A method for determining required routes through an Ether based network associated with VLANs by determining a set of spanning trees. The set of spanning trees is determined to provide a number of routes for consideration. Each spanning tree comprising a plurality of links, sorts the VLANs into an order based on one or more VLAN criteria for the network topology, and maps the sorted VLANs onto the set of spanning trees in an order to optimise one or more characteristics relating to the combination of spanning tree and VLAN to determine an optimised VLAN tree mapping for each set of spanning trees for each route. A best primary tree for each route is selected. Possible failures for each link in the best primary tree for each route are analyzed to derive for a backup tree optimised to determine one or more best backup trees in the event of a possible failure.
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