speed

When a value greater than 0 is set, configures the device to use the specified speed.

If "auto-negotiate" is "yes" the specified speed will be the only one advertised during link negotiation: this works only for BASE-T 802.3 specifications and is useful for enforcing gigabit speeds, as in this case link negotiation is mandatory. If the value is unset (0, the default) , the link configuration will be either skipped (if "auto-negotiate" is "no", the default) or will be auto-negotiated (if "auto-negotiate" is "yes") and the local device will advertise all the supported speeds. In Mbit/s, ie 100 == 100Mbit/s. Must be set together with the "duplex" property when non-zero. Before specifying a speed value be sure your device supports it.