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: July 2019                                     January 2, 17, 2019

         Ethernet Traffic Parameters with Availability Information


   A packet switching network may contain links with variable
   bandwidth, e.g., copper, radio, etc. The bandwidth of such links is
   sensitive to external environment. environment (e.g., climate). Availability is
   typically used for describing the link these links when during network
   planning. This document introduces an optional Availability TLV in
   Resource ReSerVation Protocol - Traffic Engineer (RSVP-TE)
   signaling. This extension can be used to set up a Generalized Multi-Protocol Multi-
   Protocol Label Switching (GMPLS) Label Switched Path (LSP) using the
   Ethernet SENDER_TSPEC object.

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Table of Contents

   1. Introduction ................................................ 3
   2. Overview .................................................... 4
   3. Extension to RSVP-TE Signaling............................... 4 5
      3.1. Availability TLV........................................ 4 5
      3.2. Signaling Process....................................... 5
   4. Security Considerations...................................... 6
   5. IANA Considerations ......................................... 6
      5.1  Ethernet Sender TSpec TLVs ............................. 6 7
   6. References .................................................. 7
      6.1. Normative References.................................... 7
      6.2. Informative References.................................. 7 8
   7. Appendix: Bandwidth Availability Example..................... 8
   8. Acknowledgments ............................................. 9 ............................................ 10

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [RFC2119].
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The following acronyms are used in this draft:

   RSVP-TE  Resource Reservation Protocol-Traffic Engineering

   LSP      Label Switched Path
   SNR      Signal-to-noise Ratio

   TLV      Type Length Value

   LSA      Link State Advertisement

1. Introduction

   The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473]
   specify the signaling message including the bandwidth request for
   setting up a Label Switched Path in a packet switching network.

   Some data communication technologies 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 based on a time scale, which is a proportion of the
   operating time that the requested bandwidth is ensured. A more
   detailed example on the bandwidth availability can be found in
   Appendix A. Assigning different bandwidth availability classes to
   different types of service services over such kind of links provides for a
   more efficient planning of link capacity. To set up an LSP across
   these links, bandwidth availability information is required for the
   nodes to verify bandwidth satisfaction and make bandwidth
   reservation. The bandwidth availability information should be
   inherited from the bandwidth availability requirements of the
   services expected to be carried on the LSP. For example, voice
   service usually needs "five nines" bandwidth availability, while
   non-real time services may adequately perform at four or three nines
   bandwidth availability. Since different service types may need
   different availabilities guarantees, multiple <availability,
   bandwidth> pairs may be required when signaling.

   If the bandwidth availability requirement is not specified in the
   signaling message, the bandwidth will be reserved as the highest
   bandwidth availability. For example, the bandwidth with 99.999%
   availability of a link is 100 Mbps; the bandwidth with 99.99%
   availability is 200 Mbps. When a video application requests for 120
   Mbps without bandwidth availability requirement, the system will
   consider the request as 120 Mbps with 99.999% bandwidth
   availability, while the available bandwidth with 99.999% bandwidth
   availability is only 100 Mbps, therefore the LSP path cannot be set
   up. But But, in fact, the video application doesn't need 99.999%
   bandwidth availability; 99.99% bandwidth availability is enough. In
   this case, the LSP could be set up if bandwidth availability is also
   specified in the signaling message.

   To fulfill LSP setup by signaling in these scenarios, this document
   specifies an Availability TLV. The Availability TLV can be
   applicable to any kind of physical links with variable discrete
   bandwidth, such as microwave or DSL. Multiple Availability TLVs
   together with multiple Ethernet Bandwidth Profiles can be carried by
   the Ethernet SENDER_TSPEC object [RFC6003]. Since the Ethernet
   FLOWSPEC object has the same format as the Ethernet SENDER_TSPEC
   object [RFC6003], the Availability TLV can also be carried by the
   Ethernet FLOWSPEC object.

2. Overview

   A tunnel in a packet switching network may span one or more links in
   a network. To setup a Label Switched Path (LSP), a node may collect
   link information which is spread advertised in a routing message, e.g.,
   OSPF TE LSA message, by network nodes to get to know about the obtain network
   topology, topology
   information, and then calculate out an LSP route based on the network
   topology, and send the
   topology. The calculated LSP route to signaling to initiate is signaled using a PATH/RESV
   message for setting up the LSP.

