CCAMP Working Group                                       Haomian Zheng
Internet-Draft                                               Italo Busi
Intended status: Standards Track                                 Huawei
                                                              Zafar Ali
                                                                  Cisco
                                                         Sergio Belotti
                                                                  Nokia
                                                     Daniele Ceccarelli
                                                               Ericsson
                                                            Daniel King
                                                   Lancaster University

Expires: September 6, 2017                            March 6, 2017


   Framework for GMPLS Control of Optical Transport Networks in G.709
                               Edition 5

                 draft-zheng-ccamp-gmpls-g709v5-fwk-00.txt


Abstract

   The International Telecommunication Union Telecommunication
   Standardization Sector (ITU-T) has extended its Recommendations
   Optical Transport Networks (OTNs, G.709) to edition 5 to support new
   features, including beyond 100 Gbps (B100G) OTN containers.

   This document summarizes the architecture and requirements, and
   provides corresponding control plane considerations to guide
   protocol extensions development in support of OTNv5 control
   mechanisms.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
   the provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."



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   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

  This Internet-Draft will expire on September 6, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with
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   document must include Simplified BSD License text as described in
   Section 4.e of the Trust Legal Provisions and are provided without
   warranty as described in the Simplified BSD License.

Table of Contents

   1. Introduction ................................................. 3
      1.1. Scope ................................................... 3
   2. Terminology .................................................. 3
      2.1. Conventions Used in this Document ....................... 3
      2.2. OTN Related Terminologies in this Document .............. 3
   3. Optical Transport Network Version 5 Overview ................. 4
      3.1. OTN B100G Network ....................................... 4
         3.1.1. Client Signal Mapping .............................. 4
         3.1.2. Supporting clients signals with ODUCn .............. 5
      3.2. MSI of ODUCn ............................................ 6
      3.3. OTUCn sub rates (OTUCn-M) ............................... 7
   4. Connection Management of ODUCn ............................... 7
   5. GMPLS Implications ........................................... 8
      5.1. Implications for GMPLS Signaling ........................ 8
      5.2. Implications for GMPLS Routing .......................... 8
   6. Security Considerations ...................................... 9
   7. Contributors' Addresses ..................................... 10
   8. References .................................................. 10
      8.1. Normative References ................................... 10
      8.2. Informative References ................................. 11
   Authors' Addresses ............................................. 11



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1. Introduction

   ITU-T G.709v3, published in 2012, defined the interfaces to Optical
   Transport Network (OTN), supporting a variety of Optical Data Unit
   (ODU) containers up to 100 Gbps and flexible multiplexing hierarchy.
   The OTN control plane framework was described in [RFC7062],
   corresponding signaling and routing extensions were further
   specified in [RFC7139] and [RFC7138] respectively. Furthermore,
   there were additional updates made to G.709v4, resulting in
   additional extensions which are described in [RFC7892] and [RFC7963].

   To meet the increasing demand for higher client bit rates, Edition 5
   of G.709 [ITU-T G.709v5] has been released to provide beyond 100G
   capabilities by introducing an ODUCn layer, which contains an
   optical payload unit(OPUCn).

   This document reviews relevant aspects of beyond 100 Gbps (B100G)
   OTN technology and how it impacts current GMPLS control-plane
   protocols. It highlights new considerations and proposes how to
   update the mechanisms described in [RFC7062] to meet B100G control
   plane requirements.

1.1. Scope

   For the purposes of the B100G control plane discussion, the OTN
   should be considered as a combination of the current OTN ODUk/Cn and
   the wavelength optical layer.  This document focuses on only the
   control of the ODUk/ODUCn layer.  The optical layer control will be
   addressed in a separate document.

2. Terminology

2.1. Conventions Used in this Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [RFC2119].

2.2. OTN Related Terminologies in this Document

   Terminologies from section 2 of [RFC7062] are reused in this
   document, with the following additional terminologies defined in
   [ITU-T G.709v5] used in this document:

   ODUCn: Optical Data Unit - Cn


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   OPUCn: Optical Payload Unit- Cn

   OTUCn: completely standardized Optical Transport Unit-Cn



3. Optical Transport Network Version 5 Overview

   This section provides an overview of new features provided by
   G.709v5 Optical Transport Network.

