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 13, August 2016                                  February 19, 2016                                October 16, 2015

     OSPF Routing Extension for Links with Variable Discrete Bandwidth


   A network MAY 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 in OSPF routing protocol. 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 .................................................... 3
   3. Extension to OSPF Routing Protocol........................... 4
      3.1. Interface Switching Capacity Descriptor................. 4
      3.2. ISCD Availability sub-TLV............................... 4
      3.2. Signaling Process....................................... 5
   4. Security Considerations...................................... 5
   5. IANA Considerations ......................................... 5
   6. References .................................................. 5
      6.1. Normative References.................................... 5
      6.2. Informative References.................................. 6
   7. Acknowledgments ............................................. 6

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:

   OSPF    Open Shortest Path First

   PSN     Packet Switched Network

   SNR     Signal-to-noise Ratio

   LSP     Label Switched Path
   ISCD    Interface Switching Capacity Descriptor

   LSA     Link State Advertisement

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 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" ''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 [ASTE].

   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 to support in
   routing signaling. The extension reuses the reserved field in the
   ISCD and also introduces an optional Availability sub-TLV.

   If there is a hop that cannot support the Availability sub-TLV, the
   Availability sub-TLV should be ignored.

2. Overview

   A node which has link(s) with variable bandwidth attached should
   contain a <bandwidth, availability> information list in its OSPF TE
   LSA messages. The list provides the information that how much
   bandwidth a link can support for a specified availability. This
   information is used for path calculation by the node(s).

   To setup a label switching path (LSP), a node may collect link
   information which is spread in OSPF TE LSA messages by network nodes
   to get know about the network topology, calculate out an LSP route
   based on the network topology and send the calculated LSP route to
   signaling to initiate a PATH/RESV message for setting up the LSP.

   Availability information is required to carry in the signaling
   message to better utilize the link bandwidth. The signaling
   extension for availability can be found in [ASTE].

3. Extension to OSPF Routing Protocol

3.1. Interface Switching Capacity Descriptor ISCD Availability sub-TLV

   The Interface Switching Capacity Descriptor (ISCD) sub-TLV is
   defined in Section 1.4 of [RFC 4203].

3.2. The ISCD Availability sub-TLV

   The Switching Capability field MAY be PSC-1, LSC.
   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: 0x01, 16 bits;

      Length: 16 bits;

       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 in the ISCD object which has the AI value
           equal to Index of this sub-TLV. The value MUST be less than

       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.


3.2. Signaling Process

   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.

4. Security Considerations

   This document does not introduce new security considerations to the
   existing OSPF protocol.

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. This document
   proposes a suggested value for the Availability sub-TLV; it is
   recommended that the suggested value be granted by IANA. Initial
   values are as follows:

   Type    Length            Format                   Description

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

   0        -                Reserved                 Reserved value

   0x01      8               see Section 3.2          Availability

6. References

6.1. Normative References

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

    [ASTE]    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

   [RFC2210] Wroclawski, J., "The ''The Use of RSVP with IETF Integrated
             Services'', RFC 2210, September 1997.

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

   [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
             V.,and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
             Tunnels", RFC 3209, December 2001.

   [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
             (GMPLS) Signaling Resource ReserVation Protocol-Traffic
             Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

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

   [MCOS]    Minei, I., Gan, D., Kompella, K., and X. Li, "Extensions
             for Differentiated Services-aware Traffic Engineered
             LSPs", Work in Progress, June 2006.

   [G.827]  ITU-T Recommendation, "Availability ''Availability performance parameters
             and objectives for end-to-end international constant bit-
             rate digital paths", paths'', September, 2003.

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

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

   [EN 302 217] ETSI standard, "Fixed ''Fixed Radio Systems; Characteristics
             and requirements for point-to-point equipment and
             antennas'', April, 2009

7. Acknowledgments

   The authors would like to thank Lou Berger for his comments on the

   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