



Internet Engineering Task Force (IETF)                          K. Patel
Request for Comments: 9816                                     A. Lindem
Category: Informational                                     Arrcus, Inc.
ISSN: 2070-1721                                                 S. Zandi
                                                                        
                                                                G. Dawra
                                                                  Google
                                                                 J. Dong
                                                     Huawei Technologies
                                                               July 2025


 Usage and Applicability of BGP Link State (BGP-LS) Shortest Path First
                     (SPF) Routing in Data Centers

Abstract

   This document discusses the usage and applicability of BGP Link State
   (BGP-LS) Shortest Path First (SPF) extensions in data center networks
   utilizing Clos or Fat Tree topologies.  The document is intended to
   provide simplified guidance for the deployment of BGP-LS SPF
   extensions.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are candidates for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9816.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   in the Revised BSD License.

Table of Contents

   1.  Introduction
   2.  Recommended Reading
   3.  Common Deployment Scenario
   4.  Justification for the BGP-SPF Extension
   5.  BGP-SPF Applicability to Clos Networks
     5.1.  Usage of BGP-LS-SPF SAFI
       5.1.1.  Relationship to Other BGP AFI/SAFI Tuples
     5.2.  Peering Models
       5.2.1.  Sparse Peering Model
       5.2.2.  Biconnected Graph Heuristic
     5.3.  BGP Spine/Leaf Topology Policy
     5.4.  BGP Peer Discovery Considerations
     5.5.  BGP Peer Discovery
       5.5.1.  BGP IPv6 Simplified Peering
       5.5.2.  BGP-LS-SPF Topology Visibility for Management
       5.5.3.  Data Center Interconnect (DCI) Applicability
   6.  Non-Clos / Fat Tree Topology Applicability
   7.  Non-Transit Node Capability
   8.  BGP Policy Applicability
   9.  IANA Considerations
   10. Security Considerations
   11. References
     11.1.  Normative References
     11.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   This document complements [RFC9815] by discussing the applicability
   of the BGP Link State (BGP-LS) Shortest Path First (SPF) technology
   in a simple and fairly common deployment scenario, which is described
   in Section 3.

   Section 4 describes the reasons for BGP modifications for such
   deployments.

   Section 5 covers the BGP SPF protocol enhancements to BGP to meet
   these requirements and their applicability to data center [Clos]
   networks.

2.  Recommended Reading

   This document assumes knowledge of existing data center networks and
   data center network topologies [Clos].  This document also assumes
   knowledge of data center routing protocols such as BGP [RFC4271],
   BGP-LS SPF [RFC9815], and OSPF [RFC2328] [RFC5340] as well as data
   center Operations, Administration, and Maintenance (OAM) protocols
   like the Link Layer Discovery Protocol (LLDP) [RFC4957] and
   Bidirectional Forwarding Detection (BFD) [RFC5880].

3.  Common Deployment Scenario

   Within a data center, servers are commonly interconnected using the
   Clos topology [Clos].  The Clos topology is fully non-blocking, and
   the topology is realized using Equal-Cost Multipath (ECMP).  In a
   multi-stage Clos topology, the minimum number of parallel paths in
   each tier is determined by the width of the stage as shown in
   Figure 1.

                                     Tier 1
                                     +-----+
                                     |NODE |
                                  +->|  1  |--+
                                  |  +-----+  |
                          Tier 2  |           |  Tier 2
                         +-----+  |  +-----+  |  +-----+
          +------------->|NODE |--+->|NODE |--+--|NODE |--------------+
          |        +-----|  5  |--+  |  2  |  +--|  7  |-----+        |
          |        |     +-----+     +-----+     +-----+     |        |
          |        |                                         |        |
          |        |     +-----+     +-----+     +-----+     |        |
          | +------+---->|NODE |--+  |NODE |  +--|NODE |-----+------+ |
          | |      | +---|  6  |--+->|  3  |--+--|  8  |---+ |      | |
          | |      | |   +-----+  |  +-----+  |  +-----+   | |      | |
          | |Tier 3| |            |           |            | |Tier 3| |
        +-----+ +-----+           |  +-----+  |          +-----+ +-----+
        |NODE | |NODE |           +->|NODE |--+          |NODE | |NODE |
        |  9  | | 10  |              |  4  |             | 11  | | 12  |
        +-----+ +-----+              +-----+             +-----+ +-----+
         | | |   | | |                                    | | |    | | |
         <- Servers ->                                    <- Servers ->

