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IETF RFC 8203
Last modified on Wednesday, July 26th, 2017
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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/RFC 8203.
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.
Snijders, et al. Standards Track PAGE 1 
RFC 8203 BGP Shutdown July 2017
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 [RFC 4271]
session teardown in the network with a notice that was transmitted
via offline methods such as email or telephone calls. This document
updates [RFC 4486] by specifying a mechanism to transmit a short
freeform UTF-8 [RFC 3629] message as part of a Cease NOTIFICATION
message [RFC 4271] 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 [RFC 2119] [RFC 8174] 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" [RFC 4486], 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 [RFC 5424].
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
Snijders, 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 [RFC 4486]) 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 [RFC 4271] and [RFC 4272].
Users of this mechanism should consider applying data minimization
practices as outlined in Section 6.1 of [RFC 6973] 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 2017
7. References
7.1. Normative References
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC 2119, March 1997,
<http://www.rfc-editor.org/info/RFC 2119>.
[RFC 3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC 3629, November
2003, <http://www.rfc-editor.org/info/RFC 3629>.
[RFC 4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC 4271, January 2006,
<http://www.rfc-editor.org/info/RFC 4271>.
[RFC 4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease
Notification Message", RFC 4486, DOI 10.17487/RFC 4486,
April 2006, <http://www.rfc-editor.org/info/RFC 4486>.
[RFC 8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC 8174,
May 2017, <http://www.rfc-editor.org/info/RFC 8174>.
7.2. Informative References
[RFC 4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC 4272, January 2006,
<http://www.rfc-editor.org/info/RFC 4272>.
[RFC 5424] Gerhards, R., "The Syslog Protocol", RFC 5424,
DOI 10.17487/RFC 5424, March 2009,
<http://www.rfc-editor.org/info/RFC 5424>.
[RFC 6973] 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/RFC 6973, July 2013,
<http://www.rfc-editor.org/info/RFC 6973>.
[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 2017
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 [RFC 4486] 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: 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.net
Snijders, et al. Standards Track PAGE 6
RFC TOTAL SIZE: 12532 bytes
PUBLICATION DATE: Wednesday, July 26th, 2017
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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