   In case that there is (are) link(s) with variable discrete bandwidth
   in a network, a <bandwidth, availability> requirement list should be
   specified for an LSP. LSP at setup. Each <bandwidth, availability> pair
   in the list means that the listed bandwidth with specified availability
   is required. The list could be inherited derived from the results of service
   planning for the LSP.

   A node which has link(s) with variable discrete bandwidth attached
   should contain 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 can
   then be used for path calculation by the node(s). The routing
   extension for availability can be found in [RFC8330].

   When a node initiates a PATH/RESV signaling to set up an LSP, the
   PATH message should carry the <bandwidth, availability> requirement
   list as a bandwidth request.  Intermediate node(s) will allocate the
   bandwidth resource for each availability requirement from the
   remaining bandwidth with corresponding availability. An error
   message may be returned if any <bandwidth, availability> request
   cannot be satisfied.

3. Extension to RSVP-TE Signaling

3.1. Availability TLV

   An Availability TLV is defined as a TLV of the Ethernet SENDER_TSPEC
   object [RFC6003] in this document. The Ethernet SENDER_TSPEC object
   MAY include more than one Availability TLV. The Availability 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
      |    Index      |                 Reserved                      |
      |                          Availability                         |

                          Figure 1: Availability TLV

      Index (1 octet):

      When the Availability TLV is included, it MUST be present along
      with the Ethernet Bandwidth Profile TLV. If the bandwidth
      requirements in the multiple Ethernet Bandwidth Profile TLVs have
      different Availability requirements, multiple Availability TLVs
      SHOULD be carried. In such a case, the Availability TLV has a one
      to one correspondence with the Ethernet Bandwidth Profile TLV by
      having the same value of Index field. If all the bandwidth
      requirements in the Ethernet Bandwidth Profile have the same
      Availability requirement, one Availability TLV SHOULD be carried.
      In this case, the Index field is set to 0.

      Reserved (3 octets): These bits SHOULD be set to zero when sent
      and MUST be ignored when received.

      Availability (4 octets): a 32-bit floating number describes the
      decimal value of availability requirement for this bandwidth
      request. The value MUST be less than 1and is usually expressed in
      the value of 0.99/0.999/0.9999/0.99999.

3.2. Signaling Process

   The source node initiates a PATH message which may carry a number of
   bandwidth request information, requests, including one or more Ethernet Bandwidth Profile
   TLVs and one or more Availability TLVs. Each Ethernet Bandwidth
   Profile TLV corresponds to an availability parameter in the
   Availability TLV.

   The intermediate and destination nodes check whether they can
   satisfy the bandwidth requirements by comparing each bandwidth
   request inside the SENDER_TSPEC objects with the remaining link
   sub-bandwidth sub-
   bandwidth resource with respective availability guarantee on the
   local link when the PATH message is received.

     o   When all <bandwidth, availability> requirements requirement requests can
        be satisfied (the requested bandwidth under each availability
        parameter is smaller than or equal to the remaining bandwidth
        under the corresponding availability parameter on its local
        link), it SHOULD reserve the bandwidth resource from each
        remaining sub-bandwidth portion on its local link to set up
        this LSP. Optionally, the higher availability bandwidth can be
        allocated to lower availability request when the lower
        availability bandwidth cannot satisfy the request.

     o   When at least one <bandwidth, availability> requirement
        request cannot be satisfied, it SHOULD generate PathErr message
        with the error code "Admission Control Error" and the error
        value "Requested Bandwidth Unavailable" (see [RFC2205]).

   When two LSPs request bandwidth with the same availability
   requirement, contention MUST be resolved by comparing the node IDs,
   with the LSP with the higher node ID being assigned the reservation.
   This is consistent with general contention resolution mechanism
   provided in section 3.2 of [RFC3473].

   When a node does not support the Availability TLV, it SHOULD
   generate PathErr message with the error code "Extended Class-Type
   Error" and the error value "Class-Type mismatch" (see [RFC2205]).

4. Security Considerations

   This document does not introduce any new security considerations to
   the existing RSVP-TE signaling protocol. [RFC5920] provides an
   overview of security vulnerabilities and protection mechanisms for
   the GMPLS control plane.

