Learn how to configure active/passive HA pair of firewalls and HA.
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The following procedure shows how to configure a pair of firewalls in an
active/passive deployment as depicted in the following example topology.
Active/Passive High Availability (HA) provides firewall redundancy by maintaining two
firewalls in a primary-secondary relationship, where one firewall actively processes
traffic while the other remains in standby mode, ready to assume control if the
primary firewall fails. In an Active/Passive HA deployment, the active firewall
handles all network traffic and maintains the runtime state, while the passive
firewall continuously synchronizes its configuration and session information with
the active unit. When a failover event occurs—whether due to hardware failure,
software issues, or network connectivity problems—the passive firewall seamlessly
transitions to the active role, ensuring minimal service disruption and maintaining
network security policies. This configuration is ideal for environments that require
high availability but do not need the increased throughput that Active/Active HA
provides, making it a cost-effective solution for ensuring business continuity while
maintaining a single point of traffic processing.
HA Active/Passive Support for PA-7500 Series Firewalls
High Availability active/passive mode, which
provides firewall redundancy and failover capabilities, is supported on PA-7500
series firewalls beginning with PAN-OS 12.1.5.
The firewalls support only HA active/passive mode;
HA active/active mode is not supported. HA active/passive includes comprehensive
network integration features such as LACP, link monitoring, and session
synchronization functionality. LACP is supported on both Layer 2 and Layer 3
aggregate interfaces, including LACP pre-negotiation capabilities that enable the
passive device to establish link aggregation readiness and reduce failover times.
Link and path monitoring is supported for network health assessments. HA
active/passive also maintains full runtime synchronization of session state between
active and passive devices, ensuring that active sessions can continue uninterrupted
during failover events and that the standby device maintains current awareness of
all network connections and their associated state information.
On PA-7500 series firewalls, HA active/passive uses dedicated High-Speed Chassis
Interconnect (HSCI) interfaces for all HA communications and maintains session state
synchronization between the active and passive devices.
- HA1 Control Link: Carries heartbeat messages, configuration
synchronization, and state information between HA peers.
- HA2 Data Link: Synchronizes session tables and forwarding information
between firewalls.
- Layer 2 Transport: All HA traffic uses Layer 2 connectivity over HSCI
interfaces.
You cannot configure HA and
NGFW clustering simultaneously on the same
firewall.
The HSCI interface assignments for HA links follow
a specific configuration pattern that ensures proper communication between HA peers.
All HSCI traffic is transmitted in cleartext format. HA1 control link and HA2 data
link are supported only on layer 2. The primary HA1 control link can only be
configured on HSCI-A, while the HA1-backup link is restricted to HSCI-B, providing
redundancy for critical control plane communications. Similarly, the HA2 data
synchronization link can only be configured on HSCI-A, with the HA2-backup link
assigned to HSCI-B for failover protection. While HSCI interfaces handle the primary
HA communications, management interfaces can be configured to support heartbeat
backup functionality, which provides an additional layer of split-brain prevention
by maintaining minimal connectivity between HA peers through the management network
when HSCI links become unavailable.
(
PA-7500 series firewalls)
- HA active/passive mode on PA-7500 series firewalls does not support encryption on HA1, HA2, or HA1/HA2
backup links. Therefore the HSCI-A and HSCI-B interfaces do not support
encryption.
- HA3 and HA4 interfaces are not supported and cannot be configured.
- HA2 and HA2 backup interfaces only support Layer 2 (L2) connectivity.
- MACsec functionality is not supported (unlike the clustering feature).
The HA1 and HA2 functions are aggregated on the HSCI-A and
HSCI-B interface. The administrator cannot assign the front port
interfaces to the HA1 or HA2 role.
The HSCI-A and HSCI-B operate exclusively at Layer 2 only and
although you have to configure an IP address on these interfaces, they
must reside on the same network.
- IPv6 is not supported for HA1/HA2 interfaces. IPv4 addresses for HA1/HA2 is
used exclusively for internal node-to-node communication. Both HA nodes must
be configured on the same subnet.
- PA-7500 firewalls require trunk
mode (tagged traffic) for HSCI port connections when a switch is present in
the connection path; access mode (untagged) is not supported in this
configuration. If you are using a switch between HSCI connections, you must
enable jumbo frames on the firewall and configure the switch ports as tagged
ports. You should enable jumbo frames first, which will require a reboot if
you're activating jumbo frames for the first time, and only then proceed to
enable HA.
- Panorama web interface may display configuration options that are not
actually supported by PA-7500
series firewalls. Always follow these documented constraints regardless of
what appears in the interface.
- Data ports cannot be configured for HA1, HA2, or HA1 and HA2 backup
interfaces. Panorama may display these as selectable options, but
they are not functional.
- HSCI-A must be used for HA1 and HA2 primary interfaces. Other
interface options may appear in Panorama but are not supported.
- HSCI-B must be used for HA1/HA2 backup interfaces. Other interface
options may appear in Panorama but are not supported.
The PA-7500 Series firewalls utilize Condor 3 architecture, which
introduces several key changes to the traditional High Availability (HA)
active/passive configuration:
PA-7500 Series firewalls uses management processor relay for HA communications. When
restarting dataplanes on the firewall HA configurations, be aware that individual
dataplane restarts will trigger a restart of the entire chassis to maintain HA
consistency between peers.
(
PA-7500 firewalls) The following additional parameters are
required when configuring HA on active/passive mode:
- (Mandatory) Device ID: A unique identifier (0 or 1) that
must be configured differently on each HA peer to ensure proper HSCI port
MAC address generation.
- (Mandatory) Group ID: A numeric identifier ranging from 0 to
63 that must match on both HA peers. This ensures the devices recognize each
other as part of the same HA pair. If the group IDs don't match, HA
formation will fail and may result in split-brain scenarios.
- (Optional) VLAN Configuration: VLAN tags (2-4094) for HSCI
traffic, with VLAN 2 used as default for back-to-back connections.
(PA-7500 firewalls) Both the Device ID and Group ID are
essential to ensure proper HSCI port MAC address generation. Misconfiguring
either parameter will cause HA communication to fail. If there is a Device ID
overlap, the devices will enter a split-brain state. If there is a Group ID
mismatch, the devices will also enter a split-brain state without transitioning
to a 'non-functional' state.