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Warning, only mid to high end models 3xxx, 5xxx ou 7xxx support prempt LACP en HA A/P
This means, that for example 820 in HA mode with LCAP link can take roughly up to 40seconds to failover due to LACP negotiation time with the switches !

https://www.paloaltonetworks.com/documentation/81/pan-os/pan-os/high-availability/ha-concepts/lacp-and-lldp-pre-negotiation-for-activepassive-ha
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