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: November 2019                                      May 5, 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 (e.g., climate). Availability is
   typically used for describing these links when doing network
   planning. This document introduces an optional Bandwidth
   Availability TLV in Resource ReSerVation Protocol - Traffic Engineer
   (RSVP-TE) signaling. This extension can be used to set up a
   Generalized Multi-Protocol Label Switching (GMPLS) Label Switched
   Path (LSP) in conjunction with the Ethernet SENDER_TSPEC object.

Status of this Memo

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   This Internet-Draft will expire on November 5, 2019.

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Table of Contents

   1. Introduction ................................................ 3
   2. Overview .................................................... 4
   3. Extension to RSVP-TE Signaling............................... 5
      3.1. Bandwidth Availability TLV.............................. 5
      3.2. Signaling Process....................................... 6
   4. Security Considerations...................................... 7
   5. IANA Considerations ......................................... 7
      5.1  Ethernet Sender TSpec TLVs ............................. 7
   6. References .................................................. 8
      6.1. Normative References.................................... 8
      6.2. Informative References.................................. 9
   7. Appendix: Bandwidth Availability Example..................... 9
   8. Acknowledgments ............................................ 11

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
   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

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   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 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 likely be reserved as the
   highest bandwidth availability. Suppose, 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 makes a
   request 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, 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.

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   To fulfill LSP setup by signaling in these scenarios, this document
   specifies a Bandwidth Availability TLV. The Bandwidth Availability
   TLV can be applicable to any kind of physical links with variable
   discrete bandwidth, such as microwave or DSL. Multiple Bandwidth
   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 Bandwidth 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 advertised in a routing message, e.g.,
   OSPF TE LSA message, by network nodes to obtain network topology
   information, and then calculate an LSP route based on the network
   topology. The calculated LSP route 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 at setup. Each <bandwidth, availability> pair
   in the list means the listed bandwidth with specified availability
   is required. The list could be 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 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.

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3. Extension to RSVP-TE Signaling

3.1. Bandwidth Availability TLV

   A Bandwidth 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 Bandwidth Availability
   TLV. The Bandwidth 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
      |               Type            |              Length           |
      |    Index      |                 Reserved                      |
      |                         Availability                          |

                     Figure 1: Bandwidth Availability TLV

      Type (2 octets): 0x04(suggested; TBD by IANA)

      Length (2 octets): 0x0C. Indicates the length in bytes of the
      whole TLV including the Type and Length fields, in this case 12

      Index (1 octet):

      When the Bandwidth Availability TLV is included, the Ethernet
      Bandwidth Profile TLV MUST also be included. If there are multiple
      bandwidth requirements present (in multiple Ethernet Bandwidth
      Profile TLVs) and they have different availability requirements,
      multiple Bandwidth Availability TLVs MUST be carried. In such a
      case, the Bandwidth 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 Bandwidth 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-point number in binary
      interchange format [IEEE754] describes the decimal value of the
      availability requirement for this bandwidth request. The value

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      MUST be less than 1 and is usually expressed in the value of
      0.99/0.999/0.9999/0.99999. The IEEE floating-point number is used
      here to align with [RFC8330]. However when representing values
      higher than 0.999999, the floating-point number starts to
      introduce errors in relation to intended precision. However in
      reality, 0.99999 is normally considered as the highest
      availability value (5 minutes outage in a year) in telecom
      network, therefore the use of floating-point number in
      availability is acceptable.

3.2. Signaling Process

   The source node initiates a PATH message which may carry a number of
   bandwidth requests, including one or more Ethernet Bandwidth Profile
   TLVs and one or more Bandwidth Availability TLVs. Each Ethernet
   Bandwidth Profile TLV corresponds to an availability parameter in
   the associated Bandwidth 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 resource with respective availability guarantee on the
   local link when the PATH message is received.

     o   When all <bandwidth, availability> 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), the node SHOULD reserve the bandwidth resource from each
        remaining sub-bandwidth portion on its local link to set up
        this LSP. Optionally, a higher availability bandwidth can be
        allocated to a lower availability request when the lower
        availability bandwidth cannot satisfy the request.

     o   When at least one <bandwidth, availability> requirement
        request cannot be satisfied, the node 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 4.2 of [RFC3471].

