Network Working Group                                     H. Long, M.Ye
Internet Draft                             Huawei Technologies Co., Ltd
Intended status: Standards Track                              G. Mirsky
                                                   Telecom Italia S.p.A
                                                                H. Shah
Expires: August 2017 February 15, 2018                                   August 8, 2017

    OSPF-TE Link Availability Extension for Links with Variable Discrete


   A network may contain links with variable discrete bandwidth, e.g.,
   copper, radio, etc. The bandwidth of such links may change
   discretely in reaction to changing external environment.
   Availability is typically used for describing such links during
   network planning. This document defines a new type of the
   Generalized Switching Capability-specific information (SCSI) TLV to
   extend the Generalized Multi-Protocol Label Switching (GMPLS) Open
   Shortest Path First (OSPF) routing protocol. The extension can be
   used for route computation in a network that contains links with
   variable discrete bandwidth. Note, this document only covers the
   mechanisms by which the availability information is distributed. The
   mechanisms by which availability information of a link is determined
   and the use of the distributed information for route computation are
   outside the scope of this document. It is intended that technology-
   specific documents will reference this document to describe specific

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Table of Contents

   1. Introduction ................................................ 3
   2. Overview .................................................... 4
   3. TE Metric Extension to OSPF-TE............................... 4
      3.1. Availability SCSI-TLV................................... 4
      3.2. Processing Procedures................................... 5
   4. Security Considerations...................................... 6
   5. IANA Considerations ......................................... 6
   6. References .................................................. 7
      6.1. Normative References.................................... 7
      6.2. Informative References.................................. 7
   7. Acknowledgments ............................................. 8

Conventions used in this document
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC-2119 [RFC2119].

   The following acronyms are used in this draft:

   GMPLS     Generalized Multi-Protocol Label Switching

   LSA       Link State Advertisement

   ISCD      Interface Switching Capability Descriptor

   LSP       Label Switched Path

   OSPF      Open Shortest Path First

   PSN       Packet Switched Network

   SCSI      Switching Capability-specific information

   SNR       Signal-to-noise Ratio

   SONET-SDH Synchronous Optical Network - Synchronous Digital

   SPF       Shortest Path First

   TE        Traffic Engineering

   TLV       Type Length Value

1. Introduction

   Some data plane technologies, e.g., microwave, and copper,   allow
   seamless change of maximum physical bandwidth through a set of known
   discrete values. The parameter, availability, as described in
   [G.827], [F.1703] and [P.530] is often used to describe the link
   capacity. The availability is a time scale, representing a proportion
   of the operating time that the requested bandwidth is ensured. To
   set up an LSP across these links, availability information is
   required by the nodes to verify the bandwidth before making a
   bandwidth reservation.  Assigning different availability classes
   over such links provides for a more efficient planning of link
   capacity to support different types of services. The link
   availability information will be determined by the operator and
   statically configured. It will usually be determined from the
   availability requirements of the services expected to be carried on
   the LSP. For example, voice service usually needs "five nines"
   availability, while non-real time services may adequately perform at
   four or three nines availability. For the route computation, both
   the availability information and the bandwidth resource information
   are needed. Since different service types may need different
   availability guarantees, multiple <availability, bandwidth> pairs
   may be required to be associated with a link.

   In this document, a new type of the Generalized SCSI TLV,
   Availability TLV is defined. It is intended that technology-specific
   documents will reference this document to describe specific uses.
   The signaling extension to support links with discrete bandwidth is
   defined in [ETPAI].

2. Overview

   A node which has link(s) with variable bandwidth attached should
   include < availability, bandwidth> information list in its OSPF
   Traffic Engineering (TE) LSA messages. The list provides the mapping
   between the link nominal bandwidth and its availability level. This
   information is used for path calculation by the node(s). The setup
   of a Label Switched Path requires this information to be flooded in
   the network and used by the nodes or the PCE for the path
   computation. In this document, a new type of the Generalized SCSI
   TLV, Availability TLV is defined. The computed path can then be
   provisioned via the signaling protocol [ETPAI].

   Note, the mechanisms described in this document only distribute
   availability information. The methods for measuring the information
   or using the information for route computation are outside the scope
   of this document.

3. TE Metric Extension to OSPF-TE

3.1. Availability SCSI-TLV

   The Generalized SCSI is defined in [GSCSI]. The Availability TLV
   defined in this document is a new type of Generalized SCSI-TLV. The
   Availability SCSI-TLV can be included for one or more times. The
   Availability SCSI-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
      |               Type            |               Length          |
      |                   Availability level                          |
      |                   LSP Bandwidth at Availability level n       |
   Type: 0x01, 16 bits.

   Length: A 16 bits field that expresses the length of the TLV in

   Availability level: 32 bits

   This field is a 32-bit IEEE floating point number which describes
   the decimal value of availability guarantee of the switching
   capability in the Interface Switching Capability Descriptor (ISCD)
   [RFC4202] object. The value MUST be less than 1. The Availability
   level is usually expressed in the value of

   LSP Bandwidth at Availability level n: 32 bits

   This field is a 32-bit IEEE floating point number which describes
   the LSP Bandwidth for the Availability level represented in the
   Availability field. The units are bytes per second.

