Bài giảng Network Certification Microsoft Press - Chapter 5

1Chapter Overview  Ethernet  Token Ring  FDDI  Wireless Networking 2Ethernet Standards  Ethernet is the most popular local area network (LAN) protocol operating at the data- link layer.  There are two sets of Ethernet standards:  DIX Ethernet  Institute of Electrical and Electronic Engineers (IEEE) 802.3 3DIX Ethernet Standards  DIX Ethernet. Also known as thick Ethernet, ThickNet, or 10Base5  DIX Ethernet II. Retains 10Base5 and adds 10Base2 (thin Ethernet) 4IEEE 802.3 Standards  IEEE 802.3. 10Base5, 10Base2, and 10Base-T  IEEE 802.3u. Fast Ethernet  IEEE 802.3z and IEEE 802.3ab. Gigabit Ethernet 5DIX Ethernet/IEEE 802.3 Components  Physical layer specifications  Frame format  CSMA/CD MAC mechanism 6Standard 10-Mbps Ethernet Specifications Designation Cable Type Topology Maximum Length 10Base5 RG-8 coaxial Bus 500 meters 10Base2 RG-58 coaxial Bus 185 meters 10Base-T Category 3 UTP Star 100 meters Fiber Optic Inter- Repeater Link (FOIRL) Multimode fiber optic Star 1,000 meters 10Base-F Multimode fiber optic Star 500–2,000 meters 7Fast Ethernet (100 Mbps) Specifications Designation Cable Type Topology Maximum Length 100Base-TX Category 5 UTP Star 100 meters 100Base-T4 Category 3 UTP Star 100 meters 100Base-FX Multimode fiber optic Star 412 meters 8Gigabit Ethernet (1,000 Mbps) Specifications Designation Cable Type Topology Maximum Length 1000Base-T Category 5 or 5E UTP Star 100 meters 1000Base-LX Various multimode fiber optic Star 550–5,000 meters 1000Base-SX Various multimode fiber optic Star 220–500 meters 1000Base-LH Singlemode fiber optic Star 10 kilometers 1000Base-ZX Singlemode fiber optic Star 100 kilometers 1000Base-CX 150-ohm copper Star 25 meters 9Coaxial Ethernet Standards  10Base5 (thick Ethernet)  10Base2 (thin Ethernet) 10 Coaxial Network Characteristics  Runs at 10 Mbps  Uses the bus topology  Uses mixing segments 11 Mixing Segments 12 UTP Ethernet Standards  10Base-T  100Base-TX (Fast Ethernet)  100Base-T4 (Fast Ethernet)  1000Base-T (Gigabit Ethernet) 13 UTP Network Characteristics  Runs at various speeds up to 1,000 Mbps  Uses the star topology  Requires a hub  Uses link segments 14 Link Segments 15 Fiber Optic Ethernet  Fiber Optic Inter-Repeater Link (FOIRL)  IEEE 802.3 fiber optic standards:  10Base-FL  10Base-FB  10Base-FP  100Base-FX  Gigabit Ethernet standards 16 The 5-4-3 Rule  A standard network can have no more than FIVE segments, connected by FOUR repeaters, of which no more than THREE segments can be mixing segments. 17 A Coaxial 5-4-3 Network 18 A UTP 5-4-3 Network 19 Fast Ethernet Hub Types Class Function I Connects different cable segment types II Connects identical cable segment types 20 Fast Ethernet Cabling Guidelines Hub Type Maximum Number of Hubs Maximum Total Cable Length (UTP) Maximum Total Cable Length (Fiber Optic) Class I 1 200 meters 272 meters Class II 2 205 meters 228 meters 21 The Ethernet Frame Format 22 Protocol Identification  DIX Ethernet frames use the Ethertype field.  IEEE 802.3 frames use the Logical Link Control (LLC) and Subnetwork Access Protocol (SNAP) subheaders. 23 Media Access Control (MAC)  Is the mechanism that enables multiple computers to use the same network medium without conflicting 24 CSMA/CD Phases Phase Description Carrier sense A computer listens to the network before transmitting. Multiple access When the network is clear, the computer transmits the packet. Collision detection The computer checks for signs of a collision. If one occurs, it retransmits the packet. 25 Collisions  Collisions are also called signal quality errors.  They are normal on Ethernet networks.  The frequency of collisions increases as network traffic increases.  Late collisions are a sign of a serious problem. 26 Token Ring Cable Types  IBM Type 1. Proprietary shielded twisted pair (STP)  IBM Type 3. Standard Category 5 unshielded twisted pair (UTP) 27 IBM Type 1 Cable 28 Token Passing  A token frame circulates continuously around the network.  Only the computer holding the token can transmit data.  The transmitting system is responsible for removing the data from the ring. 29 Token Ring Frame Types  Data frame  Token frame  Command frame  Abort delimiter frame 30 The Data Frame Format 31 The Token Frame Format 32 Fiber Distributed Data Interface (FDDI) Characteristics  First commercial 100-Mbps fiber optic protocol  Uses the token passing MAC mechanism  Supports both singlemode and multimode cable 33 FDDI Topologies  Double ring  Logical ring  Dual ring of trees 34 Dual Ring of Trees 35 The FDDI Data Frame 36 IEEE 802.11 Standards  IEEE 802.11a. Speeds of 1 to 2 Mbps  IEEE 802.11b. Speeds of 5.5 to 11 Mbps 37 IEEE 802.11 Topologies  Ad hoc. Wireless computers communicating with each other  Infrastructure. Wireless computers using an access point to communicate with a cabled network 38 CSMA/CA  Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a variation of CSMA/CD.  It uses packet acknowledgment messages instead of collision detection. 39 Chapter Summary  Ethernet  Supports multiple cable types and speeds  Uses the CSMA/CD MAC mechanism to detect collisions  Token Ring  Uses a logical ring topology  Uses the token passing MAC mechanism  FDDI  Uses a double ring or star topology  Uses the token passing MAC mechanism  Wireless Networking  Runs at speeds up to 11 Mbps  Uses the CSMA/CA MAC mechanism