Local-Area Networks Topology Defines the Structure of the Network Physical topology actual layout of the wire (media) Logical topology defines how the media is accessed by the hosts Physical Topology LAN Devices in a Topology Network Interface Cards (NICs) When Selecting a NIC, Consider the Following: Network architecture Operating system Media type Data transfer speed Available bus types NICs Bus Architectures ISA (Industry Standard Architecture) EISA (Extended ISA) PCI (Peripheral Component Interconnect) MCA (Micro Channel Architecture) PCMCIA (Personal Computer Memory Card International Association) NICs in the OSI Model Media The basic function of media is to carry a flow of information, in the form of bits. Layer 1 components. Repeaters: Layer 1 Repeaters A repeater solves the problem of too many nodes and not enough cable cleans, amplifies, and resends a signal that is weakened by long cable length. Hubs: Layer 1 Hubs Regenerate and repeat signals Used as network concentration points Multiport repeater Bridges: Layer 2 Bridges Designed to create two or more LAN segments, each of which is a separate collision domain Bridges filter traffic by looking at MAC addresses. Switches: Layer 2 LAN Switches Combine the connectivity of a hub with the traffic regulation of a bridge on each port Switches Routers: Layer 3 Routers Two primary purposes: path selection, and switching of packets to the best route Use logical addresses (network layer addresses) Network Cloud Layer 1 through 7 device Network Segments Connected by networking devices Devices / Function / Layers Data Flow Through LANs