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This document describes the extensions to the OSPF Link TLV to support Routing and Wavelength Assignment (RWA) in Wavelength Switched Optical Networks (WSON) under the control of Generalized MPLS (GMPLS).
This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 2, 2010.
Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved.
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This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.
1.
Introduction
1.1.
Requirements Language
2.
Usage Scenarios
2.1.
Client signals that require specific wavelengths on a given link
2.2.
Wavelengths reserved for specific uses
2.3.
Wavelength Availability based on adjacent channel usage
3.
Link Information
3.1.
Sublink Wavelength Set sub-TLV
3.1.1.
Label Set
3.2.
Sublink Modulation Format Compatibility Set
3.3.
Signal Dependency sub-TLV
3.4.
Sublink Administrative Group sub-TLV
4.
IANA Considerations
5.
Security Considerations
Appendix A.
Usage Examples
Appendix A.1.
Simple set of wavelengths
Appendix A.2.
Simple set of wavelengths with exclusions
Appendix A.3.
Multiple sublinks per link
Appendix A.4.
Sublink Modulation Format Compatibility Set
Appendix A.5.
Signal Dependency Set
6.
Normative References
§
Authors' Addresses
| TOC |
The current Internet Draft describing the Wavelength Switched Optical Network (WSON) information model [I‑D.ietf‑ccamp‑rwa‑info] (Bernstein, G., Lee, Y., Li, D., and W. Imajuku, “Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks,” February 2010.) defines the links in a WSON network with respect to their connectivity matrix, their label restrictions (essentially the set of allowed or usable wavelengths) and additional information from the MPLS-TE routing protocol extensions for OSPF and IS-IS [RFC3630] (Katz, D., Kompella, K., and D. Yeung, “Traffic Engineering (TE) Extensions to OSPF Version 2,” September 2003.), [RFC5305] (Li, T. and H. Smit, “IS-IS Extensions for Traffic Engineering,” October 2008.) along with the GMPLS routing protocols extensions for OSPF and IS-IS [RFC4203] (Kompella, K. and Y. Rekhter, “OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS),” October 2005.), [RFC5307] (Kompella, K. and Y. Rekhter, “IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS),” October 2008.).
At a high level, the information models for WSON described in [I‑D.ietf‑ccamp‑rwa‑info] (Bernstein, G., Lee, Y., Li, D., and W. Imajuku, “Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks,” February 2010.) and [WSON‑Encode] (Bernstein, G., Lee, Y., Li, D., and W. Imajuku, “Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks,” February 2010.) model the connectivity through the WSON switching node as well as the connectivity between links at a WSON switching node. The current information model is sufficient to describe the structure of a WSON node as well as the possible interconnection of wavelengths between links and their local processing (e.g. regeneration or wavelength conversion). This document describes extensions to that model and their encoding that allow a more granular approach to provide hints to the Routing and Wavelength Assignment (RWA) algorithm regarding the placement of client signals within a set of available wavelengths and a more granular approach towards the association of channels or channel sets with Administrative Groups.
| TOC |
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 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].
| TOC |
This section provides some usage scenarios of the proposed extension.
| TOC |
Assume a link between two nodes that can carry a specific client signal type (identified by the modulation format of the client signal) only on a specific subset of the supported wavelengths of that link. This restriction may be due to the optical parameters of the link or administrative preference of the operator.
In a setup as shown in Figure 1 (40G Client Signal may only be carried on WL3) the physical link may only support 40G on wavelength #3 (denoted as WL3). The document defines extensions to the OSPF Link TLV that allow the logical partitioning of the link into two sub-links. Hints to the Routing and Wavelength Assignment (RWA) algorithm on where to place a client signal using a 10G vs. 40G modulation format can then be provided through the use of the Sublink Modulation Format Compatibility Set sub-TV (see Section 3.2 (Sublink Modulation Format Compatibility Set)) and the Sublink Administrative Group sub-TLV (see Section 3.4 (Sublink Administrative Group sub-TLV)).
