Internet Engineering Task Force (IETF) G. Bernstein, Ed. Request for Comments: 7581 Grotto Networking Category: Standards Track Y. Lee, Ed. ISSN: 2070-1721 D. Li Huawei W. Imajuku NTT J. Han Huawei June 2015
Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks
Abstract
A Wavelength Switched Optical Network (WSON) requires certain key information fields be made available to facilitate path computation and the establishment of Label Switched Paths (LSPs). The information model described in "Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks" (RFC 7446) shows what information is required at specific points in the WSON. Part of the WSON information model contains aspects that may be of general applicability to other technologies, while other parts are specific to WSONs.
This document provides efficient, protocol-agnostic encodings for the WSON-specific information fields. It is intended that protocol- specific documents will reference this memo to describe how information is carried for specific uses. Such encodings can be used to extend GMPLS signaling and routing protocols. In addition, these encodings could be used by other mechanisms to convey this same information to a Path Computation Element (PCE).
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 5741.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7581.
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Copyright Notice
Copyright (c) 2015 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 (http://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.
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Table of Contents
1. Introduction ....................................................4 1.1. Terminology ................................................4 1.2. Conventions Used in This Document ..........................5 2. Resources, Resource Blocks, and the Resource Pool ...............5 2.1. Resource Block Set Field ...................................6 3. Resource Accessibility/Availability .............................7 3.1. Resource Accessibility Field ...............................7 3.2. Resource Wavelength Constraints Field ......................9 3.3. Resource Block Pool State Field ...........................10 3.4. Resource Block Shared Access Wavelength Availability Field ........................................12 4. Resource Block Information Field ...............................13 4.1. Optical Interface Class List Subfield .....................15 4.1.1. ITU-T G.698.1 Application Code Mapping .............17 4.1.2. ITU-T G.698.2 Application Code Mapping .............18 4.1.3. ITU-T G.959.1 Application Code Mapping .............20 4.1.4. ITU-T G.695 Application Code Mapping ...............22 4.2. Acceptable Client Signal List Subfield ....................23 4.3. Input Bit Rate List Subfield ..............................24 4.4. Processing Capability List Subfield .......................24 5. Security Considerations ........................................26 6. IANA Considerations ............................................26 6.1. Types for Subfields of WSON Resource Block Information ....26 7. References .....................................................27 7.1. Normative References ......................................27 7.2. Informative References ....................................28 Appendix A. Encoding Examples .....................................30 A.1. Wavelength Converter Accessibility Field ..................30 A.2. Wavelength Conversion Range Field .........................32 A.3. An OEO Switch with DWDM Optics ............................32 Contributors ......................................................35 Authors' Addresses ................................................37
A Wavelength Switched Optical Network (WSON) is a Wavelength Division Multiplexing (WDM) optical network in which switching is performed selectively based on the center wavelength of an optical signal.
[RFC6163] describes a framework for Generalized Multiprotocol Label Switching (GMPLS) and Path Computation Element (PCE) control of a WSON. Based on this framework, [RFC7446] describes an information model that specifies what information is needed at various points in a WSON in order to compute paths and establish Label Switched Paths (LSPs).
This document provides efficient encodings of information needed by the Routing and Wavelength Assignment (RWA) process in a WSON. Such encodings can be used to extend GMPLS signaling and routing protocols. In addition, these encodings could be used by other mechanisms to convey this same information to a PCE. Note that since these encodings are efficient, they can provide more accurate analysis of the control-plane communications/processing load for WSONs looking to utilize a GMPLS control plane.
In parallel to this document, [RFC7579] provides efficient encodings of information needed by the routing and label assignment process that are potentially applicable to a wider range of technologies.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
2. Resources, Resource Blocks, and the Resource Pool
This section provides encodings for the information fields defined in [RFC7446] that have applicability to WSON. The encodings are designed to be suitable for use in the GMPLS routing protocols OSPF [RFC4203] and IS-IS [RFC5307] and in the PCE Communication Protocol (PCEP) [RFC5440]. Note that the information distributed in [RFC4203] and [RFC5307] is arranged via the nesting of sub-TLVs within TLVs; this document defines elements to be used within such constructs. Specific constructs of sub-TLVs and the nesting of sub-TLVs of the information fields defined by this document will be defined in the respective protocol enhancement documents.
This document defines the following information fields pertaining to resources within an optical node:
o Resource Accessibility <ResourceAccessibility>
o Resource Wavelength Constraints <ResourceWaveConstraints>
o Resource Block Pool State <RBPoolState>
o Resource Block Shared Access Wavelength Availability <RBSharedAccessWaveAvailability>
o Resource Block Information <ResourceBlockInfo>
Each of these information fields works with one or more sets of resources rather than just a single resource block. This motivates the field definition in Section 2.1.
In a WSON node that includes resource blocks (RBs), denoting subsets of these blocks allows one to efficiently describe common properties of the blocks and to describe the structure and characteristics, if nontrivial, of the resource pool. The Resource Block Set (RB Set) Field is defined in a similar manner to the label set concept of [RFC3471].
The information carried in an RB Set Field is defined as follows:
Indicates that the TLV contains one or more ranges of RBs. Each individual range is denoted by two 32-bit RB identifiers. The first 32 bits is the RB identifier for the start of the range, and the next 32 bits is the RB identifier for the end of the range. Note that the Length field is used to determine the number of ranges.
Set to 0 to denote fixed (possibly multicast) connectivity, and set to 1 to denote potential (switched) connectivity. Used in Resource Accessibility field. Ignored elsewhere.
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Reserved: 7 bits
This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt.
Length: 16 bits
The total length of this field in bytes.
RB Identifier:
The RB identifier represents the ID of the resource block, which is a 32-bit integer. The scope of the RB identifier is local to the node on which it is applied.
Usage Note: The inclusive range "Action" can result in very compact encoding of resource sets, and it can be advantageous to number resource blocks in such a way so that status updates (dynamic information) can take advantage of this efficiency.
This section defines the information fields for dealing with accessibility and availability of resource blocks within a pool of resources. These include the <ResourceAccessibility>, <ResourceWaveConstraints>, <RBPoolState>, and <RBSharedAccessWaveAvailability> fields.
This information field describes the structure of the resource pool in relation to the switching device. In particular, it indicates the ability of an input port to reach sets of resources and the ability of sets of resources to reach a particular output port. This is the <PoolInputMatrix> and <PoolOutputMatrix> of [RFC7446].
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The Resource Accessibility field 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(8bits)|C| Reserved (23 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Input Link Set Field A #1 | : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RB Set Field A #1 | : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Additional Link set and RB set pairs as needed to | : specify PoolInputMatrix : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Output Link Set Field B #1 | : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RB Set B Field #1 (for output connectivity) | : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Additional Link Set and RB set pairs as needed to | : specify PoolOutputMatrix : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
C (Connectivity bit): Connectivity indicates how the input/output ports connect to the resource blocks.
0 - the device is fixed (e.g., a connected port must go through the resource block)
1 - the device is switched (e.g., a port can be configured to go through a resource but isn't required)
For the Input and Output Link Set Fields, the Link Set Field encoding defined in [RFC7579] is to be used.
Note that the direction parameter within the Link Set Field is used to indicate whether the link set is an input or output link set, and the bidirectional value for this parameter is not permitted in this field.
See Appendix A.1 for an illustration of this encoding.
