Applying the Building Blocks

Applying the Building Blocks
Remember the saying, “Everything I need to know I learned in kindergarten?” Well, it appears
to be true. Cisco has determined that following the hierarchical mode they have created promotes
a building-block approach to network design. If you did well with building blocks in your
younger years, you can just apply that same technique to building large, multimillion-dollar networks.
Kind of makes you glad it’s someone else’s money you’re playing with, doesn’t it?
In all seriousness, Cisco has determined some fundamental campus elements that help you
build network building blocks:
Switch blocks Access layer switches connected to the distribution layer devices
Core blocks Support of multiple switch blocks connected together with 4000, 6500, or
8500 switches
Within these fundamental elements, there are three contributing variables:
Server blocks Groups of network servers on a single subnet
WAN blocks Multiple connections to an ISP or multiple ISPs
Mainframe blocks Centralized services to which the enterprise network is responsible for providing
complete access
By understanding how these work, you can build large, expensive networks with confidence
(using someone else’s money). After the network has been built, you need to allow the switches
to talk to each other to allow for redundancy and to route around outages. We will cover these
topics later in this section after the blocks are discussed.