Networking Devices
Lesson 6
Objectives
Exam Objective Matrix
Technology Skill Covered Exam Objective Exam Objective Number
Network Interface Cards Classify how applications, devices, and protocols relate to the OSI model layers.
• NIC
1.2
Modems
Media Converters Categorize standard media types and
associated properties.
• Media converters:
• Singlemode fiber to Ethernet
• Multimode fiber to Ethernet
• Fiber to Coaxial
• Singlemode to multimode fiber
3.1
Repeaters and Hubs Classify how applications, devices, and protocols relate to the OSI model layers.
• Hub
1.2
Bridges and Switches Classify how applications, devices, and protocols relate to the OSI model layers.
• Switch
• Multilayer switch
• Bridge
1.2
Objectives
Exam Objective Matrix
Technology Skill Covered Exam Objective Exam Objective Number
Explain the purpose and properties of routing and switching.
• Spanning Tree Protocol
• VLAN (802.1q)
• Port mirroring
Given a scenario, install and configure routers and switches.
• VLAN (trunking)
• Managed vs. unmanaged
• PoE
• Diagnostics
• VTP configuration
• Port mirroring
1.4
2.1
Channel Service Unit/Data Service Unit
(CSU/DSU) Identify components of wiring distribution.
• CSU/DSU
3.8
Objectives
Exam Objective Matrix
Technology Skill Covered Exam Objective Exam Objective Number
Routers and Firewalls Classify how applications, devices, and protocols relate to the OSI model layers.
• Router
Given a scenario, install and configure a basic firewall.
• Types:
• Software and hardware firewalls
• Firewall rules:
• Block/allow
• Implicit deny
• ACL
1.2
5.5
Servers Summarize DNS concepts and its
components.
• DNS servers
• DNS records (A, MX, AAAA, CNAME, PTR)
• Dynamic DNS
Explain the purpose and properties of DHCP.
• Static vs. dynamic IP addressing
• Reservations
• Scopes
• Leases
• Options (DNS servers, suffixes)
1.7
2.3
Objectives
Exam Objective Matrix
Technology Skill Covered Exam Objective Exam Objective Number
Explain the purpose and features of various network appliances.
• Proxy server
4.1
Additional Specialized Network Devices Classify how applications, devices, and protocols relate to the OSI model layers.
• Encryption devices
Explain the purpose and features of various network appliances.
• Load balancer
Categorize different types of network security appliances and methods.
• IDS and IPS:
• Behavior based
• Signature based
1.2
4.1
5.6
Wireless Devices Given a scenario, install and configure a wireless network.
• Compatibility (802.11 a/b/g/n)
Compare and contrast different wireless standards.
• 802.11 a/b/g/n standards
• Distance
• Speed
2.2
3.3
Objectives
Exam Objective Matrix
Technology Skill Covered Exam Objective Exam Objective Number
Virtual Networking Identify virtual network components.
• Virtual switches
• Virtual desktops
• Virtual servers
• Virtual PBX
• Onsite vs. offsite
• Network as a Service (NaaS)
1.9
Network Interface Cards
• An expansion card or motherboard module that enables a computer to communicate over a network
• Often called a Network Interface Controller
Means of Communication and Media Used for Communication
• Means of communications refers to
whatever is used to communicate data across a network such as electrical
impulses, light pulses, or radio wave/microwave modulations
• The media used for communications is whatever carries those communications across a network
Means of Communication and Media Used for Communication (Continued)
• NIC works on Data Link and Physical layers of OSI Model
• Acts as translator between software in upper layers of OSI Model and physical
components of the media
• Must use NIC designed to work with a specific type of media and associated means of communication
Addressing
• Each NIC has a unique physical address programmed into its ROM chip during
manufacture
• Each manufacturer has about 16 million unique addresses, may have to begin
reusing physical addresses
• Two NICs on a network segment with the same physical address can make entire network unstable
Modem
• Modem stands for Modulator/Demodulator
• Can be hardware or software based
• Modulates analog signal of a regular
telephone line to encode digital information into it
• Demodulates return signals to view digital content from outer sources
Media Converter
• Device used to convert one type of media to another type
• Used to convert coaxial to twisted pair or fiber to copper
A 9-pin serial connection converted to a RJ-45 connection
Media Converter (Continued)
Transceiver
Switches with fiber-optic
cables
Fiber to Ethernet
• Singlemode or multimode Fiber to Ethernet converts different types of fiber-optic cables to Ethernet
• Consider:
– How fast the Ethernet is you are trying to convert to
– What type of fiber technology you are converting from
Fiber to Coaxial
• Possible to convert between fiber and coaxial cables
• Most commonly done by cable TV companies – Run fiber-optic cables into a neighborhood
– Convert to coaxial for home installation
Singlemode Fiber to Multimode Fiber
• Can convert fiber to fiber
• Singlemode and multimode fiber use different techniques to encode data
