Internet Engineering Task Force (IETF)                       J. Snijders
Request for Comments: 8203                                           NTT
Updates: 4486                                                   J. Heitz
Category: Standards Track                                          Cisco
ISSN: 2070-1721                                               J. Scudder
                                                                Juniper
                                                              July 2017


              BGP Administrative Shutdown Communication

Abstract

  This document enhances the BGP Cease NOTIFICATION message
  "Administrative Shutdown" and "Administrative Reset" subcodes for
  operators to transmit a short freeform message to describe why a BGP
  session was shutdown or reset.  This document updates RFC 4486.

Status of This Memo

  This is an Internet Standards Track document.

  This document is a product of the Internet Engineering Task Force
  (IETF).  It represents the consensus of the IETF community.  It has
  received public review and has been approved for publication by the
  Internet Engineering Steering Group (IESG).  Further information on
  Internet Standards is available in Section 2 of RFC 7841.

  Information about the current status of this document, any errata,
  and how to provide feedback on it may be obtained at
  http://www.rfc-editor.org/info/rfc8203.

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
  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.





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Table of Contents

  1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
    1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
  2.  Shutdown Communication  . . . . . . . . . . . . . . . . . . .   2
  3.  Operational Considerations  . . . . . . . . . . . . . . . . .   3
  4.  Error Handling  . . . . . . . . . . . . . . . . . . . . . . .   4
  5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
  6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
  7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
    7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
    7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   6
  Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

  It can be troublesome for an operator to correlate a BGP-4 [RFC4271]
  session teardown in the network with a notice that was transmitted
  via offline methods such as email or telephone calls.  This document
  updates [RFC4486] by specifying a mechanism to transmit a short
  freeform UTF-8 [RFC3629] message as part of a Cease NOTIFICATION
  message [RFC4271] to inform the peer why the BGP session is being
  shutdown or reset.

1.1.  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 [RFC2119] [RFC8174] when, and only when, they appear in all
  capitals, as shown here.

2.  Shutdown Communication

  If a BGP speaker decides to terminate its session with a BGP
  neighbor, and it sends a NOTIFICATION message with the Error Code
  "Cease" and Error Subcode "Administrative Shutdown" or
  "Administrative Reset" [RFC4486], it MAY include an UTF-8 encoded
  string.  The contents of the string are at the operator's discretion.











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  The Cease NOTIFICATION message with a Shutdown Communication is
  encoded as below:

   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
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Error Code 6  |    Subcode    |    Length     |     ...       \
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               /
  \                                                               \
  /                 ... Shutdown Communication ...                /
  \                                                               \
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                Figure 1

  Subcode:  the Error Subcode value MUST be one of the following
     values: 2 ("Administrative Shutdown") or 4 ("Administrative
     Reset").

  Length:  this 8-bit field represents the length of the Shutdown
     Communication field in octets.  The length value MUST range from 0
     to 128 inclusive.  When the length value is zero, no Shutdown
     Communication field follows.

  Shutdown Communication:  to support international characters, the
     Shutdown Communication field MUST be encoded using UTF-8.  A
     receiving BGP speaker MUST NOT interpret invalid UTF-8 sequences.
     Note that when the Shutdown Communication contains multibyte
     characters, the number of characters will be less than the length
     value.  This field is not NUL terminated.

  Mechanisms concerning the reporting of information contained in the
  Shutdown Communication are implementation specific but SHOULD include
  methods such as Syslog [RFC5424].

3.  Operational Considerations

  Operators are encouraged to use the Shutdown Communication to inform
  their peers of the reason for the shutdown of the BGP session and
  include out-of-band reference materials.  An example of a useful
  Shutdown Communication would be:

  "[TICKET-1-1438367390] software upgrade; back in 2 hours"

  "[TICKET-1-1438367390]" is a ticket reference with significance to
  both the sender and receiver, followed by a brief human-readable
  message regarding the reason for the BGP session shutdown followed by




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  an indication about the length of the maintenance.  The receiver can
  now use the string 'TICKET-1-1438367390' to search in their email
  archive to find more details.

