Cisco’s SLA features, available in IOS other than IP Base, allow modification of the routing table based on a monitored item. In this example, we’ll monitor an Internet address, and change the default route if that address is unreachable.
This is a BASIC explanation of Standard ACL’s that SHOULD be fairly easy to understand and span the spectrum of most Cisco routers.
Daylights Savings Time workaround for Cisco IOS devices. Of course, updating the IOS to a DST-corrected version will eliminate the need for this fix, but…
You’ve got two Cisco routers, and two links to a remote site. How do you make your hosts use the backup when needed? One method is HSRP.
Running debug commands can bring a busy router to a crawl. Not sending the output to the console can help. This tech-recipe describes turning off console debugging output and techniques for viewing debug information in a router-friendly way.
An NTP server can provide synchronized date and times for devices in a network. Since a router cannot be a Stratum 1 device (cannot connect to a Stratum 0 device such as a GPS clock), a router is not an accurate source of time information. If this is not important to you, then using a [...]
Using NTP to synchronize the date and time of multiple devices makes sense even in a small network. When performing forensic analyses or troubleshooting connection problems, having consistent logging timestamps from multiple devices can save time and simplify the task.
Setting the internal clock in a Cisco router allows timestamping of logging information which makes troubleshooting much easier. If you do not have an NTP server running, you can set the time manually with a simple command.
The default source IP address when telnetting from a Cisco router is that of the interface closest to the destination. Because some access lists may block traffic from the default IP address, it may be useful to temporarily or permanently set the telnet source IP address. This also helps test access lists.
Multiple users can be logged into a Cisco router at the same time. It may be necessary (or sometimes just fun) to send a text message to one or all users on a router. For example, if you are preparing to reload the router, admin etiquette dictates that you should warn other users.