TLV support for BMP Route Monitoring and Peer Down Messages
draft-ietf-grow-bmp-tlv-05
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|---|---|---|---|
| Authors | Paolo Lucente , Yunan Gu | ||
| Last updated | 2021-07-27 | ||
| Replaces | draft-lucente-bmp-tlv | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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| Additional resources | Mailing list discussion | ||
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draft-ietf-grow-bmp-tlv-05
Global Routing Operations P. Lucente
Internet-Draft NTT
Updates: 7854 (if approved) Y. Gu
Intended status: Standards Track Huawei
Expires: 28 January 2022 27 July 2021
TLV support for BMP Route Monitoring and Peer Down Messages
draft-ietf-grow-bmp-tlv-05
Abstract
Most of the message types defined by the BGP Monitoring Protocol
(BMP) do provision for optional trailing data. However, Route
Monitoring messages (to provide a snapshot of the monitored Routing
Information Base) and Peer Down messages (to indicate that a peering
session was terminated) do not. Supporting optional data in TLV
format across all BMP message types allows for an homogeneous and
extensible surface that would be useful for the most different use-
cases that need to convey additional data to a BMP station. While it
is not intended for this document to cover any specific utilization
scenario, it defines a simple way to support optional TLV data in all
message types.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 January 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. TLV encoding . . . . . . . . . . . . . . . . . . . . . . . . 3
4. BMP Message Format . . . . . . . . . . . . . . . . . . . . . 4
4.1. Common Header . . . . . . . . . . . . . . . . . . . . . . 4
4.2. TLV data in Route Monitoring . . . . . . . . . . . . . . 4
4.3. TLV data in Peer Down . . . . . . . . . . . . . . . . . . 5
4.4. TLV data in other BMP messages . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Operational Considerations . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 6
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The BGP Monitoring Protocol (BMP) is defined in The Route Monitoring
message consists of: The Peer Down Notification message consists of:
RFC 7854 [RFC7854].
* Common Header
* Per-Peer Header
* BGP Update PDU
* Common Header
* Per-Peer Header
* Reason
* Data (only if Reason code is 1, 2 or 3)
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This means that both Route Monitoring and Peer Down messages have a
non-extensible format. In the Route Monitoring case, this is
limiting if wanting to transmit characteristics of transported NLRIs
(ie. to help stateless parsing) or to add vendor-specific data. In
the Peer Down case, this is limiting if matching TLVs sent with the
Peer Up is desired. The proposal of this document is to bump the BMP
version, for backward compatibility, and allow all message types to
provision for trailing TLV data.
2. Terminology
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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
3. TLV encoding
The TLV data type is already defined in Section 4.4 of [RFC7854] for
the Initiation and Peer Up message types. A TLV consists of:
* 2 octets of TLV Type,
* 2 octets of TLV Length,
* 0 or more octets of TLV Value.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (2 octets) | Length (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Value (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
TLVs SHOULD be sorted by their code point. Multiple TLVs of the same
type can be repeated as part of the same message, and it is left to
the specific use-cases whether all, any, the first or the last TLV
should be considered.
Route Monitoring messages may require per-NLRI TLVs, that is, there
may be a need to map TLVs to NLRIs contained in the BGP Update
message, for example, to express additional characteristics of a
specific NLRI. For this purpose specifically, TLVs in Route
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Monitoring messages can be optionally indexed, with the index
starting at zero to refer to the first NLRI, and encoded as in the
following figure:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (2 octets) | Length (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Index (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Value (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Of the BMP message types defined so far, indexed TLVs do apply only
to Route Monitoring messages and, for example, they do not apply to
Route Mirroring ones because the sender may not be aware of the
payload of the transported BGP Update message.
4. BMP Message Format
4.1. Common Header
Section 4.1 of [RFC7854] defines the Common Header. While the
structure remains unaltered, the following two definitions are
changed:
* Version: Indicates the BMP version. This is set to '4' for all
messages.
* Message Length: Total length of the message in bytes (including
headers, encapsulated BGP message and optional data)
4.2. TLV data in Route Monitoring
The Route Monitoring message type is defined in Section 4.6 of
[RFC7854]. The BGP Update PDU Section 4.3 of [RFC4271] MAY be
followed by TLV data. This document defines the following new code
points to help stateless parsing of BGP Update PDUs:
* Type = TBD1: the BGP Update PDU is encoded with support for the
4-octet AS number capability RFC 6793 [RFC6793], value MUST be
boolean.
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* Type = TBD2: the BGP Update PDU is encoded with the ADD-PATH
capability RFC 7911 [RFC7911], value MUST be boolean.
* Type = TBD3: the BGP Update PDU is encoded with the Multiple
Labels capability RFC 8277 [RFC8277], value MUST be boolean.
4.3. TLV data in Peer Down
The Peer Down Notification message type is defined in Section 4.9 of
[RFC7854]. For Reason codes 1 or 3, a BGP Notification PDU follows;
the PDU MAY be followed by TLV data. For Reason code 2, a 2-byte
field to give additional FSM info follows; this field MAY be followed
by TLV data. For all other Reason codes, TLV data MAY follow the
Reason field.
4.4. TLV data in other BMP messages
All other message types defined in RFC7854 [RFC7854] do already
provision for TLV data. It is RECOMMENDED that all future BMP
message types will provision for trailing TLV data.
5. Security Considerations
It is not believed that this document adds any additional security
considerations.
6. Operational Considerations
In Route Monitoring messages, the number of TLVs can be bound to the
amount of NLRIs carried in the BGP Update message. This may degrade
the packing of information in such messages and have specific impacts
on the memory and CPU used in a BMP implementation. As a result of
that it should always be possible to disable such features to
mitigate their impact.
7. IANA Considerations
This document defines the following new TLV types for BMP Route
Monitoring and Peer Down messages (Section 4.2):
* Type = TBD1: Support for the 4-octet AS number capability. The
value field contains a boolean value of 1 if the BGP Update PDU
enclosed in the Route Monitoring message was encoded according to
the capability.
* Type = TBD2: ADD-PATH capability. The value field contains a
boolean value of 1 if the BGP Update PDU enclosed in the Route
Monitoring message was encoded according to the capability.
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* Type = TBD3: Multiple Labels capability. The value field contains
a boolean value of 1 if the BGP Update PDU enclosed in the Route
Monitoring message was encoded according to the capability.
8. 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>.
[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>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793,
DOI 10.17487/RFC6793, December 2012,
<https://www.rfc-editor.org/info/rfc6793>.
[RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
Monitoring Protocol (BMP)", RFC 7854,
DOI 10.17487/RFC7854, June 2016,
<https://www.rfc-editor.org/info/rfc7854>.
[RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder,
"Advertisement of Multiple Paths in BGP", RFC 7911,
DOI 10.17487/RFC7911, July 2016,
<https://www.rfc-editor.org/info/rfc7911>.
[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>.
[RFC8277] Rosen, E., "Using BGP to Bind MPLS Labels to Address
Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017,
<https://www.rfc-editor.org/info/rfc8277>.
Acknowledgements
The authors would like to thank Jeff Haas, Camilo Cardona, Thomas
Graf and Pierre Francois for their valuable input. The authors would
also like to thank Greg Skinner for his review.
Authors' Addresses
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Paolo Lucente
NTT
Siriusdreef 70-72
2132 Hoofddorp
Netherlands
Email: paolo@ntt.net
Yunan Gu
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing
100095
China
Email: guyunan@huawei.com
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