ccna 2 audiobook

ccna 2 audiobook.the ARP global consistency. Logical DLCI values in the same network are illustrated in Figure 14-2. Subnet 199.1.11.0/24 Subnet 199.1.12.0/24 Figure 14-2 Full Mesh Interconnection with Local DLCI ValuesThe Frame Relay "mapping" establishes a correspondence between the Layer 3 address and its corresponding Layer 2 address. This concept is analogous to the ARP cache of a LAN interface. For example, the IP Address Resolution Protocol (ARP) cache used on the LAN is an example of a Layer 3 and Layer 2 address mapping. For IPARP, the IP address of another device in the same LAN can be known, not the MAC address. When ARP is completed, the LAN (Layer 2) address of the other device is known. Similarly, a router using Frame Relay needs to use a mapping between the router's Layer 3 address and the DLCI to reach the other router.a mapping between the router's Layer 3 address and the DLCI to reach the other router.This subsection discusses the basics of why LAN connections and Frame Relay require mapping, with a focus on Frame Relay. A more general definition of mapping is given here. , . The information associated with the Layer 3 address of the next-hop router and the Layer 2 address that reaches this router is called a mapping. The use of mappings is required in multi-access' sprawl interrogation networks.It helps to consider routing to understand more clearly the need for mapping. Suppose a host on the Mayberry LAN interface of network 199.1.11.0/24 wants to send an IP packet to a host on the MountPilotLAN interface of a Class C network (as shown in Figure 14-3). In this figure the router discards the Ethernet header and tail through the normal routing steps. It then chooses to route the packet out of Maybeny's S0/1/1 interface to the next hop MountPilot, and so on. But should Mayberry put that DLCI into the new Frame Relay header?On the left side of the diagram is the table that Mayberry uses to select the correct DLCI. First, Mayberry looks for the route used to forward the packet and finds the IP address of the next-hop router. Next, the Frame Relay mapping table gives the same next-hop router IP address, along with the DLCI used to send the frame to that IP address (the same as the ARP table.) Mayberry next takes that DLCI (52,Mayberr's local DLCI, used to connect the PVC to MountPilot)292 Chapter 14 Implementing Frame Relay Packets to Frame Relay Headers.13.2 Basic Content 293Routing TableSubnet Next Hop