The Physical layer Flashcards
Twisted Pair Cabling
1 - The most common type of cabling used for connecting computing devices is known as twisted pair. It’s called a twisted pair cable because it features pairs of copper wires that are twisted together. These pairs act as a single conduit for information, and their twisted nature helps protect against electromagnetic interference and crosstalk from neighboring pairs.
2 - A standard cat six cable has eight wires consisting of four twisted pairs inside a single jacket. Exactly how many pairs are actually in use depends on the transmission technology being used.
3 - Duplex communication is the concept that information can flow in both directions across the cable. On the flip side, a process called simplex communication is unidirectional.
4 - Devices on either side of a networking link that can both communicate with each other at the exact same time, is known as full duplex.
5 - Half-duplex means that, while communication is possible in each direction, only one device can be communicating at a time.
Network Ports and Patch Panels
1 - Network ports are generally directly attached to the devices that make up a computer network. Switches would have many network ports because their purpose is to connect many devices. But servers and desktops, usually only have one or two. Your laptop, tablet or phone probably don’t have any(wireless).
2 - Most network ports have two small LEDs. One is the Link LED, and the other is the activity LED. The link LED will be lit when a cable is properly connected to two devices that are both powered on. The activity LED will flash when data is actively transmitted across the cable.
3 - A long time ago, the flashing activity LED corresponded directly to the ones and zeros being sent. Today, computer networks are so fast that the activity LED doesn’t really communicate much other than if there’s any traffic or not.
4 - On switches, sometimes the same LED is used for both link and activity status. It might even indicate other things like link speed.
5 - Sometimes a network port isn’t connected directly to a device. Instead, there might be network ports mounted on a wall or underneath your desk. These ports are generally connected to the network via cables, run through the walls that eventually end at a patch panel. A patch panel, is a device containing many network ports. But it does no other work. It’s just a container for the endpoints of many runs of cable.
