BGP Administrative Shutdown Communication
draft-ietf-idr-shutdown-03

Abstract

This document enhances the BGP Cease NOTIFICATION message "Administrative Shutdown" subcode for operators to transmit a short freeform message to describe why a BGP session was shutdown.

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

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 http://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 July 23, 2017.

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.

Table of Contents

• 1. Introduction
• 2. Shutdown Communication
• 3. Operational Considerations
• 4. Error Handling
• 5. IANA Considerations
• 6. Security Considerations
• 7. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION
• 8. References
• 8.1. Normative References
• 8.2. Informative References
• Appendix A. Acknowledgements
• Authors' Addresses

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 off-line methods such email or telephone calls. This document specifies a mechanism to transmit a short freeform UTF-8 [RFC3629] message as part of a Cease NOTIFICATION message [RFC4486] to inform the peer why the BGP session is being shutdown.

2. Shutdown Communication

If a BGP speaker decides to terminate its session with a BGP neighbor, then the BGP speaker MAY send to the neighbor a NOTIFICATION message with the Error Code "Cease" and the Error Subcode "Administrative Shutdown" followed by a length field and an UTF-8 encoded string. The contents of the string are at the operator's discretion.

 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 2   |    Length     |     ...       \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               /
\                                                               \
/                 ... Shutdown Communication ...                /
\                                                               \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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

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.

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 now use the string 'TICKET-1-1438367390' to search in their email archive to find more details.

4. Error Handling

Any erroneous or malformed Shutdown Communication received SHOULD be logged for the attention of the operator and then MAY be discarded.

5. IANA Considerations

Per this document, IANA is requested to reference this document at subcode "Administrative Shutdown" in the "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 operator are advised to review UNICODE TR36 [UTR36] to learn about these issues. This document guards against the technical issues outlined in UTR36 by REQUIRING "shortest form" encoding. However, the visual spoofing due to character confusion still persists. This specification minimizes the effects of visual spoofing by limiting the length of the Shutdown Communication.

Users of this mechanism should be aware that unless a transport that provides integrity (such as TCP-AO [RFC5925]) is used for the BGP session in question, a Shutdown Communication message could be forged. Unless a transport that provides confidentiality (such as IPSec [RFC4303]) 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.

7. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION

This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in RFC7942. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.

As of today these vendors have produced an implementation of the Shutdown Communication:

• ExaBGP
• pmacct
• OpenBGPD
• GoBGP
• Wireshark (packet analyser)
• tcpdump, (alt) (packet analyser)

8. References

8.1. Normative References

8.2. Informative References

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, and Saku Ytti.

Authors' Addresses