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GMPLS OSPF Enhancement for Signal and Network Element Compatibility for Wavelength Switched Optical Networks
draft-ietf-ccamp-wson-signal-compatibility-ospf-07

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7688.
Authors Greg M. Bernstein , Young Lee
Last updated 2011-10-30 (Latest revision 2011-09-15)
Replaces draft-lee-ccamp-wson-signal-compatibility-ospf
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draft-ietf-ccamp-wson-signal-compatibility-ospf-07
Network Working Group                                            Y. Lee
Internet Draft                                                   Huawei
Intended status: Standards Track                           G. Bernstein
Expires: April 2012                                   Grotto Networking

                                                       October 30, 2011

    GMPLS OSPF Enhancement for Signal and Network Element Compatibility
                 for Wavelength Switched Optical Networks

          draft-ietf-ccamp-wson-signal-compatibility-ospf-07.txt

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
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Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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
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   warranty as described in the Simplified BSD License.

Abstract

   This document provides GMPLS OSPF routing enhancements to support
   signal compatibility constraints associated with WSON network
   elements. These routing enhancements are required in common optical
   or hybrid electro-optical networks where not all of the optical
   signals in the network are compatible with all network elements
   participating in the network.

   This compatibility constraint model is applicable to common optical
   or hybrid electro optical systems such as OEO switches,
   regenerators, and wavelength converters since such systems can be
   limited to processing only certain types of WSON signals.

Conventions used in this document

   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].

Table of Contents

   1. Introduction...................................................3
      1.1. Revision History..........................................3
   2. The Optical Node Property TLV..................................4
      2.1. Sub-TLV Details...........................................5
         2.1.1. Resource Block Information...........................5
         2.1.2. Resource Pool Accessibility..........................6
         2.1.3. Resource Block Wavelength Constraints................6
         2.1.4. Resource Pool State..................................6
         2.1.5. Block Shared Access Wavelength Availability..........7
   3. WSON Specific Scalability and Timeliness.......................7
      3.1. Different Sub-TLVs into Multiple LSAs.....................7
      3.2. Separating a Sub-TLV into Multiple LSAs...................8

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         3.2.1. Sub-Division by Sets.................................8
         3.2.2. Sub-Division by Options..............................9
   4. Security Considerations.......................................10
   5. IANA Considerations...........................................10
   6. References....................................................12
      6.1. Normative References.....................................12
   7. Authors and Contributors......................................13
   Authors' Addresses...............................................13
   Intellectual Property Statement..................................14
   Disclaimer of Validity...........................................14

1. Introduction

   The documents [RFC6163, WSON-Info, WSON-Encode] explain how to
   extend the wavelength switched optical network (WSON) control plane
   to allow both multiple WSON signal types and common hybrid electro
   optical systems as well hybrid systems containing optical switching
   and electro-optical resources. In WSON, not all of the optical
   signals in the network are compatible with all network elements
   participating in the network. Therefore, signal compatibility is an
   important constraint in path computation in a WSON.

   This document provides GMPLS OSPF routing enhancements to support
   signal compatibility constraints associated with general WSON
   network elements. These routing enhancements are required in common
   optical or hybrid electro-optical networks where not all of the
   optical signals in the network are compatible with all network
   elements participating in the network.

   This compatibility constraint model is applicable to common optical
   or hybrid electro optical systems such as OEO switches,
   regenerators, and wavelength converters since such systems can be
   limited to processing only certain types of WSON signals.

   1.1. Revision History

   From 00 to 01: The details of the encodings for compatibility moved
   from this document to [WSON-Encode].

   From 01 to 02: Editorial changes.

   From 02 to 03: Add a new Top Level Node TLV, Optical Node Property
   TLV to carry WSON specific node information.

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   From 03 to 04: Add a new sub-TLV, Block Shared Access Wavelength
   Availability TLV to be consistent with [WSON-Encode] and editorial
   changes.

   From 04 to 05: Add a new section that discusses OSPF scalability and
   timeliness and editorial changes.

   From 05 to 06: Change the title of the draft to "GMPLS OSPF
   Enhancement" from "OSPF Enhancement" to make sure the changes apply
   to the GMPLS OSPF rather than the base OSPF. Add specific OSPF
   procedures on how sub-TLVs are packaged per [RFC3630] and editorial
   changes.

