1.4 On Architectures

The network topology architecture encompasses how a network is to be architected in an operational environment while accounting for future growth.

Topology refers to the form a network will adopt, such as a star, ring, or a combination of them.

The different types of topologies (Figure 1.2) are: Mesh topology, Ring Topology, Bus topology, Star topology, Tree topology, Hybrid topology etc. (For details about each refer Section 9.8)

Figure 1.2: Different types of network topologies.

1.4 On Architectures

The topological architecture then covers architecting a network topology those factors in economic issues, different technological capabilities, and limitations of devices to carry a certain volume of expected traffic for an operational environment. Certainly, network topology architecture also needs to take into account routing capability, including any limitation or flexibility provided by a routing protocol.

It is up to a network provider, also referred to as a network operator or a service provider, to determine the best topological architecture for the network. Many different aspects of networking environments can be covered by architectures. Network routing must account for each of the following architectural components. Some aspects of the architectures listed below are critical to routing issues:

	Service Architecture: The basic framework for the type of services a network offers.
	Protocol Stack Architecture: Defines how service delivery may require different functions to be divided along well-defined boundaries so that responsibilities can be decoupled. It does not describe how actual resources might be used or needed.
	Router Architecture: A router is a specialized computer that is equipped with hardware/software for packet processing. It is also equipped for processing of routing protocols and can handle configuration requirements. A router is architected differently depending on its role in a network, such as a core router or an edge router, although all routers have a common set of requirements.

1.4 On Architectures

Network Topology Architecture: For efficient operation as well as to provide acceptable service to its users, a network is required to be organized based on a network topology architecture that is scalable and allows growth.

Network Management Architecture: A network needs to provide several additional functions in addition to carrying the user traffic from point A to point B; for clarity, the user data traffic forwarding is considered as the data plane. For example, from an operational point of view, a management plane handles the configuration responsibility of a network, and a control plane addresses routing information exchanges.