Each of first and second bridges of a data network having respective links to an external node implement a network bridge component that forwards traffic inside the data network and a virtual bridge component that forwards traffic outside of the data network. A virtual bridge is formed including the virtual bridge components of the first and second bridges and an interswitch link (ISL) between the virtual bridge components of the first and second bridges. Data frames are communicated with each of multiple external network nodes outside the data network via a respective one of multiple link aggregation groups all commonly supported by the virtual bridge.