Testing Network Changes When No Test Labs Exist?

vvaduva writes "The ugly truth is that many network guys secretly work on production equipment all the time, or test things on production networks when they face impossible deadlines. Management often expects us to get a job done but refuse to provide funds for expensive lab equipment, test circuits and for reasonable time to get testing done before moving equipment or configs into production. How do most of you handle such situations, and what recommendation do you have for creating a network test lab on the cheap, especially when core network devices are vendor-centric, like Cisco?"