Automating Mass Cisco IOS Upgrades

This morning I needed to upgrade the IOS on 29 Cisco 3560G switches. Rather than login to each one, clean up the flash storage, FTP on the IOS image and set the boot image, I wrote a simple shell script and used clogin from RANCID to automate this task. Of course, nearly every Network Configuration Management platform that’s any good should be able to do this but I prefer the personal

Automating Cisco Switch Swap Outs

So you can’t automate the entire process unfortunately. You’re still going to need to pull a late night and get your hands dirty… Recently I was tasked with swapping out 4 old Cisco 10/100Mb switches with new 10/100/1000Mb switches. The old switches were a combination of Cisco 3560, 2950 and 3548 series. The old switches also had some old configurations that needed to be updated and the interface configurations weren’t consistent. The

Should Network Engineers Also Be Programmers?

Short answer: Yes. Maybe not a programmer in the sense that you need to be proficient in C++, .NET, assembler, know UML etc but having some general programming knowledge is very useful. In my opinion and experience the most important programming skill to have is a fairly in-depth knowledge of a scripting language. Be that shell, Perl, Powershell or even batch scripts. A week doesn’t go by where I don’t write a

Editing Cisco IOS ACLs

If you’ve administered Cisco PIX or ASA security appliances, you’ll know how easy editing ACLs is. If you want to insert a new rule in to an existing ACL you can easily insert it where you want. For example:

  This will insert the rule at position 12 of the outside_access_in ACL, pushing the existing rule at position 12 down to position 13 and re-ordering everything. In Cisco IOS