Article summary: This article explains how to resolve connectivity issues with DAC (Twinax) cables.
When using DAC (Direct attached copper, also known as Twinax) cables, you may run into link connectivity issues when not using cr4 auto negotiation. This is resolved by enabling cr4 auto negotiation, which is not enabled by default. The example below shows how to do this on interface 37 on unit 0, and then saves the configuration.
Ftos>enable
Ftos#config
Ftos(config)#interface fortyGigE 0/37
Ftos(config-if-fo-0/37)#intf-type cr4 autoneg
Ftos(config-if-fo-0/37)#end
Ftos#write memory
To remove the above configuration run the following command in the interface configuration.
Ftos(config-if-fo-0/37)#no intf-type cr4 autoneg