Re: [Lsr] Fwd: Open issues with Dynamic Flooding

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Hi Dave,

> So for my edification/education, this is a general behavior that in the absence of any specific algorithm is postulated.  (?)


Yes.


> The piece I do not quite get is "adding until fixed".  Is the working assumption that things have broken down to the point that there is no synchronization of the topology and the repairs are "blind”?


Yes.  We are using a centralized algorithm and have had multiple near simultaneous failures that have partitioned the flooding topology. While the area leader can (and probably will) compute a new flooding topology that repairs everything, it cannot be easily distributed across the partition of the flooding topology.


> Hence "adding until fixed" is adding until IGP exchange appears to have  minimized the changes in the LSDB from some previous state of the FT or some other criteria?  


Adding links temporarily to the FT should restore flooding, at which point an updated FT from the area leader can easily propagate.

Note that this is a convergence time issue: the new FT could slowly propagate, but it does require that each node at the partition unpack the new FT, install it, and then perform synchronization on the new links before proceeding.

Tony