Technical Note : Changing the speed of a FortiGate interface
Products
FortiGate
Purpose

This article explains how to change the port speed of a FortiGate interface via CLI.

Expectations, Requirements
.
Configuration
The default value for all interfaces is auto-negotiate. This should automatically set the speed for that port appropriate to the speed set on your other network hardware. If this does not happen, you can edit your configuration using the following CLI commands:

conf sys int
  edit <interface-name>
  set speed <1000full/10000half/100full/100half/10full/10half/auto>
end


Note that only some models support gigabit Ethernet speeds.
The device attached should match the settings. If the FortiGate unit is set to 100Full, the device on the end should also be set to 100Full.

The interface speed

· auto, the default speed. The interface uses auto-negotiation to determine the connection speed. Change the speed only if the interface is connected to a device that does not support auto-negotiation.
· 10full, 10 Mbps, full duplex
· 10half, 10 Mbps, half duplex
· 100full, 100 Mbps, full duplex
· 100half, 100 Mbps, half duplex
· 1000full, 1000 Mbps, full duplex
· 1000half, 1000 Mbps, half duplex

Speed options vary for different models and interfaces. Enter a space and a “?” after the speed keyword to display a list of speeds available for your model and interface.

You cannot change the speed for interfaces that are 4-port switches. This includes the internal interfaces of FortiGate models 60, 60M, 100A, 200A, and FortiWiFi-60. This also includes the LAN interface of the FortiGate-500A.

However there is a command in config system global that allows to set the internal switch speed. To configure this use the following CLI commands :-

FGT200A-1 # config sys global
FGT200A-1 (global) # set internal-switch-speed

100full    100M Full
100half    100M half
10full     10M Full
10half     10M half
auto       auto

 
Troubleshooting
For interface diagnostics:

   diag hardware deviceinfo nic

Refer to the related article "Troubleshooting Note : FortiGate interface error counters" for more information on understanding the output of this diagnostic command.
Related Articles
How to best configure Ethernet (Full/Half duplex, Auto-negotiation) settings.
Troubleshooting Note : FortiGate interface error counters
Configuring port speeds
Last Modified Date: 06-14-2011 Document ID: FD30018