Resources, such as wavelength converters, etc., may have limited input or output wavelength ranges. Additionally, due to the structure of the optical system, not all wavelengths can necessarily reach or leave all the resources. These properties are described by using one or more Resource Wavelength Constraints fields as defined below:
The state of the pool is given by the number of resources available with particular characteristics. A resource block set is used to encode all or a subset of the resources of interest. The usage state of resources within a resource block set is encoded as either a list of 16-bit integer values or a bitmap indicating whether a single resource is available or in use. The bitmap encoding is appropriate when resource blocks consist of a single resource. This information can be relatively dynamic, i.e., can change when a connection (LSP) is established or torn down.
Action = 0 denotes a list of 16-bit integers, and Action = 1 denotes a bitmap. Action = 0 covers the case where there are multiple elements for each resource block. Action = 1 covers the case where each resource block only contains a single element.
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In both cases, the elements of the RB Set Field are in a one-to-one correspondence with the values in the RB Usage State area.
RB Usage State Bitmap: Variable length but must be a multiple of 4 bytes.
Each bit indicates the usage status of one RB with 0 indicating the RB is available and 1 indicating the RB is in use. The sequence of the bitmap is ordered according to the RB Set Field with this element.
Padding bits: Variable length
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3.4. Resource Block Shared Access Wavelength Availability Field
Resource blocks may be accessed via a shared fiber. If this is the case, then wavelength availability on these shared fibers is needed to understand resource availability.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |I|O|B| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RB Set Field | : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Input Available Wavelength Set Field | : (Optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Output Available Wavelength Set Field | : (Optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
I (Input):
1 - indicates the presence of the Input Available Wavelength Set Field.
0 - indicates the absence of the Input Available Wavelength Set Field.
O (Output):
1 - indicates the presence of the Output Available Wavelength Set Field.
0 - indicates the absence of the Output Available Wavelength Set Field.
B (Both):
1 - indicates that a single Available Wavelength Set Field represents both Input and Output Available Wavelength Set Fields.
Currently, the only valid combinations of (I,O,B) are (1,0,0), (0,1,0), (1,1,0), and (0,0,1).
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RB Set Field:
A resource block set in which all the members share the same input or output fiber or both.
Input Available Wavelength Set Field:
Indicates the wavelengths currently available (not being used) on the input fiber to this resource block. This field is encoded via the Label Set Field of [RFC7579].
Output Available Wavelength Set Field:
Indicates the wavelengths currently available (not being used) on the output fiber from this resource block. This field is encoded via the Label Set Field of [RFC7579].
As defined in [RFC7446], the Resource Block Information <ResourceBlockInfo> field is used to represent resource signal constraints and processing capabilities of a node.
The fundamental properties of a resource block are:
o Optical Interface Class List(s)
o Acceptable Client Signal (shared input, modulation, Forward Error Correction (FEC), bit rate, and Generalized Protocol Identifier (G-PID))
o Input Bit Rate
o Processing Capabilities (number of resources in a block, regeneration, performance monitoring, vendor specific)
<ResourceBlockInfo> fields are used to convey relatively static information about individual resource blocks, including the resource block properties and the number of resources in a block.
When more than one <ResourceBlockInfo> field is used, there are no ordering requirements amongst these fields. The length of the <ResourceBlockInfo> field is determined from the length of the object that includes it.
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The <ResourceBlockInfo> field has the following format:
The Length field defines the length of the value portion in bytes (thus, a subfield with no value portion would have a length of zero). The subfield is padded to 4-byte alignment; padding is not included in the Length field (so a 3-byte value would have a length of three, but the total size of the subfield would be 8 bytes). Unrecognized types are not processed. If multiple subfields of the same type are present, only the first of the type SHOULD be processed.
The following sub-TLV types are defined:
Value Length Sub-TLV Type
1 variable Optical Interface Class List 2 variable Acceptable Client Signal List 3 variable Input Bit Rate List 4 variable Processing Capability List
See the IANA Considerations section for allocation of new types.
Where the first 32 bits of the encoding shall be used to identify the semantics of the Optical Interface Class in the following way:
S (Standard bit):
S=0: identifies non-ITU code points
S=1: identifies ITU application codes
With S=0, the OI Code Points field can take the following value:
0: reserved
Future work may add support for vendor-specific application codes once the ITU-T has completed its work in that area.
