A method of transmitting data in a network, said network comprising a sending node, a relay node and a receiving node, the receiving node being arranged to receive data via the network at a first protocol layer and a second protocol layer of a protocol layer stack, the first protocol layer being for handling transmission of data between adjacent nodes of a connection and the second protocol layer being for establishing data connections, wherein, in said network, different types of notification are used to identify receipt of data, the different types of notification including: a first type of notification identifying receipt of data at the first protocol layer of the node from which the notification is sent and at the second protocol layer of the receiving node; a second type of notification identifying receipt of data at the first protocol layer, but not identifying receipt of data at the second protocol layer, of the node from which the notification is sent; a third type of notification identifying receipt of data at the second protocol layer of the receiving node, but not identifying receipt of data at the first protocol layer, of the node from which the notification is sent; said method comprising: receiving first data sent from said sending node at said relay node, and sending said first data to said receiving node; monitoring for a notification at said relay node identifying receipt of said first data at the first protocol layer of the receiving node; receiving (S810, S811) a notification at said relay node identifying receipt of data at the receiving node; determining (S812, S824) whether the received notification is of the first type, the second type or the third type of notification; in the case that the received notification is determined to be of the first type, ceasing said monitoring, not sending a confirmation of receipt of said notification at said relay node to said receiving node, and sending a notification of the third type to the sending node; in the case that the received notification is determined to be of the second type, ceasing said monitoring; and in the case that the received notification is determined to be of the third type, sending a confirmation of receipt of the received notification to the receiving node, and sending a notification of the third type to the sending node. a first type of notification identifying receipt of data at the first protocol layer of the node from which the notification is sent and at the second protocol layer of the receiving node; a second type of notification identifying receipt of data at the first protocol layer, but not identifying receipt of data at the second protocol layer, of the node from which the notification is sent; a third type of notification identifying receipt of data at the second protocol layer of the receiving node, but not identifying receipt of data at the first protocol layer, of the node from which the notification is sent; said method comprising: receiving first data sent from said sending node at said relay node, and sending said first data to said receiving node; monitoring for a notification at said relay node identifying receipt of said first data at the first protocol layer of the receiving node; receiving (S810, S811) a notification at said relay node identifying receipt of data at the receiving node; determining (S812, S824) whether the received notification is of the first type, the second type or the third type of notification; in the case that the received notification is determined to be of the first type, ceasing said monitoring, not sending a confirmation of receipt of said notification at said relay node to said receiving node, and sending a notification of the third type to the sending node; in the case that the received notification is determined to be of the second type, ceasing said monitoring; and in the case that the received notification is determined to be of the third type, sending a confirmation of receipt of the received notification to the receiving node, and sending a notification of the third type to the sending node. receiving first data sent from said sending node at said relay node, and sending said first data to said receiving node; monitoring for a notification at said relay node identifying receipt of said first data at the first protocol layer of the receiving node; receiving (S810, S811) a notification at said relay node identifying receipt of data at the receiving node; determining (S812, S824) whether the received notification is of the first type, the second type or the third type of notification; in the case that the received notification is determined to be of the first type, ceasing said monitoring, not sending a confirmation of receipt of said notification at said relay node to said receiving node, and sending a notification of the third type to the sending node; in the case that the received notification is determined to be of the second type, ceasing said monitoring; and in the case that the received notification is determined to be of the third type, sending a confirmation of receipt of the received notification to the receiving node, and sending a notification of the third type to the sending node.