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Networking Working Group                                       Ran. Chen
Internet-Draft                                              Zheng. Zhang
Intended status: Standards Track                         ZTE Corporation
Expires: January 16, 2018                                  July 15, 2017


                        PCEP Extensions for BIER
                      draft-chen-bier-pce-bier-03

Abstract

   Bit Index Explicit Replication (BIER)-TE shares architecture and
   packet formats with BIER as described in
   [I-D.ietf-bier-architecture].  BIER-TE forwards and replicates
   packets based on a BitString in the packet header, but every
   BitPosition of the BitString of a BIER-TE packet indicates one or
   more adjacencies.BIER-TE Path can be derived from a Path Computation
   Element (PCE).

   This document specifies extensions to the Path Computation Element
   Protocol (PCEP) to handle requests and responses for the computation
   of paths for BIER-TE.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on January 16, 2018.

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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  Overview of PCEP Operation in BIER Networks . . . . . . . . .   3
   4.  BIER PCEP Message Extensions  . . . . . . . . . . . . . . . .   3
     4.1.  BIER Capability Advertisement . . . . . . . . . . . . . .   3
       4.1.1.  The OPEN Object . . . . . . . . . . . . . . . . . . .   3
         4.1.1.1.  The BIER PCE Capability TLV . . . . . . . . . . .   3
     4.2.  Path Computation Request/Reply Message Extensions . . . .   4
       4.2.1.  The RP/SPR Object . . . . . . . . . . . . . . . . . .   4
       4.2.2.  The New BIER END-POINT Object . . . . . . . . . . . .   5
       4.2.3.  ERO Object  . . . . . . . . . . . . . . . . . . . . .   5
         4.2.3.1.  BIER-ERO Subobject  . . . . . . . . . . . . . . .   6
       4.2.4.  RRO Object  . . . . . . . . . . . . . . . . . . . . .   7
         4.2.4.1.  RRO Processing  . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  PCEP Objects  . . . . . . . . . . . . . . . . . . . . . .   7
     6.2.  PCEP-Error Objects and Types  . . . . . . . . . . . . . .   8
     6.3.  PCEP TLV Type Indicators  . . . . . . . . . . . . . . . .   8
     6.4.  New Path Setup Type . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  Normative references  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative references  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Bit Index Explicit Replication (BIER)-TE shares architecture and
   packet formats with BIER as described in
   [I-D.ietf-bier-architecture].  BIER-TE forwards and replicates
   packets based on a BitString in the packet header, but every
   BitPosition of the BitString of a BIER-TE packet indicates one or
   more adjacencies.BIER-TE Path can be derived from a Path Computation
   Element (PCE).

   This document specifies extensions to the Path Computation Element
   Protocol (PCEP) to handle requests and responses for the computation
   of paths for BIER-TE.




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2.  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 RFC2119.

3.  Overview of PCEP Operation in BIER Networks

   BIER-TE forwards and replicates packets based on a BitString in the
   packet header.  In a PCEP session, An ERO object specified in
   [RFC5440] can be extended to carry a BIER-TE path consists of one or
   more BIER-ERO subobject(s).  BIER-TE computed by a PCE can be
   represented in the following forms:

   o  An ordered set of adjacencies BitString(s) in which each bit
      represents that the adjacencies to which the BFR should replicate
      packets to in the domain.

   In this document, we define a set of PCEP protocol extensions,
   including a new PCEP capability,a new Path Setup Type (PST) ,a new
   BIER END-POINT Object, new ERO subobjects, new RRO subobjects, new
   PCEP error codes and procedures.

4.  BIER PCEP Message Extensions

   The following section describes the protocol extensions required to
   support BIER-TE path.

4.1.  BIER Capability Advertisement

4.1.1.  The OPEN Object

   This document defines a new optional TLV for use in the OPEN Object.

4.1.1.1.  The BIER PCE Capability TLV

   The BIER-PCE-CAPABILITY TLV is an optional TLV associated with the
   OPEN Object to exchange BIER capability of PCEP speakers.  The format
   of the BIER-PCE-CAPABILITY TLV is shown in the following figure:












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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Type               |            Length             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Reserved              |         Flags                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 1

   The code point for the TLV type is to be defined by IANA.

   Length: 4 bytes.

   The "Reserved" (2 octet) and "Flags" (2 octet) fields are currently
   unused, and MUST be set to zero on transmission and ignored on
   reception.

