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: April 2017                                    October 8, 24, 2016

    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 introduces an optional ISCD Interface
   Switching Capability Descriptor (ISCD) Availability sub-TLV to
   extend the Generalized Multi-Protocol Label Switching (GMPLS) Open
   Shortest Path First (OSPF) routing protocol. This 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. Extension to OSPF Routing Protocol........................... 4
      3.1. ISCD Availability sub-TLV............................... 4
      3.2. Signaling Process....................................... 5
   4. Security Considerations...................................... 5 6
   5. IANA Considerations ......................................... 6
   6. References .................................................. 6 7
      6.1. Normative References.................................... 6 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 Capacity Capability Descriptor

   LSP       Label Switched Path

   OSPF      Open Shortest Path First

   PSN       Packet Switched Network

   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, an extension on Interface Switching Capacity Capability
   Descriptor (ISCD) [RFC4202] for availability information 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 a < a< availability, bandwidth> information list in its OSPF TE
   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, an extension to Interface Switching Capacity Capability
   Descriptor (ISCD) [RFC4202] for availability information is defined.
   The computed path can then be provisioned via the signaling protocol[ETPAI]. protocol

   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. ISCD Availability sub-TLV

   The ISCD sub-TLV is defined in Section 1.4 of [RFC4203]. The ISCD
   Availability sub-TLV defined in this document is a sub-TLV of ISCD.
   The Switching Capability specific information field of ISCD MAY
   include one or more ISCD Availability sub-TLV(s). The ISCD
   Availability 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
      |               Type            |               Length          |
      |                   Availability level                          |
      |                   LSP Bandwidth at Availability level n       |
   Type: TBA by IANA, suggested value is 0x01, 16 bits; 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 ISCD 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 which has link(s) advertising an interface with a Switching Capability which
   supports variable bandwidth attached SHOULD contain one or more ISCD
   Availability sub-TLVs in its OSPF TE LSA messages. Each ISCD
   Availability sub-TLV provides the information about how much
   bandwidth a link can support for a specified availability. This
   information SHOULD MAY be used for path calculation by the node(s).

   A node

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

   Absence of the ISCD Availability sub-TLV but it SHOULD be included in LSAs
   sent to OSPF neighbors [RFC3630]. If a node who supports an ISCD
   Availability sub-TLVs does not receive the TLV, it SHOULD assume containing
   Switching Capability field values that have been defined to support
   the link is with fixed bandwidth, and the availability can ISCD Availability sub-TLV, SHALL be interpreted as representing
   fixed-bandwidth link with the highest availability value, e.g., five nines.
   It's not allowed to send multiple value.

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

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] 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 an Availability sub-TLV of the ISCD sub-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 sub-TLV. IANA is requested to create a new
   sub-registry, the ''Types for sub-TLV of Interface Switching
   Capability Descriptor'' registry under the "Open Shortest Path First
   (OSPF) Traffic Engineering TLVs" registry, see

   This document proposes a suggested value for the Availability sub-
   TLV; it is requested that the suggested value be granted by IANA.

   Type             Description                    Reference

   ---              ------------------             -----------

   0                Reserved                       [This ID]

   0x01             Availability                   [This ID]

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

6. References

6.1. Normative References

   [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. and H. Alvestrand, ''Guidelines for Writing an
             IANA Considerations Section in RFCs'', RFC 5226, May 2008.

   [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, June, 2015

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