                  Figure 1: Illustration of the Basic Clos

   *  Tier 1 is comprised of Nodes 1, 2, 3, and 4

   *  Tier 2 is comprised of Nodes 5, 6, 7, and 8

   *  Tier 3 is comprised of Nodes 9, 10, 11, and 12

4.  Justification for the BGP-SPF Extension

   To simplify Layer 3 (L3) routing and operations, many data centers
   use BGP as a routing protocol to create both an underlay and an
   overlay network for their Clos topologies [RFC7938].  However, BGP is
   a path-vector routing protocol.  Since it does not create a fabric
   topology, it uses hop-by-hop External BGP (EBGP) peering to
   facilitate hop-by-hop routing to create the underlay network and to
   resolve any overlay next hops.  The hop-by-hop BGP peering paradigm
   imposes several restrictions within a Clos.  It prohibits the
   deployment of route reflectors / route controllers as the EBGP
   sessions are congruent with the data path.  The BGP best-path
   algorithm is prefix based, and it prevents announcements of prefixes
   to other BGP speakers until the best-path decision process has been
   performed for the prefix at each intermediate hop.  These
   restrictions significantly delay the overall convergence of the
   underlay network within a Clos network.

   The BGP SPF modifications allow BGP to overcome these limitations.
   Furthermore, using the BGP-LS Network Layer Reachability Information
   (NLRI) format allows the BGP SPF data to be advertised for nodes,
   links, and prefixes in the BGP routing domain [RFC9552] and used for
   SPF computations [RFC9815].

   Additional motivation for deploying BGP-SPF is included in [RFC9815].

5.  BGP-SPF Applicability to Clos Networks

   With the BGP-SPF extensions [RFC9815], the BGP best-path computation
   and route computation are replaced with link-state algorithms such as
   those used by OSPF [RFC2328], both to determine whether a BGP-LS-SPF
   NLRI has changed and needs to be readvertised and to compute the BGP
   routes.  These modifications will significantly improve convergence
   of the underlay while affording the operational benefits of a single
   routing protocol [RFC7938].

   Data center controllers typically require visibility to the BGP
   topology to compute traffic-engineered paths.  These controllers
   learn the topology and other relevant information via the BGP-LS
   address family [RFC9552], which is totally independent of the
   underlay address families (usually IPv4/IPv6 unicast).  Furthermore,
   in usual BGP underlays, all the BGP routers will need to advertise
   their BGP-LS information independently.  With the BGP-SPF extensions,
   controllers can learn the topology using the same BGP advertisements
   used to compute the underlay routes.  Furthermore, these data center
   controllers can avail the convergence advantages of the BGP-SPF
   extensions.  The placement of controllers can be outside of the
   forwarding path or within the forwarding path.

   Alternatively, as each and every router in the BGP-SPF domain will
   have a complete view of the topology, the operator can also choose to
   configure BGP sessions in the hop-by-hop peering model described in
   [RFC7938] along with BFD [RFC5880].  In doing so, while the hop-by-
   hop peering model lacks the inherent benefits of the controller-based
   model, BGP updates need not be serialized by the BGP best-path
   algorithm in either of these models.  This helps overall network
   convergence.

5.1.  Usage of BGP-LS-SPF SAFI

   Section 5.1 of [RFC9815] defines a new BGP-LS-SPF SAFI for
   announcement of the BGP-SPF link-state.  The NLRI format and its
   associated attributes follow the format of BGP-LS for node, link, and
   prefix announcements.  Whether the peering model within a Clos
   follows hop-by-hop peering as described in [RFC7938] or any
   controller-based or route-reflector peering, an operator can exchange
   BGP-LS-SPF SAFI routes over the BGP peering by simply configuring
   BGP-LS-SPF SAFI between the necessary BGP speakers.