4.1.1.1.1.  Exchanging BIER Capability

   This document defines a new optional BIER-PCE-CAPABILITY TLV for use
   in the OPEN object to negotiate the BIER capability.  The inclusion
   of this TLV in the OPEN message destined to a PCC indicates the PCE's
   capability to perform BIER-TE path computations, and the inclusion of
   this TLV in the OPEN message destined to a PCE indicates the PCC's
   capability to support BIER-TE Path.

   A PCE that is able to support the BIER extensions defined in this
   document SHOULD include the BIER-PCE-CAPABILITY TLV on the OPEN
   message.  If the PCE does not include the BIER-PCE-CAPABILITY TLV in
   the OPEN message and PCC does include the TLV, it is RECOMMENDED that
   the PCC indicates a mismatch of capabilities.

4.2.  Path Computation Request/Reply Message Extensions

4.2.1.  The RP/SPR Object

   In order to setup an BIER-TE, a new PATH-SETUP-TYPE
   TLV[I-D.ietf-pce-lsp-setup-type] MUST be contained in RP or SRP
   object.  This document defines a new Path Setup Type (PST) for BIER
   as follows:

   o  PST = 2: Path is setup using BIER Traffic Engineering technique.

   If a PCEP speaker does not recognize the PATH-SETUP-TYPE TLV, it MUST
   ignore the TLV in accordance with [RFC5440].  If a PCEP speaker
   recognizes the TLV but does not support the TLV, it MUST send PCErr
   with Error-Type = 2 (Capability not supported).



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4.2.2.  The New BIER END-POINT Object

   The END-POINTS object is used in a PCReq message to specify the BIER
   information of the path for which a path computation is requested.
   To represent the end points for a BIER path efficiently, we define a
   new END-POINT Object for the BIER path:

   The format of the new END-POINTS Object is as follows:


       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Subdomain-ID   |   BS Length   |         Source BFR-id         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Destination  BFR-id         ~        ...                    ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ~        ...                    ~   Destination BFR-id          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                                 Figure 2

   Subdomain-id: Unique value identifying the BIER sub-domain. 1 octet

   BS Length: A 1 octet field encoding the supported BitString length.

   Source BFR-id:A 2 octet field encoding the source BFR-id.

   Destniation BFR-id:A 2 octet field encoding the destniation BFR-id.

4.2.3.  ERO Object

   BIER-TE consists of one or more adjacencies BitStrings where every
   BitPosition of the BitString indicates one or more adjacencies, as
   described in([I-D.eckert-bier-te-arch]).

   The ERO object specified in [RFC5440] is used to encode the path of a
   TE LSP through the network.The ERO is carried within a PCRep message
   to provide the computed TE LSP if the path computation was
   successful.In order to carry BIER-TE explicit paths, this document
   defines a new ERO subobjects referred to as "BIER-ERO subobjects"
   whose formats are specified in the following section.  An BIER-ERO
   subobjects carrying a adjacencies BitStrings consists of one or more
   BIER-ERO subobject(s).






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4.2.3.1.  BIER-ERO Subobject


        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              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     BS Length |   Reserved    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Adjacency BitString                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3

   Type: TBD

   Length: 4 bytes

   BS Length: A 1 octet field encoding the supported BitString length.

   The "Reserved" (1 octets) fields are currently unused, and MUST be
   set to zero on transmission and ignored on reception.

   Adjacency BitString: A 4 octet field encoding the Adjacency BitString
   where every BitPosition of the BitString indicates one or more
   adjacencies.

4.2.3.1.1.  BIER-ERO Processing

   If a PCC finds a non-recognize the BIER-ERO subobject, the PCC MUST
   respond with a PCErr message with Error-Type=3 ("Unknown Object") and
   Error-Value=2 ("Unrecognized object Type") or Error-Type=4 ("Not
   supported object") and Error-Value=2 ("Not supported object Type") as
   described in [RFC5440] .

   If a PCC receives an BIER-ERO subobject in which either
   BitStringLength or Adjacency BitString is absent, it MUST consider
   the entire BIER-ERO subobject invalid and send a PCErr message with
   Error-Type = 10 ("Reception of an invalid object") and Error-Value =
   TBD ("BitStringLength is absent ") and Error-Value = TBD ("Adjacency
   BitString is absent ")

   If a PCC detects that all subobjects of BIER-ERO are not identical,
   it MUST send a PCErr message with Error-Type = 10 ("Reception of an
   invalid object") and Error-Value = TBD ("Non-identical BIER-ERO
   subobjects").




