ched to packets for each protocol. Routers attach a different type of tag to packets containing e-mail messages from those that contain video. Carriers that don't meet these SLAs generally rebate agreed-upon credits to customers. MPLS Service Components In addition to classes of service, customers also specify the following: A port speed at the provider's POP, often at a lower speed than their access line. The port speed refers to the number of bits per second that can enter the carrier's network. Additional managed services including managed security, and the use of the provider's network and staff for operating, setting up, and managing the videoconferences. The speed of the access line, which is the circuit connecting the customer to the provider's network. Typically, remote offices use slower-speed Gigabit Ethernet; higher-trafficked headquarters use Carrier Gigabit Ethernet at speeds ranging from 100Mbps to 400Gbps. Higher-capacity services cost more than slower services. IP VIRTUAL PRIVATE NETWORKS OVER THE INTERNET Internet Protocol Virtual Private Networks (IP VPNs) provide the features of private dedicated links, without the cost of leasing dedicated circuits from ISPs or leasing MPLS. Rather, each location leases a line connected to the Internet from the local telephone company. These leased lines use IP VPN technology for site-to-site links, access to the cloud, and for remote access from: Branch offices www.TechnicalPDF.com Employees' homes to access computer files at headquarters Other cities in which employees are traveling Using IP VPNs between Offices-Less Costly than MPLS Organizations use IP VPNs to link sites together SO that remote offices can share resources such as centrally located e-mail, Internet access, and applications. A particular difference between IP VPN, SDN, and MPLS services is that organizations that use IP VPNs only pay for Internet access. This is a major cost advantage in favor of IP VPNs. Some companies do pay carriers for security services to screen incoming traffic for vir