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Transcript
Chapter 6 Network Hardware, Switching, and Routing Identify the functions of LAN connectivity hardware Install, configure, and differentiate between network devices such as NICs, hubs, bridges, switches, routers, and gateways Explain the advanced features of a switch and understand popular switching techniques, including VLAN management Explain the purposes and properties of routing Describe common IPv4 and IPv6 routing protocols Network+ Guide to Networks, 6th Edition 2 Connectivity devices o Enable device transmission o Transceiver • Transmits and receives data Physical layer and Data Link layer functions o Issue data signals o Assemble and disassemble data frames o Interpret physical addressing information o Determine right to transmit data Network+ Guide to Networks, 6th Edition 3 Smart hardware o Prioritization o Network management o Buffering o Traffic-filtering Do not analyze information o Added by Layers 3 through 7 OSI model protocols Importance o Common to every networking device, network Network+ Guide to Networks, 6th Edition 4 Expansion slots o Multiple electrical contacts on motherboard o Allow bus expansion Expansion card (expansion board) o Circuit board for additional devices o Inserts into expansion slot, establishes electrical connection o Device connects to computer’s main circuit or bus o Computer centrally controls device Network+ Guide to Networks, 6th Edition 5 Multiple bus types o PCIe bus: most popular expansion board NIC PCIe (Peripheral Component Interconnect Express) o 32-bit bus o Maximum data transfer rate: 1 Gbps o Introduced in 2004 Figure 6-1 PCIe expansion board NIC Courtesy of Intel Corporation Network+ Guide to Networks, 6th Edition 6 On-Board NICs o Connect device directly to motherboard o On-board ports: mouse, keyboard New computers, laptops o Use onboard NICs integrated into motherboard Advantages o Saves space o Frees expansion slots Network+ Guide to Networks, 6th Edition 7 Figure 6-3 Motherboard with on-board NICs Courtesy of EVGA USA Network+ Guide to Networks, 6th Edition 8 Installing NIC hardware o Read manufacturer’s documentation Install expansion card NIC o Gather needed tools o Unplug computer, peripherals, and network cable o Ground yourself o Open computer case • Select slot, insert NIC, attach bracket, verify cables o Replace cover, turn on computer • Configure NIC software Network+ Guide to Networks, 6th Edition 9 Figure 6-4 A properly inserted expansion board NIC Courtesy of Gary Herrington Photography Network+ Guide to Networks, 6th Edition 10 Repeaters o Operate in Physical OSI model layer o No means to interpret data o Regenerate signal Hub o Repeater with more than one output port o Typically contains multiple data ports • Patch cables connect printers, servers, and workstations o Most contain uplink port Network+ Guide to Networks, 6th Edition 11 Connectivity devices that subdivide a network o Segments Traditional switches o Operate at Data Link OSI model layer Modern switches o Can operate at Layer 3 or Layer 4 Switches interpret MAC address information Common switch components o Internal processor, operating system, memory, ports Network+ Guide to Networks, 6th Edition 12 Follow manufacturer’s guidelines General steps (assume Cat 5 or better UTP) o Verify switch placement o Turn on switch o Verify lights, self power tests o Configure (if necessary) o Connect NIC to a switch port (repeat for all nodes) o After all nodes connected, turn on nodes o Connect switch to larger network (optional) Network+ Guide to Networks, 6th Edition 13 Figure 6-13 A switch on a small network Courtesy Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition 14 Difference in switches o Incoming frames interpretation o Frame forwarding decisions making Four switching modes exist o Two basic methods discussed • Cut-through mode • Store-and-forward mode Network+ Guide to Networks, 6th Edition 15 Cut-through mode o Switch reads frame’s header o Forwarding decision made before receiving entire packet • Uses frame header: first 14 bytes contains destination MAC address o Cannot verify data integrity using frame check sequence o Can detect erroneously shortened packets (runts) o Runt detected: wait for integrity check Network+ Guide to Networks, 6th Edition 16 Cut-through mode (cont’d.) o Cannot detect corrupt packets o Advantage: speed o Disadvantage • Data buffering (switch flooded with traffic) o Best use • Small workgroups needing speed • Low number of devices Network+ Guide to Networks, 6th Edition 17 Store-and-forward mode o Switch reads entire data frame into memory o Checks for accuracy before transmitting information o Transmit data more accurately than cut-through mode o Slower than cut-through mode o Best uses • Larger LAN environments; mixed environments o Can transfer data between segments running different transmission speeds Network+ Guide to Networks, 6th Edition 18 VLANs (virtual local area networks) o Logically separate networks within networks • Groups ports into broadcast domain Broadcast domain o Port combination making a Layer 2 segment o Ports rely on Layer 2 device to forward broadcast frames Collision domain o Ports in same broadcast domain • Do not share single channel Network+ Guide to Networks, 6th Edition 19 20 Advantage of VLANs o Flexible • Ports from multiple switches or segments • Use any end node type o Reasons for using VLAN • Separating user groups • Isolating connections • Identifying priority device groups • Grouping legacy protocol devices • Separating large network into smaller subnets Network+ Guide to Networks, 6th Edition 21 Switch typically preconfigured o One default