Frequent route changes in modern SDN-based net works are known to severely degrade the performance of TCP Cubic. This degradation is caused by two factors: sudden RTT changes, and packet reordering which Cubic misinterprets as congestion. This research investigates how a modern alter native, BBRv3, performs under these same conditions. Using ns-3 simulations with rerouting intervals of 3, 5, and 10seconds, we show that BBRv3is significantly more resilient. While Cubic through put is reduced by nearly 50% at 3-second intervals, BBRv3 performance degrades by less than 10%, as its probing mechanism does not use packet re ordering as a congestion signal. We also examined a second scenario where a flow leaves a saturated link. We concluded Cubic flows take much longer to fill the newly freed up bandwidth, as much as 8 seconds for a 25% increase in available bandwidth. BBR performs much better as its able to recognize that the link is not saturated during its next probing phase and mediately fill it. Therefore, we conclude that BBRv3 is better suited for the dynamic network conditions found in SDN environments