Internet DRAFT - draft-ietf-idr-rfc8203bis
draft-ietf-idr-rfc8203bis
IDR J. Snijders
Internet-Draft NTT
Obsoletes: 8203 (if approved) J. Heitz
Updates: 4486 (if approved) Cisco
Intended status: Standards Track J. Scudder
Expires: April 17, 2021 Juniper
A. Azimov
Yandex
October 14, 2020
Extended BGP Administrative Shutdown Communication
draft-ietf-idr-rfc8203bis-08
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 and
obsoletes RFC 8203 by defining an Extended BGP Administrative
Shutdown Communication of up to 255 octets to improve communication
using multibyte character sets.
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.
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
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."
This Internet-Draft will expire on April 17, 2021.
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Copyright Notice
Copyright (c) 2020 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
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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. 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 . . . . . . . . . . . . . . . . . 6
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 6
Appendix B. Changes to RFC 8203 . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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. This document obsoletes [RFC8203]; the specific
differences and rationale are discussed in detail in Appendix B.
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 a 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. 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. UTF-8 "Shortest Form"
encoding is REQUIRED to guard against the technical issues
outlined in [UTR36].
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.
If a Shutdown Communication longer than 128 octets is sent to a BGP
speaker that implements [RFC8203], then that speaker will treat it as
an error, the consequence of which should be a log message.
If a Shutdown Communication of any length is sent to a BGP speaker
that implements neither [RFC8203] nor this specification, then that
speaker will treat it as an error, the consequence of which should be
a log message.
In any case, a receiver of a NOTIFICATION message is unable to
acknowledge the receipt and correct understanding of any Shutdown
Communication.
Operators should not rely on Shutdown Communications as their sole
form of communication with their peer for important events.
If it is known that the peer BGP speaker supports this specification,
then a Shutdown Communication that is not longer than 255 octets MAY
be sent. Otherwise, a Shutdown Communication MAY be sent, but it
SHOULD NOT be longer than 128 octets.
4. Error Handling
If a Shutdown Communication with 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 is requested to reference this document at subcode
"Administrative Shutdown", and at subcode "Administrative Reset" in
the "BGP Cease NOTIFICATION message subcodes" registry under the
"Border Gateway Protocol (BGP) Parameters" group in addition to
[RFC4486].
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].
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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. The 255 octet length limit on the BGP
Shutdown Communication may help limit the ability to mount such an
attack.
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.
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,
<https://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, <https://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,
<https://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, <https://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, <https://www.rfc-editor.org/info/rfc8174>.
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7.2. Informative References
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424,
DOI 10.17487/RFC5424, March 2009,
<https://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,
<https://www.rfc-editor.org/info/rfc6973>.
[RFC8203] Snijders, J., Heitz, J., and J. Scudder, "BGP
Administrative Shutdown Communication", RFC 8203,
DOI 10.17487/RFC8203, July 2017,
<https://www.rfc-editor.org/info/rfc8203>.
[UTR36] Davis, M. and M. Suignard, "Unicode Security
Considerations", Unicode Technical Report #36, August
2010, <http://unicode.org/reports/tr36/>.
Appendix A. 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 BCP 78 rights to the
IETF Trust.
The authors would like to acknowledge Misha Grishin (MSK-IX) for
raising awareness that [RFC8203]'s length specification was
insufficient in context of multibyte character sets.
Appendix B. Changes to RFC 8203
The maximum permitted length was changed from 128 to 255.
Feedback from operators based in regions which predominantly use
multibyte character sets, showed that messages similar in meaning to
what can be send in other languages in using single-byte encoding,
failed to fit within the Length constraints as specified by
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[RFC8203]. For example, the phrase: 'Planned work to add switch to
stack. Completion time - 30 minutes' has length 65 bytes. Its
translation in Russian has length 139 bytes.
If a Shutdown Communication message longer than 128 octets is sent to
a BGP speaker that implements [RFC8203], then that speaker will bring
it to the attention of an operator, but will otherwise process the
NOTIFICATION message as normal.
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
Alexander Azimov
Yandex
Email: a.e.azimov@gmail.com
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