Filtering Adj-Rib-In and Adj-Rib-Out to BMP receivers
draft-pcmy-grow-bmp-adj-ribs-filtered-03

Global Routing Operations                                     P. Lucente
Internet-Draft                                                C. Cardona
Updates: 7854 (if approved)                                          NTT
Intended status: Standards Track                           M. Srivastava
Expires: 10 March 2026                                  Juniper Networks
                                                        6 September 2025

         Filtering Adj-Rib-In and Adj-Rib-Out to BMP receivers
                draft-pcmy-grow-bmp-adj-ribs-filtered-03

Abstract

   Filtering RIBs in BMP (BGP Monitoring Protocol) can be desirable for
   several use-cases like, for example, limiting the amount of data a
   collector station has to process or allow a sender to export only a
   certain afi/safi of interest.  This document defines a light way to
   inform a collector station that a Adj-Rib-In / Adj-Rib-Out data feed
   is being filtered.

Status of This Memo

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   This Internet-Draft will expire on 10 March 2026.

Copyright Notice

   Copyright (c) 2025 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
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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Motivation and use Cases  . . . . . . . . . . . . . . . . . .   2
   4.  Filtered RIB Flag . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Operational Considerations  . . . . . . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   While RFC9069 [RFC9069] does define a light way to mark a Loc-Rib as
   filtered, there is no equivalent mechanism for Adj-Rib-In RFC7854
   [RFC7854] and Adj-Rib-Out RFC8671 [RFC8671].  This can be easily
   addressed through the introduction of a Peer F Flag in the "BMP Peer
   Flags for Peer Types 0 through 2" registry.

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.  Motivation and use Cases

   Marking that the (Adj-RIB-in, Adj-RIB-Out) BMP session is filtered
   can be informative to the rest of the system that they should not
   make decisions assuming that this stream is transmitting all the
   information about it.

   BMP producers (routers) need to send RM updates per peer while
   meeting several requirements, such as minimizing CPU consumption,
   avoiding impact on key routing functions, and providing near real-

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   time updates to the collector.  As network scale increases,
   satisfying these requirements becomes increasingly challenging.
   Therefore, any mechanism that enables data filtering is beneficial.
   On the BMP collector side, excessive data imposes costs on storage
   and processing.  Reducing the volume of data limited to key points of
   interest (for example, edge peering), can help alleviate these costs.

4.  Filtered RIB Flag

   As a recap, a BMP session is regarded as carrying Adj-Rib-In by
   defining the Peer Type to 0, 1 or 2 values and setting the O flag to
   zero (0) in the BMP Peer Flags (for Peer Types 0 through 2) registry.
   Similarly, Adj-Rib-Out is set by defining the Peer Type to 0, 1 or 2
   values and setting the O flag to one (1) in the BMP Peer Flags (for
   Peer Types 0 through 2) registry.  Both Adj-Rib-In and Adj-Rib-Out
   can be further defined as Pre-Policy, setting the Peer L Flag to zero
   (0), or Post-Policy, setting the Peer L Flag to one (1).

   For both Adj-Rib-In and Adj-Rib-Out, for both Pre-Policy and Post-
   Policy cases, a new Peer F Flag is defined in the "BMP Peer Flags for
   Peer Types 0 through 2" registry.  If the RIB was filtered, the flag
   MUST be set to one (1).

   In Stats messages, counts MUST reflect the filtered RIB numbers and
   not the original RIB ones.

   Also should any characteristic of the filtering change, the sender
   MUST trigger a Peer Down then followed by a new Peer Up.

5.  Operational Considerations

   It is recommended that when filtering RIBs, the VRF/Table Name TLV -
   as defined in RFC9069 [RFC9069], TLV support for BMP Route Monitoring
   and Peer Down Messages [I-D.ietf-grow-bmp-tlv] and BMP Peer Up
   Namespace [I-D.ietf-grow-bmp-peer-up] - is specified to a meaningful
   string that can help discriminate the nature of filtering.

   The VRF/Table Name TLV can be either set in the Peer Up message, so
   to implicitely apply to all NLRIs received by the peer, or set via a
   Group TLV in Route Monitoring messages, to esplicitely apply to all
   NLRIs in the group.  Going down the Peer Up model is certainly
   optimal on the wire and simplifies packing at the sender side; going
   down the Route Monitoring model, instead, allows the receiver side to
   operate non-contextually (ie.  no need to look back at the Peer Up to
   make due associations).

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6.  Security Considerations

   It is not believed that this document adds any additional security
   considerations.

7.  IANA Considerations

   This document asks IANA to add a new F Flag to the "BMP Peer Flags
   for Peer Types 0 through 2" registry.  The recommended value for the
   registry is 4.

8.  Normative References

   [I-D.ietf-grow-bmp-peer-up]
              Scudder, J. and P. Lucente, "BMP Peer Up Message
              Namespace", Work in Progress, Internet-Draft, draft-ietf-
              grow-bmp-peer-up-05, 2 October 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-grow-
              bmp-peer-up-05>.

   [I-D.ietf-grow-bmp-tlv]
              Lucente, P. and Y. Gu, "BMP v4: TLV Support for BGP
              Monitoring Protocol (BMP) Route Monitoring and Peer Down
              Messages", Work in Progress, Internet-Draft, draft-ietf-
              grow-bmp-tlv-18, 3 September 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-grow-
              bmp-tlv-18>.

   [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>.

   [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>.

   [RFC8671]  Evens, T., Bayraktar, S., Lucente, P., Mi, P., and S.
              Zhuang, "Support for Adj-RIB-Out in the BGP Monitoring
              Protocol (BMP)", RFC 8671, DOI 10.17487/RFC8671, November
              2019, <https://www.rfc-editor.org/info/rfc8671>.

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   [RFC9069]  Evens, T., Bayraktar, S., Bhardwaj, M., and P. Lucente,
              "Support for Local RIB in the BGP Monitoring Protocol
              (BMP)", RFC 9069, DOI 10.17487/RFC9069, February 2022,
              <https://www.rfc-editor.org/info/rfc9069>.

Acknowledgements

   The authors would like to thank Jeff Haas for his valuable input.

Authors' Addresses

   Paolo Lucente
   NTT
   Veemweg 23
   3771 Barneveld
   Netherlands
   Email: paolo@ntt.net

   Camilo Cardona
   NTT
   164-168, Carrer de Numancia
   08029 Barcelona
   Spain
   Email: camilo@ntt.net

   Mukul Srivastava
   Juniper Networks
   10 Technology Park Dr
   Westford, MA 01886
   United States of America
   Email: msri@juniper.net

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