Carrier Grade: RANCID

Generally the word rancid doesn’t impart an idea of good things. The RANCID we’re talking about certainly doesn’t match the definition of the word. For those amongst us who appreciated a nicely manufactured acronym, Really Awesome New Cisco confIg Differ (RANCID), rates quite high on the creativity scale. For those running networks of any size RANCID is also a good thing. It does appear that from Google’s perspective the band Rancid rates higher than the networking tool RANCID.

Here at CounterPath, we’ve been using RANCID for a few years to monitor and backup the configuration of our network devices. Recently we built a new instance of RANCID and migrated all of our devices over. We had to spend some time re-remembering how all of the internals worked, but it didn’t take very long before we were up and running.

I’ll attempt a brief explanation of what RANCID is. RANCID watches all of your network devices by checking in on their configuration every hour (configurable). RANCID sends your team a email with the differences between the last known configuration and the updated configuration. This is brilliant. The team needs to know about changes that happen across the infrastructure, or minimally know that changes are happening. We’ve seen this as almost a e-learning tool. When someone sets up something new on a switch or router or firewall, the team is updated with exactly the changes are in place for that customer.

RANCID also creates a CVS/SVN archive of your network devices configurations. This means that you can look back in time to see what the configuration used to be 2 months ago. This often helps when you are troubleshooting a problem that has popped up. Often problems surfacing today have roots in the unintended consequences of a change a few days or weeks ago.

RANCID had a database of different vendors and types of equipments it supports. As we’re primarily a Cisco shop from a networking perspective it works flawlessly with our gear. As an example we have some Nortel gear we use for non-production services and and our mileage has varied with this solution.

For more details on RANCID, check out Shrubbery Networks homepage. A outstanding tutorial for RHEL/Centos/Fedora shops is available on the linux home networking website.