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Versions: (draft-zhang-ccamp-general-constraints-ospf-ext) 00 01 02 03 04 05 06 07 08 09 10 RFC 7580

Network work group                                           Fatai Zhang
Internet Draft                                                 Young Lee
Intended status: Standards Track                             Jianrui Han
                                                                  Huawei
                                                            G. Bernstein
                                                       Grotto Networking
                                                               Yunbin Xu
                                                                    CATR
Expires: March 13, 2012                               September 13, 2011




         OSPF-TE Extensions for General Network Element Constraints



         draft-ietf-ccamp-gmpls-general-constraints-ospf-te-01.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 March 13, 2012.



Abstract

   Generalized Multiprotocol Label Switching can be used to control a
   wide variety of technologies including packet switching (e.g., MPLS),
   time-division (e.g., SONET/SDH, OTN), wavelength (lambdas), and



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   spatial switching (e.g., incoming port or fiber to outgoing port or
   fiber). In some of these technologies network elements and links may
   impose additional routing constraints such as asymmetric switch
   connectivity, non-local label assignment, and label range limitations
   on links. This document describes OSPF routing protocol extensions to
   support these kinds of constraints under the control of Generalized
   MPLS (GMPLS).

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
   3. Link Information ............................................ 4
      3.1. Port Label Restrictions................................. 5
      3.2. Available Labels........................................ 5
      3.3. Shared Backup Labels.................................... 6
   4. Routing Procedures .......................................... 6
   5. Security Considerations...................................... 7
   6. IANA Considerations ......................................... 7
      6.1. Node Information........................................ 7
      6.2. Link Information........................................ 7
   7. References .................................................. 8
      7.1. Normative References.................................... 8
      7.2. Informative References.................................. 9
   8. Authors' Addresses .......................................... 9
   Acknowledgment ................................................ 11



1. Introduction

   Some data plane technologies that wish to make use of a GMPLS control
   plane contain additional constraints on switching capability and
   label assignment. In addition, some of these technologies should be
   capable of performing non-local label assignment based on the nature
   of the technology, e.g., wavelength continuity constraint in WSON
   [RFC6163]. Such constraints can lead to the requirement for link by
   link label availability in path computation and label assignment.



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   [GEN-Encode] provides efficient encodings of information needed by
   the routing and label assignment process in technologies such as WSON
   and are potentially applicable to a wider range of technologies.

   This document defines extensions to the OSPF routing protocol based
   on [GEN-Encode] 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
   [RFC5786]. In this document, we enhance the sub-TLVs for the Link TLV
   and Node Attribute TLV in support of the general network element
   constraints under the control of GMPLS.

   The detailed encoding of OSPF extensions are not defined in this
   document. [GEN-Encode] provides encoding detail.

2. Node Information

   According to [GEN-Encode], the additional node information
   representing node switching asymmetry constraints includes Node ID,
   connectivity matrix. Except for the Node ID which should comply with
   Routing Address described in [RFC3630], the other pieces of
   information are defined in this document.

   [RFC5786] 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.

   Per [GEN-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

   In some specific technologies, e.g., WSON networks, Connectivity
   Matrix sub-TLV may be optional, which depends on the control plane
   implementations. Usually, for example, in WSON networks, 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.



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2.1. Connectivity Matrix

   It is necessary to identify which ingress ports and labels can be
   switched to some specific labels on a specific egress port, if the
   switching devices in some technology 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 5.3 of
   [GEN-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.

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

   Per [GEN-Encode], we add the following additional link sub-TLVs to
   the link-TLV in this document.



      Sub-TLV Type    Length         Name

         TBD          variable    Port Label Restrictions

         TBD          variable    Available Labels

         TBD          variable    Shared Backup Labels

   Generally all the sub-TLVs above are optional, which depends on the
   control plane implementations. If it is default no restrictions on
   labels, Port Label Restrictions sub-TLV may not appear in the LSAs.
   In order to be able to compute label assignment, Available Labels
   sub-TLV may appear in the LSAs. For example, in WSON networks,
   without available wavelength information, path computation need guess



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   what lambdas may be available (high blocking probability or
   distributed wavelength assignment may be used).

