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Versions: 00 01 02 03                                                   
Network work group                                           Fatai Zhang
Internet Draft                                                 Young Lee
Intended status: Standards Track                             Jianrui Han
                                                                  Huawei
                                                            G. Bernstein
                                                       Grotto Networking
                                                               Yunbin Xu
                                                                    CATR
Expires: April 2010                                     October 23, 2009




            OSPF Extensions in Support of Routing and Wavelength
      Assignment (RWA) in Wavelength Switched Optical Networks (WSONs)



              draft-zhang-ccamp-rwa-wson-routing-ospf-02.txt


Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
   the provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on April 22, 2010.

Abstract

   This document describes OSPF routing protocols extensions to support
   Routing and Wavelength Assignment (RWA) in Wavelength Switched
   Optical Networks (WSON) under the control of Generalized MPLS (GMPLS).




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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............................................. 2
   2. Node Information......................................... 3
      2.1. Connectivity Matrix................................. 4
      2.2. Wavelength Converter Pool........................... 4
         2.2.1. Wavelength Converter Accessibility............. 5
         2.2.2. Wavelength Conversion Range.................... 5
         2.2.3. WC Usage State................................. 5
   3. Link Information......................................... 5
      3.1. WSON Port Wavelength Restrictions................... 6
      3.2. Available Wavelengths............................... 6
      3.3. Shared Backup Wavelengths........................... 7
   4. Procedures for Routing Flooding.......................... 7
   5. Security Considerations.................................. 8
   6. IANA Considerations...................................... 8
      6.1. Node Information.................................... 8
      6.2. Link Information.................................... 8
   7. References............................................... 9
   8. Authors' Addresses...................................... 10
   Acknowledgment ............................................ 12



1. Introduction

   Wavelength switched optical networks (WSONs) are based on Wavelength
   Division Multiplexing (WDM) in which user traffic is carried by data
   channels of different optical wavelengths. In traditional WDM
   Networks, each wavelength path is statically configured. With the
   deployment of Reconfigurable Optical Add-Drop Multiplexers (ROADMs),
   photonic cross-connects (PXCs), and tunable laser, WSONs have become
   more dynamic, and operators can flexibly set up wavelength paths to
   carry user traffic.

   In WSONs where there are no or a limited number of switches capable
   of wavelength conversion paths must be set up subject to the
   "wavelength continuity" constraint. This leads to a path computation
   problem known as routing and wavelength assignment (RWA). In order to



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   perform such computations, it is necessary to collect information
   about the available wavelengths within the network.

   [WSON-Frame] provides a framework for applying GMPLS [RFC3945] and
   the Path Computation Element (PCE) architecture [RFC4655] to the
   control of WSONs to address the RWA problem. [WSON-Info] describes an
   information model that specifies the information needed at various
   points in a WSON in order to compute paths and establish Label
   Switched Paths (LSPs). Based on the information model of [WSON-Info],
   [WSON-Encode] provides efficient protocol-independent encodings of
   the information needed by the RWA process in a WSON. Such encodings
   can be used to extend GMPLS signaling and routing protocols.

   Therefore, in order to enable GMPLS to support Routing and Wavelength
   Assignment (RWA) in Wavelength Switched Optical Networks (WSON)
   networks, this document follows on from [WSON-Info], [WSON-Encode],
   and [WSON-IGP-Eval] to define extensions to the OSPF routing protocol
   to enhance the Traffic Engineering (TE) properties of GMPLS TE which
   are defined in [RFC3630], [RFC4202], and [RFC4203]. The enhancements
   to the Traffic Engineering (TE) properties of GMPLS TE links can be
   announced in OSPF TE LSAs. The TE LSA, which is an opaque LSA with
   area flooding scope [RFC3630], has only one top-level
   Type/Length/Value (TLV) triplet and has one or more nested sub-TLVs
   for extensibility. The top-level TLV can take one of three values (1)
   Router Address [RFC3630], (2) Link [RFC3630], (3) Node Attribute
   [OSPF-Node].  In this document, we enhance the sub-TLVs for the Link
   TLV and Node Attribute TLV in support of RWA in WSON under the
   control of GMPLS.

   The detail encoding of OSPF extensions is not defined in this
   document. [WSON-Encode] provides encoding detail.

   No consideration of optical impairment routing related information is
   included in this document.

2. Node Information

   According to [WSON-Info] and [WSON-Encode], the node information
   about WSON nodes includes Node ID, connectivity matrix, wavelength
   converter pool information. Except for the Node ID which should
   comply with Routing Address described in [RFC3630], the other pieces
   of information are defined in this document.

