A node of a frame-based network has a group of outgoing links which are to be treated as an aggregated group of links. A frame distributor performs a distribution function on data frames which are intended for transmission on the group of links. The frame distributor determines if the data frame is an encapsulated data frame which forms part of a tunnelled traffic path across the network. If the data frame does form part of a tunnelled traffic path across the network, the frame distributor allocates the data frame to one of the group of links using at least part of an identifier from the header of the data frame. The identifier represents a service with which the data frame is associated, a customer or user of the data frame, or the tunnelled traffic path, which have greater variability than the backbone destination and source addresses.