------------------------- ------+------------------
+------+ | +------+
L | WL 1 | L | | WL 1 |
+------+ | +------+
|
+------+ | +------+
I | WL 2 | I | | WL 2 | Sublink 1
+------+ | +------+ for 10G
|
+------+ | +------+
N | WL 3 | N | | WL 4 |
+------+ | +------+
+------------------
+------+ | +------+
K | WL 4 | K | | WL 3 | Sublink 2
+------+ | +------+ for 40G
------------------------- ------+------------------
| Figure 1: 40G Client Signal may only be carried on WL3 |
| TOC |
Assume a link between two nodes where the operator wants to reserve a number of wavelengths for a specific purpose. Such purposes may include these wavelengths being available to the RWA algorithm only for backup purposes or being only available to client signals that require wavelength conversion or regeneration. Such preferences and restrictions on the usage of wavelengths can be described using the Administrative Group concept when the Administrative Group is associated with a sublink.
In a setup as shown in Figure 2 (Client Signal may only be carried on WL3) assume that wavelength #4 (WL4) may only be used for 40G signals that belong to a specific Administrative Group (AG=3 in this example). This restriction may be due to policy choice by the operator or due to structural restrictions in the node itself (e.g. access to wavelength converters). In such cases, the hints to the Routing and Wavelength Assignment (RWA) algorithm on where to place a client signal can then be provided through the use of the Sublink Modulation Format Compatibility Set sub-TV (see Section 3.2 (Sublink Modulation Format Compatibility Set)) and the Sublink Administrative Group sub-TLV (see Section 3.4 (Sublink Administrative Group sub-TLV)).
------------------------- ------+------------------
+------+ | +------+
L | WL 1 | L | | WL 1 |
+------+ | +------+ Sublink 1
| for 10G
+------+ | +------+ with AG=1
I | WL 2 | I | | WL 2 |
+------+ | +------+
+------------------
+------+ | +------+
N | WL 3 | N | | WL 3 | Sublink 2
+------+ | +------+ for 40G AG=2
+------------------
+------+ | +------+
K | WL 4 | K | | WL 4 | Sublink 3
+------+ | +------+ for AG=3
------------------------- ------+------------------
| Figure 2: Client Signal may only be carried on WL3 |
| TOC |
In some cases the placement of a client signal may depend on the modulation format of a signal in an adjacent channel or a client signal of a specific set of modulation formats requires a number of adjacent channels not to be in use. Assume a link that supports four channels at a given channel spacing when using a 10G modulation format. 40G signals are also supported, but the modulation format requires or the operator mandates that the adjacent channels must not be in use if a channel carries a 40G signal. Such dependencies can be expressed using the Signal Dependency sub-TLV (see Section 3.3 (Signal Dependency sub-TLV)).
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The Link TLV describes a single link with respect to the available bandwidth and any administrative or signal-related restrictions on the wavelength use. It is constructed of a number of sub-TLVs which may appear in the TLV in any order. The Link TLV MUST contain exactly one Link Wavelength Set sub-TLV for each sublink. At least one Wavelength Set sub-TLV MUST be present in the Link TLV. All other sub-TLVs described in this document are OPTIONAL.
The following sub-TLVs of the Link TLV are defined:
TBD - Sublink Wavelength Set
TBD - Sublink Modulation Format Compatibility Set
TBD - Signal Dependency Set
TBD - Sublink Administrative Group
This document introduces the concept of logical sublinks within a physical link connecting two nodes. A sublink is uniquely identified through the tuple (Link ID, Sublink ID). Sublink IDs MUST be unique on a per-link basis.
The Link TLV can be represented through a RBNF in the following way:
<WSON_LINK_TLV> ::= [ <Sublink Definition> ]
Where the <Sublink Definition> consist of a variable set of sub-TLV associated with a sublink.
<Sublink Definition> ::= <SL_WL_SET> [ <SL_WL_SET> ...]
[ <SL_FORMAT_COMPAT> ] [ <SL_SIGNAL_DEP> ]
[ <SL_ADMIN_GROUP> ]
The objects composing <Sublink Definition> are the sub-TLV defined along this section.
| TOC |
The Link wavelength set sub-TLV specifies the wavelengths that this link can support and any restrictions on the usage of these wavelengths from administrative choice by the operator or signal compatibility of the client signal with respect to a set of wavelengths.
