@digvijay. I completely disagree with your explanation for S3. COnsider the following example:
COnsider the situation where the link cost for BC changes from 20 to 19.
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For link state routing, the link cost will first propagate to all nodes and then each node will do calculation of its own.
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For distnace vector, the link cost change will be first informed to B and C . But after B and C do some computations, the vectors at B and C remain the same. So, the algorithm has converged in just 1 step.
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So, I think its not possible to decide until exact toplogy is known. Even verifying for a given toplogy may be difficult ( which may be NP-hard ).
Plz correct me if wrong.