   From 06 to 07: Add clarifying texts on how to sub-divide the Optical
   Node TLV in case it exceeds the IP MTU fragmentation limit. Delete
   Section 3.2. to avoid multiple rules so as to avoid confusion.

2. The Optical Node Property TLV

   [RFC3630] defines OSPF TE LSA using an opaque LSA. This document
   adds a new top level TLV for use in the OSPF TE LSA: the Optical
   Node Property TLV. The Optical Node property TLV describes a single
   node. It is constructed of a set of sub-TLVs. There are no ordering
   requirements for the sub-TLVs. Only one Optical Node TLV shall be
   advertised in each LSA.

   The Optical Node Property TLV contains all WSON-specific node
   properties and signal compatibility constraints. The detailed
   encodings of these properties are defined in [WSON-Encode].

   The following sub-TLVs of the Optical Node Property TLV are defined:

   Value       Length      Sub-TLV Type

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   TBA         variable    Resource Block Information
   TBA         variable    Resource Pool Accessibility
   TBA         variable    Resource Block Wavelength Constraints
   TBA         variable    Resource Pool State
   TBA         variable    Block Shared Access Wavelength Availability

   The detail encodings of these sub-TLVs are found in [WSON-Encode] as
   indicated in the table below.

   Sub-TLV Type                              Section [WSON-Encode]

   Resource Block Information                      4.1
   Resource Pool Accessibility                     3.1
   Resource Block Wavelength Constraints           3.2
   Resource Pool State                             3.3
   Block Shared Access Wavelength Availability     3.4

   All sub-TLVs defined here may occur at most once in any given
   Optical Node TLV. "At most once" means that if there is sub-TLV
   related information, it should be always included. These
   restrictions need not apply to future sub-TLVs. Unrecognized sub-
   TLVs are ignored.

   2.1. Sub-TLV Details

   Among the sub-TLVs defined above, the Resource Pool State sub-TLV
   and Block Shared Access Wavelength Availability are dynamic in
   nature while the rest are static. As such, they can be separated out
   from the rest and be advertised with multiple TE LSAs per OSPF
   router, as described in [RFC3630] and [RFC5250].

   2.1.1. Resource Block Information

   Resource Block Information sub-TLVs are used to convey relatively
   static information about individual resource blocks including the
   resource block properties and the number of resources in a block.

   There are seven nested sub-TLVs defined in the Resource Block
   Information sub-TLV.

   Value          Length      Sub-TLV Type

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   TBA            variable    Input Modulation Format List
   TBA            variable    Input FEC Type List
   TBA            variable    Input Bit Range List
   TBA            variable    Input Client Signal List
   TBA            variable    Processing Capability List
   TBA            variable    Output Modulation Format List
   TBA            variable    Output FEC Type List

   The detail encodings of these sub-TLVs are found in [WSON-Encode] as
   indicated in the table below.

   Name                             Section [WSON-Encode]

   Input Modulation Format List                 4.2
   Input FEC Type List                          4.3
   Input Bit Range List                         4.4
   Input Client Signal List                     4.5
   Processing Capability List                   4.6
   Output Modulation Format List                4.7
   Output FEC Type List                         4.8

   2.1.2. Resource Pool Accessibility

   This sub-TLV describes the structure of the resource pool in
   relation to the switching device. In particular it indicates the
   ability of an ingress port to reach a resource block and of a
   resource block to reach a particular egress port.

   2.1.3. Resource Block Wavelength Constraints

   Resources, such as wavelength converters, etc., may have a 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. Resource Block Wavelength
   Constraints sub-TLV describe these properties.

   2.1.4. Resource Pool State

   This sub-TLV describes the usage state of a resource that can be
   encoded as either a list of 16 bit integer values or a bit map
   indicating whether a single resource is available or in use. This
   information can be relatively dynamic, i.e., can change when a
   connection is established or torn down.

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   2.1.5. Block Shared Access Wavelength Availability

   Resources 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.