4.  Error Handling

  If a Shutdown Communication with an invalid Length value, or an
  invalid UTF-8 sequence is received, a message indicating this event
  SHOULD be logged for the attention of the operator.  An erroneous or
  malformed Shutdown Communication itself MAY be logged in a hexdump
  format.

5.  IANA Considerations

  IANA references this document (in addition to [RFC4486]) for subcodes
  "Administrative Shutdown" (2) and "Administrative Reset" (4) in the
  "Cease NOTIFICATION message subcodes" registry under the "Border
  Gateway Protocol (BGP) Parameters" group.

6.  Security Considerations

  This document uses UTF-8 encoding for the Shutdown Communication.
  There are a number of security issues with Unicode.  Implementers and
  operators are advised to review Unicode Technical Report #36 [UTR36]
  to learn about these issues.  UTF-8 "Shortest Form" encoding is
  REQUIRED to guard against the technical issues outlined in [UTR36].

  As BGP Shutdown Communications are likely to appear in syslog output,
  there is a risk that carefully constructed Shutdown Communication
  might be formatted by receiving systems in a way to make them appear
  as additional syslog messages.  To limit the ability to mount such an
  attack, the BGP Shutdown Communication is limited to 128 octets in
  length.

  Users of this mechanism should be aware that unless a transport that
  provides integrity is used for the BGP session in question, a
  Shutdown Communication message could be forged.  Unless a transport
  that provides confidentiality is used, a Shutdown Communication
  message could be snooped by an attacker.  These issues are common to
  any BGP message but may be of greater interest in the context of this
  proposal since the information carried in the message is generally
  expected to be used for human-to-human communication.  Refer to the
  related considerations in [RFC4271] and [RFC4272].

  Users of this mechanism should consider applying data minimization
  practices as outlined in Section 6.1 of [RFC6973] because a received
  Shutdown Communication may be used at the receiver's discretion.




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7.  References

7.1.  Normative References

  [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>.

  [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
             10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
             2003, <http://www.rfc-editor.org/info/rfc3629>.

  [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,
             <http://www.rfc-editor.org/info/rfc4271>.

  [RFC4486]  Chen, E. and V. Gillet, "Subcodes for BGP Cease
             Notification Message", RFC 4486, DOI 10.17487/RFC4486,
             April 2006, <http://www.rfc-editor.org/info/rfc4486>.

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

7.2.  Informative References

  [RFC4272]  Murphy, S., "BGP Security Vulnerabilities Analysis",
             RFC 4272, DOI 10.17487/RFC4272, January 2006,
             <http://www.rfc-editor.org/info/rfc4272>.

  [RFC5424]  Gerhards, R., "The Syslog Protocol", RFC 5424,
             DOI 10.17487/RFC5424, March 2009,
             <http://www.rfc-editor.org/info/rfc5424>.

  [RFC6973]  Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
             Morris, J., Hansen, M., and R. Smith, "Privacy
             Considerations for Internet Protocols", RFC 6973,
             DOI 10.17487/RFC6973, July 2013,
             <http://www.rfc-editor.org/info/rfc6973>.

  [UTR36]    Davis, M., Ed. and M. Suignard, Ed., "Unicode Security
             Considerations", Unicode Technical Report #36, August
             2010, <http://unicode.org/reports/tr36/>.






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Acknowledgements

  The authors would like to gratefully acknowledge Tom Scholl, David
  Freedman, Jared Mauch, Jeff Haas, Peter Hessler, Bruno Decraene, John
  Heasley, Peter van Dijk, Arjen Zonneveld, James Bensley, Susan Hares,
  Saku Ytti, Lou Berger, Alvaro Retana, and Adam Roach.

  The authors would like to thank Enke Chen and Vincent Gillet for
  their work on [RFC4486] and granting the related rights to the IETF
  Trust per BCP 78.

Authors' Addresses

  Job Snijders
  NTT Communications
  Theodorus Majofskistraat 100
  Amsterdam  1065 SZ
  The Netherlands

  Email: [email protected]


  Jakob Heitz
  Cisco
  170 West Tasman Drive
  San Jose, CA  95134
  United States of America

  Email: [email protected]


  John Scudder
  Juniper Networks
  1194 N. Mathilda Ave
  Sunnyvale, CA  94089
  United States of America

  Email: [email protected]













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