An Introduction to MPLS (continued)

However, for months now, some departments have been complaining that they require overnight delivery and package-tracking services.  As a manager, you set up a system to send three levels of mail between campuses – first class, priority, and express mail.  In order to offset the increased expense of the new services, you bill the departments that use these premium services at the regular USPS rate plus 10%.

Priority and express mail are processed by placing the package into a special envelope with a distinctive label.  These special packets with distinctive labels assure the package priority handling and tracking capability within the postal network.  In order to avoid slowdowns and bottlenecks, the postal facilities in the network created a system that uses sorting tables or sorting databases to expedite these special packets.  

The Construction of an MPLS Network

In an IP network, you can think of routers as post offices or postal sorting stations.  Without a means to mark, classify, and monitor mail, there would be no way to process different classes of mail.  In IP networks, you find a similar situation.  Figure 1 below shows a typical IP network with traffic having no specified route.