I have typically known 'flat network' to be a non-vlan network, typically a single /24. We have a new hire (security analyst) at my company and he asked the desktop support supervisor if he had "trouble getting your job done on this flat network". I'm a bit unsure how he means this, unless he is referring to it being a layer 2 domain as opposed to a routed site. Currently the site in question is multiple vlans, each in it's own /24 with the site as a /16. It's all L2, except for intervlan routing in the core.
Am I wrong in my usage of 'flat network', or am I missing something here?
Best Answer
There is no official definition, and it means different things to different people. In general, the term, "flat network," means that the network isn't hierarchical (network engineer definition), or it is not security segmented (security engineer definition). You could have multiple VLANs all terminating in a single layer-3 device, and some consider that to be a flat network.
Networks with hierarchies and/or security segmentation aren't usually considered flat networks, but it depends on the audience.