1. A network access node (300) for a packet switching communication network (200) comprising a plurality of network nodes (201-208) interconnected with transmission links (209), said network nodes being connected to termination nodes, said access node including means for receiving and transmitting data packets (301, 302, 304), and data storage means (306) for storing data representing the network configuration, said network access node further including: selecting means for selecting a set of links suitable for use as part of a path to each destination termination node located in the network, said selecting means further include clustering means for decomposing said network into a set of backbone nodes and a plurality of subarea nodes, said clustering means further comprising data retrieval means for retrieving the network configuration data from said data storage means, sorting means for ranking all nodes according to the number of links connected to the nodes, tree forming means for constructing a connectivity tree in which each node in the network appears only once and in which the tree origin is the highest rank node found by said sorting means, classifying means for classifying nodes into backbone nodes and subarea nodes, backbone nodes being all non-termination nodes and any termination node which is connected only to one other node and subarea nodes being any node that is not a backbone node, subarea nodes having the same parent being categorized in the same subarea, means for defining a backbone path between two subareas, the backbone path including a link to each subarea interconnected through the highest ranked node from the set of nodes connecting the two links, means for removing from the set of backbone to subarea links, any link in which the parent node in the subarea is not connected to the parent in the backbone and any link to a subarea having less than a predetermined number of nodes; storage means for storing data representing the sets of links selected by said selecting means; and means responsive to a request for a connection between said access node and a destination node to establish a routing path including links from the set of links selected for the destination node.