Eircom subsidiary Lan Communications has signed a three-year contract with the ESB said to be worth around €2.3 million.
Under the deal, Lan, which provides systems integration and professional services, will supply infrastructure equipment to the ESB for its ongoing network upgrade.
The ESB's IT Technical Services Manager, Mr Tony Keane, said: "Market deregulation and the need to provide highly available applications with full disaster recovery services across two independent data centres has presented us with a unique opportunity to streamline the way in which we traditionally deliver IT services."
He said: "Splitting business units into separate logical networks which share the same physical infrastructure but communicate independently of one another is a new approach which will allow us to build a more responsive, efficient and fault-tolerant IT infrastructure for the ESB group of companies."