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With S=1, the OI Code Points field can take the following values:
0: reserved
1: [G.698.1] application code
2: [G.698.2] application code
3: [G.959.1] application code
4: [G.695] application code
In the case of ITU application codes, the mapping between the string defining the application code and the 64 bits implementing the optical interface class is given in the following sections.
v: takes values S (Short wavelength), C (Conventional), or L (Long wavelength)
The F flag indicates the presence or absence of an optional FEC encoding suffix.
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These get mapped into the 64-bit Optical Interface Class field 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |B| D |S| c | W | y | t | z | v | F | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where (values between parentheses refer to ITU-defined values as reported above):
B: 1 bidirectional, 0 otherwise
D (prefix): 0 reserved, 1 (D)
S: 0 (N), 1 (W)
c: Channel Spacing, 4 bits mapped according to the same definition as in the third figure in Section 3.2 of [RFC6205] (note that DWDM spacing applies here).
W: 0 reserved, 2 (S), 3 (L)
y: 0 reserved, 1 (1), 2 (2)
t: 0 reserved, 4 (D)
z: 0 reserved, 2 (2), 3 (3), 5 (5)
v: 0 reserved, 1 (S), 2 (C), 3 (L)
F (suffix): 0 No FEC encoding suffix present, 1 FEC encoding suffix present
Values not mentioned here are not allowed in this application code; the last 32 bits are reserved and shall be set to zero.
v: takes values S (Short wavelength), C (Conventional), or L (Long wavelength)
An optional F can be added to indicate a FEC encoding.
These get mapped into the 64-bit Optical Interface Class field 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |B| D |S| c | W | y | t | z | v | F | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where (values between parentheses refer to ITU-defined values as reported above):
B: 1 bidirectional, 0 otherwise
D (prefix): 0 reserved, 1 (D)
S: 0 (N), 1 (W)
c: Channel Spacing, 4 bits mapped according to the same definition as in the third figure in Section 3.2 of [RFC6205] (note that DWDM spacing applies here).
W: 0 reserved, 10 (C), 11 (U)
y: 0 reserved, 1 (1), 2 (2)
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t: 0 reserved, 1 (A)
z: 0 reserved, 2 (2), 3 (3), 5 (5)
v: 0 reserved, 1 (S), 2 (C), 3 (L)
F (suffix): 0 reserved, 1 FEC encoding
Values not mentioned here are not allowed in this application code. The last 32 bits are reserved and shall be set to zero.
t: takes values A (power levels suitable for a booster amplifier in the originating ONE and power levels suitable for a pre- amplifier in the terminating ONE), B (booster amplifier only), C (pre-amplifier only), or D (no amplifiers)
z: takes values 1 (1310 nm sources on [G.652] fibre), 2 (1550 nm sources on [G.652] fibre), 3 (1550 nm sources on [G.653] fibre), or 5 (1550 nm sources on [G.655] fibre).
The following list of suffixes can be added to these application codes:
t: takes value D (link does not contain any optical amplifier).
z: takes values 1 (1310 nm region for [G.652] fibre), 2 (ITU-T [G.652] fibre), 3 ([G.653] fibre), or 5 ([G.655] fibre)
The following list of suffixes can be added to these application codes:
F: FEC encoding
Since the application codes are very similar to the ones from the [G.959.1] section, most of the fields are reused. The 64-bit Optical Interface Class field is encoded 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | p | C | n | W | x | reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | y | t | z | suffix | reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Where (values between parentheses refer to ITU-defined values as reported above):
p: 0 no prefix, 1 (B) bidirectional, 2 (S) black link
C: 0 reserved, 3 (C)
n: maximum number of channels (10 bits, up to 1023 channels)
Where the T bit indicates the type of regenerator:
T=0: Reserved
T=1: 1R Regenerator
T=2: 2R Regenerator
T=3: 3R Regenerator
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And where the C bit indicates the capability of the regenerator:
C=0: Reserved
C=1: Fixed Regeneration Point
C=2: Selective Regeneration Pools
Note that when the capability of the regenerator is indicated to be "Selective Regeneration Pools", regeneration pool properties such as input and output restrictions and availability need to be specified. These properties will be encoded in the field providing additional capability parameters, starting with the bits marked Reserved in the figure immediately above. An additional specification describing the encoding of these parameters is required before the value C=2 can be used.