   [OSPF-Node] defines a new top TLV named the Node Attribute TLV which
   carries attributes related to a router/node. This Node Attribute TLV
   contains one or more sub-TLVs.



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   Per [WSON-Encode], we have identified the following new Sub-TLVs to
   the Node Attribute TLV. Detail description for each newly defined
   Sub-TLV is provided in subsequent sections:

      Sub-TLV Type    Length       Name

         TBD          variable    Connectivity Matrix

         TBD          variable    Wavelength Converter Accessibility

         TBD          variable    Wavelength Conversion Range

         TBD          variable    WC Usage State

   In WSON networks, generally all the sub-TLVs above are optional,
   which depends on the implementations. Usually, Connectivity Matrix
   sub-TLV may appear in the LSAs because WSON switches are asymmetric
   at present. It is assumed that the switches are symmetric switching,
   if there is no Connectivity Matrix sub-TLV in the LSAs. Wavelength
   Converter Accessibility, Wavelength Conversion Range and WC Usage
   State sub-TLVs should appear in the LSAs, if there is wavelength
   conversion functionality in the WSON networks.

2.1. Connectivity Matrix

   It is necessary to identify which ingress ports and wavelengths can
   be connected to (the same wavelength on) a specific egress port,
   because the switching devices in a WSON are highly asymmetric.

   The Connectivity Matrix is used to identify these restrictions, which
   can represent either the potential connectivity matrix for asymmetric
   switches (e.g. ROADMs and such) or fixed connectivity for an
   asymmetric device such as a multiplexer as defined in [WSON-Info].

   The Connectivity Matrix is a sub-TLV (the type is TBD by IANA) of the
   Node Attribute TLV. The length is the length of value field in octets.
   The meaning and format of this sub-TLV are defined in Section 4.3 of
   [WSON-Encode]. One sub-TLV contains one matrix. The Connectivity
   Matrix sub-TLV may occur more than once to contain multi-matrices
   within the Node Attribute TLV.

2.2. Wavelength Converter Pool

   A WSON node may include wavelength converters. The encoding of
   structure and properties of a general wavelength converter pool
   utilizes a Converter Accessibility sub-TLV, a Wavelength Converter



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   Range sub-TLV, and a Wavelength Converter Usage State sub-TLV as
   described in [WSON-Encode].

2.2.1. Wavelength Converter Accessibility

   Wavelength Converter Accessibility represents the ability of an
   ingress port to reach a wavelength converter and of a wavelength
   converter to reach a particular egress port as described in [WSON-
   Encode].

   The Wavelength Converter Accessibility is a sub-TLV (the type is TBD
   by IANA) of the Node Attribute TLV. The length is the length of value
   field in octets. The meaning and format of this sub-TLV are defined
   in Section 5.2 of [WSON-Encode]. The Wavelength Converter
   Accessibility sub-TLV may occur at most once within the Node
   Attribute TLV.

2.2.2. Wavelength Conversion Range

   Wavelength converters may have a limited input or output range which
   can be described using one or more Wavelength Conversion Range sub-
   TLV as described in [WSON-Encode].

   The Wavelength Converter Range is a sub-TLV (the type is TBD by IANA)
   of the Node Attribute TLV. The length is the length of value field in
   octets. The meaning and format of this sub-TLV are defined in Section
   5.3 of [WSON-Encode]. The Wavelength Converter Range sub-TLV may
   occur more than once within the Node Attribute TLV.

2.2.3. WC Usage State

   WC Usage Sate indicates the usage state of wavelength converters as
   described in [WSON-Encode]

   The WC Usage State is a sub-TLV (the type is TBD by IANA) of the Node
   Attribute TLV. The length is the length of value field in octets. The
   meaning and format of this sub-TLV are defined in Section 5.4 of
   [WSON-Encode]. The WC Usage State sub-TLV may occur at most once
   within the Node Attribute TLV.

3. Link Information

   The most common link sub-TLVs nested to link top-level TLV are
   already defined in [RFC3630], [RFC4203]. For example, Link ID,
   Administrative Group, Interface Switching Capability Descriptor
   (ISCD), Link Protection Type, Shared Risk Link Group Information



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   (SRLG), and Traffic Engineering Metric are among the typical link
   sub-TLVs.

   For WSONs, per [WSON-Info] and [WSON-Encode], we add the following
   additional link sub-TLVs to the link-TLV in this document.



