Technical Tip: FortiGate MAC address table aging timer when in transparent mode
| Description | This article describes how to view or change the MAC address table aging parameter on a FortiGate. |
| Scope | FortiGate in transparent mode. |
| Solution | In a situation where a FortiGate is operating in transparent mode, and there is a need to verify or adjust the timer of the MAC address table aging, also known as MAC address table TTL.
When the FortiGate is operating in transparent mode, the MAC addresses dynamically learned are stored in a MAC address table. The MAC address aging feature provides a mechanism to remove the dynamic MAC addresses that remain inactive for a specified amount of time.
By default, each learned MAC address is aged out after 300 seconds. After this amount of time, the inactive MAC address is removed from the table.
View configured parameter (at VDOM level if VDOM is enabled):
The FortiGate (or VDOM) is well in transparent mode, and the MAC address table aging value is 300 seconds (default value).
Here is the information to change the MAC address table aging parameter. Command Syntax (at VDOM level if VDOM is enabled):
This example sets the MAC address aging time to 600 seconds (10 minutes). The valid range is 300–8640000 seconds.
When a MAC address is learned from a source device, FortiGate retains it in its bridging table (MAC address table). If no packets from that MAC address are observed during the value of max-ttl, the entry is aged out(removed). This prevents stale forwarding information and ensures the FortiGate maintains efficient and accurate Layer 2 forwarding.
This setting is relevant in transparent mode only, where the FortiGate acts as a Layer 2 bridge, forwarding frames based on MAC addresses rather than IP routing.
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