Imported debug from /usr/lib/site-python/debug.pyc draft-heitz-idr-diagnostic-attr-00 - BGP Diagnostic Path Attribute
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Versions: 00

IDR                                                             J. Heitz
Internet-Draft                                              P. Narasimha
Intended status: Standards Track                            S. Gulrajani
Expires: September 11, 2019                                        Cisco
                                                          March 10, 2019


                     BGP Diagnostic Path Attribute
                   draft-heitz-idr-diagnostic-attr-00

Abstract

   A BGP path attribute for the purpose of network diagnostics is
   described.  It is non-transitive, such that BGP speakers will not
   forward it by default.  It is structured as a list of elements.  An
   element begins with the BGP identifier and AS number of the speaker
   that adds the element and includes a list of TLVs.  Any speaker can
   add or remove an element to/from the list.  TLVs for a timestamp and
   for a checksum are described.

Requirements Language

   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].

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 September 11, 2019.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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
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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.  Data Formats  . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.1.  Timestamp TLV . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Checksum TLV  . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Operational Considerations  . . . . . . . . . . . . . . . . .   4
   4.  Error Handling  . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   A BGP path attribute for the purpose of network diagnostics is
   described.  It is non-transitive, such that BGP speakers will not
   propagate it by default.  It is structured as a list of elements.  An
   element begins with the BGP identifier and AS number of the speaker
   that adds the element and includes a list of TLVs.  Any speaker can
   add or remove an element to/from the list.  TLVs for a timestamp and
   for a checksum are described.  The diagnostic attribute may be sent
   in a withdraw message.

2.  Data Formats

   The BGP diagnostic consists of a series of elements, each of which is
   formatted as follows.













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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ASN                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         BGP Identfifier                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Length           |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                              TLVs                             +
   :                                                               :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields are as follows:

      ASN             - 4 octet Autonomous System Number of the speaker
                        that added this element.

      BGP Identfifier - BGP Identifier of the speaker that added this
                        element.

      Length          - The number of octets comprising this element, If
                        there were no TLVs included, this length would
                        be 10.

      TLVs            - Any number of TLVs as further described.  Each
                        TLV is optional.

2.1.  Timestamp TLV

   The time at which the indicated speaker created this attribute during
   the process of creating to message to be sent.  The precision of the
   timestamp depends upon the diagnostic application that requires it
   and is out of scope of this document.

    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 = 1             |        Length = 12            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            Seconds                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            Fraction                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields are as follows:




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      Type       - 1.

      Length     - 12.

      Seconds    - The number of Seconds since 0 h 1 January 1900 UTC as
                   further described in Section 6 of [RFC5905].

      Fraction   - A fraction of the above seconds also described in
                   Section 6 of [RFC5905].

2.2.  Checksum TLV

   A checksum of the BGP message, including the marker field.  The
   checksum is only valid between the sending and receiving speaker.
   Since a receiving speaker may propagate an update, it will likely
   change the set of attributes or their order in its own update
   message, thus making the checksum useless in the propagated update.
   A BGP speaker MAY remove the checksum TLV from a propagated
   Diagnostic Path Attribute.

    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 = 2             |        Length = 6             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Checksum            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields are as follows:

      Type       - 2.

      Length     - 6.

      Checksum   - The 16 bit checksum computed according to [RFC1071].

3.  Operational Considerations

   As with any new BGP attribute, if it is propagated, NLRI packing into
   BGP UPDATE messages may be affected.  This needs to be taken into
   consideration when using the Timestamp TLV to measure bulk update
   message timing.

   The Checksum TLV is useful to narrow down a source of corruption of
   UPDATE messages in each of the software and hardware layers between
   the actual BGP processes.





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   The Diagnostic Path Attribute MAY be sent in an UPDATE message that
   does not contain an NLRI field [RFC4271] or an MP_REACH_NLRI Path
   Attribute [RFC4760].  When carried in such a message, it is unlikely
   to be propagated, although it is possible.

4.  Error Handling

   A checksum error shall not be treated as a protocol error.  The
   response is implementation dependent.

   A TLV length error shall be treated as attribute-discard according to
   [RFC7606].

   An unrecognized TLV MUST not be treated as a protocol error.

5.  Security Considerations

   This attribute is not forwarded by default.  Therefore, it should
   cause no unexpected ill effects.

6.  IANA Considerations

   IANA is requested to assign a BGP path attribute value for the BGP
   Diagnostic Path Aattribute.

   IANA is requested to create and maintain a registry for the TLV
   types.  The allocation policies as per [RFC8126] are stated for the
   range of values.

         Range        Allocation Policy
         -----------  ------------------------------
             0-32767  First Come First Served
         32768-65535  Experimental

         Value      Description                     Reference
         ---------  ------------------------------  ---------
         0          Reserved                        This RFC
         1          Timestamp                       This RFC
         2          Checksum                        This RFC

7.  Normative References

   [RFC1071]  Braden, R., Borman, D., and C. Partridge, "Computing the
              Internet checksum", RFC 1071, DOI 10.17487/RFC1071,
              September 1988, <https://www.rfc-editor.org/info/rfc1071>.






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   [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>.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,
              <https://www.rfc-editor.org/info/rfc4760>.

   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
              "Network Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
              <https://www.rfc-editor.org/info/rfc5905>.

   [RFC7606]  Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
              Patel, "Revised Error Handling for BGP UPDATE Messages",
              RFC 7606, DOI 10.17487/RFC7606, August 2015,
              <https://www.rfc-editor.org/info/rfc7606>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

Authors' Addresses

   Jakob Heitz
   Cisco
   170 West Tasman Drive
   San Jose, CA, CA  95134
   USA

   Email: jheitz@cisco.com


   Prasad S. Narasimha
   Cisco
   170 West Tasman Drive
   San Jose, CA, CA  95134
   USA

   Email: snprasad@cisco.com



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   Sameer Gulrajani
   Cisco
   170 West Tasman Drive
   San Jose, CA, CA  95134
   USA

   Email: sameerg@cisco.com












































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