In studying for the CCIEv5, the older routers that GNS3 supports won’t cut it for some of the new things being tested on. At this moment, the best and cheapest way to lab up different scenarios is to use Cisco’s CSR1000v virtual routers. However, the requirements for running several of them simultaneously can be pretty stressing on a computer, and the average desktop computer just isn’t going to cut it! This post is about my experience of deciding whether to buy an older server or build one myself for the purposes of labbing.
I started out with an Ivy Bridge system with a Z77 motherboard and a Core i3-3220 CPU (dual core, hyper-threaded). The system was maxed out with 32 GB of RAM (4x8GB) DDR3. When I would fire up 10 router instances (using the Small / 2.5 GB RAM setting), it would typically take 15 minutes for all 10 instances to be “usable” (whether I started them individually or all at once), and my CPU would stay at about 90-100% even with a blank config on all the routers.
The ESXi memory optimization trick helps tremendously (Advanced Settings > Mem > Mem.AllocGuestLargePage > 0), but with the CPU at a constant 90+% with 10 routers, there was no way I was going to be able to spin up 20 routers with the Core i3-3220.