3.1. OTN B100G Network

3.1.1. Client Signal Mapping





   +-----------------------+-----------------------------------+
   |       ODU Type        |       ODU nominal bit rate        |
   +-----------------------+-----------------------------------+
   |         ODU0          |          1,244,160 Kbps           |
   |         ODU1          |     239/238 x 2,488,320 Kbps      |
   |         ODU2          |     239/237 x 9,953,280 Kbps      |
   |         ODU3          |     239/236 x 39,813,120 Kbps     |
   |         ODU4          |     239/227 x 99,532,800 Kbps     |
   |         ODUCn         |   n x 239/226 x 99,532,800 Kbps   |
   |                       |                                   |
   |     ODUflex for       |                                   |
   |Constant Bit Rate (CBR)| 239/238 x client signal bit rate  |
   |    Client signals     |                                   |
   |                       |                                   |
   |   ODUflex for Generic |                                   |
   |   Framing Procedure   |        Configured bit rate        |
   |   - Framed (GFP-F)    |                                   |
   | Mapped client signal  |                                   |
   +-----------------------+-----------------------------------+

                     Table 1: ODU Types and Bit Rates


   NOTE: The nominal ODUCn rates are approximately n x 105,258,138.053
   kbit/s.



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   Furthermore, and per [ITU-T G.709v5], the tolerance of ODUCn is +/-
   20 ppm. The frame period for ODUCn is 1.163 s. Additionally, it
   defined 5 Gbps tributary slots for ODU Cn. The number of tributary
   slots (TS) defined in [ITU-T G.709v5] for each ODU are shown in
   Table 2.

           +------------+-------------------------------------+
           |            |        Nominal TS capacity          |
           | ODU Server +-------------------------------------+
           |            | 1.25 Gbit/s | 2.5 Gbit/s | 5 Gbit/s |
           +------------+-------------+------------+----------+
           |   ODU0     |      1      |    N/A     |   N/A    |
           +------------+-------------+------------+----------+
           |   ODU1     |      2      |    N/A     |   N/A    |
           +------------+-------------+------------+----------+
           |   ODU2     |      8      |     4      |   N/A    |
           +------------+-------------+------------+----------+
           |   ODU3     |     32      |    16      |   N/A    |
           +------------+-------------+------------+----------+
           |   ODU4     |     80      |    N/A     |   N/A    |
           +------------+-------------+------------+----------+
           |   ODUCn    |     N/A     |    N/A     |   20*n   |
           +------------+-------------+------------+----------+

                 Table 2: Number of tributary slots (TS)


3.1.2. Supporting clients signals with ODUCn

   According to [ITU-T G.709v5], various client signals can be mapped
   to be supported by ODUCn. Typical client signal includes Ethernet,
   MPLS and IP. The signal hierarchies can be found in Figure 1.



               Client (e.g., IP, Ethernet, MPLS, ...)

                              |

                    OTN client signals (ODUk)

                              |

                            ODUCn



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                              |

                            OTUCn

                 Figure 1: Mapping Client Signal to ODUCn

   Packet streams (e.g., Ethernet, MPLS, IP) which are encapsulated
   with the generic framing procedure is considered as the client and
   can be carried by OTN client signals (known as ODUk, including
   ODU0~4 and ODUflex). Then the OTN client signals will be further
   mapped into ODUCn containers and multiplexed into OTUCn. It is worth
   noting that the maximum bit rate for ODUk is 100G (ODU4), which is
   the same rate of ODUC1. The mapping from ODU client signal to ODU
   Containers is also required when ODU4 is multiplexed into ODUC1.

   Examples of multiplexing can be found as follow:



      -  ODU0/ ODU1/ ODU2/ ODU3/ ODU4 into ODUC1 multiplexing with
   5Gbps TS granularity: ODU0/ ODU1/ ODU2/ ODU3/ ODU4 occupies
   1/1/2/8/20 of the 20 TSs for ODUC1. It is worth noting that for ODU0
   and ODU1, the 5G TS is only partially occupied.

   The type of the transported payload, encoded as the payload type, is
   set to 22 for ODUCn.

