Cisco router tutorials

Tutorial: Standard ACL (Access Control List) Basics

Contributed by aaronm on June 18, 2007 under Cisco router

This is a BASIC explanation of Standard ACL’s that SHOULD be fairly easy to understand and span the spectrum of most Cisco routers.

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Cisco IOS DST Daylight Savings Time Workaround

Contributed by abanks on March 13, 2007 under Cisco router

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…

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Cisco HSRP (like VRRP) - Redundant gateway router configuration

Contributed by abanks on December 17, 2006 under Cisco router

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.

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How to (more) safely run debugs on Cisco routers

Contributed by abanks on December 15, 2006 under Cisco router

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.

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Configure Cisco router as an NTP server

Contributed by qmchenry on June 19, 2006 under Cisco router

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 router as an NTP server may be acceptable.

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Configure Cisco router to set time from NTP server

Contributed by qmchenry on under Cisco router

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 your life. Well, at least help keep your hair attached to your head.

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Set the time on a Cisco router manually

Contributed by qmchenry on under Cisco router

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.

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Set the telnet source IP address for a Cisco router

Contributed by qmchenry on June 18, 2006 under Cisco router

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, or to help test access lists, it may be useful to temporarily or permanently set the telnet source IP address.

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