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 2018                                     January 30, 2018

         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. Availability is typically used for
   describing the link 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 Label Switched Path (LSP) in a Packet Switched
   Network (PSN) that contains links with discretely variable

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   This Internet-Draft will expire on July 30, 2018.

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Table of Contents

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

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:

   RSVP-TE  Resource Reservation Protocol-Traffic Engineering

   LSP      Label Switched Path

   PSN      Packet Switched Network

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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 PSN 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 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 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.

   If the availability requirement is not specified in the signaling
   message, the bandwidth will be reserved as the highest 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 availability
   requirement, the system will consider the request as 120 Mbps with
   99.999% availability, while the available bandwidth with 99.999%
   availability is only 100 Mbps, therefore the LSP path cannot be set
   up. But in fact, video application doesn't need 99.999% availability;
   99.99% availability is enough. In this case, the LSP could be set up
   if availability is 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

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   bandwidth, such as microwave or DSL. Multiple Availability TLVs
   together with multiple Ethernet Bandwidth Profiles can be carried in
   the Ethernet SENDER_TSPEC object.

2. Overview

   A PSN tunnel 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 in routing message, e.g., OSPF TE LSA message, by network
   nodes to get to know about the network topology, and 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.

   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. Each <bandwidth, availability> pair in the
   list means that listed bandwidth with specified availability is
   required. The list could be inherited 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
   used for path calculation by the node(s). The routing extension for
   availability can be found in [ARTE].

   When a node initiates a PATH/RESV signaling to set up an LSP, the
   PATH message should carry the <bandwidth, availability> requirement
   list as 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
   SENDEDR_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:

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       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):

      The Availability TLV MUST come along with 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 one to one correspondence
      with 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 PATH messages which carry a number of
   bandwidth request information, 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
   requirement inside the SENDER_TSPEC objects with the remaining link
   sub-bandwidth resource with respective availability guarantee on the
   local link when received the PATH message.

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

   If two LSPs request for the bandwidth with the same availability
   requirement, a way to resolve the contention is comparing the node
   ID, the node with the higher node ID will win the contention. More
   details can be found in [RFC3473].

   If a node does not support 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 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 to be updated to include the Availability TLV which is
   defined as follow. This document proposes a suggested value for the

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   Availability sub-TLV; it is recommended 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.

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.

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   [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

   [ARTE]    H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
             "OSPF Routing Extension for Links with Variable Discrete
             Bandwidth", Work in Progress, October, 2016

7. Appendix: Bandwidth Availability Example

   In mobile backhaul network, microwave links are very popular for
   providing connection of last hops. In case of heavy rain, to
   maintain the link connectivity, the microwave link MAY lower the
   modulation level since demodulating the lower modulation level needs
   a lower Signal-to-Noise Ratio (SNR). 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 traffic is dropped.
   Similarly, the 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 Mbps;

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

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

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

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   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 unavailable, which only
   happens for 5 minutes in a year. So the 100 Mbps bandwidth of the
   modulation level 1 owns the availability of 99.999%.

   In a word, 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 Khuzema Pithewan, Lou Berger, Yuji
   Tochio, Dieter Beller, and Autumn Liu for their comments on the

   Authors' Addresses

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   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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