e of content, as well as flexible, real time routing. An example is Comcast that no longer offers MPLS and is promoting WA SDNs instead for enterprise customers. MPLS Virtual Private Network-A Managed Service MPLS provides VPN (Virtual Private Network) features. VPNs have the features and functionality of private networks. However, unlike private lines, which are not shared and are for the exclusive use of a single organization, MPLS operates on network links shared by www.TechnicalPDF.com other customers. The links are virtually private, and offer many of the features found on private lines such as user control and privacy. In addition, they are less costly than private lines to lease and operate. MPLS has the capability to classify traffic SO that voice and video have higher priorities than services such as file transfer and e-mail, which are less sensitive to delay. Because of these and other capabilities managed by providers, MPLS is also referred to as a managed network service. Routes and Security on MPLS MPLS is inherently more secure than using the Internet for site-to-site traffic and access to other networks because it is transmitted over a carrier's private data network. For added protection from hackers, customers often use separate circuits to access MPLS circuits and the Internet. This is more costly than combining access to both services on the same line, but it isolates MPLS transmissions even further from viruses and attacks sent over the Internet. Figure 5-2 illustrates an example of segregated circuits for Internet access and MPLS service. MPLS network Internet Access lines www.TechnicalPDF.com Customer premises Router LAN switch VollP phone Figure 5-2 Implementing separate access to the Internet and a Multi-Protocol Label Switching (MPLS) network. MPLS minimizes traffic jams by selecting the shortest, least-congested route for all messages in each transmission. All packets in every message are sent over the same route. In contrast, in WA SDN networks, each packet can travel on a different path