A communication network system is disclosed in which local-branch-site-line network switches accommodating local-branch-site lines, and at least one data-center-site-line network switch accommodating at least one data-center-site line, are interconnected via a carrier network. This system include: a first bandwidth controller, disposed at each local-branch-site-line network switch, configured to limit a bandwidth of each of inbound packets and/or outbound packets to a pre-selected bandwidth α, wherein the inbound packets flow from the instant local-branch-site-line network switch or other local-branch-site-line network switches, and the outbound packets flow to the instant local-branch-site-line network switch or other local-branch-site-line network switches; and a second bandwidth controller, disposed at each local-branch-site-line network switch, configured to limit a bandwidth of each of inbound packets and/or outbound packets to a pre-selected bandwidth β broader than the bandwidth α, wherein the inbound packets flow from the data-center-site-line network switch, and the outbound packets flow to the data-center-site-line network switch.