3.2. MSI of ODUCn

      When multiplexing an OTN client signal into ODUCn, [ITU-T G.709v5]
   specifies the information that must be transported in-band to
   correctly demultiplexing the signal.  MSI is used to specify the
   identifier of each multiplexing section. The MSI information is
   located in the mapping specific area of the PSI signal and is local
   to each link.

      The MSI information is organized as a set of entries, with n
   entries for each OPUC TS.  The MSI has a fixed length of 40n bytes
   and indicates the ODTU content of each tributary slot (TS) of an
   OPUCn.

   Two bytes are used for each tributary slot.  The information carried
   by each entry is:

      - TS availability bit 1 indicates if the tributary slot is
   available or unavailable.



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      - The TS occupation bit 9 indicates if the tributary slot is
   allocated or unallocated.

       - The tributary port number in bits 2 to 8 and 10 to 16 indicates
   the port number of the ODTUCn.ts that is being transported in this
   TS; a flexible assignment of tributary port to tributary slots is
   possible. ODTUC.ts tributary ports are numbered 1 to 10n. The value
   is set to all-0s when the occupation bit has the value 0 (tributary
   slot is unallocated).

   Tributary Port Number (TPN) indicates the port number of the OTN
   client signal transported by the ODUCn.  The TPN is the same for all
   the TSs assigned to the transport of the same OTN client signal.

3.3. OTUCn sub rates (OTUCn-M)

   An OTUCn with a bit rate that is not an integer multiple of 100
   Gbit/s can be described as an OTUCn-M. An OTUCn-M frame contains n
   instances of OTUC overhead, ODUC overhead and OPUC overhead together
   with M 5Gbit/s OPUCn TS.

   When an OTUCn-M is used to carry an ODUCn (20n-M) TS are marked as
   unavailable, in the OPUCn multiplex structure identifier (MSI),
   since they cannot be used to carry a client signal.



4. Connection Management of ODUCn

   ODUk based connection management has been described in section 4 of
   [RFC7062]. In this section the connection management of ODUCn is
   described, which is independent but used together with ODUk based
   connection management.

   ODUCn based connection management is concerned with controlling the
   connectivity of ODUCn paths. According to ITU-T G.872, the
   intermediate nodes with ODUCn do not support the switching of ODUCn
   time slot. Intermediate ODUCn points are only considered as a
   forwarding node.  Once an ODUCn path is used to transport client
   signal, the TS occupied will not change across the ODUCn network.









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5. GMPLS Implications

5.1. Implications for GMPLS Signaling

   For OTNv3 network control, [RFC7139] defines RSVP-TE signaling
   extensions, extending the base specifications [RFC3473] and
   [RFC4328].

   As described in Section 3, [ITU-T G.709v5] introduced some new
   features including the ODUCn, OTUCn for beyond 100G control.  The
   mechanisms defined in [RFC7139] do not support such features, and
   protocol extensions SHALL be necessary to allow them to be
   controlled by a GMPLS control plane.  In summary, the following new
   signaling aspects SHOULD be considered:

   -  Support for specifying new signal types and related traffic
   information: The traffic parameters should be extended in a
   signaling message to support the new ODUCn;

   -  Support the new TS granularity: the signaling protocol should be
   able to identify the TS granularity (i.e., the new 5 Gbps TS
   granularity) to be used for establishing a Hierarchical LSP that
   will be used to carry service LSP(s) requiring a specific TS
   granularity.

   -  Support for LSP setup of new ODUCn containers with related
   mapping and multiplexing capabilities: A new label format must be
   defined to carry the exact TS's allocation information related to
   the extended mapping and multiplexing hierarchy (for example, ODU4
   into ODUCn multiplexing (with 5 Gbps TS granularity)), in order to
   set up all the possible ODU connections.

   - Support for TPN allocation and negotiation: TPN needs to be
   configured as part of the MSI information (see more information in
   Section 3.1.2.1).  A signaling mechanism must be identified to carry
   TPN information if the control plane is used to configure MSI
   information.

   - Support for LSP setup of OTUCn sub rates (OTUCn-M) path: based on
   previous extensions, there should be new signal mechanism to declare
   the OTUCn-m information.