   The BGP-LS-SPF SAFI can also coexist with BGP IP Unicast SAFI
   [RFC4760], which could exchange overlapping IP routes.  One use case
   for this is where BGP-LS-SPF routes are used for the underlay and BGP
   IP Unicast routes for VPNs are advertised in the overlay as described
   in [RFC4364].  The routes received by these SAFIs are evaluated,
   stored, and announced independently according to the rules of
   [RFC4760].  The tiebreaking of route installation is a matter of the
   local policies and preferences of the network operator.

   Finally, as the BGP-SPF peering is done following the procedures
   described in [RFC4271], all the existing transport security
   mechanisms including those in [RFC5925] are available for the BGP-LS-
   SPF SAFI.

5.1.1.  Relationship to Other BGP AFI/SAFI Tuples

   Normally, the BGP-LS-SPF AFI/SAFI is used solely to compute the
   underlay and is given precedence over other AFI/SAFIs in route
   processing.  Other BGP SAFIs, e.g., IPv6/IPv6 unicast VPN, would use
   the BGP-SPF computed routes for next-hop resolution.

5.2.  Peering Models

   As previously stated, BGP-SPF can be deployed using the existing
   peering model where there is a single-hop BGP session on each and
   every link in the data center fabric [RFC7938].  This provides for
   both the advertisement of routes and the determination of link and
   neighboring router availability.  With BGP-SPF, the underlay will
   converge faster due to changes to the decision process that will
   allow NLRI changes to be advertised faster after detecting a change.

5.2.1.  Sparse Peering Model

   Alternately, BFD [RFC5880] can be used to swiftly determine the
   availability of links, and the BGP peering model can be significantly
   sparser than the data center fabric.  BGP-SPF sessions only need to
   be established with enough peers to provide a biconnected graph.  If
   Internal BGP (IBGP) is used, then the BGP routers at tier N-1 will
   act as route-reflectors for the routers at tier N.

   The obvious usage of sparse peering is to avoid parallel BGP sessions
   on links between the same two routers in the data center fabric.
   However, this use case is not very useful since parallel L3 links
   between the same two BGP routers are rare in Clos or Fat Tree
   topologies.  Additionally, when there are multiple links, they are
   often aggregated using Link Aggregation Groups (LAGs) at the link
   layer [IEEE.802.1AX] rather than at the IP layer.  Two more
   interesting scenarios are described below.

   In current data center topologies, there is often a very dense mesh
   of links between levels, e.g., leaf and spine, providing 32-way
   paths, 64-way paths, or more ECMPs.  In these topologies, it is
   desirable not to have a BGP session on every link, and techniques
   such as the one described in Section 5.2.2 can be used to establish
   sessions on some subset of northbound links.  For example, in a
   Spine/Leaf topology, each leaf router would only peer with a subset
   of the spines dependent on the flooding redundancy required to be
   reasonably certain that every node within the BGP-SPF routing domain
   has the complete topology.

   Alternately, controller-based data center topologies are envisioned
   where BGP speakers within the data center only establish BGP sessions
   with two or more controllers.  In these topologies, fabric nodes
   below the first tier, as shown in Figure 1 of [RFC7938], will
   establish BGP multi-hop sessions with the controllers.  For the
   multi-hop sessions, determining the route to the controllers without
   depending on BGP would need to be through some other means, which is
   beyond the scope of this document.  However, the BGP discovery
   mechanisms described in Section 5.5 would be one possibility.

5.2.2.  Biconnected Graph Heuristic

   With a biconnected graph heuristic, discovery of BGP SPF peers is
   assumed, e.g., as described in Section 5.5.  In this context,
   "biconnected" refers to the fact that there must be an advertised
   Link NLRI for both BGP SPF peers associated with the link before the
   link can be used in the BGP SPF route calculation.  Additionally, it
   is assumed that the direction of the peering can be ascertained.  In
   the context of a data center fabric, the direction is either
   northbound (toward the spine), southbound (toward the Top-of-Rack
   (ToR) routers), or east-west (same level in the hierarchy).  The
   determination of the direction is beyond the scope of this document.
   However, it would be reasonable to assume a technique where the ToR
   routers can be identified and the number of hops to the ToR is used
   to determine the direction.

