A system comprising: a source node to transmit a data packet to a target node; and a plurality of intermediate nodes communicatively coupled in succession between the source node and the target node, each of the intermediate nodes to receive the data packet from either the source node or a previous intermediate node in succession, and transmit the data packet to either the next intermediate node in succession or to the target node, each of the intermediate nodes and the source node having a programmable retry timer associated therewith, each retry timer programmed with retry time period after which the intermediate node or the source node will retransmit a data packet if the intermediate node or the source node has not received an appropriate response to said data packet, characterised in that: the source node and the intermediate nodes are configured to employ a transaction control scheme wherein the retry timer of the source node is programmed with a relatively larger retry time period than any of the intermediate nodes and wherein intermediate nodes located relatively further in succession from the source node have their retry timers programmed with relatively smaller retry time periods than intermediate nodes located relatively closer in succession to the source node, wherein the source node and the intermediate nodes are each configured to attempt a number of retries to retransmit the data packet, wherein the source node is configured to retransmit the data packet in an increased number of retries relative to any of the intermediate nodes, and wherein intermediate nodes located relatively further in succession from the source node are configured to attempt to retransmit the data packet in a relatively fewer number of retries than intermediate nodes located relatively closer in succession to the source node. a source node to transmit a data packet to a target node; and a plurality of intermediate nodes communicatively coupled in succession between the source node and the target node, each of the intermediate nodes to receive the data packet from either the source node or a previous intermediate node in succession, and transmit the data packet to either the next intermediate node in succession or to the target node, each of the intermediate nodes and the source node having a programmable retry timer associated therewith, each retry timer programmed with retry time period after which the intermediate node or the source node will retransmit a data packet if the intermediate node or the source node has not received an appropriate response to said data packet, characterised in that: the source node and the intermediate nodes are configured to employ a transaction control scheme wherein the retry timer of the source node is programmed with a relatively larger retry time period than any of the intermediate nodes and wherein intermediate nodes located relatively further in succession from the source node have their retry timers programmed with relatively smaller retry time periods than intermediate nodes located relatively closer in succession to the source node, wherein the source node and the intermediate nodes are each configured to attempt a number of retries to retransmit the data packet, wherein the source node is configured to retransmit the data packet in an increased number of retries relative to any of the intermediate nodes, and wherein intermediate nodes located relatively further in succession from the source node are configured to attempt to retransmit the data packet in a relatively fewer number of retries than intermediate nodes located relatively closer in succession to the source node. the source node and the intermediate nodes are configured to employ a transaction control scheme wherein the retry timer of the source node is programmed with a relatively larger retry time period than any of the intermediate nodes and wherein intermediate nodes located relatively further in succession from the source node have their retry timers programmed with relatively smaller retry time periods than intermediate nodes located relatively closer in succession to the source node, wherein the source node and the intermediate nodes are each configured to attempt a number of retries to retransmit the data packet, wherein the source node is configured to retransmit the data packet in an increased number of retries relative to any of the intermediate nodes, and wherein intermediate nodes located relatively further in succession from the source node are configured to attempt to retransmit the data packet in a relatively fewer number of retries than intermediate nodes located relatively closer in succession to the source node.