Hi Tony,

if we start with a single standardized algorithm, that is easy to implement and deploy. We can leave the door open for additional algorithms to be defined later together with the selection mechanism.

I have the feeling that the dependency of the "flooding topology" on the flooded data is going to bring more complexity, than the selection of the distributed algorithm to be used, if we ever need to support more then one.

thanks,
Peter


On 06/04/18 17:19 , tony...@tony.li wrote:

Hi Peter,

Thank you for your comments.

while I appreciate the flexibility associated with the centralized
computation of the flooding topology, it has some drawbacks as well:

1. "flooding topology" must be flooded. This makes the flooding
dependent on the flooded data itself.


Absolutely true. If the computation of the topology is incorrect, that
would certainly be a bug.


2. The extra flooding of "flooding topology" adds some delay in the
convergence towards the new "flooding topology”.


Since we distribute the flooding topology before there are topology
failures, it would seem like the latency is not a significant concern.


Have you considered the distributed computation of "flooding topology"
using some standardized algorithm?


Yes, Kireeti raised this in London as well. There are some practical
issues with this. How do we ever converge on an algorithm?

There are many perspectives on what an adequate flooding topology might
be. Different administrations have different considerations and risk
tolerances.

Debugging is going to be more challenging, as inconsistencies between
two nodes with different ideas of the topology will be difficult to
detect until there is a catastrophic failure.

I’m trying to do something practical, and it seems like doing this in a
centralized fashion is the quickest, easiest, and most robust way forward.


Eventually we can support multiple standardized algorithms. A node can
advertise support for several algorithms and the "active" algorithm is
selected based on some criteria that would guarantee that all nodes in
the flooding domain select the same one.


Seems like that would also require some administrative input.

So, I agree that that’s a technical possibility, but I think that
there’s significant problems in making that work. I prefer to focus on
something that we can implement more quickly.

Tony



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