The Churn – Type II
In a nutshell, the churn happens because E does not always know about the Y0 path but the Y0 path has an effect on what E considers to be his best path
Without Y0, E considers Y1 as best
With Y0, E considers X as best
From C and D’s point of view
Y0 < Y1 < X < Y0 ? This happens because MED is not compared every time
Sequence
C selects Y0 and Y0 is propagated to D, E
E receives Y0 which forces E to select X
D receives X and selects it over Y0
C receives X and selects it over Y0
C sends a withdrawal for Y0
E receives the withdrawal for Y0 so E now prefers Y1
C, D receive Y1 but select Y0
And so on and so on…