ccna 1 practice skills exam

ccna 1 practice skills exam.13.2 Basic Content 276 users will spend less as well. For connecting many WAN sites, Frame Relay is more cost effective than leased lines. When designing a Frame Relay network design build, it is not possible for the design solution to include VCs between each pair of sites. figure 13-3 includes PVCs between each pair of sites, which is called a fully meshed interconnected Frame Relay network. If not all sites are connected directly to each other via PVCs, it is referred to as a locally interconnected network. The network shown in Figure 13-4 is the same as Figure 13-3, but this time it is only partially interconnected, with only two PVCs. when R1 is at the primary site and R2 and R3 are at the remote office site, there is generally little need for direct communication.Figure 13-4 Typical Locally Interconnected Frame Relay NetworkLocal interconnection networks have a number of advantages and disadvantages compared to fully meshed interconnection networks. The main advantage is that local interconnection networks are cheaper because service providers are billed on a per VC basis. The disadvantage is that traffic from site R2 to site R3 must first reach R1 and then be transmitted out. If this traffic is small, then the cost is small. If the traffic is larger, it may be worth the extra cost to set up a fully meshed interconnection network, since the traffic has to pass through R1's access link twice to transmit traffic between the two remote sites.LMI and Encapsulation TypeWhile PVCs provide a logical means of sending frames to each other between two client routers, Frame Relay also has many physical and logical components that work together to implement PVCs. physically, each router requires an access link from that router to a particular Frame Relay switch. The Frame Relay provider must create some type of physical network between those switches. In addition, the provider must also find a way to get the frames sent over the PVC to the correct destination.Frame Relay uses the Local Management Interface (LMI) protocol to manage each physical access link and the PVCs that use that link.These LMI messages operate between a DTE (for example, a router) and a DCE (for example, a service provider's Frame Relay switch).The LMI status interrogation message is the most important LMI message associated with the exam question. LMI status messages perform the following two key functions.They perform a survival function between the DTE and the DCE. If there is a problem with the access link, the failure to receive a survive message means that the linklink is down.They signal whether a PVC is active or not. Even though each PVC is predefined, its state can be changed