The Link wavelength sub-TLV has the following format:
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID | Encoding | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Wavelength Descriptor : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 3: Sublink Wavelength Set sub-TLV |
Sublink ID: 8 bits
- 0x00 - Reserved
- 0x01 ... 0xFE - Sublink ID
- Unique identifier for the wavelength set. This identifier is unique on a per-link basis.
- 0xFF - reserved
Encoding: 8 bits
- 0x00 - Reserved
- 0x01 - Label Sets
- Wavelength Set encoding based on Label Sets per Section 3.1.1 (Label Set). The format of the labels follows [I‑D.ietf‑ccamp‑gmpls‑g‑694‑lambda‑labels] (Otani, T., Tsuritani, T., Li, D., Rabbat, R., Shiba, S., Guo, H., Miyazaki, K., and D. Caviglia, “Generalized Labels for Lambda-Switching Capable Label Switching Routers,” December 2009.).
- 0x02 - Label Bitset
- Label Set encoding per []
- 0x03 ... 0xFF - reserved
Reserved: 16 bits
- This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt.
Wavelength Descriptor: variable
- The Wavelength Descriptor identifies the wavelengths being available for this sublink. The format and length depends on the encoding format.
If Encoding is 1 then at least one Label Set with Action set to 0 or 2 MUST be present in the Link Wavelength Set sub-TLV. There MAY be multiple Label Sets per Link Wavelength Set sub-TLV. The set of available channels on a (Link ID, Sublink ID) tuple is given by the set complement of the union of all Label Sets with Action set to 0 or 2 and the union of all Label Sets with Action set to 1 or 3.
| TOC |
The encoding of the Label Sets is based on the similar concept introduced in [RFC3471] (Berger, L., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description,” January 2003.).
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 | Reserved | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Wavelength 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Wavelength N | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 4: Label Set |
Action : 8 bits
0 - Inclusive List
Indicates that the object contains one or more wavelength elements that are included in the Label Set.
1 - Exclusive List
Indicates that the object contains one or more wavelength elements that are excluded from the Label Set.
2 - Inclusive Range
Indicates that the object contains a range of labels that are included in the Label Set. The object/TLV contains two wavelength elements. The first element indicates the start of the range. The second element indicates the end of the range.
3 - Exclusive Range
Indicates that the object contains a range of labels that are excluded from the Label Set. The object/TLV contains two wavelength elements. The first element indicates the start of the range. The second element indicates the end of the range.
Reserved: 8 bits
This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt.
Length: 16 bits
Length in octets of this Label Set
Wavelength: 32 bits
The wavelength represents the individual channel to be included in or excluded from the list of available channels (if Action is 0 or 1) or the start or end of the channel range (If Action is 2 or 3). If Action is 2 or 3 exactly two wavelength entries MUST be present. If Action is 0 or 1 there MUST be at least one Wavelength element.
The encoding of the wavelength field follows [I‑D.ietf‑ccamp‑gmpls‑g‑694‑lambda‑labels] (Otani, T., Tsuritani, T., Li, D., Rabbat, R., Shiba, S., Guo, H., Miyazaki, K., and D. Caviglia, “Generalized Labels for Lambda-Switching Capable Label Switching Routers,” December 2009.)
| TOC |
The OPTIONAL Sublink Modulation Format Compatibility Set sub-TLV carries the list of acceptable modulation formats for any wavelength in the sublink.
The Wavelength Set Modulation Format Compatibility Set has the following format:
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID | Encoding | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modulation Type 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Modulation Type N : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 5: Sublink Modulation Format |
Sublink ID: 8 bits
- 0x00 - Reserved
- 0x01 ... 0xFE - Sublink ID
- Unique identifier for the wavelength set. This identifier is unique on a per-link basis.
- 0xFF - Reserved
Encoding: 8 bits
0x00 - Reserved
0x01 - Encoding using modulation type per [WSON‑Encode] (Bernstein, G., Lee, Y., Li, D., and W. Imajuku, “Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks,” February 2010.).