VLAN o Cannot be deleted or renamed Create additional VLANs o Indicate to which VLAN each port belongs o Additional specifications • Security parameters, filtering instructions, port performance requirements, network addressing and management options Maintain VLAN using switch software Network+ Guide to Networks, 6th Edition 22 Potential problem o Cutting off group from rest of network • Correct by using router or Layer 3 switch Trunking o Switch’s interface carries traffic of multiple VLANs Trunk o Single physical connection between switches VLAN data separation o Frame contains VLAN identifier in header Network+ Guide to Networks, 6th Edition 23 24 IEEE standard 802.1D Operates in Data Link layer Prevents traffic loops o Calculating paths avoiding potential loops o Artificially blocking links completing loop Three steps o Select root bridge based on Bridge ID o Examine possible paths between network bridge and root bridge o Disables links not part of shortest path Network+ Guide to Networks, 6th Edition 25 Figure 6-17 Enterprise-wide switched network 26 Layer 3 switch (routing switch) o Interprets Layer 3 data Layer 4 switch o Interprets Layer 4 data Content switch (application switch) o Interprets Layer 4 through Layer 7 data Advantages o Advanced filtering o Keeping statistics o Security functions Network+ Guide to Networks, 6th Edition 27 Multiport connectivity device o Directs data between network nodes o Integrates LANs and WANs • Different transmission speeds, protocols Operate at Network layer (Layer 3) o Directs data from one segment or network to another o Logical addressing o Protocol dependent Slower than switches and bridges o Need to interpret Layers 3 and higher information Network+ Guide to Networks, 6th Edition 28 Intelligence o Tracks node location o Determine shortest, fastest path between two nodes o Connects dissimilar network types Large LANs and WANs o Routers indispensable Router components o Internal processor, operating system, memory, input and output jacks, management control interface Network+ Guide to Networks, 6th Edition 29 Figure 6-19 Routers Courtesy Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition 30 Router capabilities o Connect dissimilar networks o Interpret Layer 3 addressing o Determine best data path o Reroute traffic Optional router functions o Filter broadcast transmissions o Enable custom segregation, security o Support simultaneous connectivity o Provide fault tolerance o Monitor network traffic o Diagnose problems and trigger alarms Network+ Guide to Networks, 6th Edition 31 Interior router o Directs data between nodes on a LAN Exterior router o Directs data between nodes external to a LAN Border routers o Connect autonomous LAN with a WAN Routing tables o Identify which routers serve which hosts Network+ Guide to Networks, 6th Edition 32 Static routing o Router configured to use specific path between nodes Dynamic routing o Automatically calculates best path between nodes Installation o Simple for small office or home office LANs • Web-based configuration o Challenging for sizable networks Network+ Guide to Networks, 6th Edition 33 34 Best path o Most efficient route from one node to another o Dependent on: • Hops between nodes • Current network activity • Unavailable link • Network transmission speed • Topology o Determined by routing protocol Network+ Guide to Networks, 6th Edition 35 Routing metric factors o Number of hops o Throughput on potential path o Delay on a potential path o Load (traffic) o Maximum transmission unit (MTU) o Cost o Reliability of potential path Network+ Guide to Networks, 6th Edition 36 Distance-vector routing protocols o Determine best route based on distance to destination o Factors • Hops, latency, network traffic conditions RIP (Routing Information Protocol) o Only factors in number of hops between nodes • Limits 15 hops o Type of IGP (Interior Gateway Protocol) • Can only route within internal network o Slower and less secure than other routing protocols Network+ Guide to Networks, 6th Edition 37 RIPv2 (Routing Information Protocol Version 2) o Generates less broadcast traffic, more secure o Cannot exceed 15 hops o Less commonly used BGP (Border Gateway Protocol) o Communicates using BGP-specific messages o Many factors determine best paths o Configurable to follow policies o Type of EGP (Exterior Gateway Protocol) o Most complex (choice for Internet traffic) Network+ Guide to Networks, 6th Edition 38 Link-state routing protocol o Routers share information • Each router independently maps network, determines best path OSPF (Open Shortest Path First) o Interior or border router use o No hop limit o Complex algorithm for determining best paths o Each OSPF router • Maintains database containing other routers’ links Network+ Guide to Networks, 6th Edition 39 Hybrid o Link-state and distance-vector characteristics o EIGRP (Enhanced Interior Gateway Routing Protocol) • Most popular • Cisco network routers only o EIGRP benefits • Fast convergence time, low network overhead • Easier to configure and less CPU-intensive than OSPF • Supports multiple protocols • Accommodates very large, heterogeneous networks Network+ Guide to Networks, 6th Edition 40 Table 6-1 Summary of common routing protocols Courtesy Course Technology/Cengage Learning Network+ Guide to Networks, 6th Edition 41 Network adapter types vary o Access method, transmission speed, connector interfaces, number of ports, manufacturer, device type Repeaters o Regenerate digital signal Bridges can interpret the data they retransmit Switches subdivide a network o Generally secure o Create VLANs Various routing protocols exist Network+ Guide to Networks, 6th Edition 42