cally, remote offices use T1 services at 1.54Mbps; higher-trafficked headquarters use T3 at 44Mbps or Carrier Gigabit Ethernet at speeds ranging from 100Mbps to 1Gbps. Higher-speed services cost more than slower services. Virtual Private LAN Service versus MPLS Virtual Private LAN Service (VPLS) emulates a private Local Area Network (LAN). It operates over a provider's MPLS networks. However, it is an end-to-end Ethernet service similar to LANs, and thus requires Ethernet access because Ethernet is based on IP. Therefore, only Ethernet or Gigabit Ethernet access can be used. The use of MPLS in the carrier's network provides higher speeds and enables VPLS to act like unified LAN segments connected to one another with physical private lines. VPLSs are considered Ethernet switched services with the core MPLS network providing the switching function present in private LANs. The MPLS network trans- mits messages to individual MAC addresses of each device as though all ends of the transmission are in the same LAN. This results in higher speeds and fewer delays. VPLSs are designed for a smaller number of sites (approximately ten). This is because the route to each site requires its own data path and control signals within the network. It is essentially a virtual mesh network. Figure 5-3 shows an example of a mesh network. VPLS is used for communications to bandwidth-intensive sites such as data centers. A large organization might have a mix of VPLS and MPLS sites. Figure 5-4 presents an example of VPLS. Internet Protocol Virtual Private Networks over the Internet Ethernet Ethernet switch Gigabit Ethernet Gigabit Ethernet switch access to VPLS access to VPLS MPLS network LAN and data center function as LAN in though they are in the same LAN Data center New York City in Chicago Figure 5-4 Using Virtual Private LAN Service (VPLS) with MPLS to connect a LAN to a remote data center. INTERNET PROTOCOL VIRTUAL PRIVATE NET- WORKS OVER THE INTERNET Internet Protocol Virtual Private Networks (IP VPNs) use the Internet to provide 