An Introduction to Authentication

Authentication is the process through which a device or a user's identity is verified before access to various types of resources can be provided. It generally includes a mechanism by which a user or device provides a password to the authenticating device. Then the device checks the password's veracity against a database of passwords. If the password is indeed correct, the user is allowed to proceed and use the resources available based on authorization parameters, if any, t..

Updating the Routing Table in Active Mode with DUAL

Figure 3-6 shows feasible and advertised distance.  Figure 3-6. Feasible and Advertised Distance—Active Mode When no alternative route is found in the routing table, the following actions are taken (using the network in Figure 3-6 as an example). The topology table of Router A starts with a path (successor) of A to D to G to X. The feasible distance is 20, and the advertised distance from Router D is 15. When Router D dies, Router A must find an alternative path to ..

Link-State Concepts

Recall that link-state protocols are based on neighbor relationships, so every router within an area knows about all the active links within its area and knows the identity of router-originating information about these active links.   Every router advertises the cost and state of its links. This state information is then propagated one hop away. This propagation of information results in all routers having identical databases. Every router is identified by its uni..

Segmenting LANs with Switches

So far, this chapter reviewed three legacy internetworking devices. These devices interconnected networks and segments together. During the early 1990s, a bridge derivative found a place in the market. Kalpana introduced a LAN switching device, called the EtherSwitch. EtherSwitch was a glorified bridge in that it offered many ports to attach directly to devices rather than to segments. Each port defined a separate collision domain providing maximum media bandwidth for the att..

Configuring an IOS DHCP Server

After you have configured a Layer 3 address on a switch interface, you can configure a DHCP server that runs natively on the switch itself. The switch will intercept DHCP broadcast packets from client machines within a VLAN. Use the following command sequence to configure a DHCP server: Switch(config)# ip dhcp excluded-address start-ip end-ip Switch(config)# ip dhcp pool pool-name Switch(config-dhcp)# network ip-address subnet-mask Switch(config-dhcp)# default-router ip-addr..