Interfaces and cables_Day_2

• Ethernet is a collection of network protocols and standards, rather than just a single protocol
• Ethernet is not one single thing, making it difficult to define exactly what it is
• Network protocols serve the purpose of allowing communication between network devices
• Standards like Ethernet exist to provide an agreed-upon system of communicating for network devices
• Ethernet standards ensure that devices can connect and communicate effectively
• Speeds in network connections are measured in bits per second
• A bit is a value represented by either a 0 or a 1
• Data on a hard drive is measured in bytes, but network speeds are measured in bits per second
• 1 byte is equal to 8 bits
• There are different units for measuring network speeds, such as kilobits per second, megabits per second, and gigabits per second
• Ethernet standards are defined in the IEEE 802.3 standard
• All Ethernet standards begin with IEEE 802.3
• There are different Ethernet standards for copper Ethernet cables, including 10 megabits per second, 100 megabits per second, 1 gigabit per second, and 10 gigabits per second
• Each standard has common names like 10 base-T, 100base-T, 1000base-T, and 10gbase-t
• The maximum cable length for twisted pair cables in Ethernet is 100 meters
• Copper cables used in Ethernet standards are UTP cables, which stands for Unshielded Twisted Pair
• UTP cables have no metallic shield, making them vulnerable to electrical interference
• UTP cables have four pairs of wires twisted together, totaling eight wires
• Ethernet cables like 10BASE-T and 100BASE-T use 2 pairs (4 wires), while 1000BASE-T and 10GBASE-T use all 4 pairs (8 wires)
• In a FastEthernet connection, devices transmit and receive data on specific pin pairs
• For FastEthernet connections, PCs transmit data on pins 1 and 2, and receive on pins 3 and 6
• Routers transmit data on pins 1 and 2, and receive on pins 3 and 6 in FastEthernet connections
• Switches receive data on pins 1 and 2, and transmit on pins 3 and 6 in FastEthernet connections
• To connect similar devices like routers, switches, or PCs, a crossover cable is needed
• A crossover cable connects transmit pins on one side to receive pins on the other side, allowing devices to exchange data without issues
• Crossover cables are used when connecting devices that transmit and receive on the same pin pairs
• Switches transmit data on pins 3 and 6, and receive data on pins 1 and 2
• Most modern networking devices have evolved beyond straight-through or crossover cables due to Auto MDI-X feature
• Auto MDI-X allows devices to automatically detect which pins their neighbor is transmitting data on and adjust their own pins accordingly
• For gigabit ethernet and 10 gigabit ethernet, all 8 wires are used
• 10GBASE-T and 1000BASE-T use bidirectional pairs of wires for faster speeds
• Fiber optic cables use light to transmit data over glass fibers
• Fiber optic cables have a fiberglass core, cladding, protective buffer, and outer jacket
• There are two main types of fiber optic cables: single-mode fiber and multimode fiber
• Single-mode fiber cables have a narrower core and support longer distances than multimode fiber cables
• Single-mode fiber cables are more expensive due to the laser-based transmitters used
• Fiber-optic cable standards include 1000BASE-LX, 10GBASE-SR, 10GBASE-LR, and 10GBASE-ER
• 1000BASE-LX supports 550 meters for multimode fiber and 5 kilometers for single-mode fiber
• 10GBASE-SR supports cable lengths up to 400 meters using multimode fiber
• 10GBASE-LR supports cable lengths up to 10 kilometers using single-mode fiber