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   If a PCC receives an BIER-ERO subobject in which BitStringLength
   values are not chosen from: 64, 128, 256, 512, 1024, 2048, and 4096,
   as it described in ([I-D.ietf-bier-architecture]).  The PCC MUST send
   a PCErr message with Error-Type = 10 ("Reception of an invalid
   object") and Error-Value = TBD ("Invalid BitStringLength").

4.2.4.  RRO Object

   A PCC can record BIER-ERO explicit paths and report the paths to a
   PCE via RRO.  An RRO object contains one or more subobjects called
   "BIER-RRO subobjects" whose formats are the same as that of BIER-ERO
   subobject.

4.2.4.1.  RRO Processing

   Processing rules of BIER-RRO subobject are identical to those of
   BIER-ERO subobject defined in section 4.2.3.1 in this document.

5.  Security Considerations

   TBD.

6.  IANA Considerations

6.1.  PCEP Objects

   As discussed in Section 4.2.2, a new END-POINTS Object-Type is
   defined.  IANA has made the following Object-Type allocations from
   the "PCEP Objects" sub-registry:


             Object                          Object-Class Value
          ---------------------               --------------------------
            BIER END-POINT Object                      TBD


   As discussed in Section 4.2.3 and 4.2.4, a new sub-object type for
   the PCEP explicit route object (ERO), and a new sub-object type for
   the PCEP record route object (RRO) are defined.

   IANA has made the following sub-objects allocation from the RSVP
   Parameters registry:









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               Object                Sub-Object                 Sub-Object Type
          --------------------- -------------------------- --------------------------
               EXPLICIT_ROUTE        BIER-ERO (PCEP-specific)          TBD
               ROUTE_RECORD          BIER-RRO (PCEP-specific)          TBD


6.2.  PCEP-Error Objects and Types

   As described in Section 4.2.3.1.1, a number of new PCEP-ERROR Object
   Error Values have been defined.


              Error-Type           Meaning                                  Reference
             ---------- ----------------------------------- ---------------------------------
                10        Reception of an invalid object.                   RFC5540
                          Error-value = TBD:  BitStringLength is absent     This document
                          Error-value = TBD:  BitString is absent           This document
                          Error-value = TBD:  Invalid BitStringLength       This document


6.3.  PCEP TLV Type Indicators

   IANA is requested to allocate a new code point in the PCEP TLV Type
   Indicators registry, as follows:


              Value                     Meaning                      Reference
     -------------------- ---------------------------- -----------------------------------
             TBD               BIER-PCE-CAPABILITY TLV             This document


6.4.  New Path Setup Type

   IANA is requested to allocate a new code point in the PCEP
   PATH_SETUP_TYPE TLV PST field registry, as follows:


               Value                     Description                  Reference
       ----------------   ------------------------------------ ----------------------------
                2             Path is setup using BIER Traffic      This document
                              Engineering technique


7.  References







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7.1.  Normative references

   [I-D.ietf-bier-architecture]
              Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
              S. Aldrin, "Multicast using Bit Index Explicit
              Replication", draft-ietf-bier-architecture-07 (work in
              progress), June 2017.

   [I-D.ietf-pce-lsp-setup-type]
              Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
              Hardwick, "Conveying path setup type in PCEP messages",
              draft-ietf-pce-lsp-setup-type-04 (work in progress), April
              2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <http://www.rfc-editor.org/info/rfc5440>.

7.2.  Informative references

   [I-D.eckert-bier-te-arch]
              Eckert, T., Cauchie, G., Braun, W., and M. Menth, "Traffic
              Engineering for Bit Index Explicit Replication BIER-TE",
              draft-eckert-bier-te-arch-05 (work in progress), June
              2017.

Authors' Addresses

   Ran Chen
   ZTE Corporation
   No.50 Software Avenue,Yuhuatai District
   Nanjing, Jiangsu Province  210012
   China

   Phone: +86 025 88014636
   Email: chen.ran@zte.com.cn









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   Zheng Zhang
   ZTE Corporation
   No.50 Software Avenue,Yuhuatai District
   Nanjing, Jiangsu Province  210012
   China

   Email: zhang.zheng@zte.com.cn












































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