IDR J. Snijders Internet-Draft NTT Obsoletes: 8203 (if approved) J. Heitz Updates: 4486 (if approved) Cisco Intended status: Standards Track J. Scudder Expires: October 17, 2020 Juniper A. Azimov Yandex April 15, 2020 Extended BGP Administrative Shutdown Communication draft-ietf-idr-rfc8203bis-06 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 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 working documents as Internet-Drafts. The list of current Internet- 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 October 17, 2020. Snijders, et al. Expires October 17, 2020 [Page 1] Internet-Draft BGP Shutdown Communication April 2020 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 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. 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 . . . . . . . . . . . . . . . . . 5 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 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. Snijders, et al. Expires October 17, 2020 [Page 2] Internet-Draft BGP Shutdown Communication April 2020 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 NULL 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 an indication about the length of the maintenance. The receiver can Snijders, et al. Expires October 17, 2020 [Page 3] Internet-Draft BGP Shutdown Communication April 2020 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 is a log message. For this reason, operators would be wise to keep shutdown communications to less than 128 octets when feasible. There is no guarantee that the receiver supports either this specification or [RFC8203], so any shutdown communication might not be logged in an easily-readable form at all. Therefore, operators would also be wise not to rely on shutdown communications as their sole form of communication with their peer for important events. 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 Per this document, 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] and [RFC8203]. 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. 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 Snijders, et al. Expires October 17, 2020 [Page 4] Internet-Draft BGP Shutdown Communication April 2020 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, . [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 2003, . [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, . [RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease Notification Message", RFC 4486, DOI 10.17487/RFC4486, April 2006, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8203] Snijders, J., Heitz, J., and J. Scudder, "BGP Administrative Shutdown Communication", RFC 8203, DOI 10.17487/RFC8203, July 2017, . 7.2. Informative References [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", RFC 4272, DOI 10.17487/RFC4272, January 2006, . Snijders, et al. Expires October 17, 2020 [Page 5] Internet-Draft BGP Shutdown Communication April 2020 [RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, DOI 10.17487/RFC5424, March 2009, . [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, . [UTR36] Davis, M. and M. Suignard, "Unicode Security Considerations", Unicode Technical Report #36, August 2010, . 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 [RFC8203]. For example, the phrase: 'Planned work to add switch to stack. Completion time - 30 minutes' has length 65 bytes. Its translation in Russian 'Плановые работы по д 86;бавлению к&# 1086;ммутатора& #1074; стек.Время 79;авершения - Snijders, et al. Expires October 17, 2020 [Page 6] Internet-Draft BGP Shutdown Communication April 2020 30минут' (See PDF for non-ASCII character string) has length 139 bytes. 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 Snijders, et al. Expires October 17, 2020 [Page 7]