3. WSON Specific Scalability and Timeliness

   This document has defined five sub-TLVs specific to WSON. The
   examples given in [WSON-Encode] show that very large systems, in
   terms of channel count, ports, or resources, can be very efficiently
   encoded. However there has been concern expressed that some possible
   systems may produce LSAs that exceed the IP Maximum Transmission
   Unit (MTU) and that methods be given to allow for the splitting of
   WSON specific LSA into smaller LSA that are under the MTU limit.
   This section presents a set of techniques that can be used for this
   purpose.

   3.1. Different Sub-TLVs into Multiple LSAs

   Five sub-TLVs are defined in this document:

     1. Resource Block Information
     2. Resource Pool Accessibility
     3. Resource Block Wavelength Constraints
     4. Resource Pool State
     5. Block Shared Access Wavelength Availability

   All these are carried in an Optical Node Property TLV (see Section 2
   for detail) of which there can be at most one in an LSA. Of these
   sub-TLVs the first three are relatively static, i.e., only would
   change with hardware changes or significant system reconfiguration.
   While the fourth and fifth are dynamic, meaning that they may change
   with LSP setup or teardown through the system. The most important
   technique for scalability and OSPF bandwidth reduction is to
   separate the dynamic information sub-TLVs from the static
   information sub-TLVs
   and advertise them in OSPF TE LSAs, each with the Optical Node
   Property TLV at the top level ([RFC3630 and RFC5250]).

   For LSA overhead reduction it is recommended to group as many of the
   three static sub-TLVs into the same LSA (within the Optical Node
   Property TLV). If the size of this LSA is greater than the MTU, then
   these sub-TLV can be packed into separate LSAs. From the point of

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   view of path computation, the presence of the Resource Block
   Information sub-TLV indicates that resources exist in the system and
   may have signal compatibility or other constraints. The other four
   sub-TLVs indicate constraints on access to, and availability of
   those resources.

   Hence the "synchronization" procedure from a path computation point
   of view is quite simple. Until a Resource Block Information sub-TLV
   is received for a system path cannot make use of the other four sub-
   TLVs since it does not know the nature of the resources, e.g., are
   the resources wavelength converters, regenerators, or something
   else. Once this sub-TLV is received path computation can proceed
   with whatever of the additional types of sub-TLVs it may have
   received (there use is dependent upon the system type). If path
   computation proceeds with out of date or missing information from
   these sub-TLVs then there is the possibility of either (a) path
   computation computing a path that does not exist in the network, (b)
   path computation failing to find a path through the network that
   actually exists. Both situations are currently encountered with
   GMPLS, i.e., out of date information on constraints or resource
   availability.

   Note that the connection establishment mechanism (signaling or
   management) is ultimately responsible for the establishment of the
   connection, and this implies that such mechanisms must insure signal
   compatibility.

   3.2. Separating a Sub-TLV into Multiple OSPF TE LSAs

   In the highly unlikely event that a WSON sub-TLV by itself would
   result in an LSA exceeding the MTU, all five WSON specific sub-TLVs
   in this document provide mechanisms that allow them to be subdivided
   into smaller sub-TLVs that can be sent in separate OSPF TE LSAs.

   What is suggested as below is the only option allowed when dividing
   up the current set of sub-TLVs into separate OSPF TE LSAs. This
   means each sub-TLV will be packaged as the sole element in an OSPF
   TE LSA with a unique Link State ID. When such division is
   implemented, then the source node must flush the existing LSA (i.e.,
   the original OSPF TE LSA with all sub-TLV's packaged together as
   described in Section 2). This will avoid duplicating the same
   information being advertised across multiple LSAs.

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   Sub-Division by Sets

   All five sub-TLVs currently make use of one or more RB Set Fields
   [WSON-Encode] or Link Set Fields [Gen-Encode]. Long set fields can
   be decomposed into multiple smaller set fields resulting in multiple
   sub-TLVs that can be sent in multiple OSPF TE LSAs. The
   interpretation of the separate pieces is quite natural and reviewed
   in the following:

   Resource Block Information
     Information about different resources of similar types would get
     sent separately (LSAs). Path computation would not know a resource
     exists until it receives the instance of a sub-TLV that mentions
     that instance.

   Resource Pool Accessibility
     Information about accessibility to resources to/from ports would
     be in as separate pieces base on port or resource set separation.
     All pieces are combined to give complete resource/port
     accessibility view. Late/missing pieces would imply resources are
     not accessible to/from given ports.

