NAT in Active/Active HA Mode

In an active/active HA configuration:
  • You must bind each Dynamic IP (DIP) NAT rule and Dynamic IP and Port (DIPP) NAT rule to either Device ID 0 or Device ID 1.
  • You must bind each static NAT rule to either Device ID 0, Device ID 1, both Device IDs, or the firewall in active-primary state.
Thus, when one of the firewalls creates a new session, the Device ID 0 or Device ID 1 binding determines which NAT rules match the firewall. The device binding must include the session owner firewall to produce a match.
The session setup firewall performs the NAT policy match, but the NAT rules are evaluated based on the session owner. That is, the session is translated according to NAT rules that are bound to the session owner firewall. While performing NAT policy matching, a firewall skips all NAT rules that are not bound to the session owner firewall.
For example, suppose the firewall with Device ID 1 is the session owner and session setup firewall. When the firewall with Device ID 1 tries to match a session to a NAT rule, it skips all rules bound to Device ID 0. The firewall performs the NAT translation only if the session owner and the Device ID in the NAT rule match.
You will typically create device-specific NAT rules when the peer firewalls use different IP addresses for translation.
If one of the peer firewalls fails, the active firewall continues to process traffic for synchronized sessions from the failed firewall, including NAT traffic. In a source NAT configuration, when one firewall fails:
  • The floating IP address that is used as the Translated IP address of the NAT rule transfers to the surviving firewall. Hence, the existing sessions that fail over will still use this IP address.
  • All new sessions will use the device-specific NAT rules that the surviving firewall naturally owns. That is, the surviving firewall translates new sessions using only the NAT rules that match its Device ID; it ignores any NAT rules bound to the failed Device ID.
For examples of active/active HA with NAT, see:

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