March 28, 2014 | How-To
Cisco Internal VLAN Usage
Charles Galler
About a month ago I worked on an old CatOS switch. Working on this switch reminded me about some of the differences between CatOS and IOS. One of the big…
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Author: Charles Galler
October 31, 2013 | How-To
Securing a DMVPN spoke – Part 2
Charles Galler
In Part 1 we went through protecting the spoke from the outside world on the Internet and using the stateful inspection firewall CBAC, Content-Based Access Control, to dynamically allow returning…
READ MOREAugust 30, 2013 | How-To
Securing a DMVPN spoke – Part 1
Charles Galler
For organizations that have many remote offices a DMVPN solution is a great option. You can purchase a cheap DSL or cable modem based solution then establish a dynamically built…
READ MOREMarch 22, 2013 | How-To
Using IP SLA Delay Feature to Safely Monitor Lossy Links
Charles Galler
IP SLA is a great feature if you want to add some automation and intelligence into the network. SLA is no SDN/OpenFlow, but it can be very useful. It can…
READ MOREFebruary 7, 2013 | How-To
Network Documentation Best Practices: What’s Important & How To Track It
Charles Galler
As a consultant, I have done several network assessments for clients. One of the biggest items that is almost always missing is documentation. In my assessment reports, I can’t just…
READ MORENovember 19, 2012 | How-To
Cisco Configuration Archive & Rollback: Using ‘Revert’ Instead of ‘Reload’
Charles Galler
I wrote an earlier blog article about using the reload command. The reload command used to be the only tool to recover from configuration errors when working on a device…
READ MOREOctober 7, 2012 | How-To
VTP v2 Transparent Mode: Mismatched Domain Names Cause Advertisements To Be Dropped
Charles Galler
Cisco’s documentation on VTP version 2 transparent mode states that it will pass VTP messages without inspecting the domain name. Let’s verify this for ourselves. We are going to use…
READ MOREAugust 24, 2012 | How-To
Cisco IOS Device Hardening
Charles Galler
Security is a part of everyday life and is everyone’s responsibility. As network engineers, it is our job to secure the plumbing that everything else rides on. While some people…
READ MOREJuly 11, 2012 | Good to Know
A Cisco IOS Template With Commands & Explanations: Expecting The Same Result
Charles Galler
Over the years, I've collected a set of basic Cisco commands that get applied to every device I install or bring up to standard. Today, I share those template commands…
READ MOREJune 9, 2012 | How-To
The Power and Peril of the IOS Reload Command
Charles Galler
Over the years, I have used the reload command for more than upgrading the IOS on a switch or router. The reload command has several parameters that you can pass…
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