NTT Communications

Theodorus Majofskistraat 100 1065 SZ Amsterdam The Netherlands job@ntt.net

Cisco

170 West Tasman Drive San Jose CA 95054 USA jheitz@cisco.com

Juniper Networks

1194 N. Mathilda Ave Sunnyvale CA 94089 USA jgs@juniper.net

Routing IDR BGP cease shutdown 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. 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 .

It can be troublesome for an operator to correlate a BGP-4 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 message as part of a Cease NOTIFICATION message to inform the peer why the BGP session is being shutdown.

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 freeform UTF-8 encoded string with a REQUIRED maximum length of 128 octets. The contents of the string are at the operator's discretion. The Shutdown Communication Cease NOTIFICATION message is encoded as below:

The Length value can range from 0 to 128 and indicates how many octets of Shutdown Communication follow. 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. Mechanisms concerning the reporting of information contained in the Shutdown Communication are implementation specific but SHOULD include methods such as SYSLOG.

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.

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

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.

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 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) is used for the BGP session in question, a Shutdown Communication message could be forged. Unless a transport that provides confidentiality (such as IPSec) 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.

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 Wireshark (packet analyser) tcpdump, (alt) (packet analyser)

The authors would like to gratefully acknowledge Tom Scholl, David Freedman, Jared Mauch, Jeff Haas, Peter Hessler, Bruno Decraene, John Heasley, Peter van Dijk, and Arjen Zonneveld.