BMP Extension for BGP Path Attribute Sets and Statistics
draft-wang-grow-bmp-attribute-sets-stats-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Zhiyuan Wang , Nan Geng , Shunwan Zhuang , Haibo Wang | ||
| Last updated | 2026-10-28 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
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| Consensus boilerplate | Unknown | ||
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draft-wang-grow-bmp-attribute-sets-stats-00
GROW Z. Wang
Internet-Draft N. Geng
Intended status: Standards Track S. Zhuang
Expires: 1 May 2027 H. Wang
Huawei Technologies
28 October 2026
BMP Extension for BGP Path Attribute Sets and Statistics
draft-wang-grow-bmp-attribute-sets-stats-00
Abstract
The BGP Monitoring Protocol (BMP) specified in RFC 7854 requires a
monitored router to send full BGP Path Attributes for every Route
Monitoring message. In networks with a large number of prefixes
sharing identical BGP Path Attributes, this requirement leads to
substantial transmission redundancy and protocol overhead.
This document specifies a decoupled architecture for BMP monitoring
that separates Path Attribute Set registration from NLRI volume
statistics. Attribute updates are triggered immediately upon path
attribute changes, while NLRI count updates can be configured for
either event-driven (immediate) or periodic reporting modes, with
mandatory instant notification when an attribute set's reference
count drops to zero.
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/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on 1 May 2027.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 3
3.1. BMP Attribute Set Declaration Message . . . . . . . . . . 3
3.2. BMP Attribute Count Update Message . . . . . . . . . . . 4
3.3. BMP Message Type Allocations . . . . . . . . . . . . . . 6
4. Operational Procedures . . . . . . . . . . . . . . . . . . . 6
4.1. Attribute Set Declaration Logic (Immediate Trigger) . . . 6
4.2. Attribute Count Update Modes . . . . . . . . . . . . . . 6
4.3. Session Re-establishment and State Synchronization . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The BGP Monitoring Protocol (BMP) [RFC7854] provides a mechanism to
monitor BGP routing state and updates on a router. Currently, BMP
encapsulates standard BGP UPDATE messages containing Network Layer
Reachability Information (NLRI) and Path Attributes [RFC4271] inside
BMP Route Monitoring (RM) messages.
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In modern scale-out networks, hundreds of thousands of NLRIs often
share identical BGP Path Attributes (e.g., AS_PATH, Local-Preference,
Communities). Transmitting identical attribute structures repeatedly
for each route update introduces significant redundancy.
To minimize export bandwidth while maintaining visibility, this draft
decouples Attribute Sets from Prefix Counts:
1. BMP Attribute Set Declaration Message: Event-driven notification
triggered immediately whenever a unique BGP Path Attribute Set is
created, modified, or deleted.
2. BMP Attribute Count Update Message: Flexible statistics report
supporting both Event-driven (Immediate) and Periodic polling
modes.
2. Terminology
* Attribute Set (AS): A canonical, ordered collection of BGP Path
Attributes contained within a BGP UPDATE message.
* Attribute Set Identifier (AS-ID): A 32-bit locally unique integer
generated by the router to represent a unique Attribute Set.
3. Protocol Extensions
3.1. BMP Attribute Set Declaration Message
The BMP Attribute Set Declaration Message is used to register a new
unique BGP Path Attribute Set or explicitly unregister an existing
one.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Set ID (AS-ID) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Attributes Length (2 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Attributes (Variable Length) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fields:
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* Attribute Set ID (AS-ID) (32 bits): A 32-bit unsigned integer
assigned locally by the monitored router to uniquely identify a
specific BGP Path Attribute Set during the active session
lifecycle. The value MUST NOT be 0 (0x00000000 is reserved).
* Action (4 bits): Specifies the operation to be performed on the
target AS-ID:
- 0x1 (REGISTER): Indicates the declaration of a new unique Path
Attribute Set. The receiver MUST associate the provided Path
Attributes with this AS-ID.
- 0x2 (UNREGISTER): Indicates that the AS-ID is explicitly
deleted. The receiver MUST purge or mark inactive the Path
Attribute Set associated with this AS-ID.
- Values 0x0 and 0x3-0xF are reserved for future use and MUST be
ignored on receipt.
* Reserved (28 bits): Reserved for future extension. MUST be set to
0 by the sender on transmission and MUST be ignored by the
receiver upon receipt.
* Path Attributes Length (16 bits): A 16-bit unsigned integer
specifying the total length, in octets, of the Path Attributes
field.
- When Action = 0x1 (REGISTER), this field MUST be greater than
0.
- When Action = 0x2 (UNREGISTER), this field SHOULD be set to 0.
* Path Attributes (Variable Length): Contains zero or more BGP Path
Attributes formatted as specified in Section 5 of [RFC4271]. This
field is evaluated only when Action = 0x1 (REGISTER).
