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Technical Tip: Configure jumbo frame support

Forum|Forum|5 years ago
October 5, 2020
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Description

This article describes how to configure jumbo frame support for standalone FortiSwitch.

Scope

FortiSwitch

Related links:
https://docs.fortinet.com/product/fortiswitch/6.2

FortiSwitch CLI guide (system interface configuration): page 136.
https://fortinetweb.s3.amazonaws.com/docs.fortinet.com/v2/attachments/0e7e2291-c2e2-11e9-8977-00505692583a/fortiSwitchOS-6.0.5-CLI-ref.pdf

Solution

By default, FortiSwitch internal interface is configured with MTU size 1500.
Configure MTU-override on the system internal interface to support jumbo frames is possible.
This particular system interface needs to configured with static mode of IP address.
DHCP mode of IP addressing is not supported for configuring jumbo frames.

# config system interface
   edit internal
        set mode static
        set ip xxx.xxx.xxx.xxx yyy.yyy.yyy.yyy     <----- 'x' is the IP address and 'y' is the subnet mask.
        set mtu-override enable
        set mtu <MTU-value> ===default 1500
   end

Note.
Set MTU ranges from 68- 10000.(interface has static mode of IP).
Once MTU size is changed, reboot the FortiSwitch to update the MTU values of the VLANs on this interface.

Verify the configuration: