tailieunhanh - Lecture Business data communications: Chapter 10 - Behrouz A. Forouzan

Chapter 10 - Local area networks part 2: Wireless and Virtual LANs. After reading this chapter, the reader should be able to: Understand the different transmission techniques used in wireless LANs, understand the main characteristics of IEEE wireless LANs, understand the applications of IEEE , understand the characteristics of LANs and the Bluetooth technology that implements this standard. | Chapter 10 Local Area Networks Part 2: Wireless and Virtual LANs Understand the different transmission techniques used in wireless LANs. Understand the main characteristics of IEEE wireless LANs. Understand the applications of IEEE . Understand the characteristics of LANs and the Bluetooth technology that implements this standard. After reading this chapter, the reader should be able to: OBJECTIVES OBJECTIVES (continued) Understand the applications and rationale for VLANs. Understand the concept of virtual LANs. WIRELESS LANs Figure 10-1 ISM bands Figure 10-2 FHSS Figure 10-3 DSSS IEEE : RF LANs Figure 10-4 BSS Figure 10-5 ESS Technical Focus: Portable versus Mobile In networking two terms are used to define nonstationary devices: portable and mobile. The term portable means that a device may move from one location to another, but it remains in a fixed place when in use. The term mobile means that the station can move during operation. . | Chapter 10 Local Area Networks Part 2: Wireless and Virtual LANs Understand the different transmission techniques used in wireless LANs. Understand the main characteristics of IEEE wireless LANs. Understand the applications of IEEE . Understand the characteristics of LANs and the Bluetooth technology that implements this standard. After reading this chapter, the reader should be able to: OBJECTIVES OBJECTIVES (continued) Understand the applications and rationale for VLANs. Understand the concept of virtual LANs. WIRELESS LANs Figure 10-1 ISM bands Figure 10-2 FHSS Figure 10-3 DSSS IEEE : RF LANs Figure 10-4 BSS Figure 10-5 ESS Technical Focus: Portable versus Mobile In networking two terms are used to define nonstationary devices: portable and mobile. The term portable means that a device may move from one location to another, but it remains in a fixed place when in use. The term mobile means that the station can move during operation. Technical Focus: Hidden Node Problem In a wired Ethernet, when a station sends a frame, every station connected to the shared medium senses (hears) the signal; stations are not hidden (electronically) from each other. On the other hand, in a wireless network, two stations may be separated from each other by a physical barrier (such as a wall). They are hidden (electronically) from each other. In this case, both of these stations may start sending a frame at the same time without sensing the signal coming from the other station. In other words, a collision may occur without either station detecting it. This means that the CSMA/CD access method, which is based on the detection of a collision by the sender, does not work here. Technical Focus: Wireless LAN Addressing The addressing mechanism in a wireless LAN is more complicated than in a wired LAN. In a wireless LAN a frame may travel from a station to another station in the same BSS, or from a station in one BSS to another station in another