Computer Networking II

1. Chapter Four: Network Design 
2. What Does Network Design Mean? Network design refers to the planning of the implementation of a computer network infrastructure. Network design is generally performed by Network Designers, Engineers, IT administrators and other related staff. It is done before the implementation of a network infrastructure. Network design involves evaluating, understanding and scoping the network to be implemented. The whole network design is usually represented as a network diagram that serves as the blueprint for implementing the network physically. Typically, network design includes the following: • Logical map of the network to be designed • Cabling structure • Quantity, type and location of network devices (router, switches, servers) • IP addressing structure • Network security architecture and overall network security processHierarchical Network Design In networking, a hierarchical design is used to group devices into multiple networks. The networks are organized in a layered approach. The hierarchical design model has three basic layers: • Core layer: Connects distribution layer devices • Distribution layer: Interconnects the smaller local networks • Access layer: Provides connectivity for network hosts and end devices Hierarchical networks have advantages over flat network designs. The benefit of dividing a flat network into smaller, more manageable hierarchical blocks is that local traffic remains local. Only traffic destined for other networks is moved to a higher layer. Layer 2 devices in a flat network provide little opportunity to control broadcasts or to filter undesirable traffic. As more devices and applications are added to a flat network, response times degrade until the network becomes unusable. Figures 1-1 and 1-2 show the advantages of a hierarchical network design versus a flat network design.