You work for a large company whose IT presence pre-dates literally everyone. IT infancy began at your workplace in the early 1950s. You’ve had use of a Class A IP network for decades.
Several years of tumultuous change later, that Class A network is no longer owned by you, your former parent company, or your current parent company. It is now owned by one of the largest providers out there. Uh oh.
And so began a year and a half long project to scrub that Class A from the internal global WAN. (For those with fewer years of IT…yes, publicly routed addresses were once commonly used on the inside of corporate networks.)
Methodically scrubbing a global WAN of every
#.x.x.x/8 address? Time consuming. Doing so safely? Even more time consuming.
Now add to this the fact there are netblocks you cannot scrub due to legacy code; you need to lease them from the new owners. And you need to lease as little as possible. Time to scrub those large-subnet leases and look for consolidation to smalls subnets, driving lease cost to as little as possible.
Tons of data analysis. Months of effort. It was a real doozy of a project!