Download Repeaters and Hubs



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