0x02-0xFF - Reserved
Reserved: 16 bits
- This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt.
Modulation Type 1..N: variable
- List of acceptable modulation formats for the wavelengths in this sublink per [WSON‑Encode] (Bernstein, G., Lee, Y., Li, D., and W. Imajuku, “Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks,” February 2010.).
Currently, the only modulation format specification is the one described in [WSON‑Encode] (Bernstein, G., Lee, Y., Li, D., and W. Imajuku, “Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks,” February 2010.). Additional encoding mechanisms for signal compatibility may be defined in the future.
| TOC |
This OPTIONAL sub-TLV indicates a wavelength blocking of adjacent wavelengths based upon the modulation format of a client signal around that client signal's center wavelength. The Signal Dependency sub-TLV has the following format:
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modulation Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S | Lower Excursion |Grid | C.S | Upper Excursion | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 6: Signal Dependency sub-TLV |
Modulation Type: variable
- Specifies the modulation type for which wavelength blocking of adjacent wavelengths around the client signal's center frequency shall be used. The format of the Modulation Type follows [WSON‑Encode] (Bernstein, G., Lee, Y., Li, D., and W. Imajuku, “Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks,” February 2010.).
Grid: 3 bits
- 0 - Reserved
- 1 - ITU-T DWDM
- 2 - ITU-T CDWDM
- 3 .. 7 - Reserved
C.S (channel spacing): 4 bits
- 0 - Reserved
- 1 - 100 GHz
- 2 - 50 GHz
- 3 - 25 GHz
- 4 - 12.5 GHz
- 5 .. 15 - Reserved
Lower Excursion: 9 bits
- Specifies the excursion from the client signal's center wavelength towards the lower frequencies. For DWDM links the lower boundary of the signal dependency wavelength range is given by center frequency - Lower Excursion * Channel Spacing. A value of 0 indicates no excursion towards the lower frequencies.
Upper Excursion: 9 bits
- Specifies the excursion from the client signal's center wavelength towards the higher frequencies. For DWDM links the upper boundary of the signal dependency wavelength range is given by center frequency + Lower Excursion * Channel Spacing. A value of 0 indicates no excursion towards the higher frequencies.
This optional sub-TLV defines a lambda range of
[Lower Excursion * Channel Spacing,Upper Excursion * Channel Spacing] for DWDM and
[Lower Excursion * 20 nm,Upper Excursion * 20 nm] for CWDM
which can not be used around a signal's center wavelength or center frequency if that signal uses the modulation format specified in the sub-TLV.
| TOC |
The OPTIONAL Administrative Group sub-TLV carries the Administrative Group for the sublink identified in this sub-TLV. The sub-TlV has the following format:
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Administrative Group | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 7: Administrative Group sub-TLV |
Sublink ID: 8 bits
- 0x00 - Reserved
- 0x01 ... 0xFE - Sublink ID
- Unique identifier for the wavelength set. This identifier is unique on a per-link basis.
- 0xFF - reserved
Reserved: 24 bits
- This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt.
Administrative Group: 32 bits
- This field contains the Administrative Group associated with the identified Sublink ID. The format of this field is defined in Section 2.5.9 of [RFC3630] (Katz, D., Kompella, K., and D. Yeung, “Traffic Engineering (TE) Extensions to OSPF Version 2,” September 2003.)
| TOC |
As per [RFC3630] (Katz, D., Kompella, K., and D. Yeung, “Traffic Engineering (TE) Extensions to OSPF Version 2,” September 2003.) all Type assignments for sub-TLVs need to be made through IANA. This document requests Type assignments for the sub-TLVs described in Section 3 (Link Information).
| TOC |
This document does not introduce any further security issues above and beyond those discussed in [RFC3630] (Katz, D., Kompella, K., and D. Yeung, “Traffic Engineering (TE) Extensions to OSPF Version 2,” September 2003.) and [RFC4203] (Kompella, K. and Y. Rekhter, “OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS),” October 2005.).
| TOC |
The appendix shows some of the use cases of the Link Extensions described in this document.
