Network Working Group                                    H. Long, M. Ye
Internet Draft                             Huawei Technologies Co., Ltd
Intended status: Standards Track                              G. Mirsky
                                                           A Alessandro
                                                   Telecom Italia S.p.A
                                                                H. Shah
Expires: October 2014                                    April 25, 2014

        RSVP-TE Signaling Extension for Links with Variable Discrete


   Packet switching network MAY contain links with variable bandwidth,
   e.g., copper, radio, etc. The bandwidth of such link is sensitive to
   external environment. Availability is typically used for describing
   the link during network planning. This document describes an
   extension for RSVP-TE signaling for setting up a label switching
   path (LSP) in a Packet Switched Network (PSN) network which contains
   links with discretely variable bandwidth by introducing an OPTIONAL
   availability field in RSVP-TE signaling.

Status of this Memo

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   This Internet-Draft will expire on October 26, 2014.

Copyright Notice

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Table of Contents

   1. Introduction ................................................ 3
   2. Overview .................................................... 4
   3. Extension to RSVP-TE Signaling............................... 5
         3.1.1. Availability sub-TLV............................... 5
      3.2. FLOWSPEC Object......................................... 6
      3.3. Signaling Process....................................... 6
   4. Security Considerations...................................... 7
   5. IANA Considerations ......................................... 7
      5.1  Ethernet Bandwidth Profile TLV ......................... 7
   6. References .................................................. 8
      6.1. Normative References.................................... 8
      6.2. Informative References.................................. 8
   7. Acknowledgments ............................................. 9
   Appendix A ..................................................... 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

   PE       Provider Edge

   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 switching path in a PSN network.

   Some data communication technologies allow seamless change of
   maximum physical bandwidth through a set of known discrete values.
   For 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 lower modulation level need
   lower signal-to-noise ratio (SNR). This is called adaptive
   modulation technology [EN 302 217]. However, lower modulation level
   also means lower link bandwidth. When link bandwidth reduced because
   of modulation down-shifting, high priority traffic can be maintained,
   while lower priority traffic is dropped. Similarly the cooper links
   MAY change their link bandwidth due to external interference.

   The parameter availability [G.827, F.1703, P.530] is often used to
   describe the link capacity during network planning. 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 guarantee, 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
   100Mbps; the bandwidth with 99.99% availability is 200Mbps. When a

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   video application requests for 120Mbps without availability
   requirement, the system will compare 120Mbps with 100Mbps, therefore
   cannot set up the LSP path. 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 a new Availability sub-TLV as the sub-TLV of Ethernet
   bandwidth profiles [RFC6003]. The Availability sub-TLV can be
   applicable to any kind of physical links with variable discrete
   bandwidth, such as microwave or DSL. Multiple bandwidth profiles
   with different availability can be carried in the SENDER_TSPEC

2. Overview

   A PSN tunnel MAY span one or more links in a network. To setup a
   label switching path (LSP), a PE 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 information that how
   much bandwidth a link can support for a specified availability. This
   information is used for path calculation by the PE node(s). The
   routing extension for availability can be found in [ARTE].

   When a PE 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.

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3. Extension to RSVP-TE Signaling

   The RSVP-TE signaling extension in this document is based on RFC6003:
   a new sub-TLV for Ethernet Bandwidth Profile TLV is defined.

3.1.1. Availability sub-TLV

   The Ethernet Bandwidth Profile TLV in RFC6003 has the following
   format. A new filed is defined in this document as shown in Figure 1.

       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               |
      |Pro|A|         |     Index     |          Reserved             |
      |                              CIR                              |
      |                              CBS                              |
      |                              EIR                              |
      |                              EBS                              |
      Figure 1: A new "AF" filed in Ethernet Bandwidth Profile TLV

   A new filed is defined in this document:

     AF filed (bit 2): Availability Field (AF)

   If the AF filed is set to 1, Availability sub-TLV MUST be included
   in the Bandwidth Profile TLV. If the AF field is set to value 0,
   then an Availability sub-TLV SHOULD NOT be included. The
   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                         |

                        Figure 2: Availability sub-TLV

      Type (2 octets): TBD

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      Length (2 octets): 4

      Availability (4 octets): a 32-bit floating number describes
      availability requirement for this bandwidth request. The value
      MUST be less than 1.

   As the Ethernet Bandwidth Profile TLV can be carried for one or more
   times in the Ethernet SENDER_TSPEC object, the Availability sub-TLV
   can also be present for one or more times.

3.2. FLOWSPEC Object

   The FLOWSPEC object (Class-Num = 9, Class-Type = TBD) has the same
   format as the Ethernet SENDER_TSPEC object.

3.3. Signaling Process

   The source node initiates PATH messages including one or more
   Bandwidth Profile TLVs with different availability value in the
   SENDER_TSPEC object. Each Bandwidth Profile TLV specifies the
   portion of bandwidth request with referred availability requirement.

   The intermediate and destination nodes checks 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 when
   received the PATH message.

     o   If all <bandwidth, availability> requirements can be
        satisfied, it SHOULD reserve the bandwidth resource from each
        remaining sub-bandwidth portion 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 the Availability sub-TLV, it SHOULD
   ignore the availability requirement in the Availability sub-TLV, and

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   SHOULD only use the bandwidth request in the Ethernet Bandwidth
   Profile TLV. The RFC6003[RFC6003] states that a node that does not
   support a flag SHOULD ignore it. Thus a legacy implementation SHOULD
   ignore the Availability Flag.

4. Security Considerations

   This document does not introduce new security considerations to the
   existing RSVP-TE signaling protocol.

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 Bandwidth Profile TLV

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

   IANA has created a new sub-registry called "Ethernet Bandwidth
   Profiles" to contain bit flags carried in the Ethernet Bandwidth
   Profile TLV of the Ethernet SENDER_TSPEC object.

   Bits are to be allocated by IETF Standards Action. Bits are numbered
   from bit 0 as the low order bit. A new bit field is as follow:

   Bit     Hex               Description              Reference

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

   2       0x03              Availability Field (AF)   [This ID]

   Sub-TLV types for Ethernet Bandwidth Profiles are to be allocated by
   IETF Standard Action. Initial values are as follows:

   Type    Length            Format                   Description

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

   0        -                Reserved                 Reserved value

   TBD      4                see Section 3.1          Availability sub-

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6. References

6.1. Normative References

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

   [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, February, 2014

6.2. Informative References

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

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7. Acknowledgments

   The authors would like to thank Khuzema Pithewan, Lou Berger, Yuji
   Tochio, Dieter Beller, and Autumn Liu for their comments on the

   Appendix A

   Presuming that a link has three discrete bandwidth levels:

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

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

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

   In sunny day, the modulation level 3 can be used to achieve 400Mbps
   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 400Mbps to 200Mbps. The probability of X mm/h rain in the local
   area is 52 minutes in a year. Then the dropped 200Mbps 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 200Mbps to 100Mbps. The probability of Y mm/h rain in the local
   area is 26 minutes in a year. Then the dropped 100Mbps 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 100Mbps bandwidth of the
   modulation level 1 owns the availability of 99.999%.

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

   Sub-bandwidth(Mbps)    Availability

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

   200                    99.99%

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   100                    99.995%

   100                    99.999%

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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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