   In this heuristic, BGP speakers allow passive session establishment
   for southbound BGP sessions.  For northbound sessions, BGP speakers
   will attempt to maintain two northbound BGP sessions with different
   routers.  For east-west sessions, passive BGP session establishment
   is allowed.  However, a BGP speaker will never actively establish an
   east-west BGP session unless it cannot establish two northbound BGP
   sessions.

   BGP SPF sparse peering deployments not using this heuristic are
   possible but are not described herein and are considered out of
   scope.

5.3.  BGP Spine/Leaf Topology Policy

   One of the advantages of using BGP-SPF as the underlay protocol is
   that BGP policy can be applied at any level.  For example, depending
   on the topology, it may be possible to aggregate or filter prefix
   advertisements using the existing BGP policy.  In Spine/Leaf
   topologies, it is not necessary to advertise a BGP-LS Prefix NLRI
   received by leaf nodes from the spine back to other spine nodes.  If
   a common Autonomous System (AS) is used for the spine nodes, this can
   easily be accomplished with EBGP and a simple policy to filter
   advertisements from the leaves to the spine if the first AS in the AS
   path is the spine AS.

   In the figure below, the leaves would not advertise any NLRIs with AS
   64512 as the first AS in the AS path.

                +--------+    +--------+             +--------+
    AS 64512    |        |    |        |             |        |
    for Spine   | Spine 1+----+ Spine 2+- ......... -+ Spine N|
    Nodes at    |        |    |        |             |        |
    this Level  +-+-+-+-++    ++-+-+-+-+             +-+-+-+-++
           +------+ | | |      | | | |                 | | | |
           |  +-----|-|-|------+ | | |                 | | | |
           |  |  +--|-|-|--------+-|-|-----------------+ | | |
           |  |  |  | | |    +---+ | |                   | | |
           |  |  |  | | |    |  +--|-|-------------------+ | |
           |  |  |  | | |    |  |  | |              +------+ +----+
           |  |  |  | | |    |  |  | +--------------|----------+  |
           |  |  |  | | |    |  |  +-------------+  |          |  |
           |  |  |  | | +----|--|----------------|--|--------+ |  |
           |  |  |  | +------|--|--------------+ |  |        | |  |
           |  |  |  +------+ |  |              | |  |        | |  |
          ++--+--++      +-+-+--++            ++-+--+-+     ++-+--+-+
          | Leaf 1|      | Leaf 2|  ........  | Leaf X|     | Leaf Y|
          +-------+      +-------+            +-------+     +-------+

                    Figure 2: Spine/Leaf Topology Policy

5.4.  BGP Peer Discovery Considerations

   The basic functionality of peer discovery is to discover the address
   of a single-hop peer in the case where the peer address is not
   preconfigured.  This is being accomplished today by using IPv6 Router
   Advertisements (RAs) [RFC4861] and assuming that a BGP session is
   desired with any discovered peer.  Beyond the basic functionality, it
   may be useful to have the following information relating to the BGP
   session:

   *  The AS and BGP Identifier of a potential peer.

   *  Supported security capabilities, and for cryptographic
      authentication, the security capabilities and possibly a key chain
      [RFC8177] for use.

   *  A Session Policy Identifier, which is a group number or name used
      to associate common session parameters with the peer.  For
      example, in a data center, BGP sessions with a ToR router could
      have different parameters than BGP sessions between leaf and spine
      nodes.

   In a data center fabric, it is often useful to know whether a peer is
   southbound (towards the servers) or northbound (towards the spine or
   super-spine), e.g., see Section 5.2.2.  One mechanism, without
   specifying all the details, might be for the ToR routers to be
   identified when installed and for the other routers in the fabric to
   determine their level based on the distance from the closest ToR
   router.

   If there are multiple links between BGP speakers or the links between
   BGP speakers are unnumbered, it is also useful to be able to
   establish multi-hop sessions using the loopback addresses.  This will
   often require the discovery protocol to install one or more routes
   toward the potential peer loopback addresses prior to BGP session
   establishment.