| TOC |
This example shows the encoding for a WSON link carrying a single sublink. The wavelengths available on this link are the channels at the frequencies between 192.0 THz (1561.41 nm) and 195.9 THz (1530.33 nm) using 100 GHz grid spacing.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID= 1 | Encoding=1 | Reserved=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action=2 | Reserved=0 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = -11 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 28 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 8: Link Wavelength Set sub-TLV Encoding Example |
| TOC |
This example shows the encoding for a WSON link carrying a single sublink. The wavelengths available on this link are the channels at the frequencies between 192.0 THz (1561.41 nm) and 195.9 THz (1530.33 nm) using 100 GHz grid spacing as before but the link uses a guard channel at every fifth channel of the 100 GHz grid ("four-skip-one").
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID= 1 | Encoding=1 | Reserved=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action=2 | Reserved=0 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = -11 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 28 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action=1 | Reserved=0 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = -6 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = -1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 9 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 14 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 19 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 24 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 9: Link Wavelength Set sub-TLV Encoding Example with excluded wavelengths |
| TOC |
An operator may want to logically subdivide the set of available wavelengths for reasons of signal compatibility with only a specific subset of wavelengths on a given link, general traffic conditioning preferences or other policy choices. In order to allow the RWA algorithm to honor such restrictions the link can be logically subdivided into sublinks that may have different Modulation format compatibility TLVs or Administrative Groups associated with them. In this example, sublink 1 carries the channels with center frequencies between 192.0 THz and 194.1 THz using a 50 GHz grid and sublink 2 contains the channels with center frequencies between 194.2 and 195.9 THz in a 100 GHz grid spacing. This change in grid spacing may be due to signal compatibility when sublink 2 is used for LSPs using a different modulation format than the ones using sublink 1.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID= 1 | Encoding=1 | Reserved=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action=2 | Reserved=0 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=2 | Reserved=0 | n = -22 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=2 | Reserved=0 | n = 20 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 10: Multiple Wavelength Sets per Link - Sublink 1 |
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID= 2 | Encoding=1 | Reserved=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action=2 | Reserved=0 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 11 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=1 | Reserved=0 | n = 28 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 11: Multiple Wavelength Sets per Link - Sublink 2 |
| TOC |
After defining the two sublinks as per the previous example, one may use the Sublink Modulation Format Compatibility Set TLV to provide hints to the RWA algorithm that a specific client types using a set of modulation formats should be use channels of a specific sublink.
In this example, the channels in sublink 1 can carry client signals using the following modulation formats:
Optical Tributary Signal Class NRZ 2.5G
Optical Tributary Signal Class NRZ 10G
The corresponding encoding 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID=1| Encoding=1 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|1| Modulation ID=2 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Possible additional modulation parameters depending upon | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : the modulation ID : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|1| Modulation ID=3 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Possible additional modulation parameters depending upon | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : the modulation ID : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 12: Sublink Modulation Format - Sublink 1 |
Optical Tributary Signal Class NRZ 40G
Which 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sublink ID=2| Encoding = 1 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|1| Modulation ID=4 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Possible additional modulation parameters depending upon | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : the modulation ID : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 13: Sublink Modulation Format - Sublink 2 |
| TOC |
In some cases a link may carry clients of a particular modulation type at a Grid spacing of 50 GHz but it may require a different spacing when a different modulation format is used. In that case a channel at center frequency x "blocks" other frequencies around its center frequency.
In this example, assume a sublink that can carry client signals at a 50 GHz spacing when the modulation format is "Optical Tributary Signal Class NRZ 10G" and all channels can also carry client signals using the "Optical Tributary Signal Class NRZ 40G" modulation format. If a channel is using this modulation format, the two adjacent channels may not be used. This information can be used by the RWA algorithm to select the correct spacing of a new "Optical Tributary Signal Class NRZ 40G" signal and mark its adjacent channels as "unusable".
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|1| Modulation ID=4 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Possible additional modulation parameters depending upon | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : the modulation ID : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | G=1 | C.S=2 | Lower Exc=1 | G=1 | C.S=2 | Upper Exc=1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Figure 14: Signal Dependency sub-TLV Example |
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| Dirk Schroetter (editor) | |
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| Giovanni Martinelli | |
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