Enable PAT Pool

Turns on Port Address Translation (PAT) using a pool of IP addresses instead of a single interface IP

• Spread outbound traffic across multiple public IPs
• Avoid port exhaustion
• Improve performance for large user bases

Use Round Robin Allocation:
Distributes sessions evenly across IPs in the PAT pool. Firewall may keep using the same IP until ports fill up, Connections rotate across pool addresses evenly, this is recommended for medium / large environments

Extended PAT Table:
“Usually fine disabled unless scaling issues exist”
Allows multiple translations using the same IP:port combination under certain conditions.
Supports higher connection density
Useful in high-volume NAT environments

Flat Port Range:
Allows PAT to use the entire available port range equally instead of reserving segments
From v6.7+, it’s always enabled automatically
Improves port utilization efficiency

Include Reserve Ports:
Allows firewall to use ports normally reserved for special services if needed
Prevents port exhaustion

Cisco ASA and FTD, the IKEv2 priority is determined by a numerical value where the lower the number, the higher the priority

Priority Ranking: A policy with a priority of 1 is the highest priority, while higher numbers (e.g., 65,535) are lower priority.

Negotiation Order: When negotiating security associations (SA), the device starts with the lowest priority number and works its way up until it finds a match.

Best Practice: It is recommended to configure your most secure, desired settings with the highest priority (lowest number). 

https://www.cisco.com/c/en/us/td/docs/security/secure-firewall/management-center/device-config/760/management-center-device-config-76/ha-scale-multi-instance.html#khoklhkl-chassis-management-interface

Secure Firewall 3100/4200 can be deployed in multi-instance mode

Data interface and Data-sharing interface are two types of interfaces that can be assigned to instances

Data interface and Data-sharing interface difference is whether multiple instances can use the same interface and talk to each other internally.

Data interface (exclusive to one instance)

• A normal traffic interface used by only one instance.
• Cannot be shared with other instances.
• If Instance A wants to reach Instance B, traffic must leave the chassis and come back in via another interface
• You want strong separation between tenants. Each instance has its own dedicated physical/VLAN interface
• Like giving each firewall its own private cable.

Data-sharing interface (shared across instances)

• A traffic interface that multiple instances can use simultaneously.
• Instances can communicate internally over the chassis backplane if they share it.
• Saves interfaces but slightly reduces isolation.
• Not allowed for failover links, inline sets, or some transparent-mode configs
• Like multiple firewalls plugged into the same internal switch port.
• If not multi-tenant environment then it is used to share Internet link between multiple instances

Continue from “Chassis Interfaces vs. Instance Interfaces”