The ISO often uses different terms than the IETF to describe the same entities, a fact that can sometimes cause confusion. ISO terms are introduced and defined in this section, but in most cases the more familiar IETF terminology used throughout the rest of this book is used in this chapter. Some ISO terms are so fundamental that they should be discussed before getting into any specifics of the IS-IS protocol.
 The temptation to use the ISO/European spelling of certain common terms such as “routeing” and “neighbour” was successfully resisted.
A router is an Intermediate System (IS), and a host is an End System