Link-state routing protocols, such as Open Shortest Path First (OSPF)[] and Intermediate System-to-Intermediate System (IS-IS)[], utilize a replicated distributed database model and are considered to be more-complex routing protocols. Link-state protocols work on the basis that routers exchange information elements, called link states, which carry information about links and nodes in the routing domain. This means that routers running link-state protocols do not exchange rout..
Cisco IOS processes the Access Control Entries (ACEs) of an ACL sequentially, either permitting or denying a packet based on the first ACE matched by that packet in the ACL. For an individual ACE, all the configured values must match before the ACE is considered a match. Table 21-8 lists several examples of named IP ACL permit and denies commands that create an individual ACE, along with their meanings. Table 21-8 Examples of ACL ACE Logic and Syntax The Port Number f..
One of the key themes that is developed throughout this chapter is the idea that routing is critical to scalable network design. Hopefully, this is not news to you. However, given the recent popularity and focus on extremely flat, "avoid-the-router" designs, a fair amount of attention is devoted to this subject. Many people are convinced that the key objective in campus network design is to eliminate as many routers as possible. On the contrary, my experience suggests that th..
Configuring the Frame Relay ELMI Feature
This section explains the configuration tasks required to configure Frame Relay QoS Autosense and Frame Relay Address Registration on Cisco devices. Practical configuration examples are used to illustrate the relevant Cisco IOS configuration commands. This section also introduces the related Cisco IOS show and debug commands for monitoring and maintaining Frame Relay ELMI configurations on a Cisco router. Configuring Frame Relay QoS Autosense This section discusses the Cisc..
