Case Study: Understanding Subinterfaces
One of the most difficult concepts to understand is the difference between point-to-point and multipoint interfaces on a router. This section briefly discusses the different scenarios regarding the use of each.
A router has two different types of serial subinterfaces that provide a flexible solution for routing various protocols over partially meshed networks. A single, physical interface can be logically divided into multiple, virtual subinterfaces. The serial subinterface can be defined as either a point-to-point connection or a multipoint connection.
The concept of subinterfaces was originally created to better handle issues caused by split horizon over NBMA networks (such as Frame Relay and X.25) and ...