5. IANA Considerations

   IANA maintains registries and sub-registries for RSVP-TE used by
   GMPLS. IANA is requested to make allocations from these registries
   as set out in the following sections.

5.1 Ethernet Sender TSpec TLVs

   IANA maintains a registry of GMPLS parameters called "Generalized
   Multi-Protocol Label Switching (GMPLS) Signaling Parameters".

   IANA has created a sub-registry called "Ethernet Sender TSpec TLVs /
   Ethernet Flowspec TLVs" to contain the TLV type values for TLVs
   carried in the Ethernet SENDER_TSPEC object. The sub-registry is
   needed needs
   to be updated to include the Availability TLV which is defined as
   follow. This document proposes a suggested value for the
   Availability sub-TLV; it is recommended requested that the suggested value be
   granted by IANA.

   Type       Description                            Reference

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

   0x04        Availability                           [This ID]

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

6. References

6.1. Normative References

   [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and
             S.Jamin, "Resource ReSerVation Protocol (RSVP) - Version 1
             Functional Specification", RFC 2205, September 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.

   [RFC6003] Papadimitriou, D. "Ethernet Traffic Parameters", RFC 6003,
             October 2010.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
             2119 Key Words", BCP 14, RFC 8174, May 2017.

6.2. Informative References

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

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

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

   [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

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

   [RFC8330] H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
             "OSPF Traffic Engineering (OSPF-TE) Link Availability
             Extension for Links with Variable Discrete Bandwidth",
             RFC8330, February, 2018

7. Appendix: Bandwidth Availability Example

   In a mobile backhaul network, microwave links are very popular for
   providing connection connections of last hops. In case of heavy rain, rain
   conditions, to maintain the link connectivity, the microwave link
   MAY lower the modulation level since demodulating the to a lower
   modulation level needs provides for a lower Signal-to-Noise Ratio (SNR). (SNR)
   requirement. This is called adaptive modulation technology [EN 302
   217]. However, a lower modulation level also means lower link
   bandwidth. When link bandwidth is reduced because of modulation
   down-shifting, high-priority traffic can be maintained, while lower-priority lower-
   priority traffic is dropped. Similarly, the copper links MAY may change
   their link bandwidth due to external interference.

   Presuming that a link has three discrete bandwidth levels:

   The link bandwidth under modulation level 1, e.g., QPSK, is 100

   The link bandwidth under modulation level 2, e.g., 16QAM, is 200

   The link bandwidth under modulation level 3, e.g., 256QAM, is 400


   On a sunny day, the modulation level 3 can be used to achieve 400
   Mbps link bandwidth.

   A light rain with X mm/h rate triggers the system to change the
   modulation level from level 3 to level 2, with bandwidth changing
   from 400 Mbps to 200 Mbps. The probability of X mm/h rain in the
   local area is 52 minutes in a year. Then the dropped 200 Mbps
   bandwidth has 99.99% availability.

   A heavy rain with Y(Y>X) mm/h rate triggers the system to change the
   modulation level from level 2 to level 1, with bandwidth changing
   from 200 Mbps to 100 Mbps. The probability of Y mm/h rain in the
   local area is 26 minutes in a year. Then the dropped 100 Mbps
   bandwidth has 99.995% availability.

   For the 100M bandwidth of the modulation level 1, only the extreme
   weather condition can cause the whole system to be unavailable,
   which only happens for 5 minutes in a year. So the 100 Mbps
   bandwidth of the modulation level 1 owns the availability of

   In a word,

   Therefore, the maximum bandwidth is 400 Mbps. According to the
   weather condition, the sub-bandwidth and its availability are shown
   as follows:

   Sub-bandwidth (Mbps)   Availability

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

   200                    99.99%

   100                    99.995%

   100                    99.999%

8. Acknowledgments

   The authors would like to thank Deborah Brungard, Khuzema Pithewan,
   Lou Berger, Yuji Tochio, Dieter Beller, and Autumn Liu for their
   comments and contributions 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 (editor)
   Huawei Technologies Co., Ltd.
   No.1899, Xiyuan Avenue, Hi-tech Western District
   Chengdu 611731, P.R.China


   Greg Mirsky (editor)


   Alessandro D'Alessandro
   Telecom Italia S.p.A


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