Extended BGP Administrative Shutdown Communication
NTT CommunicationsTheodorus Majofskistraat 1001065 SZAmsterdamThe Netherlandsjob@ntt.netCisco170 West Tasman DriveSan JoseCA95134United States of Americajheitz@cisco.comJuniper Networks1194 N. Mathilda AveSunnyvaleCA94089United States of Americajgs@juniper.netQrator Labsaa@qrator.net
Routing
IDRBGPceaseshutdown
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.
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 when,
and only when, they appear in all capitals, as shown here.
It can be troublesome for an operator to correlate a BGP-4 session teardown in the network with a notice that was transmitted via offline methods such email or telephone calls.
This document updates by specifying 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 or reset.
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" , it MAY include an UTF-8 encoded string.
The contents of the string are at the operator's discretion.
The Cease NOTIFICATION message with a Shutdown Communication is encoded as
below:
the Error Subcode value MUST be one of the following
values: 2 ("Administrative Shutdown") or 4
("Administrative Reset").
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.
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.
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.
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.
Per this document, IANA is requested to reference this document at subcode "Administrative Shutdown", and at subcode "Administrative Reset" in the "Cease NOTIFICATION message subcodes" registry under the "Border Gateway Protocol (BGP) Parameters" group in addition to and .
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 to learn about these issues.
UTF-8 "Shortest Form" encoding is REQUIRED to guard against the technical issues outlined in .
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 255 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 and .
Users of this mechanism should consider applying data minimization practices as outlined in Section 6.1 of because a received Shutdown Communication may be used at the receiver's discretion.
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:
Juniper Junos......Unicode Security Considerations
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 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 's length specification was insufficient in context of multibyte character sets.
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 .
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 добавлению коммутаторав стек.Время завершения - 30минут' (See PDF for non-ASCII character string) has length 139 bytes.