A forecast model processes performance data from a site, e.g., a cable modem termination system (CMTS), to obtain a set of concurrency equations for existing speed tiers that is based on an observed subscriber bandwidth for the site. A new set of concurrency equations is obtained for new speed tiers so that a new subscriber bandwidth can be predicted for the new speed tiers. Based on the new subscriber bandwidth, expected subscriber growth, and changes in data consumption, the site is reconfigured with additional ports based on the forecast. This process can be repeated for the other sites. Sites may be grouped together based on the observed subscriber bandwidth. A new subscriber bandwidth may be predicted for the group with the new speed tiers so that additional ports can be configured for each of the sites in the group.