   When a node does not support the Bandwidth Availability TLV, the
   node should send a PathErr message with error code "Unknown

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   Attributes TLV", as specified in [RFC5420]. An LSP could also be set
   up in this case if there's enough bandwidth (the availability level
   of the reserved bandwidth is unknown). When a node receives
   Bandwidth Availability TLVs with a mix of zero index and non-zero
   index, the message MUST be ignored and MUST NOT be propagated. When
   a node receives Bandwidth Availability TLVs (non-zero index) with no
   matching index value among the bandwidth-TLVs, the message MUST be
   ignored and MUST NOT be propagated. When a node receives several
   <bandwidth, availability> pairs, but there are extra bandwidth-TLVs
   without matching the index of any Availability-TLV, the extra
   bandwidth-TLVs MUST be ignored and MUST NOT be propagated.

4. Security Considerations

   This document defines a Bandwidth Availability TLV in RSVP-TE
   signaling used in GMPLS networks. [RFC3945] notes that
   authentication in GMPLS systems may use the authentication
   mechanisms of the component protocols. [RFC5920] provides an
   overview of security vulnerabilities and protection mechanisms for
   the GMPLS control plane. Especially section 7.1.2 of [RFC5920]
   discusses the control-plane protection with RSVP-TE by using general
   RSVP security tools, limiting the impact of an attack on control-
   plane resources, and authentication for RSVP messages. Moreover, the
   GMPLS network is often considered to be a closed network such that
   insertion, modification, or inspection of packets by an outside
   party is not possible.

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 needs
   to be updated to include the Bandwidth Availability TLV which is
   defined as follow. This document proposes a suggested value for the
   Availability sub-TLV; it is requested that the suggested value be
   granted by IANA.

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   Type                     Description                 Reference

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

   0x04                     Bandwidth Availability      [This ID]

   (Suggested; TBD by IANA)

   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.

   [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
             (GMPLS) Signaling Functional Description", RFC 3471,
             January 2003.

   [RFC5420] Farrel, A., Papadimitriou, D., Vasseur JP., and Ayyangar
             A., "Encoding of Attributes for MPLS LSP Establishment
             Using Resource Reservation Protocol Traffic Engineering
             (RSVP-TE)", RFC 5420, February 2009.

   [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.

   [IEEE754]  IEEE, "IEEE Standard for Floating-Point Arithmetic",IEEE
             754-2008, DOI 10.1109/IEEESTD.2008.4610935, 2008,

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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.

   [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
             (GMPLS) Architecture", RFC 3945, October 2004.

   [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 connections of last hops. In case of heavy rain
   conditions, to maintain the link connectivity, the microwave link
   may lower the modulation level since moving to a lower modulation
   level provides for a lower Signal-to-Noise Ratio (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-

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   priority traffic can be maintained, while lower-priority traffic is
   dropped. Similarly, copper links 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

   There are discrete buckets per availability level. Under the worst
   weather conditions, there's only 100 Mbps capacity and that's
   99.999% available.  It's treated as effectively "always available"
   since there's no way to do any better. If the weather is bad but not
   the worst weather, modulation level 2 can be used, which gets an
   additional 100 Mbps bandwidth (i.e., 200 Mbps total), so there are
   100 Mbps in the 99.999% bucket and 100 Mbps in the 99.995% bucket.
   In clear weather, modulate level 3 can be used to get 400 Mbps
   total, but that's only 200 Mbps more than at modulation level 2, so
   99.99% bucket has that "extra" 200 Mbps, and the other two buckets
   still have their 100 Mbps each.

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   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.

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   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


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