A connection-oriented optical network (2) comprises nodes (10) and optical links (5) between nodes. Each node (10) has a power control unit (60) for controlling an optical amplifier (43) at the node. A node, in response to a requirement to set up a new connection in the network, signals to a power control unit (60) at each of a plurality of downstream nodes along a path of the new connection to cause the power control unit at the node to adjust the optical amplifier at the node to support a new optical channel to carry the new connection. The node (10) can signal to tear down an existing connection in a similar way. A downstream node determines a number of optical channels for which the optical amplifier can be adjusted concurrently, based on an existing number of active optical channels.