Configuring Port Redundancy

Port Redundancy provides a simple method for configuring a redundant port for a physical Ethernet port. This is a valuable feature, particularly in high-end deployments, to protect against switch failures being a single point of failure.

When the primary interface is active, it processes all traffic to and from the interface. If the primary interface goes down, the secondary interface takes over all outgoing and incoming traffic. The secondary interface assumes the MAC address of the primary interface and sends the appropriate gratuitous ARP on a failover event. When the primary interface comes up again, it resumes responsibility for all traffic handling duties from the secondary interface.

In a typical Port Redundancy configuration, the primary and secondary interfaces are connected to different switches. This provides for a failover path in case the primary switch goes down. Both switches must be on the same Ethernet domain. Port Redundancy can also be configured with both interfaces connected to the same switch.

Port Redundancy Failover

SonicWall provides multiple methods for protecting against loss of connectivity in the case of a link failure, including High Availability (HA), Load Balancing Groups (LB Groups), and now Port Redundancy. If all three of these features are configured on a firewall, the following order of precedence is followed in the case of a link failure:

When Port Redundancy is used with HA, Port Redundancy takes precedence. Typically an interface failover will cause an HA failover to occur, but if a redundant port is available for that interface, then an interface failover will occur but not an HA failover. If both the primary and secondary redundant ports go down, then an HA failover will occur (assuming the secondary firewall has the corresponding port active).

When Port Redundancy is used with a LB Group, Port Redundancy again takes precedence. Any single port (primary or secondary) failures are handled by Port Redundancy just like with HA. When both the ports are down then LB kicks in and tries to find an alternate interface.

Port Redundancy Configuration

To configure Port Redundancy:
On the Network > Interfaces page, click the configure icon for the interface that is to be designated the master of the Link Aggregation Group. The Edit Interface dialog displays.
Click on the Advanced tab.
In the Redundant/Aggregate Ports drop-down menu, select Port Redundancy.
The Redundant Port drop-down menu is displayed, with all of the currently unassigned interfaces available. Select one of the interfaces.
Set the Link Speed for the interface to Auto-Negotiate.