3.2. Processing Procedures

   A node advertising an interface with a Switching Capability which
   supports variable bandwidth attached SHOULD contain one or more
   Availability SCSI-TLVs in its OSPF TE LSA messages. Each
   Availability SCSI-TLV provides the information about how much
   bandwidth a link can support for a specified availability. This
   information MAY be used for path calculation by the node(s).

   The Availability SCSI-TLV MUST NOT be sent in ISCDs with Switching
   Capability field values that have not been defined to support the
   Availability SCSI-TLV. Non-supporting nodes would see such as a
   malformed ISCD/LSA.

   Absence of the Availability SCSI-TLV in an ISCD containing Switching
   Capability field values that have been defined to support the
   Availability SCSI-TLV, SHALL be interpreted as representing fixed-
   bandwidth link with the highest availability value.

   Only one Availability SCSI-TLV for the specific availability level
   SHOULD be sent. If multiple are present, only the first Availability
   SCSI-TLV for an availability level carried in the same ISCD SHALL be

4. Security Considerations

   This document does not introduce security issues beyond those
   discussed in [RFC4203].  As with [RFC4203], it specifies the content
   of an Opaque LSAs in OSPFv2.  As Opaque LSAs are not used for
   Shortest Path First (SPF) computation or normal routing, the
   extensions specified here have no direct effect on IP routing.
   Tampering with GMPLS TE LSAs may have an impact on the ability to
   set up connections in the underlying data plane network. As the
   additional availability information may represent information that
   an operator may wish to keep private, consideration should be given
   to securing this information. [RFC3630] notes that the security
   mechanisms described in [RFC2328] apply to Opaque LSAs carried in
   OSPFv2.  An analysis of the security of OSPF is provided in
   [RFC6863] and applies to the extensions to OSPF as described in this
   document.  Any new mechanisms developed to protect the transmission
   of information carried in Opaque LSAs will also automatically
   protect the extensions defined in this document.

   Please refer to [RFC5920] for details on security threats; defensive
   techniques; monitoring, detection, and reporting of security
   attacks; and requirements.

5. IANA Considerations

   This document introduces a new type for availability of the
   Generalized SCSI-TLV of the TE Link TLV in the TE Opaque LSA for
   OSPF v2. Technology-specific documents will reference this document
   to describe specific use of this Availability SCSI-TLV.

   IANA has created a registry called the "Generalized SCSI (Switching
   Capability Specific Information) TLVs Types" registry. The registry
   is needed to be updated to include the Availability SCSI-TLV. This
   document proposes a suggested value for the Availability SCSI-TLV;
   it is requested that the suggested value be granted by IANA.

   Type             Description                    Reference
   ---              ------------------             -----------

   0x01             Availability                   [This ID]

   The registration procedure for this registry is Standards Action as
   defined in [RFC5226]. [RFC8126].

6. References

6.1. Normative References

   [GSCSI]   Ceccarelli, D. and Berger, L., "Generalized Routing
             Interface Switching Capability Descriptor Switching
             Capability Specific Information", Work in Progress,
             January, 2017.

   [RFC4202] Kompella, K. and Rekhter, Y. (Editors), "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.

6.2. Informative References

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

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

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

   [RFC5226] Narten,T.

   [RFC8126] Cotton,M. and H. Alvestrand, Leiba,B., and Narten T., "Guidelines for
             Writing an IANA Considerations Section in RFCs",
             RFC 5226, May 2008. 8126, June 2017.

   [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
             Networks", RFC 5920, July 2010.

   [RFC6863] Hartman, S. and D. Zhang, "Analysis of OSPF Security
             According to the Keying and Authentication for Routing
             Protocols (KARP) Design Guide", RFC 6863, March 2013.

   [G.827]  ITU-T Recommendation, "Availability performance parameters
             and objectives for end-to-end international constant bit-
             rate digital paths", September, 2003.

   [F.1703]  ITU-R Recommendation, "Availability objectives for real
             digital fixed wireless links used in 27 500 km
             hypothetical reference paths and connections", January,

   [P.530]   ITU-R Recommendation," Propagation data and prediction
             methods required for the design of terrestrial line-of-
             sight systems", February, 2012

   [ETPAI]   H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
             "Ethernet Traffic Parameters with Availability
             Information", Work in Progress, August, 2016

7. Acknowledgments

   The authors would like to thank Acee Lindem, Daniele Ceccarelli, Lou
   Berger for their comments on the document.

   Authors' Addresses
   Hao Long
   Huawei Technologies Co., Ltd.
   No.1899, Xiyuan Avenue, Hi-tech Western District
   Chengdu 611731, P.R.China

   Phone: +86-18615778750

   Min Ye
   Huawei Technologies Co., Ltd.
   No.1899, Xiyuan Avenue, Hi-tech Western District
   Chengdu 611731, P.R.China


   Greg Mirsky


   Alessandro D'Alessandro
   Telecom Italia S.p.A


   Himanshu Shah
   Ciena Corp.
   3939 North First Street
   San Jose, CA 95134