Technical Tip: Port speed configuration for DAC (Direct Attach Copper) cable

[sachitdas_FTNT]

Description
This article describes the Port speed configuration recommended when using DAC cable.

Scope
For FortiSwitch-448 series and above.

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

# config switch physical-port
    edit "port52"
        set lldp-profile "default-auto-isl"
        set speed auto-module
    next
end

While using DAC cable for example: 10gbps, consider changing the speed to 10000cr.

# config switch physical-port
    edit port52
        set speed 10000cr
end

Reason: It is recommended to change the speed configuration for DAC cable to avoid CRC allignment errors and Rx errors.