cisco ccna hands-on labs

cisco ccna hands-on labs.11.Bo GRE encapsulation configuration is optional and defaults to GRE point-to-point. A, C, and D are all essential commands, so they are not the correct answer.Chapter 2525.01 Virtual Circuits 25.04 Non-Broadcast Multiple Access Environment II 25.02 Frame Relay Terminology Minute Sprint 25.03 Configuring Frame Relay Self-Test QuestionsChapter 24 introduces WANs and also describes point-to-point connections that encapsulate Advanced Data Link Control (HDLC) and Point-to-Point Protocol (PPP) with R as the data link layer. These protocols are commonly used for leased-line and circuit-switched connections. This chapter introduces another WAN topic: Frame Relay. Frame Relay is a data link layer packet switching protocol that uses digital circuits to transmit data with little to no errors, so it performs only error detection, leaving error correction to higher layer protocols (such as TCP) or to the application itself.Frame Relay is actually a series of separate standards, including those developed by the ITU-T and ANSI. Interestingly, the Frame Relay standard only defines the interaction between Frame Relay customer front-end equipment (CPE) and the Frame Relay carrier switch, not the connection across the carrier network, although most carriers use Asynchronous Transfer Mode (ATM) to transport Frame Relay between sites.Authentication Objectives 25.0125.1 Virtual circuitsFrame Relay is connection-oriented: to send information to a remote device, a Layer 2 connection must be established. The connections used by Frame Relay are provided by Virtual Circuits (VCs), which are logical connections between two devices, so there can be many VCs on the same physical interface. it is much cheaper to use VCs to provide a full mesh connection than leased lines. VCs are also full-duplex: data can be sent and received simultaneously on the same VC. Other packet and element switching technologies such as ATM and X.25 also use VCs; much of the information in this chapter about VCs applies to both Frame Relay and other technologies.25.1.1 Full Mesh DesignAs mentioned earlier, VCs are more cost-effective than leased lines because fewer physical connections are required when using them to implement a full-mesh topology. Suppose you want to connect four WAN devices together and you have two options: leased lines and VCs. in the top half of Figure 25.1, leased lines are used to connect these devices together. Note that to achieve full network connectivity (each device connected to all other devices), a total of 6 leased lines are required, and each router requires 3 serial interfaces.