3.1. Port Label Restrictions

   Port label restrictions describe the label restrictions that the
   network element (node) and link may impose on a port. These
   restrictions represent what labels may or may not be used on a link
   and are intended to be relatively static. More dynamic information is
   contained in the information on available labels. Port label
   restrictions are specified relative to the port in general or to a
   specific connectivity matrix for increased modeling flexibility.

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

   The Port Label 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 in Section 5.4 of
   [GEN-Encode]. The Port Label Restrictions sub-TLV may occur more than
   once to specify a complex port constraint within the link TLV.

3.2. Available Labels

   Available Labels indicates the labels available for use on a link as
   described in [GEN-Encode]. The Available Labels 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 5.1 of [GEN-Encode]. The Available Labels sub-TLV
   may occur at most once within the link TLV.

   Note that there are five approaches for Label Set which is used to
   represent the Available Labels described in [GEN-Encode]. Usually, it
   depends on the implementation to one of the approaches. In WSON
   networks, 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.




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   The "Base Label" and "Last Label" in label set defined in [GEN-Encode]
   corresponds to base wavelength label and last wavelength label in
   WSON, the format of which is described 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Grid |  C.S. |      Reserved   |    n                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The detailed information related to wavelength label can be referred
   to [RFC6205].

3.3. Shared Backup Labels

   Shared Backup Labels indicates the labels available for shared backup
   use on a link as described in [GEN-Encode].

   The Shared Backup Labels 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 5.2 of
   [GEN-Encode]. The Shared Backup Labels 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 [RFC5786].

   Considering the routing scalability issues in some cases, the routing
   protocol should be capable of supporting the separation of dynamic
   information from relatively static information to avoid unnecessary
   updates of static information when dynamic information is changed. A
   standard-compliant approach is to separate the dynamic information
   sub-TLVs from the static information sub-TLVs, each nested to top-
   level TLV ([RFC3630 and RFC5876]), and advertise them in the separate
   OSPF TE LSAs.

   For node information, since the Connectivity Matrix information is
   static, the LSA containing the Node Attribute TLV can be updated with
   a lower frequency to avoid unnecessary updates.

   For link information, a mechanism MAY be applied such that static
   information and dynamic information of one TE link are contained in
   separate Opaque LSAs. For example, the Port Label Restrictions


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   information sub-TLV and Available Labels information sub-TLV can be
   nested to the top level link TLVs and advertised in the separate LSAs.

   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 label availability
   information (e.g., wavelength availability) 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, 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 [RFC5786]):

      Type     sub-TLV

      TBD      Connectivity Matrix

6.2. Link Information

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



      Type     sub-TLV

      TBD      Port Label Restrictions



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      TBD      Available Labels

      TBD      Shared Backup Labels

7. References

7.1. Normative References

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

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

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

   [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.

   [RFC5786] R. Aggarwal and K. Kompella, "Advertising a Router's Local
             Addresses in OSPF Traffic Engineering (TE) Extensions", RFC
             5786, March 2010.

   [GEN-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, " General
             Network Element Constraint Encoding for GMPLS Controlled
             Networks", work in progress: draft-ietf-ccamp-general-
             constraint-encode-05.txt, May 2011.

   [RFC6205] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, " Generalized
             Labels for Lambda-Switching Capable Label Switching
             Routers", work in progress: draft-ietf-ccamp-gmpls-g-694-
             lambda-labels-11.txt, January 2011.








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7.2. Informative References

   [RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS and
             PCE Control of Wavelength Switched Optical Networks (WSON)",
             work in progress: draft-ietf-ccamp-rwa-WSON-Framework-
             12.txt, February 2011.

   [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-12.txt, September 2011.



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


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

   Phone: +86-755-28977943


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   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


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

   Phone: 0049-89158834072


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   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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