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..
Classless and Classful Routing
So far this chapter has reviewed the basic forwarding process for IP packets in a Cisco router. The logic requires matching the packet destination with the routing table, or with the CEF FIB if CEF is enabled, or with other tables for the other options Cisco uses for route table lookup. (Those options include fast switching in routers and NetFlow switching in multilayer switches, both of which populate an optimized forwarding table based on flows, but not on the contents of t..
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..
How Multicasting Provides a Scalable and Manageable Solution
The six basic requirements for supporting multicast across a routed network are as follows: ■ A designated range of Layer 3 addresses that can only be used by multicast applications must exist. A network administrator needs to install a multicast application on a multicast server using a Layer 3 multicast address from the designated range. ■ A multicast address must be used only as a destination IP address, and specifically not as a source IP address. Unlike a unicast I..
Adjusting for Daylight Saving Time
Some areas, such as most of North America and Europe, have consistent and common rules for when to switch between winter or Standard time and summer or Daylight Saving Time. The traditional North American rule, and the default for Cisco routers when they are configured for summer time, is to move an hour ahead at 2:00 AM on the first Sunday in April, and back an hour at 2:00 AM on the last Sunday in October. Router#configure terminal Enter configuration commands, one per li..
