Network Fundamentals: Ch9 - Ethernet

• 1. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Network Fundamentals Abdelkhalik Elsaid Mousa [email protected] http://abdelkhalik.staff.scuegypt.edu.eg/

2. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy IEEE - Standards The first LAN in the world was the original version of Ethernet. The first Ethernet standard (802.3) was published in 1980. Ethernet is the predominant LAN technology in use today. Ethernet standards define both L2 protocols and L1 technologies. 3. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet- L1 and L2 4. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Logical Link Control Connecting to the upper layers Ethernet separates the functions of the Data Link layer into two distinct sublayers, LLC and MAC. LLC has the following characteristics IEEE 802.2. is implemented in software. can be considered the driver software for the NIC. 5. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy MAC Getting data to the media IEEE 802.3. MAC is implemented in hardware. Typically in the computer NIC. The underlying logical topology of Ethernet is a multi-access bus. 6. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Historic Ethernet The foundation for Ethernet technology in 1970 was Alohanet. Alohanet was a digital radio network that transmits information over a shared radio frequency between the Hawaiian Islands. The techniques for using a shared medium were later applied to wired technology in the form of Ethernet. 7. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Early Ethernet Media Used coaxial cable to connect computers in a bus topology. It was known as Thicknet (10BASE5) and Thinnet (10BASE2). 8. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Collision Management Legacy Ethernet Based on hubs. 10BASE-T networks. half-duplex communication. Uses CSMA/CD. Current Ethernet Based on switches. 100BASE-TX. Full-duplex communication. Gigabit Ethernet. 9. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy The Frame Encapsulating the packet There are two styles of Ethernet framing: IEEE 802.3 (original) and the revised IEEE 802.3 (Ethernet). The IEEE 802.3ac standard, released in 1998, extended the maximum allowable frame size to 1522 bytes. 10. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy The Ethernet MAC The MAC address (BIA) because it is burned into ROM on the NIC. IEEE requires a vendor to follow two simple rules: 1. All MAC addresses must use vendor's OUI as the first 3 bytes. 2. All MAC addresses with the same OUI must be assigned a unique value (vendor code) in the last 3 bytes. 11. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy The Ethernet MAC The OUI and the vendor assigned number ensure that the assigned MAC addresses remains unique. You will see them expressed in different ways. Cisco MAC Address 00-60-2F-3A-07-BC 00:60:2F:3A:07:BC 0060.2F3A.07BC Intel MAC Address 00-20-E0-6B-17-62 00:20:E0:6B:17:62 0020.E06B.1762 12. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Another layer of Addressing The Network layer address enables the packet to be forwarded toward its destination. The Data Link layer address enables the packet to be carried by the local media across each segment. 13. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Unicast 14. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Broadcast 15. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Broadcast 16. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Multicast 17. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Multicast The multicast MAC address begins with 01-00-5E in hexadecimal. The value ends by converting the lower 23 bits of the IP multicast group address into the remaining 6 hexadecimal characters of the Ethernet address. The remaining bit is always a "0". 18. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Media Access Control in Ethernet 19. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy CSMA/CD The process 20. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy CSMA/CD The process Carrier Sense Multiple Access Collision Detection JAM Signal Random Backoff 21. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy CSMA/CD The process Hubs, multi-port repeaters, and repeaters are intermediary devices that extend the distance that Ethernet cables can reach. Collision domain: The area of a network where collisions can occur. 22. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Timing Latency The electrical signal that is transmitted takes a certain amount of time (latency) to propagate (travel) down the cable. Each hub or repeater in the signal's path adds latency as it forwards the bits from one port to the next. This delay increases the likelihood that collisions will occur because a listening node may transition into transmitting signals while the hub or repeater is processing the message. 23. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Timing Timing and Synchronization Ethernet with throughput speeds of 10 Mbps and slower are asynchronous. Ethernet implementations with throughput of 100 Mbps and higher are synchronous. 24. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Timing Bit Time: The period of time required for a bit to be placed and sensed on the media. Slot Time: is the time it takes for an electronic pulse to travel the length of the maximum theoretical distance between two nodes. It is also the time that a transmitting station waits before attempting to retransmit following a collision 25. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Interframe Spacing The minimum interval, in bit-times, that a station has to wait before sending another frame Allows slower stations to process the frame and get ready for the next frame. 26. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Types of Ethernet Ethernet Type Bandwidth Cable Type Maximum Distance (m) 10BASE5 10 Mbps Thick Coax 500 10BASE2 10 Mbps Thin Coax 185 10BASE-T 10 Mbps Cat3/Cat5 UTP 100 100BASE-TX 100 Mbps Cat5 UTP 100 100BASE-FX 100 Mbps MM or SM Fiber 400/2000 1000BASE-T 1 Gbps Cat5e UTP 100 1000BASE-TX 1 Gbps Cat6 UTP 100 1000BASE-SX 1 Gbps MM Fiber 550 1000BASE-LX 1 Gbps SM Fiber 2000 10GBASE-T 10 Gbps Cat6a/Cat7 UTP 100 10GBASE-LX4 10 Gbps MM Fiber 300 10GBASE-LX4 10Gbps SM Fiber 10,000 27. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy 10 Mbps Ethernet The principal 10 Mbps implementations of Ethernet include: 1. 10BASE5 using Thicknet coaxial cable 2. 10BASE2 using Thinnet coaxial cable 3. 10BASE-T using Cat3/Cat5 unshielded twisted-pair cable 10BASE5, and 10BASE2 used coaxial cable in a physical bus, no longer used. 10BASE-T uses Manchester-encoding over 2 UTP cables. Early used Cat3, Now Cat5. Physical star using hub, up to 100 m. 28. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy 100 Mbps Ethernet (FastEthernet) The popular implementations of 100 Mbps Ethernet are: 1. 100BASE-TX using Cat5 or later UTP 2. 100BASE-FX using fiber-optic cable 100BASE-TX support transmission over two pairs of Cat 5 UTP copper, Uses 4B/5B encoding, Physical star using switch. The 100BASE-FX standard uses the same signaling procedure as 100BASE- TX, but over optical fiber media rather than UTP copper. 100BASE-FX uses SC connector. 29. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy 1000 Mbps Ethernet (GigabitEthernet) 1000BASE-T Ethernet provides full-duplex transmission using all four pairs in Category 5 or later UTP cable. 1000BASE-T uses 4D-PAM5 line encoding to obtain 1 Gbps data throughput. 1000BASE-SX and 1000BASE-LX Ethernet Using Fiber-Optics. 1000BASE-SX and 1000BASE-LX - offer the following advantages over UTP: noise immunity, small physical size, and increased unrepeated distances and bandwidth. The transmission coding is based on the 8B/10B encoding scheme. 30. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Ethernet Future Options The IEEE 802.3ae standard was adapted to include 10 Gbps, full-duplex transmission over fiber-optic cable. 10GbE is evolving for use not only in LANs, but also for use in WANs and MANs. With 10Gbps Ethernet, flexible, efficient, reliable, relatively low cost end-to- end Ethernet networks become possible. 31. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Layer 1 Devices Repeater: is a network device used to regenerate a signal. Repeaters regenerate signals distorted by transmission loss due to attenuation. Rule: no more than four repeaters can be used between hosts on a LAN. 32. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Layer 1 Devices A Hub: is a multi-port Repeater. Hubs takes data bits from input port and floods it to all other ports (logically bus). Repeater and hub work in half duplex mode. All ports of the Repeaters and Hubs are members in a single collision domain, and single broadcast domain Rule: no more than four hubs can be used between hosts on a LAN. 33. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy Layer 2 devices A layer 2 device is a device that understand MAC, for example: NIC (Network Interface Card) Bridge: address learning forwarding decisions are based on software bridge is used for LAN segmentation max. 16 port. Switch: a multi-port bridge up to 256 port forwarding decisions are based on hardware ASIC faster than bridge 34. Suez Canal University Faculty of Computers & Informatics - Cisco Local Academy