An Implementation Engineer is performing a FlashArray//X to FlashArray//XL HWNDU.

Upgrading from a FlashArray//X to a FlashArray//XL is a complex procedure involving significant hardware and network architecture changes. A known issue during specific phases of this upgrade involves the synchronization of ARP tables and IP neighbor entries between the legacy environment and the new controller architecture, which can prevent the High Availability (HA) link from establishing correctly.

If the new controller hangs or fails to reach a "Ready" state after a reboot, the engineering-level script ha_sync.py --resync ipneigh is the prescribed resolution.

This script forces a resynchronization of the IP neighbor table (ARP cache) and HA state information.

It clears stale entries that might be pointing to old MAC addresses or interfaces that moved during the X-to-XL transition.

Once cleared, the controllers can correctly rediscover each other over the internal HA interconnect and proceed to a healthy clustered state.

Options like hardware_check.py are diagnostic only, and firewall.py is for packet filtering, not ARP/HA sync issues.

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