Most network setups consist of a combination of systems that have varying speed capabilities. Each system advertises speed capabilities to other systems on the network that informs how each system transmits and receives network traffic.
The following paired datalink properties regulate the speed capabilities that are advertised by a system:
Each link speed capability is referred to by a pair of properties: the advertised speed (adv_*_cap) and the enabled advertised speed (en_*_cap). Further, datalink speed information is also provided for both full-duplex and half-duplex capabilities, as designated by *fdx* and *hdx* in the property names. The advertised speed property is a read-only property that indicates whether the specific datalink speed is advertised. You determine whether a specific datalink speed is advertised by setting the corresponding en_*_cap property.
By default, all of the speed and duplex capabilities of a datalink are advertised. However, cases might exist where a new system is communicating with an older system and auto-negotiation is disabled or unsupported. To enable communication between these two systems, the advertised speed between an older system and a newer system might need to be changed to a lower value. The Gigabit capabilities of the system might need to be switched off and only the slower speed capabilities are advertised. In this case, you would type the following command to switch off the advertisement of the Gigabit capabilities for both the full-duplex capability and the half-duplex capability:
# dladm set-linkprop -p en_1000fdx_cap=0 datalink # dladm set-linkprop -p en_1000hdx_cap=0 datalink
To display the new values of these properties, use the dladm show-linkprop command as follows:
# dladm show-linkprop -p adv_10gfdx_cap datalink # dladm show-linkprop -p adv_1000hdx_cap datalink
Normally, the values of a given enabled speed property and the corresponding advertised property are identical. However, if a NIC supports some advanced features such as Power Management, those features might set limits on the bits that are actually advertised between the host and its link partner. For example, with Power Management, the settings of the adv_*_cap properties might only be a subset of the settings of the en_*_cap properties.