described in Section 4.1.
+
+ Encoding (8 bits): As defined in [RFC7579], MUST be consistent with
+ the one specified in ISCD as described in Section 4.1.
+
+ C.S. (4 bits): As defined in [RFC7699]. For flexi-grid, it is 5 to
+ denote 6.25 GHz.
+
+ C.F.G (Central Frequency Granularity, 8 bits): A positive integer.
+ Its value indicates the multiple of C.S., in terms of central
+ frequency granularity.
+
+ S.W.G (Slot Width Granularity, 8 bits): A positive integer. Its
+ value indicates the multiple of 2*C.S., in terms of slot width
+ granularity.
+
+ Min Slot Width (16 bits): A positive integer. Its value indicates
+ the multiple of 2*C.S. (in GHz), in terms of the supported minimal
+ slot width.
+
+ Reserved: The Reserved field MUST be set to zero on transmission and
+ SHOULD be ignored on receipt.
+
+
+
+
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 12]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+5. IANA Considerations
+
+5.1. New ISCD Switching Type
+
+ IANA has made the following assignment in the "Switching Types" sub-
+ registry of the "Generalized Multi-Protocol Label Switching (GMPLS)
+ Signaling Parameters" registry located at
+ <https://www.iana.org/assignments/gmpls-sig-parameters>:
+
+ Value Name Reference
+ ------- ---------------- ----------
+ 152 Flexi-Grid-LSC RFC 8363
+
+5.2. New SCSI Type
+
+ This document defines a new generalized SCSI sub-TLV that is carried
+ in the Interface Switching Capability Descriptors [RFC4203] when the
+ Switching Type is set to Flexi-Grid-LSC.
+
+ IANA has made the following assignment in the "Generalized SCSI
+ (Switching Capability Specific Information) TLV Types" sub-registry
+ [RFC8258] of the "Generalized Multi-Protocol Label Switching (GMPLS)
+ Signaling Parameters" registry located at
+ <https://www.iana.org/assignments/gmpls-sig-parameters>:
+
+ Value SCSI-TLV Switching Type Reference
+ ----- ----------------------------- -------------- ---------
+ 11 Frequency Availability Bitmap 152 RFC 8363
+
+6. Security Considerations
+
+ This document extends [RFC4203] and [RFC7580] to carry flexi-grid-
+ specific information in OSPF Opaque LSAs. This document does not
+ introduce any further security issues other than those discussed in
+ [RFC3630] and [RFC4203]. To be more specific, the security
+ mechanisms described in [RFC2328], which apply to Opaque LSAs carried
+ in OSPF, still apply. An analysis of the OSPF security is provided
+ in [RFC6863] and applies to the extensions to OSPF in this document
+ as well.
+
+
+
+
+
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 13]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+7. References
+
+7.1. Normative References
+
+ [G.694.1] International Telecommunication Union, "Spectral grids for
+ WDM applications: DWDM frequency grid", ITU-T
+ Recommendation G.694.1, February 2012,
+ <https://www.itu.int/rec/T-REC-G.694.1/en>.
+
+ [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>.
+
+ [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>.
+
+ [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>.
+
+ [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>.
+
+ [RFC7580] Zhang, F., Lee, Y., Han, J., Bernstein, G., and Y. Xu,
+ "OSPF-TE Extensions for General Network Element
+ Constraints", RFC 7580, DOI 10.17487/RFC7580, June 2015,
+ <https://www.rfc-editor.org/info/rfc7580>.
+
+ [RFC7699] Farrel, A., King, D., Li, Y., and F. Zhang, "Generalized
+ Labels for the Flexi-Grid in Lambda Switch Capable (LSC)
+ Label Switching Routers", RFC 7699, DOI 10.17487/RFC7699,
+ November 2015, <https://www.rfc-editor.org/info/rfc7699>.
+
+ [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>.
+
+
+
+Zhang, et al. Standards Track [Page 14]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+ [RFC8258] Ceccarelli, D. and L. Berger, "Generalized SCSI: A Generic
+ Structure for Interface Switching Capability Descriptor
+ (ISCD) Switching Capability Specific Information (SCSI)",
+ RFC 8258, DOI 10.17487/RFC8258, October 2017,
+ <https://www.rfc-editor.org/info/rfc8258>.
+
+7.2. Informative References
+
+ [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
+ DOI 10.17487/RFC2328, April 1998,
+ <https://www.rfc-editor.org/info/rfc2328>.
+
+ [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>.
+
+ [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>.
+
+ [RFC6863] Hartman, S. and D. Zhang, "Analysis of OSPF Security
+ According to the Keying and Authentication for Routing
+ Protocols (KARP) Design Guide", RFC 6863,
+ DOI 10.17487/RFC6863, March 2013,
+ <https://www.rfc-editor.org/info/rfc6863>.
+
+ [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>.
+
+ [RFC7698] Gonzalez de Dios, O., Ed., Casellas, R., Ed., Zhang, F.,
+ Fu, X., Ceccarelli, D., and I. Hussain, "Framework and
+ Requirements for GMPLS-Based Control of Flexi-Grid Dense
+ Wavelength Division Multiplexing (DWDM) Networks",
+ RFC 7698, DOI 10.17487/RFC7698, November 2015,
+ <https://www.rfc-editor.org/info/rfc7698>.
+
+ [RFC7792] Zhang, F., Zhang, X., Farrel, A., Gonzalez de Dios, O.,
+ and D. Ceccarelli, "RSVP-TE Signaling Extensions in
+ Support of Flexi-Grid Dense Wavelength Division
+ Multiplexing (DWDM) Networks", RFC 7792,
+ DOI 10.17487/RFC7792, March 2016,
+ <https://www.rfc-editor.org/info/rfc7792>.
+
+
+
+Zhang, et al. Standards Track [Page 15]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+Acknowledgments
+
+ This work was supported in part by the FP-7 IDEALIST project under
+ grant agreement number 317999.
+
+ This work was supported in part by NSFC Project 61201260.
+
+Contributors
+
+ Adrian Farrel
+ Juniper Networks
+
+ Email: afarrel@juniper.net
+
+
+ Fatai Zhang
+ Huawei Technologies
+
+ Email: zhangfatai@huawei.com
+
+
+ Lei Wang
+ Beijing University of Posts and Telecommunications
+
+ Email: wang.lei@bupt.edu.cn
+
+
+ Guoying Zhang
+ China Academy of Information and Communication Technology
+
+ Email: zhangguoying@ritt.cn
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 16]
+
+RFC 8363 GMPLS OSPF-TE for Flexi-Grid DWDM May 2018
+
+
+Authors' Addresses
+
+ Xian Zhang
+ Huawei Technologies
+
+ Email: zhang.xian@huawei.com
+
+
+ Haomian Zheng
+ Huawei Technologies
+
+ Email: zhenghaomian@huawei.com
+
+
+ Ramon Casellas, Ph.D.
+ CTTC
+ Spain
+
+ Phone: +34 936452916
+ Email: ramon.casellas@cttc.es
+
+
+ Oscar Gonzalez de Dios
+ Telefonica Investigacion y Desarrollo
+ Emilio Vargas 6
+ Madrid, 28045
+ Spain
+
+ Phone: +34 913374013
+ Email: oscar.gonzalezdedios@telefonica.com
+
+
+ Daniele Ceccarelli
+ Ericsson
+ Via A. Negrone 1/A
+ Genova - Sestri Ponente
+ Italy
+
+ Email: daniele.ceccarelli@ericsson.com
+
+
+
+
+
+
+
+
+
+
+
+
+Zhang, et al. Standards Track [Page 17]
+