U-Boot has networking support for VLANs (802.1q), and CDP (CiscoDiscovery Protocol).You control the sending/receiving of VLAN tagged packets with the"vlan" environmental variable. When not present no tagging isperformed.CDP is used mainly to discover your device VLAN(s) when connected toa Cisco switch.Note: In order to enable CDP support a small change is needed in thenetworking driver. You have to enable reception of the01:00:0c:cc:cc:cc MAC address which is a multicast address.Various defines control CDP; see the README section.