   Finally, a simple BGP discovery protocol may be used to establish a
   multi-hop session with one or more controllers by advertising
   connectivity to one or more controllers.

5.5.  BGP Peer Discovery

5.5.1.  BGP IPv6 Simplified Peering

   To conserve IPv4 address space and simplify operations, BGP-SPF
   routers in Clos / Fat Tree deployments can use IPv6 addresses as the
   peer address.  For IPv4 address families, IPv6 peering as specified
   in [RFC8950] can be deployed to avoid configuring IPv4 addresses on
   router interfaces.  When this is done, dynamic discovery mechanisms,
   as described in Section 5.5, can be used to learn the global or link-
   local IPv6 peer addresses, and IPv4 addresses need not be configured
   on these interfaces.  If IPv6 link-local peering is used, then
   configuration of IPv6 global addresses is also not required
   [RFC7404].  The Link Local/Remote Identifiers of the peering
   interfaces must be used in the Link NLRI as described in
   Section 5.2.2 of [RFC9815].

5.5.2.  BGP-LS-SPF Topology Visibility for Management

   Irrespective of whether or not BGP-SPF is used for route calculation,
   the BGP-LS-SPF route advertisements can be used to periodically
   construct the Clos / Fat Tree topology.  This is especially useful in
   deployments where an Interior Gateway Protocol (IGP) is not used and
   the base BGP-LS routes [RFC9552] are not available.  The resultant
   topology visibility can then be used for troubleshooting and
   consistency checking.  This would normally be done on a central
   controller or other management tool that could also be used for
   fabric data path verification.  The precise algorithms and
   heuristics, as well as the complete set of management applications,
   is beyond the scope of this document.

5.5.3.  Data Center Interconnect (DCI) Applicability

   Since BGP-SPF is to be used for the routing underlay and Data Center
   Interconnect (DCI) gateway boxes typically have direct or very simple
   connectivity, BGP external sessions would typically not include the
   BGP-LS-SPF SAFI.

6.  Non-Clos / Fat Tree Topology Applicability

   The BGP-SPF extensions [RFC9815] can be used in other topologies and
   avail the inherent convergence improvements.  Additionally, sparse
   peering techniques may be utilized as described in Section 5.2.
   However, determining whether to establish a BGP session is more
   complex, and the heuristic described in Section 5.2.2 cannot be used.
   In such topologies, other techniques such as those described in
   [RFC9667] may be employed.  One potential deployment would be the
   underlay for a Service Provider (SP) backbone where usage of a single
   protocol, i.e., BGP, is desired.

7.  Non-Transit Node Capability

   In certain scenarios, a BGP node wishes to participate in the BGP-SPF
   topology but never be used for transit traffic.  These include
   situations where a server wants to make application services
   available to clients homed at subnets throughout the BGP-SPF domain
   but does not ever want to be used as a router (i.e., carry transit
   traffic).  Another specific instance is where a controller is
   resident on a server and direct connectivity to the controller is
   required throughout the entire domain.  This can readily be
   accomplished using the BGP-LS-SPF Node NLRI Attribute SPF Status TLV
   as described in [RFC9815].

8.  BGP Policy Applicability

   Existing BGP policy such as prefix filtering may be used in
   conjunction with the BGP-LS-SPF SAFI.  When BGP policy is used with
   the BGP-LS-SPF SAFI, BGP speakers in the BGP-LS-SPF routing domain
   will not all have the same set of NLRIs and will compute a different
   BGP local routing table.  Consequently, care must be taken to assure
   that routing is consistent and that routes to unreachable
   destinations or routing loops do not ensue.  However, this is no
   different than if classical BGP routing using the IPv4 and IPv6
   address families were used.

9.  IANA Considerations

   This document has no IANA actions.

10.  Security Considerations

   This document introduces no new security considerations above and
   beyond those already specified in [RFC4271] and [RFC9815].

11.  References

11.1.  Normative References

   [RFC9815]  Patel, K., Lindem, A., Zandi, S., and W. Henderickx, "BGP
              Link State (BGP-LS) Shortest Path First (SPF) Routing",
              RFC 9815, DOI 10.17487/RFC9815, July 2025,
              <https://www.rfc-editor.org/info/rfc9815>.

