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How to change the MTU value of an aggregate interface

By: Author Alex Lim

Posted on

Categories Troubleshooting

This article describes the impact of Changing the MTU value of an aggregate interface.

Scope

FortiGate.

Solution

If there are two or three interfaces are part of the aggregate interface, so changing the MTU value of the aggregate interface will also change the MTU size of all physical interfaces. For Example:

Port3 and port4 are part of the aggregate interface:

Port3 and port4 are part of the aggregate interface

Initially, MTU size of port 3 and port 4 is set as a default value of 1500 as shown in the screenshot. To check the MTU size use the below command:

diag netlink interface list <NIC name>

Changing MTU size of Aggregate interface named as ‘Test’ to value 1300.

After changing the MTU value of the aggregate interface, the Port3 and port4 MTU values will also change.