• Singlemode to multimode fiber converter may need to accommodate different data rates for the two types of fiber
• You need to know exactly how your network works to get proper converter
Repeater
• A Layer 1 device that repeats a signal it receives in order to rebroadcast it, thus
extending the range of a particular cable run
• Always active and requires a power source
• It has one cable coming in and one going out
• Follow the 5-4-3 rule to determine how and where to connect repeater on a network
Hub
• A Layer 1 device
• Works as if it is the bus of a larger network
• A computer connected to a hub broadcasts its signal to all the devices connected to that hub
• Two primary types:
– Passive hub – Active hub
Active hub
Bridge
• A Layer 2 device that separate networks into smaller sections
• More intelligent than average hub
• Based on MAC or physical addresses,
bridges can determine if a frame is allowed to pass through to the other side of the
bridge
How a Basic Bridge Works
Basic Switch
• Layer 2 device that connects multiple
networking devices, usually computers, to form LANs
• Can be called a multiport bridge because, like a bridge, it separates a network into multiple collision domains
– Difference: Each port on basic switch is essentially its own collision domain
• Can convert media from one type to another
A 24-port Switch
Switch in IDF Used to Convert Fiber Optic to Copper UTP
• Switch can push fiber-optic data input to twisted-pair ports
• Switches often placed in
intermediate distribution frames (IDFs) to break out a signal to
network devices
Switch Interface Configuration
• To program/configure switch, use:
– Graphical interface
– Command-line interface (CLI)
• Most configuration involves VLANs and trunking (to be addressed shortly)
Managed versus Unmanaged Switches
• Unmanaged
– Common for home use – Preconfigured setup
• Managed
– Enables you to perform complex filtering or segregate ports into VLANs
Virtual LAN (VLAN)
• A group of hosts that share a common set of communications requirements, grouped
together via Layer 2 of the OSI Model
Spreading a VLAN Across Multiple Switches
VoIP VLAN and a Data VLAN Stretched Across Two Switches
Trunking
• VLAN multiplexing
• Data from multiple VLANs carried across a single cable or other network link
• Special “trunking” protocols required – Example: IEEE 802.1Q
– Adds a special tag in the header of an
Ethernet frame that identifies the frame as belonging to a particular VLAN
Port Mirroring and Port Authentication
• Port mirroring
– The act of sending a copy of the frames from one or more ports on a switch to another port on the same switch
• Port authentication
– The ability to limit access to a specific port to specific MAC addresses
– Provides security to network by limiting access
Spanning Tree Protocol (STP)
• A Layer 2 protocol used primarily to prevent loops from developing in switch-based LANs
• Gets its name from spanning tree algorithm
• Takes a group of points and connects them without
allowing any loops to form
Power over Ethernet (PoE)
• The protocol used to safely transfer power over Ethernet cabling
• Most common use is with VoIP installations where power is needed for the phone to
work properly
Channel Service Unit/Data Service Unit (CSU/DSU)
• Converts a digital signal from one frame format to another
• Most commonly used to convert Frame Relay or T-1 signals (WAN) to Ethernet signals
(LAN)
• CSU side receives and transmits WAN signals
• DSU side converts LAN signal to or from the CSU side and manages the connection
Routers
• Networking devices that move packets around a larger network
• Read data packets for delivery information
• Send data packets on to next stop toward destination
• Work primarily on Layer 3 and Layer 4 of the OSI Model
Stack of Routers
Router Configuration Interface
• Primarily CLI but some new units have graphics interface
• Router configuration is more complex than switch configuration
• Important variable when configuring a router is port speed
• Refers to how fast a specific port on the router is able to send and receive data
Routing Tables
• What routers use to determine the best route to send a packet toward destination
• Contain:
– Router name
– IP address of the network each interface is configured to connect to
– Interface identifier for each interface
• Can populate routing table manually or dynamically
Firewall
• Networking device or networking software used to prevent unauthorized packets from getting into your network
• Firewall rules indicate which packets to block or allow
– Rules in access control list (ACL) – Block/allow method
– Implicit deny method
Firewall Placement in a Basic Network
Two Firewalls Used to Create a Demilitarized Zone (DMZ)
Software Firewall
• Hardware firewalls generally reside on a router or specialized hardware device
• Software firewall usually resides on a computer or other type of host
• Example: Windows Vista and Windows 7 come bundled with Windows Firewall, a software-based firewall
Servers
DHCP
servers DNS
servers
