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IS-IS Optimal Distributed Flooding for Dense Topologies

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft whose latest revision state is "Active".
Expired & archived
Authors Russ White , Shraddha Hegde , Tony Przygienda
Last updated 2023-07-25 (Latest revision 2023-01-16)
Replaces draft-white-lsr-distoptflood
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state Expired
Consensus boilerplate Unknown
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


In dense topologies (such as data center fabrics based on the Clos and butterfly topologies, though not limited to those exclusively), IGP flooding mechanisms designed originally for sparse topologies can "overflood," or in other words generate too many identical copies of topology and reachability information arriving at a given node from other devices. This normally results in slower convergence times and higher resource utilization to process and discard the superfluous copies. The modifications to the flooding mechanism in the Intermediate System to Intermediate System (IS-IS) link state protocol described in this document reduce resource utilization significantly, while increaseing convergence performance in dense topologies. Beside reducing the extraneous copies it uses the dense topologies to "load-balance" flooding across different possible paths in the network to prevent build up of flooding hot-spots. Note that a Clos fabric is used as the primary example of a dense flooding topology throughout this document. However, the flooding optimizations described in this document apply to any arbitrary topology.


Russ White
Shraddha Hegde
Tony Przygienda

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)