Technical Tip: Recommended Port speed configuration for SR (short range) SFP cable

Description

This article describes the recommended Port speed configuration for SR (short range) SFP cable.

Scope

FortiSwitch.

Solution

By default, the speed config set on SFP port is auto-module:

config switch physical-port
    edit "port52"
        set speed auto-module
    next
end

While using an SR cable, for example: consider changing the 10gbps speed to 10000sr.

config switch physical-port
    edit port52
        set speed 10000sr
end

To push the speed configuration from the Fortigate for Managed FortiSwitches, run the below command on FortiGate:

config switch-controller managed-switch

FortiGate(managed-switch) # edit <SWITCH-ID>

FortiGate(SWITCH-ID) # config ports

FortiGate(ports) # edit port#

FortiGate(port#) # set speed 10000sr

FortiGate(port#) # end

FortiGate(SWITCH-ID) # end

Reason: It is recommended to change the speed configuration for SR cable to avoid CRC alignment errors and Rx errors/discards.