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Internet Engineering Task Force (IETF)                       J. SnijdersRequest for Comments: 8203                                           NTTUpdates:4486                                                   J. HeitzCategory: Standards Track                                          CiscoISSN: 2070-1721                                               J. Scudder                                                                 Juniper                                                               July 2017BGP Administrative Shutdown CommunicationAbstract   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 updatesRFC 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 inSection 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://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 toBCP 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.Snijders, et al.             Standards Track                    [Page 1]

RFC 8203                      BGP Shutdown                     July 2017Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .21.1.  Requirements Language . . . . . . . . . . . . . . . . . .22.  Shutdown Communication  . . . . . . . . . . . . . . . . . . .23.  Operational Considerations  . . . . . . . . . . . . . . . . .34.  Error Handling  . . . . . . . . . . . . . . . . . . . . . . .45.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .46.  Security Considerations . . . . . . . . . . . . . . . . . . .47.  References  . . . . . . . . . . . . . . . . . . . . . . . . .57.1.  Normative References  . . . . . . . . . . . . . . . . . .57.2.  Informative References  . . . . . . . . . . . . . . . . .5   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .6   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .61.  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 inBCP 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.Snijders, et al.             Standards Track                    [Page 2]

RFC 8203                      BGP Shutdown                     July 2017   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 bySnijders, et al.             Standards Track                    [Page 3]

RFC 8203                      BGP Shutdown                     July 2017   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 inSection 6.1 of [RFC6973] because a received   Shutdown Communication may be used at the receiver's discretion.Snijders, et al.             Standards Track                    [Page 4]

RFC 8203                      BGP Shutdown                     July 20177.  References7.1.  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 inRFC2119 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/>.Snijders, et al.             Standards Track                    [Page 5]

RFC 8203                      BGP Shutdown                     July 2017Acknowledgements   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 perBCP 78.Authors' Addresses   Job Snijders   NTT Communications   Theodorus Majofskistraat 100   Amsterdam  1065 SZ   The Netherlands   Email: job@ntt.net   Jakob Heitz   Cisco   170 West Tasman Drive   San Jose, CA  95134   United States of America   Email: jheitz@cisco.com   John Scudder   Juniper Networks   1194 N. Mathilda Ave   Sunnyvale, CA  94089   United States of America   Email: jgs@juniper.netSnijders, et al.             Standards Track                    [Page 6]