nsistent, high-speed network connections. This is particularly applicable for audio and video conferences, where latency (delays) noticeably degrades quality. Operating conferencing services over data networks is less costly than using long- distance services. Some organizations save money by using the Internet for confer- encing services. Thus, prioritization is an important element toward ensuring that audio is clear and the video is continuous and without distortions. However, there is no guarantee of consistent quality levels on Internet-based video conferences. Specifying Performance Levels in Service-Level Agreements As part of their MPLS contracts, for an additional fee, most carriers offer Service- Level Agreements (SLAs) in conjunction with MPLS VPNs. These agreements offer guarantees regarding issues such as the following. Uptime, which is the percentage of time that the service operates. Latency, which is the delay in milliseconds between when packets are sent and received. Low latency is important for voice and video quality. Restoral time per failure. Packet loss. Access line (the line from the customer to the carrier) uptime. Broadband and Wide Area Network Services Carriers apply CoS according to tags attached to packets for each protocol. Rout- ers attach a different type of tag to packets containing e-mail messages than for 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 Point of Presence (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, CoS, and the use of the provider's network and staff for operating, setting up, and managing the video conferences. The speed of the access line, which is the circuit connecting the customer to the provider's network. Typi