Fortunately, most router configuration tasks can be broken down into several independent steps more or less: you configure an interface, you configure a routing protocol, you set up backup links, you implement packet filters and other access control mechanisms. What you actually need is a set of recipes that show you how to perform most common tasks, so you can quickly come up with a good configuration for your site. because your main link is down and the backup link you set when you install a router that is not true. Completely revised and expanded, Cisco IOS Cookbook, 2nd Edition, adds sections on MPLS, Security, IPv6, and IP Mobility, and presents solutions to common problems most configurations, including: Configuring interfaces of many types, from serial to ATM and Frame Relay Configuring all the common IP routing protocols (RIP, EIGRP, OSPF, and BGP) Configuring authentication Configuring other services, including DHCP and NTP Setting the backup link, and using HSRP to configure router Manage backup router, including SNMP and other solutions Using access lists to control traffic through the router If you work with Cisco routers, you need a book like this to help you solve problems quickly and effectively. Even if you are experiencing, solutions and extensive explanations will give you new ideas and insights into router configuration.