A system comprises: a first network node (3); a second network node (4); at least one communication path (702, 703) connecting the first network node to the second network node; a first cache (706) forming part of the first network node; and a second cache (705) forming part of the second network node, wherein: the first cache is configured to cache data received from a host; the first network node is configured to transmit the data from the first cache to the second network node over the at least one communication path; the second network node is configured to receive the data transmitted by the first network node and to store the received data in the second cache prior to providing the data from the second cache to a connected device; the second network node is configured to use operating parameters of the second cache to calculate a hunger parameter representative of the capability of the second cache to receive more data; the second network node is configured to communicate the hunger parameter to the first network node; and the first network node is configured to use the hunger parameter received from the second network node to change the configuration of the first cache.