[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Nits]

Versions: 00

Network Working Group                                         C. Cardona
Internet-Draft                                                P. Lucente
Intended status: Standards Track                                     NTT
Expires: January 6, 2020                                     P. Francois
                                                                    INSA
                                                                   Y. Gu
                                                                  Huawei
                                                           July 05, 2019


                   BMP Extension for Path Marking TLV
                draft-cppy-grow-bmp-path-marking-tlv-00

Abstract

   The BGP Monitoring Protocol (BMP) provides the monitoring of BGP adj-
   rib-in [RFC7854], BGP local-rib [I-D.ietf-grow-bmp-local-rib] and BGP
   adj-rib-out [I-D.ietf-grow-bmp-adj-rib-out] through Route Monitoring
   (RM) messages.  With the capability of allowing optional data to be
   added to the RM Messages in the format of TLV draft-lucente-bmp-tlv
   [I-D.lucente-bmp-tlv], more information about the BGP Update message
   encapsulated in the RM can be revealed.  This document proposes an
   extension to BMP to describe the BGP path status through the
   definition and use of Path Marking TLV.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
   appear in all capitals, as shown here.

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 https://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."




Cardona, et al.          Expires January 6, 2020                [Page 1]


Internet-Draft            BMP path marking tlv                 July 2019


   This Internet-Draft will expire on January 6, 2020.

Copyright Notice

   Copyright (c) 2019 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
   (https://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 respect
   to this document.  Code Components extracted from this 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Path Marking TLV for the RM Message . . . . . . . . . . . . .   3
     2.1.  Path Type . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Reason String . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Path Marking TLV  . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Path Marking TLV Reason String  . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   For a given prefix, multiple paths with different path status, e.g.,
   the "best-path", the "best-external-path" and so on, may co-exist in
   the BGP module upon the local policy processing.  In addition, during
   the whole process, from receiving a BGP route to advertising it, a
   path can also undergo various status in different processing states.
   Such path status information is currently not carried in the BGP
   Update Message RFC4271 [RFC4271].  However, they can be useful to
   enable a lot of applications.  For example, for traffic steering
   purposes in a SDN enviroment, the operator/SDN controller needs the
   reachability information of multiple paths to ensure the selected
   optimized route is reachable.

   This document defines a so-called Path Marking TLV to convey the BGP
   path status information to the BMP server.  The BMP Path Marking is
   defined to be prepended in the BMP Route Monitoring (RM) Message.



Cardona, et al.          Expires January 6, 2020                [Page 2]


Internet-Draft            BMP path marking tlv                 July 2019


2.  Path Marking TLV for the RM Message

   Per RFC4271 [RFC4271], the BMP RM Message consists of the Common
   Header, Per-Peer Header, and the BGP Update PDU.  According to draft-
   lucente-bmp-tlv [I-D.lucente-bmp-tlv], optional trailing data in TLV
   format is allowed in the BMP RM Message to convey characteristics of
   transported NLRIs (ie. to help stateless parsing) or vendor-specific
   data.  Such TLV types are to be defined per each application.

   To include the path status along with each BGP path, we define the
   Path Marking TLV, shown as follows.

      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 (2 octets)        |     Length (2 octets)         |
     +-------------------------------+-------------------------------+
     |                       Path Type(4 octets)                     |
     +---------------------------------------------------------------+
     |                     Reason String(Variable)                   |
     +---------------------------------------------------------------+

                       Figure 1: Path Marking TLV

   o  Type = TDB1 (2 Octets): Path Marking.

   o  Length (2 Octets): indicates the length of the value field of the
      Path Marking TLV.  The value field further consists of the Path-
      Type field and Reason String field.

   o  Path-Type (4 Octets): indicates the path status of the BGP Update
      PDU encapsulated in the RM Message.  Currently 8 types of path
      status are defined, as shown in Table 1.

   o  Reason String (Variable): indicates the reasons/explanations of
      the path status indicated in the Path Type field.  The detailed
      Reason String format is defined in Figure 2.

2.1.  Path Type













Cardona, et al.          Expires January 6, 2020                [Page 3]


Internet-Draft            BMP path marking tlv                 July 2019


                     +--------+----------------------+
                     | Value  | Path type            |
                     +-------------------------------+
                     | 0x0000 | Unknown              |
                     | 0x0001 | Best path            |
                     | 0x0002 | Best external path   |
                     | 0x0004 | Primary path         |
                     | 0x0008 | Backup path          |
                     | 0x0010 | Non-installed path   |
                     | 0x0020 | Unreachable next-hop |
                     +--------+----------------------+

                          Table 1: Path Type

   The Path type field contains a bitfield where each bit encodes a
   specific role of the path.  Multiple bits may be set when a path is
   used in multiple roles.

   The best-path is defined in RFC4271 [RFC4271] and the best-external
   path is defined in draft-ietf-idr-best-external
   [I-D.ietf-idr-best-external].

   A primary path is a recursive or non-recursive path that can be used
   all the time as long as a walk starting from this path can end to an
   adjacency draft-ietf-rtgwg-bgp-pic [I-D.ietf-rtgwg-bgp-pic].  A
   prefix can have more than one primary path.  A best-path is also
   considered as a primary path.

   A backup path is also installed in the RIB, but it is not used until
   some or all primary paths become unreachable.  Backup paths are used
   for fast convergence in the event of failures.

