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: December 2016                                     June 3, February 2017                                  August 19, 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
   Availability sub-TLV to extend the Open Shortest Path First (OSPF)
   Generalized Multi-Protocol Label Switching (GMPLS) as defined in
   [RFC4203]. (GMPLS). This extension
   can be used for route computation in a network that contains links
   with variable discrete bandwidth.

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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
   5. IANA Considerations ......................................... 6
   6. References .................................................. 6
      6.1. Normative References.................................... 6
      6.2. Informative References.................................. 6
   7. Acknowledgments ............................................. 7

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 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

1. Introduction

   Some data communication technologies, e.g., microwave, and copper,
   allow seamless change of maximum physical bandwidth through a set of
   known discrete values. The parameter availability [G.827], [F.1703],
   [P.530] is often used to describe the link capacity during network
   planning. The availability is a time scale, which is a proportion of
   the operating time that the requested bandwidth is ensured.
   Assigning different availability classes to different types of
   service over such kind of links provides more efficient planning of
   link capacity. To set up an LSP across these links, availability
   information is required for the nodes to verify bandwidth
   satisfaction and make bandwidth reservation. The availability
   information should be inherited 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. Since different service types may need different
   availabilities guarantees, multiple <availability, bandwidth> pairs
   may be required when signaling. The signaling extension for links
   with discrete bandwidth is defined in [ETPAI].

   For the route computation, the availability information should be
   provided along with bandwidth resource information. In this document,
   an extension on Interface Switching Capacity Descriptor (ISCD)
   [RFC4202] for availability information is defined. The extension
   reuses the reserved field in the ISCD and also introduces an
   optional Availability sub-TLV.

2. Overview

   A node which has link(s) with variable bandwidth attached should
   include a <bandwidth, availability> information list in its OSPF 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 piece of information to be flooded in the network and
   used by the nodes or the PCE for the path computation. The computed
   path can then be provisioned via the signaling protocol.

   For links with variable discrete bandwidth, Availability information
   is needed to be carried by the signaling for a better link bandwidth
   utilization. Extensions to RSVP-TE can be found in [ETPAI].

3. 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 is defined in this document as 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;

      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 capacity capability in the ISCD object which has the AI value
           equal to Index of this sub-TLV. object. The value MUST be
           less than 1. The Availability level is usually expressed in
           the value of 0.99/0.999/0.9999/0.99999.

       LSP Bandwidth at Availability level n: 32 bits

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

3.2. Processing Procedures

   A node which has link(s) with 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 be used for path calculation
   by the node(s).

   A node that doesn't support ISCD Availability sub-TLV SHOULD ignore
   ISCD Availability sub-TLV. If a node who supports ISCD Availability
   sub-TLVs doesn't receive the TLV, it indicates that the link is with
   fixed bandwidth, and the availability can be interpreted as the
   highest availability value, e.g., five nines. It's legal to send
   multiple ISCD Availability sub-TLVs for the same availability level.

4. Security Considerations

   This document extends [RFC4203].  As with [RFC4203], it specifies
   the contents of 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 effect on the underlying
   transport (optical and/or Synchronous Optical Network - Synchronous
   Digital Hierarchy (SONET-SDH)) network.  [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. IANA will
   created and maintain 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 recommended 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.

   [ETPAI]   H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
             "Ethernet Traffic Parameters with Availability
             Information", Work in Progress, June, 2015

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