The problem of distributing gas through a network of pipelines is formulated as an linearized nonstationary differential repetitive model subject to some flow-pressure constraints of material balances and pressure bounds. The linear model is constructed in the neighborhood of the known basic operating regime of gas delivery. The considered problem is to minimize the total supply cost of a gas transmission company with the minimal guaranteed pressure at the nodes. Some aspects of a comprehensive optimization theory based on a 'constructive approach' are discussed.