The initial deployment of the Internet addressed the requirements of data transfer over the network. This network catered to simple applications such as file transfer and remote login. To carry out these requirements, a simple software-based router platform, with network interfaces to support the existing T1/E1– or T3/E3–based backbones, was sufficient. As the demand for higher speed and the ability to support higher-bandwidth transmission rates emerged, devices with capabilities to switch at the Level-2 (data link) and the Level-3 (network layer) in hardware had to be deployed. Layer-2 switching devices addressed the switching bottlenecks within the subnets of a local-area network (LAN) environment. Layer-3 switching devices helped alleviate the bottleneck in Layer-3 routing by moving the route lookup for Layer-3 forwarding to high-speed switching hardware.

These early solutions addressed the need for wire-speed transfer of packets as they traversed the network, but they did not address the service requirements of the information contained in the packets. Also, most of the routing protocols deployed today are based on algorithms designed to obtain the shortest path in the network for packet traversal and do not take into account additional metrics (such as delay, jitter, and traffic congestion), which can further diminish network performance. Traffic engineering is a challenge for network managers.