Chapter 10 - EPS network entities and interfaces

Abstract

This chapter illustrates the different network entities, interfaces, protocols and procedures used in Evolved Packet System (EPS). EPS is an “all IP” system where all protocols are transported over IP networks. A network entity in EPS is what sometimes called a “logical entity.” This means that in the 3GPP standard it is a logically separate entity with a well-defined functionality. There are also well-defined interfaces between different network entities. This does not, however, imply that actual physical “boxes” implemented by vendors and deployed in real networks have to correspond one-to-one with the network entities in the standard. Vendors may implement a network entity as a standalone product, or may choose to combine different network entities in the same product. It can for example be beneficial to combine a Serving GW and a PDN GW in the same node in order to reduce the number of physical in order to nodes that the user plane has to traverse in nonroaming cases.