      Sub-TLV Type    Length       Name

         TBD          variable    WSON Port Wavelength Restrictions

         TBD          variable    Available Wavelengths

         TBD          variable    Shared Backup Wavelengths

   In WSON networks, generally all the sub-TLVs above are optional,
   which depends on the implementations. It is default no restrictions
   on wavelength, so WSON Port Wavelength Restrictions sub-TLV may not
   appear in the LSAs. In order to be able to compute RWA, Available
   Wavelengths sub-TLV may appear in the LSAs. Without available
   wavelength information, path computation need guess what lambdas may
   be available (high blocking probability or distributed wavelength
   assignment may be used). Shared Backup Wavelengths sub-TLV SHOULD not
   appear in the LSAs, if there is no wavelength backup functionality in
   the WSON networks.

3.1. WSON Port Wavelength Restrictions

   Port Wavelength Restrictions describes the wavelength (label)
   restrictions that the link and various optical devices such as OXCs,
   ROADMs, and waveband multiplexers may impose on a port. These
   restrictions represent what wavelength may or may not be used on a
   link and are relatively static. The detailed information about Port
   wavelength restrictions is described in [WSON-Info].

   The WSON Port Wavelength Restrictions is a sub-TLV (the type is TBD
   by IANA) of the Link TLV. The length is the length of value field in
   octets. The meaning and format of this sub-TLV are defined Section
   4.4 of [WSON-Encode]. The WSON Port Wavelength Restrictions sub-TLV
   may occur more than once to specify a complex port constraint within
   the link TLV.

3.2. Available Wavelengths

   Available Wavelengths indicates the wavelengths available for use on
   a link as described in [WSON-Encode].The Available Wavelengths is a


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   sub-TLV (the type is TBD by IANA) of the Link TLV. The length is the
   length of value field in octets. The meaning and format of this sub-
   TLV are defined in Section 4.1 of [WSON-Encode]. The Available
   Wavelengths sub-TLV may occur at most once within the link TLV.

   Note that there are five approaches for Wavelength Set which is used
   to represent the Available Wavelengths described in [WSON-Encode].
   Considering that the continuity of the available or unavailable
   wavelength set can be scattered for the dynamic wavelength
   availability, so it may burden the routing to reorganize the
   wavelength set information when the Inclusive (/Exclusive) List
   (/Range) approaches are used to represent Available Wavelengths
   information. Therefore, it is RECOMMENDED that only the Bitmap Set be
   used for representation Available Wavelengths information.

3.3. Shared Backup Wavelengths

   Shared Backup Wavelengths indicates the wavelengths available for
   shared backup use on a link as described in [WSON-Encode].

   The Shared Backup Wavelengths is a sub-TLV (the type is TBD by IANA)
   of the Link TLV. The length is the length of value field in octets.
   The meaning and format of this sub-TLV are defined in Section 4.2 of
   [WSON-Encode]. The Shared Backup Wavelengths sub-TLV may occur at
   most once within the link TLV.

4. Routing Procedures

   All the sub-TLVs are nested to top-level TLV(s) and contained in
   Opaque LSAs. The flooding of Opaque LSAs must follow the rules
   specified in [RFC2328], [RFC2370], [RFC3630], [RFC4203] and [OSPF-
   Node].

   In the WSON networks, the node information and link information can
   be classified as two kinds: one is relatively static information such
   as Node ID, Connectivity Matrix information; the other is dynamic
   information such as WC Usage State, Available Wavelengths information.
   [WSON-Encode] give recommendations of typical usage of previously
   defined sub-TLVs which contain relatively static information and
   dynamic information. An implementation SHOULD take measures to avoid
   frequent updates of relatively static information when the relatively
   static information is not changed. A mechanism MAY be applied such
   that static information and dynamic information are contained in
   separate Opaque LSAs to avoid unnecessary updates of static
   information when dynamic information is changed.




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   Note that as with other TE information, an implementation SHOULD take
   measures to avoid rapid and frequent updates of routing information
   that could cause the routing network to become swamped. A threshold
   mechanism MAY be applied such that updates are only flooded when a
   number of changes have been made to the wavelength availability
   information within a specific time. Such mechanisms MUST be
   configurable if they are implemented.

5. Security Considerations

   This document does not introduce any further security issues other
   than those discussed in [RFC 3630], [RFC 4203].

6. IANA Considerations

   [RFC3630] says that the top level Types in a TE LSA and Types for
   sub-TLVs for each top level Types must be assigned by Expert Review,
   and must be registered with IANA.

