|  | 3.3 | How to Identify and Select Networking Capabilities
| 3.3.5 | Core-layer functions
The core layer's function is to provide a fast path between remote sites, as shown in the figure. This layer of the network should not perform any packet manipulation, such as using access control lists and performing filtering, that would slow down the switching of packets. The core layer is usually implemented as a WAN. The WAN needs redundant paths so that the network can withstand individual circuit outages and continue to function. Load sharing and rapid convergence of routing protocols are also important design features. Efficient use of bandwidth in the core is always a concern.
| Threaded Case Study
Washington Project: The WAN Core

The WAN core for the Washington School District network should be a high-speed backbone designed to route packets as quickly as possible. School locations should connect to the WAN core based on physical location.