This document defines protocol-independent encodings for WSON information and does not introduce any security issues.
However, other documents that make use of these encodings within protocol extensions need to consider the issues and risks associated with inspection, interception, modification, or spoofing of any of this information. It is expected that any such documents will describe the necessary security measures to provide adequate protection. A general discussion on security in GMPLS networks can be found in [RFC5920].
This document introduces a new top-level registry for GMPLS routing parameters for WSON encoding. This new IANA registry has been created to make the assignment of a new type and new values for the new "GMPLS Routing Parameters for WSON" registry. Note that this registry is only used in routing, not in signaling.
6.1. Types for Subfields of WSON Resource Block Information
Under the new "GMPLS Routing Parameters for WSON" registry, a new IANA subregistry has been created for nested subfields of the Resource Block Information field to create a new section named "Types for Subfields of WSON Resource Block Information Registry". This registry will be maintained via Standards Action as defined by [RFC5226].
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The initial values in the registry are as follows:
Value Length Description Reference ----- ------ ------------ --------- 0 Reserved 1 variable Optical Interface Class List [RFC7581] 2 variable Acceptable Client Signal List [RFC7581] 3 variable Input Bit Rate List [RFC7581] 4 variable Processing Capability List [RFC7581] 5-65535 Unassigned
[RFC4328] Papadimitriou, D., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Extensions for G.709 Optical Transport Networks Control", RFC 4328, DOI 10.17487/RFC4328, January 2006, <http://www.rfc-editor.org/info/rfc4328>.
[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, <http://www.rfc-editor.org/info/rfc7446>.
[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, <http://www.rfc-editor.org/info/rfc6163>.
This example, based on Figure 1, shows how to represent the wavelength conversion range of wavelength converters. Suppose the wavelength range of input and output of WC1 and WC2 are {L1, L2, L3, L4}:
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 Note: WC Set +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action=0 |1| Reserved | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | WC ID = #1 | WC ID = #2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Note: wavelength input range +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 2 | Num Wavelengths = 4 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. | Reserved | n for lowest frequency = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Note: wavelength output range +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 2 | Num Wavelengths = 4 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. | Reserved | n for lowest frequency = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 shows an electronic switch fabric surrounded by DWDM optics. In this example, the electronic fabric can handle either G.709 or Synchronous Digital Hierarchy (SDH) signals only (2.5 or 10 Gbps). To describe this node, the following information in Reduced Backus- Naur Form (RBNF) form [RFC5511] is needed:
<Node_Info> ::= <Node_ID>
[Other GMPLS info-elements]
[<ConnectivityMatrix>...]
[<ResourcePool>]
[<RBPoolState>]
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In this case, there is complete port-to-port connectivity, so the <ConnectivityMatrix> is not required. In addition, since there are sufficient ports to handle all wavelength signals, the <RBPoolState> element is not needed.
Hence, the attention will be focused on the <ResourcePool> field:
<ResourcePool> ::= <ResourceBlockInfo>
[<RBAccessibility>...]
[<ResourceWaveConstraints>...]
