Hierarchical network topology: this topology comprises of high-end routers and switches that are optimized for availability and performance. When scalability is your major goal, this topology suitable too because the modularity in a design enables creating design elements that can be replicated as the network grows. And since each instance of a module is consistent, expansion is easy to plan and implement.

Redundant network topology: this design lets you meet requirements for network availability by duplicating elements in a network. Redundancy attempts to eliminate any single point of failure on the network. The goal is to duplicate any required component whose failure could disable critical applications.

Enterprise Composite network Model: is a blueprint that network designers can use to simplify the complexity of a large Internet work. With the Enterprise Composite Network Model, you can analyze the functional, logical, and physical components of a network, and thus simplify the process of designing an overall enterprise network. The topology includes the modules required to build a robust networks that provides high availability, scalability, and flexibility.



References:
http://www.edrawsoft.com/Campus-Network.php
http://en.wikipedia.org/wiki/Network_topology
http://support.packeteer.com/documentation/packetguide/6.0.0/nav/overviews/high-availability-overview.htm