Most people use the Cisco Campus reference architecture (three-tier architecture), or a variation, to implement the LAN of an underlay network. So traditionally, a standard data center architecture may include a core switch/router, a distribution layer, and finally an access layer. Access layers are for connecting end users and servers. The distribution and core layers help in dividing the LAN into smaller chunks by using the VLANs, then connect them using trunks such as dot1q trunks.
However, with the advent of more powerful switches, the switching architecture has now changed to a collapsed core architecture and sometimes ...