3.2. BMP Attribute Count Update Message
The BMP Attribute Count Update Message is used to convey prefix
volume statistics bound to a previously registered AS-ID.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Set ID (AS-ID) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Op | Mode | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Count / Delta |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fields:
* Attribute Set ID (AS-ID) (32 bits): A 32-bit unsigned integer
referencing a valid AS-ID previously announced via a BMP Attribute
Set Declaration Message (Action = REGISTER).
* Op (Operation Type) (4 bits): Defines how the receiver interprets
the value in the NLRI Count / Delta field:
- 0x1 (ABSOLUTE_COUNT): The value represents the exact total
number of prefixes (NLRIs) currently bound to this AS-ID.
- 0x2 (DELTA_ADD): The value represents an incremental addition
(+N) to the current prefix count associated with this AS-ID.
- 0x3 (DELTA_DEL): The value represents an incremental
subtraction (-N) from the current prefix count associated with
this AS-ID.
- 0x4 (ZERO_REF): Indicates that the prefix count bound to this
AS-ID has dropped to 0. The NLRI Count / Delta field MUST be
set to 0.
* Mode (4 bits): Indicates the operational context under which this
report was generated:
- 0x1 (EVENT_DRIVEN): Sent immediately in response to a routing
state change (e.g., prefix addition/withdrawal).
- 0x2 (PERIODIC): Sent as part of a scheduled, regular telemetry
sweep.
* Reserved (24 bits): Reserved for future extension. MUST be set to
0 on transmission and ignored on receipt.
* NLRI Count / Delta (32 bits): A 32-bit unsigned integer
representing either the total prefix volume or the change delta,
interpreted according to the Op field.
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3.3. BMP Message Type Allocations
This document defines two new BMP message types to be registered by
IANA under the "BMP Message Types" registry:
* BMP Message Type = TBD1: Attribute Set Declaration Message (used
to register or unregister canonical path attribute sets).
* BMP Message Type = TBD2: Attribute Count Update Message (used to
report prefix volume statistics associated with a specific AS-ID).
4. Operational Procedures
4.1. Attribute Set Declaration Logic (Immediate Trigger)
1. The router MUST monitor unique Path Attribute combinations in its
RIB.
2. When a route arrives with a previously unseen Path Attribute
combination, the router MUST immediately allocate a new AS-ID and
transmit an Attribute Set Declaration Message (Action =
REGISTER).
4.2. Attribute Count Update Modes
An implementation SHOULD allow the operator to configure one of the
following export modes for Attribute Count Update messages:
Option 1: Event-Driven Mode (Immediate Reporting)
* Whenever prefixes associated with an AS-ID are added or withdrawn,
the router immediately transmits a Count Update Message using
either DELTA or ABSOLUTE values.
Option 2: Periodic Reporting Mode (Interval Polling + Zero Threshold)
* The router suppresses real-time per-route update messages and
instead transmits ABSOLUTE count reports for all active AS-IDs at
a configured interval (e.g., every 30 seconds).
* EXCEPTION: If the prefix count for any AS-ID drops to 0 prior to
the next periodic timer expiration, the router MUST immediately
emit a Count Update Message (Op = ZERO_REF, NLRI Count = 0).
* Upon emitting or receiving Op = ZERO_REF, the router and server
MAY initiate unregistration/garbage collection for that AS-ID.
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4.3. Session Re-establishment and State Synchronization
When a BMP session between the Monitored Router and the Monitoring
Station is established or re-established after a failure:
1. The Monitored Router MUST re-advertise all currently active Path
Attribute Sets present in its RIB using Attribute Set Declaration
Messages (Action = REGISTER) with their corresponding valid AS-
IDs.
2. Following the attribute declarations, the router SHOULD transmit
initial Attribute Count Update Messages (Op = ABSOLUTE_COUNT,
Mode = EVENT_DRIVEN) to synchronize current prefix volumes for
each AS-ID, ensuring the BMP Monitoring Station rapidly achieves
state convergence without waiting for the next periodic polling
interval.
5. Security Considerations
This extension introduces no new security vulnerabilities beyond
those described in [RFC7854].
6. IANA Considerations
This document requests IANA to allocate two new message types in the
"BMP Message Types" registry defined in [RFC7854]:
+-------+----------------------------------+---------------+
| Value | Description | Reference |
+-------+----------------------------------+---------------+
| TBD1 | Attribute Set Declaration Message| This document |
| TBD2 | Attribute Count Update Message | This document |
+-------+----------------------------------+---------------+
7. Acknowledgements
TBD
8. References
8.1. 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,
<https://www.rfc-editor.org/info/rfc2119>.
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[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>.
[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>.
[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>.
8.2. Informative References
Authors' Addresses
Zhiyuan Wang
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: wangzhiyuan51@huawei.com
Nan Geng
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: gengnan@huawei.com
Shunwan Zhuang
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: zhuangshunwan@huawei.com
Haibo Wang
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
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Beijing
100095
China
Email: rainsword.wang@huawei.com
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