A method of operating a communications network, the network comprising a plurality of nodes, a plurality of communications links interconnecting the nodes and a plurality of tunnels, each of the plurality of tunnels comprising one or more of the plurality of communications links, the method comprising the steps of: a) creating a datastore, the datastore comprising, for each of the plurality of tunnels connecting a first network node to a second network node, one or more parameter values for a plurality of time intervals over a pre-determined duration, the one or more parameter values being selected from a group of service related parameters and/or a group of network related parameters; b) receiving a request to admit a session to the communications network, the session being routed between the first network node and the second network node; the method comprising the further steps of: for each of the plurality of tunnels connecting the first network node to the second network node accessing the one or more parameter values held within the datastore in order to: i) determine, based on the accessed one or more parameter values held within the datastore, the expected performance of the tunnel for the duration of the requested session if the request is accepted; ii) determine the impact on the sessions already supported by the tunnel if the request is accepted; and iii) evaluate the historical performance of the tunnel to determine the effect of accepting previous similar requests; wherein the request to admit a session to one of the plurality of tunnels is accepted if it is determined in each of steps i) to iii) that the admission of the session has no adverse impact. a) creating a datastore, the datastore comprising, for each of the plurality of tunnels connecting a first network node to a second network node, one or more parameter values for a plurality of time intervals over a pre-determined duration, the one or more parameter values being selected from a group of service related parameters and/or a group of network related parameters; b) receiving a request to admit a session to the communications network, the session being routed between the first network node and the second network node; the method comprising the further steps of: for each of the plurality of tunnels connecting the first network node to the second network node accessing the one or more parameter values held within the datastore in order to: i) determine, based on the accessed one or more parameter values held within the datastore, the expected performance of the tunnel for the duration of the requested session if the request is accepted; ii) determine the impact on the sessions already supported by the tunnel if the request is accepted; and iii) evaluate the historical performance of the tunnel to determine the effect of accepting previous similar requests; i) determine, based on the accessed one or more parameter values held within the datastore, the expected performance of the tunnel for the duration of the requested session if the request is accepted; ii) determine the impact on the sessions already supported by the tunnel if the request is accepted; and iii) evaluate the historical performance of the tunnel to determine the effect of accepting previous similar requests;