Why convergence time in Unidirectional Traffic & Bidirectional Traffic are different?

Hi everybody,

My question may be insufficient information.

I think that Unidirectional traffic can occur BUM traffic.

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Traffics

1.UP_to_Down (Unidirectional, Bi-directional)

2.Down_to_UP (Unidirectional, Bi-directional)

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When SW-3 is restarted,

Bi-directional -> 3s convergence time for both traffic

Uni-directional -> 1s for Down_to_UP & 5s for UP_to_Down

UP

SW-1______________SW-2

| |

SW-3______________SW-4

| |

SW-5______________SW-6

| _______SW-7______|

DOWN