5.2. Implications for GMPLS Routing

   The path computation process needs to select a suitable route for an
   ODUCn connection request.  Evaluation of the available bandwidth on
   each candidate link is required for path computation. The routing


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   protocol SHOULD be extended to carry sufficient information to
   represent ODU Traffic Engineering (TE) topology.

   The Interface Switching Capability Descriptors defined in [RFC4203]
   present a new constraint for LSP path computation.  [RFC4203]
   defines the Switching Capability, related Maximum LSP Bandwidth, and
   Switching Capability specific information. [RFC7138] updates the
   ISCD to support ODU4, ODU2e and ODUflex. The new Switching
   Capability specific information provided in [RFC7138] have to be
   adapted to support new features contained in [ITU-T G.709v5].  The
   following requirements should be considered:

   -  Support for carrying the link multiplexing capability: As
   discussed in Section 3.1.2, many different types of ODUk can be
   multiplexed into the ODUCn.  For example, ODU4 may be multiplexed
   into ODUC1.  An OTUCn link may support one or more types of ODUk
   signals.  The routing protocol should be capable of carrying this
   multiplexing capability.

   - Support for additional Tributary Slot Granularity advertisement:
   as new tributary slot granularity (5G TS) is introduced in [G.709
   v5], there is a need to specify this parameter.

   - Support for advertisement of OTUCn sub rates support information:
   Given the same n value, there is possible different OTUCn sub rates.
   Corresponding information should be defined in the routing mechanism
   to satisfy this feature.




6. Security Considerations

   TBD.














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7. Contributors' Addresses

   Xian Zhang
   Huawei Technologies
   Email: zhang.xian@huawei.com

   Antonello Bonfanti
   Cisco
   Email: abonfant@cisco.com

   Dieter Beller
   Nokia
   Email: Dieter.Beller@nokia.com


8. References

8.1. Normative References

   [RFC2119] S. Bradner, "Key words for use in RFCs to indicate
             requirements levels", RFC 2119, March 1997.

   [ITU-T G.709v5] ITU-T, "Interface for the Optical Transport Network
             (OTN)", G.709/Y.1331 Recommendation, June 2016.

   [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Resource ReserVation
             Protocol-Traffic Engineering (RSVP-TE) Extensions",
             RFC 3473, DOI 10.17487/RFC3473, January 2003,

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

   [RFC4328]  Papadimitriou, D., Ed., "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Extensions for G.709 Optical
             Transport Networks Control", RFC 4328, January 2006,

   [RFC7138] D. Ceccarelli, F. Zhang, S. Belotti, R. Rao, J. Drake,
             'Traffic Engineering Extensions to OSPF for GMPLS Control
             of Evolving G.709 Optical Transport Networks', RFC7138,
             March 2014.

   [RFC7139] F. Zhang, G. Zhang, S. Belotti, D. Ceccarelli, K. Pithewan,
             'GMPLS Signaling Extensions for Control of Evolving G.709
             Optical Transport Networks', RFC7139, March 2014.



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   [RFC7892] Z. Ali, A. Bonfanti, M. Hartley, F. Zhang, 'IANA
             Allocation Procedures for the GMPLS OTN Signal Type
             Registry', RFC7892, May 2016.

8.2. Informative References

   [RFC7062] F. Zhang, D. Li, H. Li, S. Belotti, D. Ceccarelli,
             'Framework for GMPLS and PCE Control of G.709 Optical
             Transport Networks', RFC 7062, November 2013.

   [RFC7963] Z. Ali, A. Bonfanti, M. Hartley, F. Zhang, 'RSVP-TE
             Extension for Additional Signal Types in G.709 Optical
             Transport Networks (OTNs)', RFC7963, August 2016.





   Authors' Addresses

   Haomian Zheng
   Huawei Technologies
   Email: zhenghaomian@huawei.com

   Italo Busi
   Huawei Technologies
   Email: Italo.Busi@huawei.com

   Zafar Ali
   Cisco
   Email: zali@cisco.com

   Sergio Belotti
   Nokia
   Email: sergio.belotti@nokia.com

   Daniele Ceccarelli
   Ericsson
   Email: daniele.ceccarelli@ericsson.com

   Daniel King
   Lancaster University
   Email: d.king@lancaster.ac.uk






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