Topologies & CablesJuly 26, 2024 Network Topologies A description of how a network is laid out Physical topologies: the actual layout of devices Logical Topologies: how the data flows from host to host Bus Topology All host are connected together by one centralized cable All host share same bandwidth Gets slower as you add more host to the topology Can have issues if the main cable is compromised Ring Topology Frames travel along a ring of host Only has issues if there is a break between host Not used very often Star Topology (Hub-And-Spoke) Multiple host connected to a centralized “box” (Ex. Hub, switch, etc.) Box determines where to send data in the network Pretty common topology Star-Bus Topology (Hybrid Topology) Main “box” houses a bus If the bus goes down the whole network goes with it Mesh Topology Every host is connected to all the other host Creates a mess of cables if it is wired Very good for wireless networks Is very fault tolerant Cabling Coaxial cable has two conductors; one center point, and a tubular conducting layer Radio grade (RG) specifies the thickness of the conductors, insulation, and shielding RG-6 has a 75-Ohm rating, is commonly used for cable networking, and uses a threaded F-type connector Coaxial Cable Construction: Core: Single central conductor (usually copper). Insulation: Surrounds the central conductor. Shielding: Braided or solid metallic shield (typically aluminum or copper) around the insulation. Outer Insulation: Plastic or rubber outer jacket. Signal Transmission: Primarily used for high-frequency signals. Suitable for radio frequencies (RF), television signals, and internet connections. Transmits signals with high bandwidth over long distances with minimal loss. Applications: Cable television (CATV). Internet and broadband connections. Radio transmitters and receivers. Closed-circuit television (CCTV). Impedance: Common impedances are 50 ohms (for radio transmitters) and 75 ohms (for television and internet). Twin-axial Cable Construction: Core: Two central conductors (usually twisted together) inside a single shield. Insulation: Each conductor is individually insulated. Shielding: Common shield around both conductors (can be braided or foil). Outer Insulation: Plastic or rubber outer jacket. Signal Transmission: Suitable for differential signal transmission, where signals are sent over two wires to improve noise immunity. Commonly used for high-speed digital data transfer. Less signal loss over shorter distances compared to coaxial cables. Applications: Data storage systems. High-speed networking environments. IBM mainframe computers (historically). Modern data centers for certain high-speed connections (e.g., Infiniband). Impedance: Common impedance for twin-axial cables is typically around 100 ohms, which matches the impedance of many digital data transmission systems. Key Differences Number of Conductors: Coaxial has a single central conductor, while twin-axial has two. Signal Transmission: Coaxial is often used for analog and RF signals, while twin-axial is used for high-speed digital signals. Noise Immunity: Twin-axial cables have better noise immunity due to differential signaling. Distance and Bandwidth: Coaxial cables can transmit signals over longer distances with less loss, but twin-axial cables are better suited for shorter distances with high-speed data transfer. Coaxial cable has two conductors; one center point, and a tubular conducting layer Radio grade (RG) specifies the thickness of the conductors, insulation, and shielding RG-6 has a 75-Ohm rating, is commonly used for cable networking, and uses a threaded F-type connector Twisted Pair Cable Very common cable Twisted cables reduce electromagnetic interference (FMI) and crosstalk Unshielded Twisted Pair Only has a sheath, no protection for exposed cables Max distance of 100 meters (325 feet) Has 4 Pairs Uses RJ-45 connector Has a single Solid Core that carries the signal Comes in Two Standards TIA/FIA-568A TIA/EIA-568B Shielded Twisted Pair Has a grounded outer copper shield around the bundle of twisted pairs for protection Not as common as unshielded, needed for added protection for the cables Fiber Optic Cabling The cable is made up of the following: Fiber optic core that carries the light Cladding that reflect the light Cable Jacket that protects the core Two types of fiber optic cable Multimode Carry LED signals Cable is usually Orange Single-mode Carry laser signals Cable is usually Yellow Fiber Optic is a Duplex Cable Connector Types for Fiber Optic ST Connectors SC Connectors FC Connector LC Connector MT-RJ Connector Fire Ratings Plenum-Rated: rated for being in area between ceilings, highest fire rating, expensive Riser-Rated: made for going through building floors, fire resistant PVC: no fire protection for the cables