   All other reachable paths are marked as 'Non-installed'.

   Lastly, all paths that are considered unreachable are marked as
   'Unreachable next-hop'.  Unreachable paths may be sent only in
   special cases.

2.2.  Reason String












Cardona, et al.          Expires January 6, 2020                [Page 4]


Internet-Draft            BMP path marking tlv                 July 2019


      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
     +-------------------------------+-------------------------------+
     |        Sub Type 1 (2 octets)  |     Length (2 octets)         |
     +-------------------------------+-------------------------------+
     |                    Non-Best Reason String(Variable)           |
     +-------------------------------+-------------------------------+
     |        Sub Type 2 (2 octets)  |     Length (2 octets)         |
     +-------------------------------+-------------------------------+
     |                  Uninstall Reason String(Variable)            |
     +-------------------------------+-------------------------------+
     |        Sub Type 3 (2 octets)  |     Length (2 octets)         |
     +-------------------------------+-------------------------------+
     |                  Unreachable Reason String(Variable)          |
     +---------------------------------------------------------------+

                        Figure 2: Reason String field

   o  Sub Type 1 (2 Octets) = TDB2: Non-Best Reason String.

   o  Length (2 Octets): indicates the length of the value field of the
      Non-Best Reason String.

   o  Non-Best Reaon String (Variable): includes user specific
      description of the non-best reason in the format of ASCII string.

   o  Sub Type 2 (2 Octets) = TDB3: Uninstalled Reason String.

   o  Length (2 Octets): indicates the length of the value field of the
      Non-Best Reason String.

   o  Uninstalled Reason String (Variable): includes user specific
      description of the uninstalled (into RIB) reason in the format of
      ASCII string.

   o  Sub Type 3 (2 Octets) = TDB4: Unreachable Reason String.

   o  Length (2 Octets): indicates the length of the value field of the
      Non-Best Reason String.

   o  Unreachable Reason String (Variable): includes user specific
      description of the unreachable reason in the format of ASCII
      string.

3.  Acknowledgements

   TBD.





Cardona, et al.          Expires January 6, 2020                [Page 5]


Internet-Draft            BMP path marking tlv                 July 2019


4.  IANA Considerations

   This document requests that IANA assign the following new parameters
   to the BMP parameters name space.

4.1.  Path Marking TLV

   This document defines the Path Marking TLV with Type = TDB1: Path
   Marking (Section 2).

4.2.  Path Marking TLV Reason String

   This document defines three new sub types of the Reason String in the
   Path Marking TLV (Section 2.2).

   Sub Type 1 = TDB2: Non-Best Reason String.

   Sub Type 2 = TDB3: Uninstalled Reason String.

   Sub Type 3 = TDB4: Unreachable Reason String.

5.  Security Considerations

   It is not believed that this document adds any additional security
   considerations.

6.  Normative References

   [I-D.ietf-grow-bmp-adj-rib-out]
              Evens, T., Bayraktar, S., Lucente, P., Mi, K., and S.
              Zhuang, "Support for Adj-RIB-Out in BGP Monitoring
              Protocol (BMP)", draft-ietf-grow-bmp-adj-rib-out-06 (work
              in progress), June 2019.

   [I-D.ietf-grow-bmp-local-rib]
              Evens, T., Bayraktar, S., Bhardwaj, M., and P. Lucente,
              "Support for Local RIB in BGP Monitoring Protocol (BMP)",
              draft-ietf-grow-bmp-local-rib-04 (work in progress), June
              2019.

   [I-D.ietf-idr-best-external]
              Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H.
              Gredler, "Advertisement of the best external route in
              BGP", draft-ietf-idr-best-external-05 (work in progress),
              January 2012.






Cardona, et al.          Expires January 6, 2020                [Page 6]


Internet-Draft            BMP path marking tlv                 July 2019


   [I-D.ietf-rtgwg-bgp-pic]
              Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix
              Independent Convergence", draft-ietf-rtgwg-bgp-pic-09
              (work in progress), April 2019.

   [I-D.lucente-bmp-tlv]
              Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP
              Route Monitoring and Peer Down Messages", draft-lucente-
              bmp-tlv-00 (work in progress), July 2019.

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

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC5492]  Scudder, J. and R. Chandra, "Capabilities Advertisement
              with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
              2009, <https://www.rfc-editor.org/info/rfc5492>.

   [RFC7854]  Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
              Monitoring Protocol (BMP)", RFC 7854,
              DOI 10.17487/RFC7854, June 2016,
              <https://www.rfc-editor.org/info/rfc7854>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Authors' Addresses

   Camilo Cardona
   NTT
   164-168, Carrer de Numancia
   Barcelona  08029
   Spain

   Email: camilo@ntt.net









Cardona, et al.          Expires January 6, 2020                [Page 7]


Internet-Draft            BMP path marking tlv                 July 2019


   Paolo Lucente
   NTT
   Siriusdreef 70-72
   Hoofddorp, WT  2132
   Netherlands

   Email: paolo@ntt.net


   Pierre Francois
   INSA
   Lyon
   France

   Email: Pierre.Francois@insa-lyon.fr


   Yunan Gu
   Huawei
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095
   China

   Email: guyunan@huawei.com



























Cardona, et al.          Expires January 6, 2020                [Page 8]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/