   Resource Block Wavelength Constraints
     Information about resource wavelength constraints can be sent in
     separate pieces based on resource sub-sets. Late/missing pieces
     (LSAs) would imply resources accessible when they might not be.

   Resource Pool State
     Information about resource state can be sent in separate pieces
     based on resource sub-sets. Late/missing pieces (LSAs) could imply
     incorrect resources availability.

   Block Shared Access Wavelength Availability
     Information about resource shared access wavelength can be sent in
     separate pieces based on resource sub-sets. Late/missing pieces
     (LSAs) could imply incorrect shared wavelength availability.

   Due to the reliability mechanisms in OSPF the phenomena of late or
   missing pieces for relatively static information (first three types
   of sub-TLVs) would be relatively rare.

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4. Security Considerations

   This document does not introduce any further security issues other
   than those discussed in [RFC3630], [RFC4203].

5. IANA Considerations

   This document introduces a new Top Level Node TLV (Optical Node
   Property TLV) under the OSPF TE LSA defined in [RFC3630].

   Value    TLV Type

   TBA      Optical Node Property

   IANA is to allocate a new TLV Type and its Value for this Top Level
   Node TLV.

   This document also introduces the following sub-TLVs associated with
   the Optical Node Property TLV as defined in Section 2.1 as follows:

   Value       Length      Sub-TLV Type

   TBA         variable    Resource Block Information
   TBA         variable    Resource Pool Accessibility
   TBA         variable    Resource Block Wavelength Constraints
   TBA         variable    Resource Pool State
   TBA         variable    Block Shared Access Wavelength Availability

   IANA is to allocate new sub-TLV Types and their Values for these
   sub-TLVs defined under the Optical Node Property TLV.

   There are seven nested sub-TLVs defined in the Resource Block
   Information sub-TLV as follows:

   Value          Length      Sub-TLV Type

   TBA            variable    Input Modulation Format List
   TBA            variable    Input FEC Type List
   TBA            variable    Input Bit Range List
   TBA            variable    Input Client Signal List
   TBA            variable    Processing Capability List
   TBA            variable    Output Modulation Format List

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   TBA            variable    Output FEC Type List

   IANA is to allocate new Sub-TLV Types and their Values for these
   Sub-TLVs defined under the Resource Block Information Sub-TLV.

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6. References

   6.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3630] Katz, D., Kompella, K., and Yeung, D., "Traffic
             Engineering (TE) Extensions to OSPF Version 2", RFC
             3630, September 2003.

   [G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM
             applications: DWDM frequency grid", June, 2002.

   [RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
             in Support of Generalized Multi-Protocol Label Switching
             (GMPLS)", RFC 4203, October 2005.

   [WSON-Encode]  G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
             Wavelength Assignment Information Encoding for Wavelength
             Switched Optical Networks", draft-ietf-ccamp-rwa-wson-
             encode, work in progress.

   [Gen-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "General
             Network Element Constraint Encoding for GMPLS Controlled
             Networks", draft-ietf-ccamp-general-constraint-encode,
             work in progress.

   6.2. Informative References

   [WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
             Wavelength Assignment Information Model for Wavelength
             Switched Optical Networks", draft-ietf-ccamp-rwa-info,
             work in progress.

   [RFC6250] T. Otani, Ed., D. Li, Ed., "Generalized Labels for G.694
             Lambda-Switching Capable Label Switching Routers", RFC
             6250, March 2011.

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   [RFC6163] Y. Lee, G. Bernstein,  W. Imajuku, "Framework for GMPLS
             and PCE Control of Wavelength Switched Optical Networks",
             RFC 6163, April 2011.

   [RFC5250] Berger, L., et al., "The OSPF Opauqe LSA option", RFC
             5250, July 2008.

7. Authors and Contributors

Authors' Addresses

   Young Lee (ed.)
   Huawei Technologies
   1700 Alma Drive, Suite 100
   Plano, TX 75075
   USA

   Phone: (972) 509-5599 (x2240)
   Email: ylee@huawei.com

   Greg M. Bernstein (ed.)
   Grotto Networking
   Fremont California, USA

   Phone: (510) 573-2237
   Email: gregb@grotto-networking.com

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Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.

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