Proxy
servers
Dynamic Host Configuration Protocol (DHCP) Server
• Controls DHCP on the network
• Automatically assigns IP address on the network
Leases Scopes
Reservations Options
DHCP Initialization Process
One DHCP Server Can Service Multiple VLANs
Domain Name System (DNS) Server
• Makes the Domain Name System work
• Server criteria:
– Has to be registered to join the DNS
– Has to run special-purpose DNS software – Has to be given a publicly registered IP
address
– Must contain a database of other network names and addresses for the Internet host and other computers
DNS Name Resolution Process
DNS Record Types
• A: Stores a 32-bit IPv4 IP address and can store a subnet mask
• AAAA: Stores 128-bit IPv6 IP addresses
• MX: Maps domain names to a list of
software agents responsible for transferring electronic messages
• CNAME: Records alias names
• PTR: Records alias and reports it back only
Proxy Server
• Intermediary between client and other server
• Uses:
– Keep computers behind the proxy server anonymous
– Speed up access to resources via caching – Set up access policies to different network
services and/or content
– Create an audit log of network usage – Bypass security or services
Role of a Proxy Server
Types of Proxy Servers
• Caching proxy server
• Web proxy server
• Content-filtering web proxy server
• Anonymizing proxy server
• Hostile proxy server
• Intercepting proxy server
Additional Specialized Network Devices
• Multifunction network devices
• Intrusion detection systems (IDS)
• Intrusion protection systems (IPS)
• Encryption devices
• Load balancers
• Bandwidth shaper
Wireless NICs
• Come built-in in most notebook computers, netbook computers, and tablets
• Can be add-on devices – Expansion boards
– USB
802.11g Wireless NIC
802.11g-n Wireless NIC USB Devices
Wireless Access Point
• A wireless device that combines the roles of a switch and a router in smaller wireless
networks
Wireless Access Point (Continued)
• Are connected to larger networks and allow access via wireless media
• .In this way, WAPs act as switches to allow wireless devices access to a specific
network
Virtual Networking
• Combines hardware and software resources into a single entity for administrative
purposes
• Are external and internal
– External: Resources and hardware from
multiple networks are combined into a single software environment
– Internal: A single device has been configured to give network-like functionality to every
software container on the device
Virtual Switch
• Similar to a physical switch
• Differences
– Spanning-Tree Protocol not needed to protect from loops; virtual switching does not allow for loops to take place
– Does not exist in the physical world; virtual switch is a software construct
Virtual Desktops
• Virtual operating system set up in a virtual environment to allow end users to run
software programs
• Multiple virtual workstations can be created on a local computer and then linked
together
• Virtual workstations can be stored on a virtual server and run inside a physical
device, physically connected to the server containing the virtual workstations
Virtual Server
• A server program designed to create and support virtual networks
– Example: VMware ESX Server Or
• A server set up in a virtual environment to support some function that a real server
would do in a physical network environment
Virtual PBX
• A PBX switch that has been virtualized on a network
• Works like a physical PBX switch
• Difference is that virtual PBX can be set up on a server instead of purchasing
specialized equipment
On-site verses Off-site
• Refer to where hardware containing virtual network is located
– On-site: Hardware containing virtual network is located on the site it is being used at
– Off-site: Hardware used to contain virtual
network is located somewhere other than the site where it is being used
Network as a Service (NaaS)
• A virtual network available over the Internet (from the “cloud”)
• Consumers purchase network service
Summary
• A NIC is an expansion card or motherboard module that enables a computer to communicate over a
network.
• You cannot have two NICs with the same physical address on same network segment.
• A media converter is a device that converts one type of media to another type.
• The most common networking devices are
repeaters, hubs, bridges, switches, and routers.
Summary (Continued)
• A virtual LAN (VLAN) is a group of hosts that share a common set of communications requirements, grouped together via Layer 2 of the OSI Model.
• Trunking is VLAN multiplexing.
• A firewall is a networking security device or
software used to prevent unauthorized packets from getting into a network.
• A DHCP server assigns IP addresses automatically to networked devices.
Summary (Continued)
• A DNS server manages the Domain Name System.
• A proxy server is an intermediary between a client and another server.
• Wireless devices include NICs and wireless access points.
• Virtual networking combines hardware and software resources into a single entity for administrative purposes.