ABSTRACT
This chapter provides greater detail on some of the lower levels of a network protocol stack. It focuses on construction of local area networks (LANs), both wired and wireless. The chapter explores the Ethernet technology and wireless technology. Ethernet is largely concerned with just the lowest layers defined in the Open Systems Interconnection (OSI) model: the physical layer and the data link layer. The chapter focuses on these two layers. A wireless access point (WAP) provides access to the LAN by offering what is called a hotspot. The WAP receives radio signals from a nearby wireless device and passes those signals onto a router. A network with more than one WAP is referred to as an Extended Service Set (ESS) topology. Wireless LAN standards have been produced. These standards specify the data transfer rate, power, frequency, distance, and modulation of wireless devices. The virtual private network (VPN) is the extension of a private network across a public network.
