Nokia This document describes a technology extension to reduce link-state flooding in highly resilient dense networks. It does this by using simple and backwards-compatible extensions to reduce the number of adjacencies over which link-state flooding takes place. "IS-IS Sparse Link-State Flooding" is an extension to the IS-IS routing protocol. It is relatively easy to understand and implement. It is backwards compatible. It requires no per-node configuration. It uses a distributed algorithm, therefor no centralized computations are required. No complex computations are required on each node in the network. The algorithm has no requirements for the network topology. It can be deployed in a redundant way to improve robustness and convergence-times.