/| +-----------+ +-------------+ +------+ /D+--->| +--->|Tunable Laser|-->| | + e+--->| | +-------------+ | C | ========>| M| | | ... | o |=======> Port I1 + u+--->| | +-------------+ | m | Port O1 \x+--->| |--->|Tunable Laser|-->| b | \| | Electric | +-------------+ +------+ | Switch | /| | | +-------------+ +------+ /D+--->| +--->|Tunable Laser|-->| | + e+--->| | +-------------+ | C | ========>| M| | | ... | o |=======> Port I2 + u+--->| | +-------------+ | m | Port O2 \x+--->| +--->|Tunable Laser|-->| b | \| | | +-------------+ +------+ | | /| | | +-------------+ +------+ /D+--->| |--->|Tunable Laser|-->| | + e+--->| | +-------------+ | C | ========>| M| | | ... | o |=======> Port I3 + u+--->| | +-------------+ | m | Port O3 \x+--->| |--->|Tunable Laser|-->| b | \| +-----------+ +-------------+ +------+
Figure 2: An Optical Switch Built around an Electronic Switching Fabric
The resource block information will tell us about the processing constraints of the receivers, transmitters, and the electronic switch. The resource availability information, although very simple, tells us that all signals must traverse the electronic fabric (fixed connectivity). The resource wavelength constraints are not needed since there are no special wavelength constraints for the resources that would not appear as port/wavelength constraints.
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The <ResourceBlockInfo> is encoded 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RB Set Field | : (only one resource block in this example with shared | | input/output case) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|1|0| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Optical Interface Class List(s) | : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Input Client Signal Type | : (G-PIDs for SDH and G.709) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Input Bit Rate Range List | : (2.5 Gbps, 10 Gbps) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Processing Capabilities List | : Fixed (non optional) 3R regeneration : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Since there is fixed connectivity to resource blocks (the electronic switch), the <RBAccessibility> is:
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Connectivity=0|Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Input Link Set Field A #1 | : (All input links connect to resource) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RB Set Field A #1 | : (trivial set only one resource block) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Output Link Set Field B #1 | : (All output links connect to resource) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Contributors
Diego Caviglia Ericsson Via A. Negrone 1/A 16153 Genoa Italy Phone: +39 010 600 3736 EMail: diego.caviglia@ericsson.com
Anders Gavler Acreo AB Electrum 236 SE - 164 40 Kista Sweden EMail: Anders.Gavler@acreo.se
Jonas Martensson Acreo AB Electrum 236 SE - 164 40 Kista Sweden EMail: Jonas.Martensson@acreo.se
Itaru Nishioka NEC Corp. 1753 Simonumabe Nakahara-ku, Kawasaki, Kanagawa 211-8666 Japan Phone: +81 44 396 3287 EMail: i-nishioka@cb.jp.nec.com
Pierre Peloso ALU EMail: pierre.peloso@alcatel-lucent.com
Cyril Margaria EMail: cyril.margaria@gmail.com
Giovanni Martinelli Cisco EMail: giomarti@cisco.com
Gabriele M Galimberti Cisco EMail: ggalimbe@cisco.com
Bernstein, et al. Standards Track [Page 35]
RFC 7581 WSON Information Encoding June 2015
Lyndon Ong Ciena Corporation EMail: lyong@ciena.com
Daniele Ceccarelli Ericsson EMail: daniele.ceccarelli@ericsson.com
Bernstein, et al. Standards Track [Page 36]
RFC 7581 WSON Information Encoding June 2015
Authors' Addresses
Greg M. Bernstein (editor) Grotto Networking Fremont, California United States Phone: (510) 573-2237 EMail: gregb@grotto-networking.com
Young Lee (editor) Huawei Technologies 5340 Legacy Drive Build 3 Plano, TX 75024 United States Phone: (469) 277-5838 EMail: leeyoung@huawei.com
Dan Li Huawei Technologies Co., Ltd. F3-5-B R&D Center, Huawei Base, Bantian, Longgang District Shenzhen 518129 China Phone: +86-755-28973237 EMail: danli@huawei.com