11.2.  Informative References

   [Clos]     Clos, C., "A Study of Non-Blocking Switching Networks",
              The Bell System Technical Journal, vol. 32, no. 2, pp.
              406-424, DOI 10.1002/j.1538-7305.1953.tb01433.x, March
              1953,
              <https://doi.org/10.1002/j.1538-7305.1953.tb01433.x>.

   [IEEE.802.1AX]
              IEEE, "IEEE Standard for Local and Metropolitan Area
              Networks--Link Aggregation", IEEE Std 802.1AX-2020,
              DOI 10.1109/IEEESTD.2020.9105034, May 2020,
              <https://doi.org/10.1109/IEEESTD.2020.9105034>.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <https://www.rfc-editor.org/info/rfc2328>.

   [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>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <https://www.rfc-editor.org/info/rfc4364>.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,
              <https://www.rfc-editor.org/info/rfc4760>.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,
              <https://www.rfc-editor.org/info/rfc4861>.

   [RFC4957]  Krishnan, S., Ed., Montavont, N., Njedjou, E., Veerepalli,
              S., and A. Yegin, Ed., "Link-Layer Event Notifications for
              Detecting Network Attachments", RFC 4957,
              DOI 10.17487/RFC4957, August 2007,
              <https://www.rfc-editor.org/info/rfc4957>.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
              <https://www.rfc-editor.org/info/rfc5340>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
              June 2010, <https://www.rfc-editor.org/info/rfc5925>.

   [RFC7404]  Behringer, M. and E. Vyncke, "Using Only Link-Local
              Addressing inside an IPv6 Network", RFC 7404,
              DOI 10.17487/RFC7404, November 2014,
              <https://www.rfc-editor.org/info/rfc7404>.

   [RFC7938]  Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of
              BGP for Routing in Large-Scale Data Centers", RFC 7938,
              DOI 10.17487/RFC7938, August 2016,
              <https://www.rfc-editor.org/info/rfc7938>.

   [RFC8177]  Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
              Zhang, "YANG Data Model for Key Chains", RFC 8177,
              DOI 10.17487/RFC8177, June 2017,
              <https://www.rfc-editor.org/info/rfc8177>.

   [RFC8950]  Litkowski, S., Agrawal, S., Ananthamurthy, K., and K.
              Patel, "Advertising IPv4 Network Layer Reachability
              Information (NLRI) with an IPv6 Next Hop", RFC 8950,
              DOI 10.17487/RFC8950, November 2020,
              <https://www.rfc-editor.org/info/rfc8950>.

   [RFC9552]  Talaulikar, K., Ed., "Distribution of Link-State and
              Traffic Engineering Information Using BGP", RFC 9552,
              DOI 10.17487/RFC9552, December 2023,
              <https://www.rfc-editor.org/info/rfc9552>.

   [RFC9667]  Li, T., Ed., Psenak, P., Ed., Chen, H., Jalil, L., and S.
              Dontula, "Dynamic Flooding on Dense Graphs", RFC 9667,
              DOI 10.17487/RFC9667, October 2024,
              <https://www.rfc-editor.org/info/rfc9667>.

Acknowledgements

   The authors would like to thank Alvaro Retana, Yan Filyurin, Boris
   Hassanov, Stig Venaas, Ron Bonica, Mallory Knodel, Dhruv Dhody, Erik
   Kline, Éric Vyncke, and John Scudder for their reviews and comments.

Authors' Addresses

   Keyur Patel
   Arrcus, Inc.
   2077 Gateway Pl
   San Jose, CA 95110
   United States of America
   Email: keyur@arrcus.com


   Acee Lindem
   Arrcus, Inc.
   301 Midenhall Way
   Cary, NC 27513
   United States of America
   Email: acee.ietf@gmail.com


   Shawn Zandi
   Email: shafagh@shafagh.com


   Gaurav Dawra
   Google
   Sunnyvale, CA
   United States of America
   Email: gdawra.ietf@gmail.com


   Jie Dong
   Huawei Technologies
   No. 156 Beiqing Road
   Beijing
   China
   Email: jie.dong@huawei.com