   IANA is requested to allocate new Types for the sub-TLVs as defined
   in Sections 2.1, 2.2, 3.1, 3.2 and 3.3 as follows:

6.1. Node Information

   This document introduces the following sub-TLVs of Node Attribute TLV
   (Value TBD, see [OSPF-Node])

   Type   sub-TLV

   TBD    Connectivity Matrix

   TBD    Wavelength Converter Accessibility

   TBD    Wavelength Conversion Range

   TBD    WC Usage State

6.2. Link Information

   This document introduces the following sub-TLVs of TE Link TLV (Value
   2)

   Type   sub-TLV

   TBD    WSON Port Wavelength Restrictions

   TBD    Available Wavelengths


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   TBD    Shared Backup Wavelengths

7. References

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

   [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
             (GMPLS) Signaling Functional Description", RFC 3471,
             January 2003.

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

   [RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions
             in Support of Generalized Multi-Protocol Label Switching
             (GMPLS)", RFC 4202, October 2005

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

   [RFC3945] E. Mannie, Ed., "OGeneralized Multi-Protocol Label Switching (GMPLS)
             Architecture", RFC 3945, October 2004.

   [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
             Computation Element (PCE)-Based Architecture ", RFC 4655,
             August 2006.

   [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July
             1998.

   [OSPF-Node] R. Aggarwal and K. Kompella, "Advertising a Router's
               Local Addresses in OSPF TE Extensions", draft-ietf-ospf-
               te-node-addr, work in progress.

   [Lambda-Labels] T. Otani, H. Guo, K. Miyazaki, D. Caviglia,
                    "Generalized Labels for G.694 Lambda-Switching
                    Capable Label Switching Routers", work in progress:
                    draft-ietf-ccamp-gmpls-g-694-lambda-labels-04.txt,
                    March 2009.





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   [WSON-Frame] G. Bernstein, Y. Lee, W. Imajuku, "Framework for GMPLS
                and PCE Control of Wavelength Switched Optical
                Networks", work in progress: draft-ietf-ccamp-rwa-WSON-
                Framework-04.txt, October 2009.

   [WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
               Wavelength Assignment Information Model for Wavelength
               Switched Optical Networks", work in progress: draft-ietf-
               ccamp-rwa-info-05.txt, October 2009.

   [WSON-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
                 Wavelength Assignment Information Encoding for
                 Wavelength Switched Optical Networks", work in progress:
                 draft-ietf-ccamp-rwa-wson-encode-03.txt, October 2009.

   [WSON-IGP-Eval] Dan Li, J. Gao, Y. Lee, "Evaluation of Possible
                    Interior Gateway Protocol Extensions for Wavelength
                    Switching Optical Networks", work in progress:
                    draft-li-ccamp-wson-igp-eval-01.txt, July 2008.



8. Authors' Addresses

   Fatai Zhang
   Huawei Technologies
   F3-5-B R&D Center, Huawei Base
   Bantian, Longgang District
   Shenzhen 518129 P.R.China

   Phone: +86-755-28972912
   Email: zhangfatai@huawei.com


   Young Lee
   Huawei Technologies
   1700 Alma Drive, Suite 100
   Plano, TX 75075
   USA

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




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   Jianrui Han
   Huawei Technologies Co., Ltd.
   F3-5-B R&D Center, Huawei Base
   Bantian, Longgang District
   Shenzhen 518129 P.R.China

   Phone: +86-755-28972913
   Email: hanjianrui@huawei.com


   Greg Bernstein
   Grotto Networking
   Fremont CA, USA

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


   Yunbin Xu
   China Academy of Telecommunication Research of MII
   11 Yue Tan Nan Jie Beijing, P.R.China
   Phone: +86-10-68094134
   Email: xuyunbin@mail.ritt.com.cn


   Guoying Zhang
   China Academy of Telecommunication Research of MII
   11 Yue Tan Nan Jie Beijing, P.R.China
   Phone: +86-10-68094272
   Email: zhangguoying@mail.ritt.com.cn


   Dan Li
   Huawei Technologies Co., Ltd.
   F3-5-B R&D Center, Huawei Base
   Bantian, Longgang District
   Shenzhen 518129 P.R.China

   Phone: +86-755-28973237
   Email: danli@huawei.com



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   Ming Chen
   European Research Center
   Huawei Technologies
   Riesstr. 25, 80992 Munchen, Germany

   Phone: 0049-89158834072
   Email: minc@huawei.com


   Yabin Ye
   European Research Center
   Huawei Technologies
   Riesstr. 25, 80992 Munchen, Germany

   Phone: 0049-89158834074
   Email: yabin.ye@huawei.com


Acknowledgment

   We thank Ming Chen and Yabin Ye from DICONNET Project who provided
   valuable information for this document.


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